How Much Electricity Harvest Can You Expect From An Off Grid System?

There is a big difference between the actual energy harvest and the possible energy harvest when relying on PV modules (Solar panels).

An off grid system if designed correctly, has a large PV array to insure a decent energy harvest even on overcast days. On sunny days there will be a surplus of energy available. The charge controller then starts rejecting the available energy to prevent the battery bank from being over-charged.

There are ways to take advantage of the available surplus energy. One option is to monitor your system and once the charge cycle is complete, (Bulk, Absorption and eventually Float) you can then starting to manually control your electrical loads. You will be able to run all of your household appliances taking the energy directly from the PV modules and invert it into AC power without taxing your batteries at all. In many off grid homes the vacuum cleaner, dishwasher, washing machine and other loads are scheduled for the sunny days. Higher end equipment can be remotely monitored and electrical loads can be turned on and off via an app. One of the Roomba models for example can be controlled via your cell phone. Most washers and dryers have timers so if the forecast looks like you get a lot of sun, set the timer for when you expect your batteries to be fully charged.

There are automatic options as well such as a relay being activated once the “Float” stage has been reached. You can control an appliance of your choice to take advantage of the available surplus energy.

Just from my own experience, in our home we use on average 7.5 kW/hr of electricity per 24 hrs. By controlling additional loads we have nearly consumed 17 kW/hr one day last year.

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