I had a tiny system used only to run a couple 12v LED lights. I'm now trying to expand.

Lannie

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May 21, 2020
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I have a 8'x16' shed in the wilderness of south Georgia. I have purchased 2 100w solar panels, a 1000w Strongway Pure Signwave inverter and 2 ECO-Worthy 12V 30Ah Lithium Iron Phosphate Batteries, Rechargeable LiFePO4 to be connected in parallel. I am connecting the panels in parallel to increase the amps and will be facing 1 to the Southeast and 1 to the Southwest due to sun availability and tree obstructions. I would like to run 4 12v LED lights (7w each) and a 24" TV and hopefully a small room A/C exactly like the one in your shed. I have an existing 30A MPPT controller. I would expect to run the lights for 4 or 5 hours a day, the TV for about 3-4 hours a day and the A/C for 3 or 4 hours a day. Is this a workable solution?

The reference to the A/C unit is to the video will made about the unit in his shed.
 
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gnubie

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Sep 20, 2019
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The lights will put away at least 140 watt/hours if they are rated correctly. If they don't use some sort of regulator their power use will change significantly with battery voltage. LEDs really start to sink current as the voltage goes up and they got hot doing it. On the other hand, they might be well under the rating, ie the wattage on the box is embiggened. A meter in series will tell you what they draw at the present voltage.

You need to work out the typical draw of the TV and aircon. Since they are highly variable loads the best thing IMO is to use a kill-a-watt style meter and measure what they get up to for at least a typical day, but a typical week would be even better.

You have 200 watts peak of panels there, doesn't matter how they are wired, the power peak is the same. Grab an isolation map for your location (check the FAQ) and, based on 200 watts of panels, work out how many kWh you can generate a day. From there, work out what the worst days of production will be and check that you still produce enough power to cover your use on those days.

There is also a clip in the Beginner Video Playlist that talks you through working out how how much energy you use.

To give you an idea of what bad weather can do, right now the weather here is terrible and my 1.9kW array is pushing out 175 watts, near midday. About now it would normally be doing 1200.
 

tictag

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Dec 31, 2019
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Everything was sounding OK until you mentioned A/C! ;)

Your 2 x 12V 30AH batteries gives you about 720Wh of energy, which would power a modest, say 600W, A/C unit for less than an hour given system losses. And a 200W PV array is at best only going to give you around 800Wh per day in Summer, maybe doubling that to at most a couple of hours.

Lights and TV will be fine (lights = ~35Wh per day, TV = ~200Wh per day) but running A/C would be challenging.

Will was measuring the energy use of his A/C in single-digit kWh per day.
 
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