On 13/02/2012 17:09, js.b1 wrote:
On Feb 13, 2:59 pm, Martin
wrote:
I happen to have a nominally 8W PV panel to hand. Today on a relatively
overcast afternoon 7/8 cloud it managed a no load terminal voltage of
20v and a much more disappointing short circuit current of under 10mA.
If you are *very* lucky it might deliver 3mA into a 12v load (40mW).

Thank you for some very useful info.
I assume polycrystalline, mono should do a bit better in overcast.

My 4.8 (claimed) solar panel is in series with a mA meter and I look
whenever I am near the car.

On a day like today, completely overcast, between 11 am and 3 pm, the mA
meter reads between 10 mA and 25 mA.

On a sunny day, in winter, it can go as high as 170 mA.

In summer, it can go over 250 mA.

David