Energy Offset

Energy offset is the percentage of your total electricity consumption that is replaced by solar production. A 100% energy offset means your solar system produces as much electricity annually as your home consumes. A 75% offset means solar covers three-quarters of your usage, with the remaining quarter drawn from the grid.

Energy offset is the primary sizing target when designing a residential solar system. Most grid-tied homeowners aim for 80-110% offset — enough to eliminate or nearly eliminate the energy charges on their utility bill. Offsetting more than 100% may not provide additional value if the utility does not pay for annual surplus credits or pays at a reduced wholesale rate.

Calculating your target energy offset starts with your annual electricity consumption in kWh (found on your utility bill or account portal). A 6 kW system in an area with 5 peak sun hours produces approximately 8,200 kWh per year after real-world derating. If your home consumes 10,000 kWh annually, the offset is 82%.

Seasonal variation affects energy offset significantly. A system sized for 100% annual offset might produce 140% of consumption during sunny summer months and only 60% during cloudy winter months. Under annual net metering, summer surplus credits offset winter shortfall, achieving the target annual offset despite seasonal imbalance.

When planning energy offset, consider future consumption changes. Adding an electric vehicle, heat pump, or home addition increases consumption and reduces your offset percentage. Sizing the system slightly above current needs provides headroom for future load growth and ensures long-term bill savings as energy usage patterns evolve.