Light intensity is logarithmic, it takes only a small perceived change for it to drop right off.
Having just checked up, my panels are mono-crystalline, it makes little odds, it just means they are slightly smaller for the same power output. They behave just the same. 10 of these :
http://www.swithenbanks.co.uk/shop.php?action=full&id=12312.
How much draw does an Arduino take in a power-saving mode that lets time be tracked? If it's only got to read a thermometer once an hour then power usage can stretch a good long ways.
Again, with solar panels you can reflect or magnify more light onto the panel if there is light to reflect or focus. Those crystalline cells can take direct sunlight in space, they should take a few x sunlight even at the equator. Even a face-tanner reflector should get some increase on a solar panel.
magnethead794:
[u]battery -> http://www.pololu.com/catalog/product/2226[/u]
If I have a solar panel array delivering 9 volts and 260mA nominal, and my project only pulls 70-90mA, would the remaining 170 or so mA get wasted, or charge the battery?
The cells are rated 9V @ 130mA nominal, I'm expecting closer to 8.5@85 out of them, thus why I'm paralleling them.
FWIW, the regulators have a 15V max input.
How would I set this up? moduli fotovoltaici I know I'll need a diode between the solar panels so one doesn't backfeed the other, and another diode before the array so the battery doesn't backfeed the panels.I've seen solar battery/load tenders for 3V3 Li-ions, but nothing for 9V NiMH's.
edit: found this -> http://ghurd.info/dc.html
I've emailed the designer to ask how to modify for 9V.
This is great option for small usage
Not sure what you are trying to do, but if all you are building is a low power temperature sensor which will transmit
data a short distance, these things draw very little power, but you cant use an arduino to do it as its total overkill
for whats needed and the power consumption is too high.
Ive just built a clone of an Oregon THGR810 battery powered temp sensor , and it draws only around 200 microamps
on average , peaking to around 10 ma when transmitting, which means around 1 - 2 years on a pair of AA batteries.
Look at using a small micro power microcontroller which can go into sleep mode when not transmitting.
I think Undrad might have a different project than the original poster of this topic.
9V NiMH charger circuits are easy to find on google for example:
In your exampel the 170mA would charge the battery.