|
It's not so easy.
I tired a 40W panel for about six months. Most I ever saw out of it was 1.1A (facing it directly at the sun at midday) or about 15W. On the vehicle, the most I ever got was 0.8A or 11W.
I used an MPPT charge controller to make the most of the available current. Problem is as soon as you start the engine, the voltage jumps to ~14v and the controller detects this as a full battery and shuts off the panel while driving.
In the end all it did was help keep the votage up during EOC, and it took about 30mins on a sunny day to top up the battery (to float charge) after the engine was shut off.
I was planning on fitting a total of 400W of panels (I had the space) and deleting the alt, but the head gasket blew and the MB100 projects got canned.
The other issue is solar panels get extremely hot and transfer heat to the paintwork of the car (paint doesn't like being constantly baked) and onto the interior. Even with a 10mm airgap the underside of the roof was much hotter than the areas adjacent. A shame as solar panels work best in hot climates.
My 40W solar panel now lives on the garage roof and is used as a maintenace charger. A small ~10W panel wouldn't be a bad idea, pariculartly if it can be mounted in free air (eg a rear spoiler or kammback), but it would be mostly to prolong battery life.
|