Solar powered lighting ??

[jerrymrc]

Ok, what about these solar deals? They look like they could power some LEDs for a long time, yet only 15-30 watt solar panel? Does this look like it will work, and can you show your math on this???

http://www.goalzero.com/shop/p/60/Es...enture-Kit/1:2

It is late but some of the basics. 200 ah battery. 10 -5 Watt led's. 50W panel.

For the sake of simplicity the lights. We have 50 watts of lights. 50 divided by 12= 4.16 amps. 4.16 x 10 hours= 41.6 AH.

So for this we have taken 41.6 out of the battery.

So now we have the panel. 50 watt panel. Under the best conditions it puts out 4.16 amps @ 12V. we took 41.6 out of the battery so we need it to provide 10 hours of light to put it back (10X4.16) = 41.6

So lets get a 100W panel. 100W panel puts out 8.32A so doing the math 8.32A X 5 hours puts back 41.6 AH.

Always better to have too much storage and more panel. With a good controller one can never have enough PV's. Now I am in the camp that I would rather have 4-50W panels than one 200. Batteries as well.

And when it comes to actual power draw you need to be able to use a meter to check. My lights that used 6-.5W led's draw 5.2W and that is with the two resistors that do get warm so anything that gets warm is drawing power.

Just some thoughts for now. I did go back and look at my old thread and much of the math has been done there as well.

In the end lighting the camper used 1/3 the power of regular bulbs. I am a goofball. Let me look at it tomorrow to answer your real question but most that I have seen do not live up to the hype. I looked.Will explain later but if you do some math on that from the numbers I posted above......... The battery alone is the size in my UPS that keeps my puter alive for 15 min.

[offgrid]

It is late but some of the basics. 200 ah battery. 10 -5 Watt led's. 50W panel.

For the sake of simplicity the lights. We have 50 watts of lights. 50 divided by 12= 4.16 amps. 4.16 x 10 hours= 41.6 AH.

So for this we have taken 41.6 out of the battery.

So now we have the panel. 50 watt panel. Under the best conditions it puts out 4.16 amps @ 12V. we took 41.6 out of the battery so we need it to provide 10 hours of light to put it back (10X4.16) = 41.6

So lets get a 100W panel. 100W panel puts out 8.32A so doing the math 8.32A X 5 hours puts back 41.6 AH.

Always better to have too much storage and more panel. With a good controller one can never have enough PV's. Now I am in the camp that I would rather have 4-50W panels than one 200. Batteries as well.

And when it comes to actual power draw you need to be able to use a meter to check. My lights that used 6-.5W led's draw 5.2W and that is with the two resistors that do get warm so anything that gets warm is drawing power.

Just some thoughts for now. I did go back and look at my old thread and much of the math has been done there as well.

In the end lighting the camper used 1/3 the power of regular bulbs. I am a goofball. Let me look at it tomorrow to answer your real question but most that I have seen do not live up to the hype. I looked.Will explain later but if you do some math on that from the numbers I posted above......... The battery alone is the size in my UPS that keeps my puter alive for 15 min.

A few things to add to the above.

Battery capacity, 3-4 day battery (bank) not going below 50% state of charge is ideal.

Charging current, 1/20th (c/20) of battery capacity is ideal.

With the above example, 41.6 amp hrs used in 24hrs suggest a battery bank of 41.6 x 4 = 166.4 x 2 = 332 AH battery bank. For a c/20 charging current, 16.6 amps of charging source.

Max current output of a nominal 12 volt panel is usually based on 17 volts +/-. So for example a 100 watt panel/17 = 5.88 max current output. Would suggest 3-100 watt panels (17.64 amps) for the system example.

HoneyBadger, if you are wiring a cabin for 12V's, simply wire it as if it's 120VAC, small breaker panel.... Only difference use DC rated light switches. An maybe DC outlets, they have a different plug/lug pattern, so a 120VAC device can't accidentally plugged into them.