Customer question (received via email 10th May 2020):
I am looking for advice on what type, size and cost I need to install a solar system to keep a car battery topped up when the car is not in use. The panel would have to be left outside as the car lives under a cover when the power would be required.
Any advice would be helpful
Willgen Reply (Email from Bill 10th May 2020):
Many thanks for getting in touch.
You need to be looking at the Optimate range of solar chargers on my website here: https://www.willgen.co.uk/solar-lights-chargers/12v-solar-chargers-for-vehicles.
The size of charger required depends on the drain on the battery when the car is parked (i.e alarm etc) and the position the solar panel will be mounted in. If there are no drains on the battery and the solar panel can be mounted in an ideal position (outside, South facing, un-shaded and at an angle of approximately 65 degrees from horizontal) a 10W Optimate will be sufficient to keep a normal sized car battery topped up throughout the year (including through mid-winter).
If there are drains on the battery when the car is parked and/or the solar panel can not be mounted in an ideal position the size of solar charger needs to be larger to account for this.
In most cases a 20W Optimate is ample for maintaining a car battery. If solar panel position is very poor or shaded a 40W Optimate may be required.
From what you describe, as long as you can get the panel facing due South in an un-shaded position, the Optimate 20 should be fine.
The Optimate solar panel can be permanently mounted outside. The charge controller although splash proof needs to be in a position out of the weather (usually either in cabin or under bonnet). You may need an extension cable to get the power from the solar panel back to the car: the solar panel comes with 2m of cable connected and a 4.6m extension cable can be purchased as an option.
Links to products of interest (and prices) :
Optimate 20, £139.95: https://www.willgen.co.uk/optimate-20w-solar-charger
Optimate Extension Cable, £12.99: https://www.willgen.co.uk/optimate-4.6m-sae-extension-cable
I hope that this helps. If you have any more questions please ask. With the exception of the Optimate 10 (which we are struggling to get stock of due to Covid-19 impact on manufacturing and the supply chain) all Optimate products on our website are currently in stock and ready for fast dispatch.