The inverter’s main job is to convert the DC electricity from the battery bank into AC electricity to be used by standard household appliances.
Solar panels convert sunlight into DC(Direct Current) electricity. This electricity is then stored in a battery or bank of batteries. Because most electronic devices and appliances run on AC(Alternating Current) electricity they can’t be powered by the battery bank directly. The DC electricity must be converted into AC electricity.
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There are mainly two types of inverters. These inverters come in many different sizes.
Modified sine wave inverters produce electricity that is “dirty” or “choppy”. These inverters will work fine for simple electronic devices but will cause problems for more complex devices like modern TVs, computers and smart controlled appliances. These inverters can save you hundreds in the cost of your solar system but maybe a bad choice depending on the complexity of your electronic devices.
Pure sine inverters produce a “clean” electrical current equal to or better than what is produced by utility companies. If you plan to use complicated electrical devices or appliances then a pure sine inverter is a must for you. It will cost more initially but will save you money down the road if you have to replace appliances because you used a modified sine wave inverter.
Inverters are sized by the wattage they are designed to handle. Inverters can be as small as 100 watts that you can plug into the power outlet in a car and they can get into the thousands of watts that are hard-wired into your home solar system and all sizes in between.
Wattage is determined by voltage and amperage. Volts x Amps = Watts.
To choose the right size inverter you need to find out the max amount of amps your whole electrical system could possibly use at any given moment. If you are tying your system into a standard breaker box you can simply add together the amp rating on all the individual circuit breakers. This will give you the maximum possible amps in that system, but it will also most likely be extreme overkill.
To get a more accurate idea of the actual maximum you need to look at each individual appliance and device that will be plugged into the system. There will be an amp rating labeled on the appliance somewhere on an electric UL listing.
Add together all the amp ratings from all the appliances. Multiply the sum by 110v (United States). This will give you the total watts of the system.
Example: 130 amps x 110 volts = 14,300 watts
The number of watts will tell you what size inverter to get.
Check out this article where I take you step by step building a simple 600-watt solar system. https://offgridmaker.com/2020/03/17/how-to-install-a-600-watt-solar-system-on-the-cheap/
Get an idea of inverter prices here. https://amzn.to/2WWWYBH