What Do I Need For My 12V Solar Power System?

When you're planning your trip off-the-grid, the last thing you want is to run out of power and have to stress about finding somewhere to charge your RV. The solution is to harness the power of the sun!

Solar power has come a long way in the last 10 years and is now a must for everyone who wants to explore the beautiful remote locations New Zealand has to offer.

It can be daunting setting up your RV for solar, but if you read through this guide you'll realise it's not difficult, and you'll question why you hadn't done it earlier.


Follow these steps to learn what you'll need for your system:

  1. Understand your requirements

    The first thing you'll need to do is to work out how much power you need to gather and retain to be comfortable. Look at all the places in your RV where power is used. This could be anything from the fridge to the laptop charger. You will need to work out approximately how much power you will use per day in amperes (A). Most appliances have a Wattage rating and you can calculate the amperes by dividing this figure by the Voltage (V). E.g. a 60W TV on a 12V system uses approximately 5A (Wattage/Voltage = Amperes).

  2. What batteries will I need?

    Next, you will need to plan out what your battery system will look like. In order to calculate the total bank required (in amps), multiply your daily usage by two and a half. E.g. If total daily usage is 50A then we need a 125A battery (50 x 2.5 = 125). We use this number because you should never run your bank below 50%, as this will damage the batteries and we need to allow for for any inefficiencies. However, this 125A battery bank will only provide 24 hours of capacity between charging, so if you need more than that, a solar panel set-up is essential.

  3. What panel/s will I need?

    The panels are where you gather the energy of the sun, and turn it into power you can use in your RV. You will need to calculate the output of the panel to work out what you will receive. Obviously, you won't receive power 24 hours of the day: typically in NZ we see a good amount of sun for only 6-8 hours every day. The simplified way to work out the output is to divide the wattage of the panel by 4. On average, that is the amount of amps you can expect to receive on a reasonable NZ day from that panel (eg. typically a 100W panel would provide 25A of power back into your bank). However, please remember that if you get a week of bad weather you could potentially get very little charge at all, so you need to factor this into your battery system.

  4. What regulator will I need?

    This is based on how much output from panel/s is going through your regulator per hour. It's much better to go larger than what you think you'll need to allow for spikes and the future addition of more panels to your system at a later date.

    MPPT regulators are a newer design of regulator and operate more efficiently than traditional regulators - this means more of the output from the panels is going directly into your bank. We recommend only MPPT regulators are used with our flexible panels, as their output is at a higher voltage and this requires a more efficient regulator.

  5. What do I need to distribute the power around?

    When you are putting your solar power system together you will need to purchase the cable to connect it all together. You can never be too safe and we recommend a minimum of 5mm cable for all solar set ups. Getting the wiring from the outside of the RV inside to your regulator can be made a lot tidier with a gland. This will ensure no weaknesses in the wire and it keeps the hole waterproof. Lastly, you will need to have solar cable connectors that are rated for your panels and are also waterproof.

  6. What else do I need to know?

    As with all electrical set ups, you need to try to make the system as efficient as possible in order to get the greatest amount of juice back into your battery bank. You must also consider the power usage of EVERY appliance and charger that is used especially when using an inverter and 230V appliances.

If you still have questions, just pop into your local Burnsco store and ask our friendly staff. They are experts in solar systems for motorhomes and caravans and can make sure you are on the right track.

Wiring Diagram