First of all, some low flow shower heads are pretty good. Some are terrible. YMMV. Also most of the time there is reducer that you can remove without resorting to drilling.
Second - location matters in these discussions. Ground water temperature varies across the country and that impacts recovery a decent amount.
Third - Gas hot water heaters have much higher standby losses than electric. With solar pre heating, this is quite important. In the summer, you could preheat the water before the gas heater and then lose the heat in the gas part. Heat that you would not lose in an electric tank. Most gas hot water heaters lose heat up the chimney. They have gotten better but it is still a pretty big issue.
Fourth - If you have solar pre heating, then you presumably have a tank before the main tank. This adds to your hot water capacity. Obviously in the summer if you have 80 gallons heated to 150 degrees, you have more than 80 extra gallons. And even in the winter, you get some pre heating. Even during a solar eclipse for a week, the tank is presumably in conditioned space and would still be slightly pre heating the ground water. But this obviously depends on your situation (tank location and ground water temp)
A well designed solar pre heat situation will still take ground water from 55 (guessing) to 90-100 in the depth of winter. Does Auburn even have a depth of winter? Heating water from 90 to shower temp (105?) is like 3 times easier than 55 to 105.
But last, you are not likely to use much electricity with a heat pump hot water heater with solar pre heat. It might be 1000 kwh a year on the high side. So don't expect to use that much free electricity. And most of that will be in Dec/Jan if that matters for your net metering/loss of excess credits.
Second - location matters in these discussions. Ground water temperature varies across the country and that impacts recovery a decent amount.
Third - Gas hot water heaters have much higher standby losses than electric. With solar pre heating, this is quite important. In the summer, you could preheat the water before the gas heater and then lose the heat in the gas part. Heat that you would not lose in an electric tank. Most gas hot water heaters lose heat up the chimney. They have gotten better but it is still a pretty big issue.
Fourth - If you have solar pre heating, then you presumably have a tank before the main tank. This adds to your hot water capacity. Obviously in the summer if you have 80 gallons heated to 150 degrees, you have more than 80 extra gallons. And even in the winter, you get some pre heating. Even during a solar eclipse for a week, the tank is presumably in conditioned space and would still be slightly pre heating the ground water. But this obviously depends on your situation (tank location and ground water temp)
A well designed solar pre heat situation will still take ground water from 55 (guessing) to 90-100 in the depth of winter. Does Auburn even have a depth of winter? Heating water from 90 to shower temp (105?) is like 3 times easier than 55 to 105.
But last, you are not likely to use much electricity with a heat pump hot water heater with solar pre heat. It might be 1000 kwh a year on the high side. So don't expect to use that much free electricity. And most of that will be in Dec/Jan if that matters for your net metering/loss of excess credits.
