Solar System for Off Grid Cabin

Allegra

Hello everyone 

I would like some advice on how to install a small solar power system in my off grid cabin. My primary objective is to supply electricity for simple devices like lights, a small refrigerator; and a few electronics. I am new to solar, so suggestions on the optimum battery configuration, inverters; and panel types for dependable; year round power would be greatly appreciated.

I would value any guidance on determining the proper system size and estimating my power requirements. Your knowledge of similar settings would be very beneficial if anyone has it.

Thank you for your input in advance

BB.

Welcome to the forum Allegra.

I would suggest that you go through this post from the other day...

https://forum.solar-electric.com/discussion/358398/new-to-solar#latest

I went into the details for a "back of the envelope" sizing of a solar power system. A 500 Watt*hour per day system, like the one in the above link is a relatively small system that supplies enough energy for a cabin. Lights, smaller water pump, and possibly some cell phone charging.

The next larger system would be around 1,000 Watt*Hours per day... 2x larger, and can run a laptop, more water pumping, more lighting, etc.

When you ask for even a smaller refrigerator, that really runs up the size of the system. In the USA, a full size fridge/freezer is around 1,000-2,000 WH per day--Meaning near a 3,000 WH per day system.

Even a small fridge--You really have to shop around (we call them Dormitory or Bar refrigerators for the smaller ones)... They can draw 800 WH or more per day.

Once you have sized your loads and done the basic back of the envelope calculations, we can start talking about the detailed hardware requirements. Highly suggest you do not buy any items (batteries, solar panels, solar charger, etc. until you have done a full paper system design).

If you are around Agra India, with a 27 degree from horizontal solar array, your hours of sun per day looks like:

https://pvwatts.nrel.gov/pvwatts.php

There are obvious weather conditions that affect solar harvest--So knowing "when" (and where) your cabin is, will help better plan out the system... Solar can make lots of sense for a sunny location like Agra and if you are there for most of the year... If this is a few weeks a year vacation cabin, a large enough solar system to run a refrigerator may not be "cost effective" for short term stays.

-Bill

MichaelK

When I am not doing anything special like pumping irrigation water, I find myself consuming around 4-5kWh per day.  This is with the inverter on 24/7, the refrigerator running, and lights and TV during the evening.

I'd suggest skipping 12V and implement at least a 24V system.  48V if you ever consider running a well-pump.  If you place the panels on a rotating mount like I use, you can make all the power you need with 1000W of panels.  I wired four 250W 30V residential panels in series for 120VDC to feed my inverter.