Matt
It comes down to simple math. 12 x 8.5 watts = 102watts. The inverter also uses some wattage (due to how efficient it is) even if none of the lights are on so maybe add another 18 watts to that 102.
With a load of 120 watts and a run time of 2 hours comes to, 120 x 2 = 240 watt hours. So that battery can run all your lights for about 2 hours and gets discharged 25% which is the most you want to do to get a long life out of it. A 50% DOD will probably cut the battery life in half.
Now a 100 watt panel with a PWM charge controller is really only a 67 watt panel. If you use 240 watt hours it will take more than 4 good sunlight hours to put back that 240 watt hours due to system losses. If you use more than 240 watts you probably won't be able to recharge that battery in a day. Also with only a 100 watt panel (~ Imp = 5.5amps) you can't provide the right amount of charging amps to go back into that 85Ah battery. You need somewhere around 9 to 10 amps which means about 190 watts of panels using a PWM CC.
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thanks for the quick reply.
can you go into a little more detail about my watt hour needs?
say 12, 8.5watt led bulbs.....through a 300watt msw inverter. how long can i run that setup before i reach the 50% battery drain limit......and then how long to recharge with say a 100watt panel.
thanks, and thank you for your patience with these 'elementary' questions...
MattLeave a comment:
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Welcome Matt. Lets get right into the meat of it. The Kill-Joy the 85 AH Battery. Nothing else matters because you are married and restricted to a 85 AH battery. You made the battery the end result, not what you want it to do. If you use 50% of the battery capacity only yields you 600 usable watt hours and would take a couple of days to fully recover. For everyday use only 200 watt hours. Based on your battery size ideally you need a 160 watt Battery Solar Panel, or two 80 watt panels with a 10 amp charge controller. There is not much wiggle room with your battery. The minimum panel wattage required to maintain the battery is 130 watts, and maximum is 190 watts. Your battery's capacity is limited to around 300 watt hours per day assuming you can fully recharge it in a day. Does not matter if it is not enough power for you, that ball-n-chain you are married too only allows up to 300 watt hours in a day and you are stuck with it.
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1st Post, Solar Shed Lighting, Need Guidance!
So here are the details that I have
I'm wanting to use some materials that I already own to light the inside (and outside) of a newly built 12x16 shed in my backyard.
I currently have......
1. (several) indoor rated 8.5 watt philips led bulbs (60watt equivalent)
2. 300watt msw inverter
3. 85AH Deep Cycle Battery
The shed will mostly be used for garden/lawn equipment, sporting goods, long term plastic clothing tub storage, etc. It has a 12x8 lofted area, the area underneath the loft, and the open ceiling 12x8 section. (14' peak)
Use: i'm guessing the inside will see a few hours at a time, tops......maybe 2 times per week. I'd also like to do some motion/dusk to dawn security lighting on the outside of the shed. This could be tied to the indoor system, or a separate solar motion light, or the like.
My questions are:
1. What size panel would i need to recharge the system based on my stated use time and lighting requirements?
2. would i need to wire all the inside lighting in series or parallel. (maybe 12 bulbs inside total)?
3. I'm an idiot about this stuff, so what red flags / problems do you see with any part of this system.
Thank you all so much,
Matt
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