Solar Self-Consumption Rate Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/10/2026
The self-consumption rate = solar energy consumed on site ÷ total solar production × 100. The self-production rate = solar energy consumed on site ÷ total consumption × 100. An installation producing 3200 kWh, of which 1900 consumed on site for a total need of 4500 kWh, shows 59% self-consumption and 42% self-production.
Explanation
Two rates describe how a self-consumption solar installation works, and they don't measure the same thing. The self-consumption rate relates the solar energy actually consumed on site to total solar production: it indicates what share of what the panels produce is used directly, the rest being fed (and generally sold at a low price) to the grid. The self-production rate, also called the coverage rate, relates that same self-consumed energy to the household's total electricity consumption: it indicates what share of electricity needs is covered by solar, with the remainder still bought from the grid at the retail rate. These two rates move in opposite directions as an installation grows: the more the panels produce, the higher the self-production rate, but the more the fed-in share increases and the lower the self-consumption rate. The economic optimum is generally a modest installation with high self-consumption (self-consumed electricity avoiding a full-rate purchase, more profitable than selling the surplus). This calculator complements our required solar panel count calculator, which sizes the installation: its profitability, and the value of the electricity it displaces on your electricity consumption bill, depend directly on these two rates. To improve the self-consumption rate without changing the panels, you can shift major electrical uses (washing machine, water heater, vehicle charging) to sunny hours, or add a storage battery.
Example: production 3200 kWh, self-consumed 1900 kWh, consumption 4500 kWh
Inputs
Solar production: 3200 kWh. Self-consumed energy: 1900 kWh. Total consumption: 4500 kWh.
Calculation
Self-consumption rate = 1900 ÷ 3200 × 100 ≈ 59.4%. Self-production rate = 1900 ÷ 4500 × 100 ≈ 42.2%. Surplus fed in = 3200 − 1900 = 1300 kWh. Electricity bought = 4500 − 1900 = 2600 kWh.
Result
This installation self-consumes 59% of its production and covers 42% of the household's needs.
Frequently asked questions
Why is a high self-consumption rate more profitable?
Because a solar kWh consumed on site replaces a kWh you would have bought from the grid at the retail rate, whereas a fed-in kWh is only sold at the buyback rate, generally much lower. Maximizing self-consumption therefore means maximizing the value of each kWh produced. This is why residential installations are often sized slightly below the need, to self-consume everything.
Does a storage battery necessarily increase profitability?
It increases the self-consumption rate (energy stored during the day is consumed in the evening rather than fed in), but its high cost and limited lifespan mean the financial gain doesn't always offset the investment, especially when the surplus buyback rate isn't zero. A battery makes more sense in areas where the grid is unreliable, or with high evening consumption.
How do I know my actual self-consumed solar energy?
Modern inverters and monitoring hubs (Enphase, SolarEdge, etc.) directly show the split between self-consumption and feed-in. Otherwise, it's derived from total production (read on the inverter) minus fed-in energy (read on the production meter in "feed-in" mode).