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.
Production has a clock
A rooftop array produces in daylight. The meter explainer is explicit about the next step: the house takes what it is using, and the rest exports. A water heater that recovers at 2 a.m. is outside that window. A water heater that recovers in the early afternoon can be inside it.
The Illinois buyback page uses the quiet midday house as the export case. Production is high, occupancy is low, and the exported kilowatt-hour is credited at the supply rate rather than the delivered rate. Moving a flexible load into that midday stretch is how a household changes the mix. The solar pages already say the mix matters. They do not assign the water heater a savings dollar.
A tank stores heat, so the electrical draw can move
Resistance elements and heat-pump compressors put heat into stored water. The tank holds that heat after the electrical equipment stops. Someone can draw hot water in the evening from a recovery cycle that ran hours earlier. That storage is why water heating is a candidate for the same move the solar notes already describe for laundry, dishwashing, and EV charging.
The ComEd billing note names the heat-pump water heater in that list directly. Running it during the production window converts kilowatt-hours that would have exported into kilowatt-hours used on site. The note says the shift does not need to be perfect to change the blended value. It does not publish a kilowatt-hour total for the appliance, and this page does not supply one.
The gap depends on the tariff already published
On ComEd, the buyback page prices on-site use near 16¢/kWh and exports at 9.66¢/kWh through May 2026, and it describes the export credit as roughly half the per-kWh value of on-site use. Shifting a water-heater cycle into the production window matters there because those two prices differ.
On We Energies, the difference is wider. The Wisconsin solar note puts the delivered rate near 19¢/kWh and the avoided-cost export credit near 4.2¢/kWh, and it states that a self-consumed kilowatt-hour is worth roughly 4.5 times an exported one. A recovery cycle that runs after sunset misses the production window entirely. The midday production it failed to absorb has already left at the lower credit. The note’s remedy language is about self-consumption and, separately, batteries. This page borrows only the rate gap and the idea that flexible daytime load changes the share.
The gap shrinks where export is credited near the retail rate. The Xcel Energy page credits residential exports at the full retail rate, near 15¢/kWh, and describes a Solar*Rewards payment of about 2¢/kWh on generation under the program terms published there. Under that structure, using a kilowatt-hour in the house and exporting it are much closer in price, so the clock on the water heater moves the bill less. Portland General Electric’s utility page describes standard net metering that credits exports against consumption. That summary does not print a cents-per-kWh export rate, so this page does not invent one. The mechanism is the same: retail-style export credit leaves less to gain by chasing the production window.
Four worked examples, four tariffs
The gaps above are the ones already written for Lake Zurich on ComEd, Brookfield on We Energies, Centennial on Xcel Energy, and Beaverton on Portland General Electric. How those pages treat a household bill is on the methodology page. None of them publishes a water-heater kilowatt-hour total, so this page does not add one.
What a shift is, on this site
A shift here means a change in when an existing electric load runs, judged against a tariff the solar research already documents. It is not a product recommendation, a control-brand endorsement, or a rebate. Occupancy, tank recovery, and the actual tariff decide whether the move is worth making. Those household facts are not in this repo.
The load itself, before the clock, is covered in electric water heating on the household bill.
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.
- ComEd Smart Solar Billing note . Describes running a heat-pump water heater, along with laundry, dishwashing, and EV charging, during the production window so more kilowatt-hours are self-consumed.
- Wisconsin solar note, 2026 . Publishes We Energies on-site value near 19¢/kWh and export value near 4.2¢/kWh, and states that a self-consumed kilowatt-hour is worth roughly 4.5 times an exported one.
- Xcel Energy utility page . Publishes retail-rate export credit near 15¢/kWh plus a Solar*Rewards production payment of about 2¢/kWh on generation.
- PGE utility page . Describes standard net metering that credits exports against consumption. The summary does not print a separate cents-per-kWh export rate, and this page does not add one.
- How solar works, the meter . Exports happen when the house is not using production in that moment. Compensation is set by the tariff, not by the appliance.