Off-Grid Power FAQ

Part 1

As many of you already know, Sierra Solar offers unparalleled customer support throughout the entire process of getting an off-grid power system up and running. With over 150 years of combined experience, we’ve most likely seen and heard of whatever problem you may have with your system. Here we address some of the not so obvious but still relatively common issues that arise when shopping for, installing, using and monitoring a remote power system.

Frequently Asked Questions

How do I figure out what size system I need?

1) Batteries

Start with your electricity usage. Find the watts (or find the amps and turn them into watts by multiplying by the voltage) that each appliance uses. Then multiply that by the hours per week that you use each one. That will be a number in the form of watt-hours (Wh). Divide by 7 to get daily average. Divide by the voltage of your battery bank to be – either 12V, 24V or 48V and you will have amp hours (Ah). Multiply by 1.25 to account for system inefficiencies, multiply that by 2 so that you will only drain your batteries halfway, than multiply that number by how many days you want the batteries to last you without a charge, such as from cloudy weather. This number will be the size, in amp-hours of your battery bank. Choose your batteries accordingly.

2) Solar Panels

Start by taking the average daily amp hours that you will be using and divide that number by the average number of sun hours per day that the solar array will get. Data on average sun hours is available in our catalog on Page 9. multiply this number by the battery voltage then multiply by 1.2 to account for battery inefficiency. This will be the number of array watts that you need. The type of panel you may choose and how they are wired depends on whether or not you have an MPPT charge controller (see below for more on MPPT and whether or not you should have one).

For the rest of the article, please click here.