Where the figures live
Rates and production facts on this page are already on the solar record. The links below are the places to read them. This page repeats only figures those pages already carry.
- Methodology, how consumption benchmarks and citations are handled.
- How solar works, the meter, production serves the house first, then exports.
- How solar works, production, daylight output and snow cover.
- How solar works, questions, sizing when a new electric load is coming.
- Research library, four worked examples and the utility tariffs.
- Utility pages: ComEd, We Energies, Xcel Energy, Portland General Electric.
The same meter the solar pages already use
Solar research on this site does not begin with an appliance catalog. It begins with kilowatt-hours the utility has already metered and with the tariff that prices them. An electric water heater is one device on that meter. While the element or compressor runs, its draw is part of the household total a production estimate gets compared against.
The methodology traces household-consumption benchmarks to EIA-861 and treats the house’s own bill as the page-level input. This page does not open that dataset and pull a water-heater line. The useful question inside the existing record is narrower: does the heater’s draw land while the array is producing?
On-site use is the kilowatt-hour the tariff prices higher
The meter section of the solar explainer states the sequence in plain terms. Production feeds the house first. Whatever the house is not using flows back through the bi-directional meter. The utility’s tariff, not the water heater, sets the credit on that export.
Under ComEd Smart Solar Billing, the buyback page separates the two prices. Production consumed as it is generated offsets the all-in delivered rate, near 16¢/kWh. Production exported from a house that is not using it is credited at the supply rate, 9.66¢/kWh through May 2026. The same page names electric water heating, with heat pumps and EVs, as a load that can earn the delivered rate when it runs against live production. The page calls the export credit roughly half the per-kWh value of that on-site use.
That is a statement about coincidence and about a tariff already on the site. It is not a statement about how many kilowatt-hours a water heater uses in a year. This page does not add that figure.
A heat-pump water heater is still an electric load
The ComEd billing note lists a heat-pump water heater beside daytime air conditioning and daytime EV charging. The point of the sentence is retail value: a house that is actually drawing power during the production window keeps more kilowatt-hours at the higher rate, and a house that is empty at midday exports a larger share.
The solar record classifies that appliance as an electric load on the same bill. Its value to a solar customer, in the pages that mention it, depends on timing under the tariff already cited. This page does not add a consumption comparison between a heat-pump water heater and a resistance tank.
The worked example for that tariff
Lake Zurich is the Illinois house the ComEd pages are written against. The ComEd net-metering page is the tariff detail behind the buyback figures above. Brookfield, Centennial, and Beaverton are the other worked examples, on different utilities, listed in the research library. This page does not turn those houses into a water-heater table.
What stays off this page
Installed price, brand, tank size, rebate, and gallons per day are not in the solar pages this explainer is allowed to use. A homeowner who wants a consumption number starts from the utility’s own usage history, which is the same input the solar research already prefers to a generic average.
The timing question, whether a storage tank lets that draw move into daylight, is the next page: when a water heater draws power.
Existing research this page uses
Every rate and consumption figure above is already published on a solar page. This explainer adds none. Where the solar record has no water or HVAC number, the paragraph states the mechanism and stops.
- Illinois solar buyback rates . Names electric water heating among loads that earn the all-in delivered rate when production is used on site. Publishes the ComEd delivered rate near 16¢/kWh and the supply-rate export credit of 9.66¢/kWh through May 2026.
- How solar works, the meter . Production feeds the house first. Kilowatt-hours the house does not use at that moment export through the bi-directional meter.
- Methodology . Household consumption benchmarks on the solar pages trace to EIA-861. This explainer does not pull a new consumption figure from that source.
- ComEd Smart Solar Billing note . Names a heat-pump water heater as one daytime load that can take solar production at the higher retail value.