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diy solar

Solar Setup

pbm1204

New Member
Joined
Jul 30, 2022
Messages
2
Hello,
I am ready to pull the trigger on setting up a solar system to power a small window ac unit. The plug indicates 10A 125V 1250W hopefully you can provide guidance on what is needed to power the ac unit and maintain the batteries. I am located in Jacksonville, FL so will get decent amount of sun on the solar panels. Here is what I already purchased but can return and purchase what is needed.

- 5 - 100 watt Eco-Friendly Panels
- Renogy Rover 40 AMP 12V/24V MPPT SCC
- Renogy 2000W Pure Sine Wave Inverter
- Renogy 12V 100Ah Deep Cycle AGM Battery x 2 (2000A Max Discharge Current)
 
You will need quite a bit more solar to be able to power the A/C unit and keep your battery charged. I would suggest you first get a Kill-A-Watt type meter and plug your A/C unit into it and get an actual measurement of running watts and watt-hours.

Production from panels is best thought of as an average over the day. With minimum watts as the sun rises, peak watts at full sun and a decrease in watts as the sun sets. You can look up your location to get the average sun hours depending on Season. For example if your area has 5 hour average you would take your panels wattage and multiply by 5. 500w X 5h =2500wh

The other thing to allow for is starting current of the A/C. This often times can be several multiple of running current and not all inverters can handle the starting surge. Compressors and pumps can be difficult to run off inverters.
 
I actually tried that with 8 100w panels, 2000w inverter and renogy 40 amp SCC and a 200ah AGM battery. Run time was a shade less than 90 minutes when the inverter kicked off for low voltage. It was pulling 9amps.
 
- Renogy 12V 100Ah Deep Cycle AGM Battery x 2 (2000A Max Discharge Current)
For the same price you can get some Chins/Powerqueen LFP batteries and get 2x the usable power out of them.

500w of panel can only provide less than half of what that AirCon is asking for. You'll be able to run it for 3-4 hours and then it's going to take 5 hours of perfect sun to refill the batteries bare minimum.

Not sure the inverter is going to be able to handle the startup surge of the compressor, hopefully you can give it a test before the return window closes.
 
Possible "cart before the horse" scenario ... it is best to do the design calcs first, and then you'll know what your choices are doing to you.

Go here, and enter in your AC unit values (watts, hours/day you want to run it, etc.):
https://unboundsolar.com/solar-information/offgrid-calculator

Go here, and fiddle with various entries/components, and you'll see in real-time what your system component sizing is:
https://www.altestore.com/store/calculators/off_grid_calculator/

These two pages should help you get through most of the necessary calculations. This helps you quickly decide if you can do what you want to do, by varying component choices. You can also use it to see if what you already bought gets you where you need to be ... just plug in your equipment (sizes, voltages, etc.)

You can also help things out by finding the most efficient, low-power ac unit that will do the job (of cooling a room), as that saves watts initially, and lowers solar gear costs. Or, at least decide if this is worth it to you to swap your ac unit out.

Hope this helps ...
 
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