Daytime electricity use matters because solar generation and household demand do not always line up. A yearly electricity bill cannot show that overlap on its own. Separate what is generated, what replaces an import and what remains surplus before deciding whether an advertised saving makes sense for your routine.
The value of solar depends partly on how generation overlaps with electricity you would otherwise buy, not simply whether you are at home.
Generation and demand happen at the same time
Energy Saving Trust explains that using solar electricity at home and exporting surplus are different outcomes. Being at home can help create demand during generation, but a person working on a laptop is not the same load as every appliance running continuously.
For a first assessment, describe an ordinary weekday and weekend. Note when electricity is used, not just whether someone is present. A household that is out during office hours can still have daytime demand; the amount needs evidence rather than an assumption.
A one-hour example
Imagine solar supplies a constant 0.4 kW for one hour while the home uses a constant 0.25 kW, with no storage and ignoring losses. Generation is 0.4 kWh, of which 0.25 kWh meets household demand and 0.15 kWh is surplus. These are invented values to explain the arithmetic.
At an illustrative import price of 25p per kWh, avoiding 0.25 kWh of imports is worth 6.25p. Multiplying the full 0.4 kWh by that import price would overstate the avoided purchase in this example. Any export payment would need a separate, eligible arrangement.
Use your own consumption information
Where available, look at the half-hourly or hourly electricity data in your energy account. Compare several ordinary days rather than choosing the busiest day. Keep holidays or unusual appliance use separate from a typical pattern.
You do not need to send a supplier your entire account history to ask a sensible first question. A summary of timing and consumption can start the discussion. Remove account numbers and unrelated personal details from any documents you share.
Do not buy storage on an assumed saving
Ask for the solar-only case before considering a battery proposal. Then request the additional cost, extra usable energy and connection requirements of storage as a separate comparison. A battery is not automatically justified by being away during the day.
Check the current plug-in specification before assuming storage can be attached to the same device; its scope excludes integrated plug-in battery systems. Use our battery guide to distinguish those routes and request a proposal for the exact equipment.
Daytime electricity use: follow one hour of energy
The example assumes constant output and demand for one hour, no storage and ignores losses. It uses invented figures to show the calculation, not an actual customer's data. Repeat the reasoning with credible time-based estimates before drawing a conclusion about a year of savings.
| Quantity | Amount | Treatment |
|---|---|---|
| Solar generated | 0.40 kWh | Total energy produced in this example. |
| Used in the home | 0.25 kWh | Replaces an import in this example. |
| Surplus | 0.15 kWh | Not valued at the import tariff here. |
| Avoided purchase at 25p/kWh | 6.25p | 0.25 × 25p; excludes any export income. |
Common questions
Is my annual electricity use enough to estimate solar savings?
It is useful background, but it does not show when demand occurs. Two households using the same annual total can have different overlap with solar generation. Ask which timing assumption a forecast uses and whether it reflects your routine rather than accepting an unexplained self-consumption percentage. Plug-in solar costs, savings and payback explained.
Should I run extra appliances just to use surplus solar?
Using electricity you did not need is not an avoided purchase. Assess demand you would otherwise have paid for, and follow appliance safety instructions when considering any timing changes. Do not inflate a savings estimate by inventing additional consumption simply to absorb the modelled generation. Plug-in solar batteries: compatibility and buying checks.
General information, checked against the linked sources on 6 September 2026. Rules and products can change. For a decision about your property, use the current official guidance and appropriate professional advice. Tell us about a correction. How we prepare our guides.
Compare for your property
Compare named plug-in kits, recorded prices and package contents, or get a shortlist for your own home.
See solar options