need help

tin_pan · March 2020

I am a good mechanic , but poor with numbers , i just bought a new ac fridge that is energy star and is estimated to use 332 kwh per year I am going to put it in my cabin up in the hills so i want to power it on solar , what size inverter , charge controller will i need , how many batteries and how many watts of panels will i need, thanks for any help you can offer

mike95490 · March 2020

We will need your location (zip code is good)

Your site needs to have a clear view of the sky, from 9am -3pm

You need to harvest about 2kwh daily, That will vary according to your site conditions

Now the tough part

What will you do when you have 2 or 4 cloudy days? Let your beer get warm, or start a backup generator?

Gee, it would be nice to charge a cell phone, and play video games on the big tube. Maybe a light or 3 at night

All that takes power and more gear.

tin_pan · March 2020

we have a 360 clear view of the sky, north west of Oroville yes i do have a generator that we run at night for lights, but when we are away from the cabin i want to keep my fridge cold, no tv or video games

706jim · March 2020

I'd go with a minimum of 1000 watts of panels. PWM or MPPT controller capable of this current. And at the very least 4 golf cart batteries.

tin_pan · March 2020

thanks 706jim what size of inverter do you think i should go with, and do you think i should find an inverter that has a battery charger

mike95490 · March 2020

Keep your inverter and charger separate. I'd go 4 golf cart batteries in series for 24V and I like the Victron Energy Phoenix Power Inverter 24V 800 Watt Pure Sine Wave 120V , should start most fridges, but try it, or get a 30 day exchange if you need the next larger one.

tin_pan · March 2020

thanks for your reply Mike ,706jim suggest to go with 1000 watts panels, would that also go for 24 volt panels,or would i need less due to the higher voltage, great info though i think we are almost there

mike95490 · March 2020

Watts are watts, doesn't matter the voltage. Panels will need to be wired to produce the proper voltage for your charge controller. Generally, over 300 or 400w, best to use a MPPT controller.
You are not "nearly there" There is housing for the gear, wiring, circuit breakers and all sorts of configuring.

Plan on looking at 200 - 300 w panels. More than 300w, they get bulky and hard to handle. Depending on their voltage configuration, dictates how they are to be wired. and what the input limits of your charge controller are.

1Kw of PV will produce about 41Amps, so you need at least a 40A controller,
How much "monitoring" do you want to be interested in ? Do you want to read data and status from the blinky lights off the controller, a meter on the controller, or a laptop connected to the controller with cable or wifi ?

tin_pan · March 2020

thanks mike, i know iv got lots to learn yet , im going to try and find some schematic tonight to look at the build design and i am hoping not to do a lot of monitoring hoping to get it properly set up so i dont need to baby sit it

mike95490 · March 2020

Monitoring is what lets you know something is wrong - before the lights go out and your batteries are ruined.

need help

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