Self-consumption and solar savings

What self-consumption means

Self-consumption is the share of your solar generation used in the home instead of exported to the grid. If your panels generate 3,600kWh and you use 1,260kWh directly, your self-consumption is 35%.

This number matters because the electricity you use at home avoids buying power from your supplier. Exported electricity earns whatever export tariff you've signed up to. Those rates are rarely identical.

Why it changes payback

If your import rate is 24.7p/kWh and export rate is 15p/kWh, a self-used kWh is worth 9.7p more than an exported kWh. That gap adds up over thousands of kWh and many years.

If export rates are strong, exporting isn't a failure. It's income. The point is to model the split honestly rather than assuming every solar unit saves you the full import price.

Ways to increase self-use

The easiest gains come from moving flexible loads into daylight hours. Washing machines, dishwashers, immersion diverters, EV charging and some heat pump operation can help, provided they're used safely and sensibly.

A battery can help by moving surplus solar into the evening. It won't create energy, and it isn't loss-free. It only improves the numbers if the extra self-use is worth enough to justify the battery cost.

• Run flexible appliances during daylight when safe.
• Use smart plugs or timers for suitable loads.
• Charge an EV during solar hours where practical.
• Consider a battery only after modelling the extra cost.

What to enter in the calculator

For a home that's empty during the day with no battery, start with a lower self-consumption figure. For a work-from-home household or a home with daytime EV charging, try a higher case. Then compare the difference.

The calculator's battery uplift is deliberately simple. Use it to test sensitivity, not as a promise of exact storage behaviour.