As per the title – How do i choose a Solar Panel?
What are the criteria (Watt, Voltage, Technology etc) that I need to take into considerations when I choose a suitable solar panel for my project?
Electronic – How to choose a Solar Panel
solar cell
Related Solutions
Vpanel >> Vbattery so panel acts as ~~ constant current source.
2 batteries in series or 4 batteries in series will still be << 9V so charge in the same time.
Imp < Icharge < Isc or
0.33A < Icharge < 0.43A
Say ~~= 350 mA.
T charge ~= Battery_mAh / Ichg x 100 / Battery_efficiency % NimH CURRENT acceptance efficiency probably 80%-90%
= 700 Mah / 350 mA x 100/80 ~~~= 2.5 hours
That's in full mid-day sun with panel square on to sun.
Charge for longer than this and you will quickly "cook" the batteries.
Vbattery_max at that charge rate should probably not be more than about 1.5V/cell when charging.
Google: your_city_name gaisma
eg Bangalore gaisma gives
http://www.gaisma.com/en/location/bangalore.html
to get SSH = sunshine hours per day (= kWh/m^2/day)
Your panel will produce ABOUT 350 mA x SSH mAh per day
Bangalore example -
Half a day on an average day will be more than enough in any month - see below.
Chart from Gaisma entry for Bangalore as above.
If you are thinking about using just one of those panels and a standard incandescent house bulb - forget about it ! -. That panel only produces 0.6 watts of power, and that's likely only in fullest sunlight.
You may be able use a very small DC bulb from a flash light (torch) with that panel. If using a small 3V 200ma incandescent bulb you could connect it directly to the leads of the solar panel. Of course with no other components (like a battery), when a cloud goes by the light goes bye-bye.
Another option would be to hook up 10 red or yellow LEDs in parallel (with a 51 ohm resistor in series with each LED). That allows about 20ma per LED. This could also be connected directly to the panel output (observing polarity of the LEDs).
The 3V output would not quite be enough to directly drive most white LEDs as they tend to need 3v or more. There are booster circuits available that could increase the voltage to drive a white LED, but with only one solar panel you would still be limited to 0.6w (or less depending on the efficiency of the booster). - Here is one example of a voltage booster that might be used - http://www.icstation.com/icstation-mt3608-step-booster-power-apply-module-p-3448.html
To get any significant light output you would need to buy several panels and place them in series or parallel to get higher power levels.
Best Answer
MUCH more information will give you a much better answer
Find average daily insolation by month from Gaisma
Watt hours max per day != Watts rate max x sunshine hours from Gaisma.
If storing in a battery and retrieving the average wWattage you can run continually ~~=
Watts = Panel_peak_Watts x Sunshine hours per day / k
k is a mimimum of about 30 and can be 60+.
Depends on how well you match panel to battery etc.
What are you operating?
what Wattage?
What location?
More ...?
Olin says black side up.
Sometimes its pretty blue side up :-)
Depends on technology used in cells.