Frequently Asked Questions


How do I Get My NZMCA Discount?

All NZMCA Members are eligible for a 5% discount on all AA Solar Products and Services. The first time you shop online with us, you will need to register. This is done by going to the “Shop” and Clicking “NZMCA Registration Button” Then follow the prompts. Once registered all prices within the shop will show your 5% discount. Once registered your complete shopping history can be viewed in “My Account” it also stores and product specification sheets you have downloaded, for handy future reference.

How do I get A Trade Discount?

We give trade discounts to businesses who make regular purchases of our products. Existing Trade Customers simply for to “Account” enter your email address then select “Set A New Password”. Once your password is set you can shop online and automatically recieve your agreed trade discounts.

I am Not an existing trade customer how do I become one?

Our trade discounts recognise businesses who shop with us on a regular basis, you can either build up your sales history with us, and then we will reach out to you. Or go to our “Shop” and click on “Trade Account Application” This application is sent directly to our CEO for review, he will assign a Solar Engineer who best fits your business profile and they will call you, to discuss your product needs and our available discounts as appropriate.


How do solar panels actually work?

Solar panels are made of highly excitable, conductive materials. When the sun’s rays hit the solar panels, the reaction creates direct current (DC) electricity. As most homes use alternating current (AC) electricity, your solar-generated DC energy will pass through an inverter to become AC electricity. Then it flows through your home’s wiring and behaves just like the power you’ve been using your whole life.

Is solar energy reliable and powerful enough for my home?

If appropriately sized and installed to maximise sun exposure, solar can meet your day time energy needs. This can be further enhanced with the adding of a battery. We are also exceptionally experienced with Off-Grid Solar Solutions, where solar is backup with a generator. There is a reason NASA powers its satellites using solar; solar is abundant, reliable, and cost effective.

Will my solar panels generate electricity during cloudy, rainy or snowy days? What about at night?

Your solar panels don’t need sunshine, per se, to generate electricity as much as they need direct, unobstructed access to the sun’s UV rays. Similar to how you skin still tans when it’s overcast outside, your solar panels will still generate electricity during cloudy rainy or snowy days – they just won’t product as much energy as they do during clear days. Solar panels do not generate electricity at night since the sun’t not out. This is when staying to the grid comes in handy. Or you can add a battery and generator to go off grid.

How much will I really save on my electricity bills every month

That depends on how much electricity you use during the day, where you live, the rate your utility company charges, whether you have gas or electric hot water and a number of other variables. The best option is to talk to our solar specialist and we will provide you with a personalized savings estimate.

What effect does shading have on a Solar Panel?

Solar Photovoltaic (PV) panels are very sensitive to the effect of shading. Shading obstructions can be defined as soft or hard sources. If a tree branch or roof rack is shading from a distance, the shadow is diffused or dispersed. These soft sources significantly reduce the amount of light reaching the cell(s) of a solar PV panel. Hard sources are defined as those that stop light from reaching the cell(s), such as a tree branch, bird dropping, or a bird sitting directly on top of the glass. Unlike a Solar Thermal panel which can tolerate some shading, many brands of solar PV panels cannot tolerate being shaded by the branch of a leafless tree. Today a range of methods are used to mitigate this shading effect, some of the methods include bypass diodes, dc-optimisers, micro-inverters, half-cut solar cells configurations in PV modules, & software optimisation in string inverters. It is always best to avoid shading altogether, but at times designers and installers can be limited so it is fortunate that alternative methods are available to mitigate the effect of shading in solar PV installations.

Waterflow analogy of shading on standard full-cell PV modules in a string of panels. Under normal circumstances the flow rate of water (in a pipe) and current (in the string of PV cells/panels) is constant. Shading a solar PV cell is like introducing a clog in a pipe. How a clog in the pipe will restrict the flow of water, a solar cell that is shaded will restrict current flow in the series connection of cells. Therefore, a small amount of shading can have a dramatic impact on the power output of a solar PV panel.

Partially shading even one cell of a 36cell solar panel (e.g. our AAS-85W) will reduce its power output. Because all the cells are connected in a series string, the weakest cell will bring the others down to its reduced power level. When a full cell is shaded it can act as a consumer of energy produced by the remainder of the cells and trigger the module to protect itself via bypass activation. The module will route the power around that series string. If even one full cell in a series string is shaded, it will most likely cause the module to reduce its power level to half or a third of its full available value depending on the number of bypass segments in the module. If a row of cells at the bottom of a module is fully shaded, the power output may drop to zero for modules using full-cell configurations. The best way to avoid loss in output power is to avoid shading whenever possible.

When a full cell is shaded, it can act as a consumer of energy produced by the remainder of the cells, and trigger the module to protect itself. The module will route the power around that series string. If even one full cell in a series string is shaded, it will most likely cause the module to reduce its power level to half of its full available value. If a row of cells at the bottom of a module is fully shaded, the power output may drop to zero.

The best way to avoid a drop in output power is to avoid shading whenever possible.

Example of full-cell shading that can reduce Solar Panel output power to ZERO
Example of full-cell shading that can reduce Solar Panel output power by HALF

Various techniques are used to mitigate shading effects in PV systems today. In a string, an alternative route is available that bypasses that panel or segment (via bypass diodes). This avoids collecting the power that could be generated in that panel or segment to maintain the current flow from the remainder. Almost all modules come out of the factory with bypass diodes pre-installed. Designers also use selective arrangements to best suit the installation location to minimise or avoid shading.

Example of bypass diodes on segments of a PV module.

Module level power electronics (MLPEs) are also used to improve module performance under shaded conditions. MLPEs can be used in the form of dc-optimisers and microinverters. Other advantages are provided by such devices, for instance monitoring power generation at the module level. DC-optimisers adjust their output voltage and current, aiming to maintain maximum power without compromising the module’s performance. Microinverters can be installed at each module to perform MPPT and the inverter function. This provides an AC output that is connected in parallel, allowing each panel to operate independently. Although we can’t always eliminate shading of solar PV panels, we can use modern optimisation methods and different techniques to minimise the effect of shading. Common practices such as microinverters can be used to reduce shading impacting an entire array of solar PV modules.

Individual modules are now also available in split/half-cut cell configurations. This is likely to become more and more common in the solar PV industry. This module configuration allows the top and bottom half of the module to operate independently as shown below.

The shading loss is negligible in half-cut cell modules due to the difference in the current of the two halves. If one half is shaded, that area is affected and the bypass diode of the half will be active, but the other half-cell segment is still in action and that bypass diode is inactive. This is clear with reference to the figure above which shows the bypass diode in as a red triangle. The power generation of the other half of the cell remains unaffected. Therefore, half-cut cells are preferred over standard cells in order to minimise shading losses. As strings are in parallel configuration, module can save up to 50% power in case of partial shading.

AA Solar can simulate the effects of shading and provide the most suitable system configuration for your next project. Call us on 09 427 4040 if you’d like to discuss a project.

What are the benefits of a solar PV systerms?
  • Solar PV is a safe and secure investment.
  • It has a diverse range of applications.
  • It can save the user thousands of dollars.
  • Increases your home/RV/boat’s value.
  • Every PV system is helping in saving our environment.
  • It is a free abundant source of energy.
  • It is energy supplied by nature.
  • Guaranteed performance.
  • Long warranties.
  • Reduce your energy bill.
  • Low maintenance cost.
How much does a solar PV System cost?

A solar system can cost anywhere from a few hundred dollars to hundreds of thousands of dollars. Come talk to us to get a free no obligation quote. Price ranges are also provided under the pricing section of our website.

What is an inverter and how does it work?

Simply it converts DC energy into AC energy, which is then channeled into your home to power your lights, appliances, and other electronics. The process of converting direct current (DC) energy into alternating current (AC) energy is performed by an inverter. A solar system is made up of several key components, with inverters being one of them. In applications where you have a battery, the inverter performs the same conversion.

When your solar photovoltaic (PV) modules absorb sunlight, they produce DC energy. However, as most homes use AC energy, DC energy on its own is not useful.

A solar inverter plays the very important role of converting the electricity produced by your solar panels into a form that can be used by your home.

Inverters can vary significantly so it is important to talk to our team before selecting an inverter for your project to ensure a nice clean waveform where needed and avoid trouble further down the track.

What is an Off-Grid Photovoltaic (PV) System?

Off-grid solar PV systems: Although they are most common in remote locations without utility service – off-grid solar systems can be utilised anywhere (e.g., RVs, campervans, lighting, pumps, & homes). These systems operate independently from the electricity grid to provide an application’s or household’s electricity needs. An off-grid system will generally require a battery bank to store the electricity generated during the sun hours by the PV modules. This allows the stored energy to be consumed during the night and/or under cloudy (low generation) conditions. A charge controller (or regulator) is used to correctly charge and prevent overcharging of the battery. An inverter can be used to convert the DC power to AC for use with AC household appliances.

Off-grid systems use to be the most common PV system, until recently with price reductions making grid-connected applications affordable and economical.

What is a Grid-Tied Photovoltaic (PV) System?

Grid-tied solar PV system: A grid-tied solar PV system is dependent upon your municipality’s electrical grid to operate in parallel. Grid-tied systems are (1) grid-tied without batteries or (2) grid-tied with batteries. The DC electricity generated by the photovoltaic (PV) panels is sent through a grid-tied inverter, which converts it to AC power that’s compatible with the grid. The system offsets your consumption from the grid. Surplus energy is exported to the grid and at times sold to the electricity retailer.

Grid-tied without batteries: In such systems, the PV modules are connected via grid-tied string inverters or microinverters. The inverters are obligated to meet local legal requirements. This ensures they operate safely in parallel with the electricity grid. The inverters and installation of the inverter(s) must comply with the current AS/NZS 4777 series and local network requirements. Talk to our friendly team to find out more.

Grid-tied with batteries: These systems are often referred to as hybrid PV systems. They are like the above (grid-tied without batteries) but contain a battery to either reduce energy export (increase self-consumption) or provide backup power. This type of system is expected to become widespread in coming years. If you would like to become an early adopter, have critical loads, or need more independence this may be the option for you.

What is a Grid-Tied Inverter

A grid-tied inverter (also known as a string inverter or grid-connected inverter): Converts the DC power from PV array(s) into AC power. It delivers the power to your loads and meets the legal requirements for the national grid for parallel operation.

MainFeatures of our Grid-Tied Inverters

High yield

  • Max 97.2% efficiency
  • Real time precise MPPT algorithm for max. harvest
  • Wide input voltage operation range 

All in one. Flexible and economical system solution

  • Free site selection due to IP65
  • Easy installation and maintenance due to “Plug & Play” connection
  • Interface selection-Wi-Fi / RS485 / GPRS
  • 4” LCD display
  • Built in zero export function (optional)

Low maintenance cost

  • Detachable cover for easy installation
  • Rust-free aluminium covers
  • Flexible monitoring solution
  • Built-in monitoring

Intelligent grid management

  • Reactive power capability
  • Self power reduction when over frequency
  • Remote active/reactive power limit control

Brand name of our grid-tied solar inverter Sofar Solar!

What is UPS?

An Uninterruptible Power Supply (UPS) is available in a range of topologies depending on the load it is protecting. Some pass grid power through and only supply a backup function. Others provide on-line functions for sensitive loads (e.g., servers, voice/data networks, medical labs, and light industrial applications) to provide a clean output and backup supply.

An inverter charger can also be used in UPS applications. Ask one of our staff to see our UPS inverter charger.

The grid, solar power, or a genset may be used to charge the storage devices via the inverter charger. We also have Hybrid Solar Inverters with inbuilt emergency power supply (EPS) functions for critical loads in your home or business.

Which energy storage system should I use for my home or bach?

The storage system depends on many factors, such as energy requirements, peak power requirements, equipment quality, enabling equipment required, install location, and many others. Your ideal solar power system and/or energy storage system is dependent on many different factors. Feel free to call our friendly team to find the system perfect for you.

How much does battery storage cost?

The cost of the battery storage system depends on many factors, such as energy requirements, equipment quality, enabling equipment required (some products have built-in inverters, others don’t), location, and many other factors. For off-grid systems, the biggest factor is how much energy you need. Generally small off-grid systems can range from $10,000 to $20,000. Most family homes usually range from $25,000 to $35,000 and large or luxury homes can be from $50,000 upwards. For an RV or motor home, your storage system could be $300 upwards.

Prices are given as general indications only, and we recommend seeking an accurate indication of what a system would cost for your specific needs. These price indications may vary without notice.

How much electricity does a typical house consume?

Energy consumption can vary significantly from one home to another. However, using the NZ Electricity Authority’s record, a house on average uses about 7,000 kWh of electricity per year, but the amount used depends where in New Zealand you’re living and how your house and hot water are heated. In 2017, the average residential consumption varied from about 5,870 kWh on the West Coast to 8,550 kWh in Canterbury.

Does roof orientation really matter?

Most certainly. For example, a system with solar panels facing in a southerly direction will generate far less than one with a northerly aspect. However, east/west installations can be a good option depending on the installation scenario. We can look at your property and provide evidence-backed figures of generation using our expertise and experience. Contact us today and talk to our friendly team about your property.

Which home inverter should I get?

Our recommendation on which inverter will be best suited for your home will depend on a number of factors. Some of the basic questions include (1) is the application grid-tied/off-grid, (2) what source(s) of DC energy do you want to connect to the inverter, and (3) what grade of inverter are you after – bronze/silver/gold/platinum. Typically, some applications need an inverter only for supplying AC loads, other times you may need an inverter charger. For grid-connected systems, you may want a multimode, hybrid or string inverter. It is best to talk to our specialist staff who will be happy to offer various suitable options to ensure you get what you want and need. If you like you can also send us an online inquiry via our website or email us today.

RV Motor Home

Why Use Solar Power
  1. The biggest advantage is the independence you will acquire from not being reliant on mains power when travelling. It will give you freedom to go wherever you want for however long you want.
  2. It will add re-sale value to your RV.
  3. Solar Power is quiet unlike generators.
  4. You will save money by avoiding tourist/caravan park fees for powered sites. With solar power you have the option of a less expensive unpowered site or staying at a more remote location.
  5. If you enjoy quiet locations without a crowd then solar power will let you enjoy the great outdoors while still enjoying all your RV luxuries.
  6. You can contribute to reducing the impacts of fossil fuel and natural gas power stations such as greenhouse gas emissions and air pollution.
  7. The components are long lasting, durable and low maintenance. For example solar panels typically produce energy for at least 25 years will no maintenance other than the occasional clean off with water,
  8. We are lucky in New Zealand that we have a high degree of sunshine which makes solar power a worthwhile option.
What is the best solar panel?

Monocrystalline solar panels have the highest efficiency rates since they are made of the highest-grade silicon cells. The efficiency rates of monocrystalline solar panels are typically 15-20%. The best solar panel will depend on what you need so don’t hesitate to discuss your solar project with our trained team.

What sizes do panels come in?

We stock different sizes of panels in our facility. Depending on the mounting space availability and requirement, we can supply the right dimension for your project. Find our list of panels with dimensions on our website (under the pricing section). Generally, the 60-cell panels are 1.6 x 1m and 72-cell panels are 2 x 1m. Our smallest 10Wp modules are 0.35 x 0.3m.

In simple terms what is a solar system for an RV

Solar cells in panels mounted on your RV’s Roof converts sunlight into Direct Current (DC) electricity. Batteries store this electricity so it is ready for use anytime. An inverter can convert the DV electricity into Alternating Current (AC) electricity that you can use at your RVs power points. You do not need an inverter if you only want 12V power.

What is a solar controller/regulator?

A solar charge controller is used to regulate the energy produced by the PV panels and manage the charging and discharging of the battery bank. Simply, it is a gateway to the battery. A solar regulator is virtually needed in all solar power systems that utilize batteries. It is commonly one of two types Pulse Width Modulation (PWM) or Maximum Power Point Tracking (MPPT). Some new units have advanced features integrated to provide controlled operation, automation, monitoring, and adjustable settings. Older charge controllers simply disconnected the PV and battery when a voltage was reached. Others opened and closed a relay stopping and starting the charge. Solar controllers also prevent reverse-current flow e.g., at night. When the PV panel is not producing electricity, it can draw energy from the battery and drain your batteries.

MPPT controllers have now become the most common type used in solar applications. They allow more energy to be generated by tracking the max. power point. You can expect up to 30% more energy yield using a MPPT regulator. The MPPT units also provide more system flexibility and configuration options.

PWM (Pulse Width Modulation) charge controllers are now outdated but can be suitable for specific applications. They are generally used in small DIY projects with low voltages. They alter the pulse width to slowly lower the amount of power applied to the batteries as the batteries get closer and closer to fully charged. It can also keep batteries in a fully charged state (called “float”) indefinitely by providing a “trickle” charge.

MPPT (Maximum Power Point Tracking) charge controller is the norm today. They basically covert excess voltage to current/amperage. They also track the output from the PV input to harvest the max. power. MPPT controllers allow the user to use higher voltages which lower cable losses on the PV side of the system. With a MPPT unit, you can use non-matching voltages for panels and batteries. When you use standard 60 or 72-cell panels, which are more economical due to mass production, your only option is a MPPT controller for charging a 12V battery.

Do I need an inverter?

An inverter can be one of the important parts of a complete solar PV system (grid-tied or off-grid). This is because most appliances and loads require AC energy. For RVs and boats where you do not need to use 230V appliances, you can get away without buying an inverter. Normally, there are three main types of inverters used in solar applications; on-grid inverter, off-grid inverter, and hybrid inverter. Our team is happy to help you in concluding which and when you will need an inverter.

What does depth of discharge mean?

The Depth of Discharge (DoD) refers to how much energy is cycled out of the battery on a given cycle, expressed as a percentage of the total capacity of the battery. The recommended maximum depth of discharge for our AGM batteries is 20% to meet our warranty conditions. This allows the battery to achieve the warranty duration (higher the DoD the shorter the life).

What is a Lithium battery?

Like the variety in lead batteries, lithium batteries also come in a diverse range.  We typically use lithium iron phosphate batteries (LiFePO4) for our general applications. This is specifically due to the fact they are one of the safest if not the safest lithium. When lithium is combined with other compounds such as Cobalt Oxide to achieve higher energy density a substantial sacrifice is made on safety.

Generally, a lithium battery is a battery that is formed using lithium metal. Today, lithium batteries are found in most applications, including phones, laptops, solar PV systems, and more. The primary advantage is the high energy density lithium batteries offer. For the user this means more energy in less space and with less weight.

What is a deep cycle solar battery?

A GEL battery (also known as a gel VRLA battery) uses a gel as part of its electrolyte. Gel batteries typically supply a higher cycle life vs the AGM, therefore we can allow you to discharge the gel battery to a higher DoD in our warranty and still achieve the long term service life.

How can I see the state of charge (SoC) of my battery?

The correct method of tracking SoC is by using a battery monitor/battery computer. Our Votronic battery monitor will instantaneously give you the answer to this question.

Marine cable and why you should use it?

Marine cable is designed to provide extra corrosion resistance.  Some marine cables can also be double insulated to provide extra mechanical resistance. For specific applications, our team will recommend or state it is mandatory to use marine cable for safety and longevity. It can also be due to legal obligations.

How far can I safely discharge my battery?

We recommend a controlled DoD for our batteries to achieve the desired service life.

For typical applications, we recommend you follow the below rule of thumb:

AGM – 20% depth of discharge

Lithium – 50-80% depth of discharge

Gel – 50% depth of discharge

What is a battery computer?

A battery computer or battery monitor device is used to manage the battery and provide information about the state of the battery. Typically, a shunt is used by the battery monitor to keep record of how much energy is put into or removed from the battery. This information is used to display the State of Charge (SoC) for that battery. This is a more accurate gauge vs a standard voltage meter which could be reading the surface charge voltage. The battery computer can also be used to disconnect the loads from a battery when a specific DoD has been met. This will ensure your battery stays within its warranty conditions and achieves the designed service life.

What information does a battery computer provide?

Different battery computers provide different bits of information. Therefore, if you have an existing battery monitor, it may be suitable to talk to our team to determine if it will meet our warranty requirements.

To be more specific, our Votronic battery monitor will provide the following information:

  • Available amp-hours (Ah) at your battery voltage.
  • Current flow in amps (A) and the direction (charging/discharging).
  • State of your relay (ON/OFF).
  • State of Charge.
  • Battery voltage for your house and start battery.
  • Historical information on battery voltage, charge, and discharge.
  • Remaining runtime available for instantaneous rate.
What is the difference between a battery computer and a voltage meter?

A voltage meter analog or digital is used to measure instantaneous voltage. This could be the charger voltage at the battery or the voltage of the battery under load. This can be a false representation of the state of charge. Whereas, a battery computer counts what is going in and coming out of the battery to give you an accurate representation of how much energy (or how many amp-hours [Ah]) you have remaining in the battery. The duration of runtime, historical information, state of connected switches, and much more. 

What is a shunt?

A shunt (current shunt resistor) is a high precision resistor that is commonly used to measure current flow through a circuit. A shunt is calibrated to have a current to voltage drop relationship that the battery monitor or inverter charger uses to keep record and provide an accurate measure of amp-hours (Ah) or amps (A) in that system.

What size shunt do I need?

The size of the shunt will depend on the continuous and maximum current that will flow in that circuit. A shunt rated to 100A will allow a short duration surge of a higher value. Commonly you need a 100, 250 or 500A Shunt.

What kind of battery should I purchase for my Motorhome?

If you are thinking of purchasing conventional, wet type batteries, most Motorhomes will require two. One for starting and one for powering the Motorhomes domestic lighting, refrigeration, pumps and accessories.

For the best performance and life, the starting battery needs to be the type that allows high cranking amps with reserve for starting. If you are purchasing Wet Type Batteries, or Flooded Acid Type as they are sometimes called, they have more plates per size (thinner) than a Deep Cycle Battery to give higher cranking ability. They are not suitable for powering the domestic requirements, as they are not designed to be deep cycled and recharged.

They will fall apart internally in a short time if used for this service and are not a good investment in the long term. For the domestic requirements in a Wet Type Battery, a true Deep Cycle Battery is required for good life and reliability. These types of wet batteries have fewer (but thicker) plates and heavier duty separators for cyclic use, deep discharging and charging. They will give good service if charged and maintained properly. If charged properly, they will require water regularly.

There are some newer types of battery technologies available, which have definite advantages for motor caravaners over the wet types for both starting and deep cycling applications. For one, they do not require any maintenance at all, other than charging correctly (i.e. you never have to add water). They do not discharge themselves like wet batteries if left standing. For instance, they can be left for 6 months or more when fully charged and still be able to start your engine or power your Motorhome requirements. Conventional wet batteries will discharge themselves as much as 5% or more per week, whereas the newer technology types discharge themselves less than 1% per month! The wet Deep Cycle type will require an Equalisation Charge regularly to get good cyclic life. The newer technol- ogy types do not require any equalisation to achieve long life and good cyclic ability. These new technology batteries are generally referred to as VRLA (Valve Regulated Lead Acid), Sealed Type or Recombination Batteries. There are two main types, GEL and AGM.

GEL Batteries are exactly as they are called. Their electrolyte or acid is combined with silica and other chemicals to “immobilise” the acid in gel form. They have the advantage of not stratifying the normally liquid acid, and generally do not require any equalising. They are quite efficient compared to wet batteries but require a very careful charging regimen, and will give good long life if charged and discharged within their prescribed regimen. They do not have, for their size, as high a cranking capability for starting, and cannot

be charged as quickly, or accept charge as well as wet type or AGM. GEL types tend to be more expensive than either wet or AGM batteries.

AGM stands for Absorbed Glass Mat and are sometimes referred to as Starved Electrolyte Batteries. They have specially constructed plates, which have been wrapped with a strong, micro-porous glass mat, and the electrolyte is held tightly to the plates. These plates are also compacted within the battery, which makes them very strong and rugged. There are a number of different varieties of this type of battery, but the better ones have the ability to operate in both a deep cycle mode with very high cranking ability for starting, and also have the ability to accept charging quickly and efficiently.

In other words, they are a true dual purpose battery, and you do not have to buy two different types of batteries which require different charging regimens to properly keep them charged. Another plus is that they are a very safe battery as they are allowed to be carried on aircraft and they are not classified as Dangerous Goods. Both GEL and AGM do not give off gas when charged normally within their specifications, so are not dangerous like wet batteries when charging and discharging. They can be safely mounted anywhere inside, and do not have to be upright.

All being equal, AGM’s will give better service, longer life and cost less to operate in the long run. Additionally, if you are considering putting Solar charging on your Motorhome, the additional charging efficiency gained and the low self discharge of AGM’s ensures they will more than pay for themselves in the long run.

How do I know if my SEALED (SLA) Batteries are charged?

SLA (Sealed Lead Acid) batteries come in a number of types: AGM, GEL and ‘so called’ Maintenance Free types. Because these batteries are sealed, you cannot use a hydrometer to measure their STATE OF CHARGE or SOC. They either need a very accurate DC Voltmeter (digital preferred), or a true Ampere Hour Meter, which is by far the most accurate and easily understood way. If you are going to use a Voltmeter, you will need one that has a resolution and accuracy of one tenth of a Volt or better. Your battery will also need to be in a steady state, that is, not to have been either charge or discharged for at least 6 hours previous, for reasonable accuracy. This Steady State, for all practical purposes, is hard to achieve in the real world. Most installations require a battery input most of the time, like powering gas alarms, monitoring systems, or the memory back-up for a car type stereo. Also, all forms of charging must be disconnected during this period. Disconnecting the battery, in most cases, is really not practical for the measuring of its SOC.

Ampere Hour Meters, or True Battery Monitors as they are sometimes referred to, are really the only practical way of telling accurately whether an SLA battery has really been charged enough. Most of the True Battery Monitors can also give you a lot of information about what is really happening in you electrical system. Because they count the real Amp Hours that your electrics have used out of your battery, you will know how much you will need to replace. Most give you Amp Hours removed and % left in you battery. Then when you battery is being charged it will count up to 0 and will let you know that all the power you have removed has been replaced. If they are programmed correctly (which is very easy in most of the newer units), they will automatically calculate for the efficiency of your battery type and give you a very accurate answer as to SOC. In our experience, the advent of Battery Monitors will make living with a DC system powered by batteries a pleasure and are a real necessity if you want your system to be reliable and your investment in batteries long lasting.

Recommended makes of battery monitors that we have tested and used are:

  • Bogart Engineering Models: TriMetric 2020 and 2025-RV, and PentaMetric
  • Trace TM-500A by Xantrex
  • XBM Battery Monitor by Xantrex
How do I know if my WET/FLOODED Acid Batteries are charged?

The best way to determine if a Wet Type Battery is charged, is to use a hydrometer. This, however, is not always convenient, for I have noticed that most batteries are located in locations difficult to access in order to do this properly. Using a hydrometer is messy, and can be dangerous, although it is a very accurate way of determining the State of Charge of a Wet Type Battery. There are some precautions – the reading will not be accurate if you have just topped up the water, or if the batteries have been stationary and not charged for some time, as the acid will start to stratify and become weaker at the top than at the bottom. All wet batteries need an equalisation charge regularly for this reason, besides bringing up the weak or lazy cells.

Below is an accurate table of % of charge in relationship to voltage and specific gravity in 12 & 24 VDC Wet Battery Systems, as measured by a hydrometer. To make determining charge state easier, Expanded Scale Voltmeters and Ampere Hour meters, or Battery Monitors, are the most convenient, especially the Ampere Hour meter. Expanded Scale Voltmeters are only accurate if the batteries have been static for some time, meaning no charging or discharging taking place for 6 hours or more. This is not always convenient or easy to achieve. A much more convenient and very accurate way is to use and Ampere Hour meter, or Battery Monitor as they are usually referred to. These not only give you very accurate voltage and instantaneous Amps, but will also show most importantly the percentage of battery charge remaining, how many Amp Hours have been used up, and when the battery is fully charged. Some also tell you how many days since the battery was fully charged. Lowest and highest battery voltage are also included in some units for keeping a check on how the battery is being charged and discharged. Some have total Amp Hours used, like an odometer in an automobile, to measure total battery life.

Specific gravity values can vary +-0.015 points off the specified values. This table is for a flooded battery in a static condition, no charging or discharging occurring, at 25C.

Charging or discharging will vary these voltages substantially.

Percentage of Charge12 Volt Battery24 Volt BatterySpecific Gravity

Relationship between voltage and specific gravity

Why do I need a Solar Controller/Regulator?

The main function of a Solar Controller or Regulator is to fully charge a battery without permitting overcharging. If a Solar array is connected to Lead Acid Batteries with no overcharge protection, battery life will be compromised. Simple controllers contain a relay that opens the charging circuit, terminating the charge at a pre-set High Voltage and, once a pre-set Low Voltage is reached, closes the circuit and allows charging to continue. The most sophisticated controllers have several stages and charging sequences to assure the battery is being fully charged. The first 70- 80% of battery capacity is easily replaced. It is the last 20- 30% that requires more attention and therefore more complexity.

How Controllers Work and Available Options

The circuitry in a controller reads the voltage of the batteries to determine the State of Charge. Designs and circuits vary, but most controllers read voltage to reduce the amount of power flowing into the battery as the battery nears its full charge. Features that can be included with controllers are:

  • Reverse Current Leakage Protection by disconnecting the array or using a blocking diode to prevent current loss into the Solar modules at night
  • Low-Voltage Load Disconnect (LVD) to reduce damage to batteries by avoiding deep discharge
  • System Monitoring with analogue or digital meters, indicator lights and/or warning alarms
  • Over-current Protection with fuses and/or circuit breakers
  • Mounting Options flush mounting, wall mounting, indoor or outdoor enclosures
  • Systems Control of other components in the systems
  • standby generator or auxiliary charging system diverting array power once batteries are charged, transfer to secondary batteries
  • Load Control automatic control of secondary loads, or control of lights, water pumps or other loads with timers or switches
  • Temperature Compensation utilised whenever batteries are placed in a non-climate controlled space. The charging voltage is adjusted to the temperature. Recommended on most systems
  • Central Wiring providing terminals to interconnect system wiring

Some systems require all of these functions, others require only one or a certain combination. We can help you select a unit to meet your specific needs.

Sizing a Controller

Charge controllers are rated and sized to the systems they protect by the array current and voltage. Most common are 12 Volt, 24 Volt and 48 Volt controllers. Amperage rating run from 4.5 Amps to 60 Amps.

For Example: if one module in your 12 Volt system produces 3.5 Amps and four modules are utilised, you produce a total of 14 Amps of current at 12 Volts. Because of light reflection and the Edge-of Cloud effect, sporadically increased current levels are not uncommon. For this reason, increase the controller Amperage by a minimum of 25%, bringing the minimum controller Amperage to 18.7 Amps. Looking through our products, you’ll find a 20 Amp controller, as close a match as possible to this. There is no problem with going to a larger controller, besides possible additional cost. If you think your system may increase in size, additional Amperage capacity should be considered at this time.

The chart below shows the average effective output to expect per day from summer to winter, with older technology PWM controllers, and newer MPPT (Maximum Power Point Tracking) style controllers. While in good solar conditions the difference is not so great, in winter and marginal light the MPPT controllers can produce about 35% more from the same solar source.

How do I know what size Deep Cycle Batteries I need?

Sizing of Deep Cycle Batteries is critical to the performance of electrical items. Insufficient capacity results in systems failure, poor battery performance and shortened battery life. Remember that a battery only stores power. Charging capacity with the number of hours is equally as critical to good battery performance. Periodically ensure your battery is fully recharged. Establish the power consumption of each accessory (in watts or amps), the number of operating hours you will use it and the electrical systems voltage.

Watts / Volts = Amps Amps x Hrs in use = Amp / Hrs

For example:

CircuitNo.xWatts/Volts=AmpsxHrs / Day=Amp / Hrs / Day
Cabin lights321125.25315.75


For this example, the total usage is 26.59 Amps between charging periods, if charged every day. For safe assurance and longevity of battery life multiply the usage (26.59 Amps) x 5 ~ 6 = 132.95 ~ 159.54 Amp / Hrs. Therefore, you will require a minimum of a 130 Amp Hr battery.

What is the difference between connecting up batteries in series or parallel?

When you connect your batteries in either series or parallel, you don’t get double the Voltage AND double the Capacity (Amp-hrs):
In series you get double the voltage, in parallel you get double the capacity.


When connecting batteries in series, you get double the Voltage at the same Capacity. For example, if you have 2x 6V260Ahr batteries, when you connect these in series, you would end up having 12V power with 260Ahr capacity.

Another way of thinking about this is if you have 2x pipes that are 6 units long and 260 units in diameter. If you put both these pipes into series (one after the other) then they are a total of 12 units long, but their diameter doesn’t change.

So if you look at batteries like this, if you put 2x batteries in series, you will add the Voltage together, where the Capacity (Ahrs) doesn’t change.


When connecting batteries in parallel, you get double the Capacity at the same Voltage. For example, if you have 2x 12V130Ahr batteries, when you connect these in parallel, you would end up having 12V power with 260Ahr capacity.

Another way of thinking about this is if you have 2x pipes that are 12 units long, and 130 units in diameter. If you put both these pipes into parallel (one beside the other) then they are a total of 130+130 in diameter, but their lengths doesn’t change.

So if you look at batteries like this, if you put 2x batteries in parallel, you will add the Capacity (Ahrs) together, where the Voltage doesn’t change.

How many Solar Panels do I need for my Motorhome?

Solar modules and Motorhomes with batteries are a natural match.

Since batteries are charged when travelling, Motorhomes normally depend mostly on the vehicle’s alternator for the primary power source. Power to charge the battery bank is also provided through a battery charger when plugged into mains power. However, for those who like to spend days, weeks or longer not travelling and not plugged in, Solar Panels can mean freedom. And because a Solar array can put as much power into you batteries during an hour of bright sun as a small petrol generator, it can also mean reclaiming peace and quiet. As well, the Motorhome’s existing battery bank and fused box make the transition to Solar a smooth and economical one.

While most Motorhome systems utilise 1 to 2 modules, it is important to analyse your power needs. Just as with all Solar systems, you need to consider the Wattage of appliances and lights you are powering, as well as the average hours used each day. Unlike most other systems however, Motorhomes travel through different regions of climate, park at varying angles to the sun, sometimes in shade and sometimes not. People with similar vehicles can have very dissimilar power usage and patterns of travel. These factors should all be considered when deciding on which, and how many, Solar Panels you need. If you have any question about how to go about this, please give us a call.

Buy now and Save later

Your Solar charging system will pay for itself several times over by increasing battery life and reducing the amount of time you spend on camp-ground hook-ups and generator maintenance. Batteries that are Deep Cycled too many times, or sit idle for several months, can be permanently damaged. Solar modules provide a daily maintenance charge for your batteries and eliminate this problem. By recharging every day, the depth of discharge is reduced, and your battery life and performance are greatly improved.

Keeps batteries charged, Summer or Winter

Solar Panel output is dependent on light intensity and exposure time in the sun. You’ll be amazed at how much power your system provides on a bright day. And even in cloudy weather, your panels will produce power although at lower output.

So, How many Solar Panels do you need?

The more Solar Panels you can fit onto your roof, the better your system will be. This does not need to be done all at once, but can be spread over time. If you have no heating or cooling loads (i.e. refrigeration is running on gas when freedom camping) then you could start with a single 90 Watt or 120 Watt Solar Panel. See how you go. Are you running out of battery power on a daily basis and having to start the engine to boost you batteries? Then you need more Solar Panels. As long as you initially install a Solar Regulator large enough to take additional panels, and leave sufficient extra cable length up top on the roof, you can easily add more Solar Panels when needed.

How much power does a Solar Panel actually produce?

While on the subject of using Solar Panels for power, it might be a good idea to explain how much power can really be produced by a Solar Panel to charge batteries and how that equates to usable power to power your loads.

A good 85 Watt Solar Panel mounted flat on the roof of a Motorhome will produce an average of 255 Watts per Summers day charging into batteries. This would be the usable power available from the batteries to run appliances, after all losses including regulators, and the efficiency of batteries. In Winter it would be a little more than half that figure.

Now, how does that equate to the Amp Hour storage in the batteries or what your loads are. If we take the figure of 255 Watts per day and divide that by the nominal charging voltage of 14 VDC for a 12VDC system, we could have replaced approximately 20 usable Amp Hours into our batteries. That would be enough for a very basic electrical system.

If, for instance, though you have an average 80 to 110 Litre fridge, which requires about 40 Amp Hours per day (running 24 hours) you would need at least 2 x 85 Watt Solar Panels to sustain the fridge only. In other words, a good installation would normally require 2 x 120 Watt Solar Panels to power both a DC fridge and other essential electrics, if there was no other charging source to keep the batteries well charged. In Winter, the above system would run at a deficit, and another 120 Watt Solar Panel would be needed in order to be completely independent. If might also require a bit of extra electrical conservation.

You can increase the average output of Solar Panels per day, especially in Winter, by aiming more at the sun. That is not as difficult as it sounds. A number of Motorhomes do this, and get almost twice the power in Summer, and 3 times the amount of power out of their Solar Panels in Winter, especially in the South Island. Most Motorhomes also have provision to charge their house batteries while driving, and if you drive for a few hours every few days, that will help put some Amp Hours back into the house batteries, especially if the system has been set up correctly. Most Motorhomes also have a 240 VAC charging system, and if this is a good Deep Cycle Battery charger, it will fully charge the batteries over night. This would, of course, require going to a Camp-ground and plugging in. It could be that the washing need to be done to, as a good excuse. Some Motorhomes also carry Generators to supplement their power usage, and also for emergency. With the new type of Inverter-Generators and a larger charger, this can be a reasonably efficient and quiet way to charge the house batteries when you do not have enough Solar Panels or you have lots of rainy days.

The size of a battery for an alternative power system is an important decision too. Too little storage will cause the battery to be too deeply discharge often and will drastically shorten its life. A rule of thumb here is to take you average consumption per day in Amp Hours and multiply that by at least 4 or even better 6 times, to get good battery life. In practice, this means that if your average daily consumption is about 50-60 Amp Hours per day, then you would need a 200 to 360 Amp Hour battery system for a reliable system and reasonable battery life.

Totally alternative power is possible, and practical (no LPG or Generators), if one is willing to spend enough money on Solar Panels, Batteries and a large Pure Sinewave Inverter.

One such installation is our own converted 9 meter Hino Bus. It is all alternative power, meaning everything is electrical operated including all of our cooking, except for barbecuing, which is wood power of course for flavour. Even the Solar Panels are raised electrically by the push of a button. The only other charging source is a very large heavy duty 24 VDC alternator with a very smart 3 stage regulator which will produce 70 Amps with the Hino engine idling, and up to 200 Amps it needed when running. We have had this system operating for 6 years now, and would do it all the same again if we did another bus, but would probably include a built in Inverter-Generator in case we stay somewhere for more than a week and it rains every day!

Features of AA Solar System


  1. Simplified electrical, utilising existing 24 VDC system
  2. Efficient direct charging from either systems charging to the other
  3. All batteries always charged
  4. Less expensive
  5. Starting and house loads isolated when not charging
  6. Redundant starting
  7. Provision for necessary 12 VDC loads
  8. Auto switch between shore side and inverter for 240 VAC system

Possession of AA Solar Systems drawings does not constitute right of use or right of copying.

Commercial and Farms

DIY And Specifier

What are typical components in a solar PV System

A solar PV system consists of solar panels, mounting equipment, solar charge controllers, batteries, inverter(s), circuit protection, conductors, and connections.

What are PV Panel(s)

produce electricity from sunlight, when sunlight hits a solar cell, the cell absorbs photons and the photons’ energy is transferred to an electron in the semiconductor material. With the energy from the photon, the electron can escape its usual position in the semiconductor atom to become part of the current in an electrical circuit. The solar cells are encapsulated within materials to protect them from environmental and mechanical damage.

The PV panels are either used individually in small applications or arranged in strings and arrays for larger applications. The panels come in various sizes and technologies. The majority of the panels produced are crystalline silicon.

What are Mounting/Racking Systems?

The PV panels are fixed to rails or brackets that form the mounting system. The mounting system is required for attaching the panels to the mounting surface. The mounting system can be ground, or roof-mounted. Commonly the mounting systems are made up of anodized aluminum, stainless steel, and galvanized steel. The mounting system is an extremely important part of the PV system. It must be designed to withstand all the forces and corrosive influences.

What is a Controller/Regulator?

They are used to regulate the energy produced by the PV panels to be stored into a battery and supplied to loads. They also protect the battery bank from overcharge to extend the battery’s service life. Some have advanced features integrated to provide controlled operation, automation, monitoring, and adjustable settings.

The solar regulator commonly comes in two types – pulse width modulation (PWM) or maximum power point tracking (MPPT). MPPT controllers have now become the most common type used in solar PV applications. They allow more energy to be generated by tracking the max. power point. You can expect up to 30% more energy yield using a MPPT regulator. The MPPT units also provide more system flexibility and configuration options.

What do batteries do?

Batteries come in a range of chemistries, shapes, and sizes. The battery stores electrical energy for later use. Batteries are very complex and so it is best to talk to one of our trained staff to help you select the correct battery for your application.

What does an inverter do?

Is used to convert direct current (DC) energy into alternating current (AC). Loads can be DC or AC. However, although a load may be operated by DC (e.g., your phone/laptop), the plug supplying the power is generally AC. Most general household appliances (e.g., washing machines, TVs, dishwashers, computers, fans, lights) are AC. Some loads can be supplied by both AC or DC (mobile phones, refrigerators, lights). Come talk to us to find out whether you need an inverter in your PV system or if you can do without one.

How many solar panels do I need?

There are many factors involved to determine how many solar panels you will need. You need to think about how your life circumstances might change in ways that increase or decrease your energy usage and plan accordingly. The system topology and your location will also impact how many panels you will need. We also can’t ignore the power class of the panel. User Beware – your solar panels will not produce consistent amounts of energy around the year. We use a combination of field experience, simulation tools, and historical data to determine the exact numbers.

To calculate “approximately” the number of panels needed (here’s the basic math – keep in mind a 1kW = 1,000W).

Step one – kWh needed per day/average sunlight hours per day = kW solar system.

Step two – kW solar system/kW per panel = ~number of panels.

To figure out how many solar panels we would recommend, feel free to ring us on 09 427 4040. We offer no obligation solar quote for your ideal system size. Find the number of panels for the wattage you’re considering (factoring your location, system topology, and much more).

Do I always need a charge controller if I am using a battery?

All batteries are rated for specific max. voltage capacity and exceeding that voltage can lead to permanent battery damage and loss of functionality over time. Most commonly, you will want to look into charge controllers if you are trying to install an off-grid solar system, from ground mount systems, rooftop systems, to smaller setups on boats or RVs.

However, if you are a homeowner looking to install a solar array with a battery that is connected to the electric grid, there is no need for a charge controller.

What is the difference between a solar controller and a solar regulator?

No difference, its one and the same thing. A solar charge controller is frequently referred to as a regulator.

A solar charge controller is needed in virtually all solar power systems that utilise batteries in off-grid applications. The job of the solar charge controller is to regulate the power going from the solar panels to the batteries like a gate keeper. Overcharging batteries will at the least significantly reduce battery life and at worst damage the batteries to the point that they are unusable.

What is a PWM solar controller?

A Pulse Width Modulation(PWM) controller slowly lower the amount of power applied to the batteries as the batteries get closer and closer to fully charged (it was the thing when Morningstar got a patent on a constant voltage charging algorithm in 1997). This type of controller allows the batteries to be more fully charged with less stress on the battery, extending battery life. This is in comparison with the previous on-off systems and chargers. It can also keep batteries in a fully charged state (called “float”) indefinitely by using a “trickle” charge.

What is a MPPT solar contoller

The Maximum Power Point Tracking (MPPT) controllers are basically able to convert excess voltage into amperage. This has advantages in a couple of different areas. A wide range of solar power systems in small off-grid applications use 12-volt batteries as you find in cars (some use other voltages and the same advantages also apply to those systems). Solar panels can deliver higher voltages than are required to charge the batteries. By converting the excess voltage into current/amps, the charge voltage can be kept at an optimal level while the time required to fully charge the batteries is reduced. This always allows the solar power system to operate optimally.

Another area that is enhanced by a MPPT charge controller is power loss. Lower voltage in the wires running from the solar panels to the charge controller results in higher energy loss in the wires than higher voltage. With a PWM charge controller used with 12V batteries, the voltage from the solar panel to the charge controller typically must be 18V. Using a MPPT controller allows much higher voltages in the wires from the panels to the solar charge controller. The MPPT controller tracks the output at selected intervals to find the maximum power point while generating power from PV modules. It then converts the excess voltage into additional current/amps while charging the battery.

What is the best solar controller to buy?

The MPPT charge controllers are more expensive than PWM charge controllers, but the advantages are worth the cost. If you can afford it, you should use an MPPT charge controller.

  • MPPT controllers offer a potential increase in charging efficiency by up to 30%.
  • These controllers also offer the potential ability to have an array with higher input voltage than the battery bank.
  • You can get a vast range of sizes.
  • MPPT controller warranties are typically longer than PWM units.
  • MPPT offers great flexibility for system growth.
  • MPPT units have more advanced features and parameter configurations.
What are the dimensions of a solar controller?

The dimensions vary across our brands and power classes. Please look at our website page for controllers. Or ask our staff to supply you with the relevant specification sheet.

What size battery do I need?

This is entirely up to the use. There are many conditions to take into consideration. Some system requires small size inverters while some require large inverters. You will need to know your nominal and peak demand to select the right inverter. You will also need to know what your inverter needs to do, e.g., connect solar PV to your house, connect batteries to your house, supply power from the battery to charge your laptop in your RV. Take the stress out of it and talk to the experts at AA Solar to help you make the right decision the first time, every time.

How do you calculate the ideal size of a solar system

There are several factors that influence the ideal size of a system – household/RV’s electricity consumption, available roof space, budget considerations. We would recommend that you aim for a system size that meets somewhere between 40% and 100% of your energy needs. With some planning and forethought, systems can be designed to be expanded later – so you can start with a smaller system and build it up over time if desired.

We assess your energy requirements, obtain load consumption patterns and discuss your motivations for getting battery storage to identify what the right solar system size is for you.

What size solar MPPT controller do I need for my solar panels?

The MPPT controller/regulator size is based on numerous factors.  Some controllers can take more than the rated charging power at the panel input. But put simply: A 400Wp solar module charging a 24V battery 400W/24V=16.67A (amps). The controller for this panel will likely be a 20A controller that can charge a 24V battery to its manufacturer’s requirements. Some 15A controllers may also be acceptable. So, come talk to us about the system so we can advise what is most suitable for your installation depending on your goals!

Why are cable sizes important?

The cable size is important for many reasons. Some of the more important reasons include:

The current carrying capacity of the cable.

The voltage drop created by the cable from source to load.

The bend radius.

The cable size should I use?

The cable size you should use is dependent on the installation and application. We recommend the AS/NZS 3008 series to be a good starting point. Better yet discuss the application with us so we can ensure you use the right conductor for the job.

Why do I need a conduit?

Conduit can be used for various reasons. Most commonly it is used to provide mechanical protection for the electrical conductor. It ensures user safety from electrical hazards and ensures no cables get damaged due to movement or accidental impact.

Why do I need to protect my cables?

Depending on the voltage range of your application, mechanical protection via conduit or other means may be mandatory to meet standards enforced by NZ law. You need to protect your cable so that you do not create an electrical hazard which can at times result in death.

What do fuses do?

Fuses are used to provide protection to equipment and conductors from being exposed to currents that will cause damage. Fuses are designed to interrupt the flow of current if it exceeds the design requirements commonly during a fault condition. It is best to replace the fuse instead of an expensive asset or have insulation break down in your cables which can cause a potential risk/electrical hazard.

Why do I need fuses in my solar PV System?

Some solar systems may, and others may not need fuses. Where fuses are needed, it is to protect the PV modules from being exposed to currents outside the acceptable range. It is mandatory to install fuses (or MCBs) in your solar system line if you have batteries in your system.

Not all fuses are equal?

Yes, all fuses are not equal they have different electrical characteristics. It is really important to use the correct fuse, or you may not be protecting your circuit or asset from damage. This could result in a void warranty. Talk to our trained team if you are unsure about the type of fuse you need.

Farm and Industrial Equipment

Do I need a three-phase inverter?

If you have a three-phase supply, you may opt to connect to all three phases with your system. On the other hand, you may only have single-phase loads that you want to focus on where you may be able to get away with a single-phase configuration. It comes back down to your needs and what you are trying to achieve.

Can I have three-phase in an off-grid system?

You can certainly have three-phases in your off-grid system, specifically if you have three-phase loads that need a three-phase supply.