PV Gap

Mae Said:

Will a solar panel discharge a battery at night without special equipment?

We Answered:

You can get one that has a diode. This will stop the discharge.

Why do you want to charge the battery with a solar panel? You may only over charge the battery and cause it to wear out earlier. It is better to to let the car's alternator do the charging for you. Unless of course you have other electrical items plugged in that drain the battery.

Daniel Said:

Solar panel placement idea?

We Answered:

outside is going to be much better. You can't tell but glass is actully opaque to many ranges of 'light'.
If you look at advertising for windows you may see claims to reduce sun fading of your carpet/ furniture. That is because the glass blocks UV. Solar panels get some of their energy from UV light.
Also some windows are engineered to block IR to help insulate better when the house is cooler than the outside. Again, solar panels get some of their energy from light in the infrared range.
And finally if you're charging batteries the 'off angle time' is still important. The amount of light absorbed is pretty closely related to the cosine of the angle that the sun is 'off' of the direct. so when the sun is 45 degrees off of perpendicular the panels still get cos45 =.707 or about 70% of the available energy. (In practice it's a little less than that because not as much energy gets to the panel to be absorbed as at midday). But anyway, you can figure two hours of morning or late afternoon sun will give you as much energy as 1 hour of midday sun. So if the panel is inside, you miss out on that available energy.