How useful is Solar ?

Over the years solar panels have become more efficient and crucially cheaper as more and more of them are made and economies of scale drive the prices down.

There are now many motorhomes, caravans and boats with solar panels installed to provide a trickle charge to their sets of batteries. But how useful are they ? and what are their limitations ?

How much power do they actually provide ?

Firstly you must remember that unfortunately it is rarely completely sunny and without clouds in the UK. And secondly the ratings quoted assume direct sunlight so the panel would have to be facing the sun to provide the maximum output. And finally depending on the type and manufacturer of the solar panel, the effeciency can vary hugely and you can assured that some loss will occure and that you will not get 100% of the quoted output. I haven't run the numbers yet but will do so in a future post.

But it must be remembered that a 100watt panel may at best provide something in the region of 30amps over the course of a sunny, clear summer afternoon. And at worst barely 10amps.

So if you are planning on extended wildcamping trip off electric hook up. It is always best to ensure you have a small generator or some other way of charging up your batteries.

For battery charging :

If you are hoping to completely charge a flat battery using solar panels on a constant and regular basis, unfortunately we do not recommended this. Your battery will last much longer if charged using a good quality multi stage charger. To top up and maintain or extend a batteries usage when not connected to electric hook-up, solar panels are great as an "addition" to a good charging regime.

For trickle charging :

Solar panels are great for supplying a small trickle charge to batteries while they are not being used to make up for alarms or other small electric drains. But you must ensure the output is not too high and there is a smart charge controller connected so as not to damage the batteries by constantly charging it.

For maintaining batteries off season :

If you have an alarm or other items on board that draw a small current while the motorhome/boat is not being used than the solar will help. But we always recommend that you use a proper multistage smart charger once a month during the off season to ensure your battery remains fully charged. Solar panels will not be able to provide the full complete charge that good quality multistage chargers can.

Having said the above solar technology and just as importantly the solar charge controllers connecting the panels to the batteries are increasing in sophistication and what is available today is a lot better than what was available 5 years ago.

If you are considering solar panels, always go for a good quality monocrystalline panel with a good quality charge controller.