Advice for roof mounting a solar panel awning.

I don't think you can get a tank style water heater to stay warm even with both elements running. They have internal baffles to try and keep the incoming cold water from mixing with the remaining hot water. That must help. Once you have used what the tank holds the water will come out cold.
I will sometimes run the 1400watt element and the propane heater. It extends the hot water a little. But will never be able to heat the incoming 2 gallons per minute fast enough to act like a tankless heater.
Correct, typically incoming water has a pipe pushing it at the bottom of the tank and the hot water flows from the top so it'll drain the hot before the cold. But running the heater or both heaters will help just not much. Might add 1 more gallon of hot during the shower might add 4 just depends.
Wait a second. I might be way off about the 24v water heater element. Maybe he used a 220v water heater element on his 120v water heater. Confusing myself here. Doesnt that 1/4 the power?
Say you take a 1000watt 220v element and give it 120v. Does it produce 500w or 250w? I feel so braindead right now!! Could go for a drink and maybe some food.