Self-consumption is the share of solar electricity the building uses while the panels are producing it. That energy never passes the meter as a purchase and never passes it as an export. What leaves the building is export. The bill treats those two flows differently as soon as the tariff stops valuing them at the same rate.
Why the hour of use matters
A household that is empty at noon exports a large share and buys power at night. A workshop that runs at noon self-consumes more of the same array. The array did not change. The overlap of load and sun did. How a tariff banks or prices the exported part is the subject of what net metering means. An export limit that refuses to let the surplus leave is a different control, in what an export limit does.
Raising self-consumption can mean moving a flexible load into the sunny hours, or storing midday energy for later. The storage version is only attractive when the export price is worse than using the energy yourself, after losses. Timers on a water heater or a pool pump are the cheap version of the same idea, and they do not cycle a battery. They also do nothing for an outage.
What a percentage on a proposal is hiding
A self-consumption percentage without the load shape is a decoration. Ask what loads were assumed to run at noon, whether a battery was included, and whether export was paid at retail or at something lower. Two proposals can show the same percentage and very different bills. Production estimates that ignore this split and treat every kilowatt-hour as retail savings are the estimates to reject. The payback page shows how that split moves the year, with figures marked as hypothetical: how a solar payback period is calculated.
Self-consumption does not keep the lights on when the grid fails. A grid-tied inverter stops with the grid. Backup is a transfer and a battery, described in home battery backup for outages.
How to read the meter, not the app slogan
On a day with steady sun, note the production the inverter reports and the energy the utility meter says you bought and sold. The gap between inverter production and utility export, during hours the building was using power, is the self-consumed part, before you argue about losses. One cloudy hour does not make a percentage. A week that includes a work-from-home day and an empty day will show how much the load, not the panels, is driving the number.
Proposals that promise to “raise self-consumption to 80 percent” without naming the battery size, the load that moved, or the export price are not yet a design. Ask which kilowatt-hours moved from export into the building, and what those kilowatt-hours were worth on your tariff before and after. If the answer is a percentage with no tariff, you are looking at a marketing slide.
