Solar water heater: single tank systems #1492
Description
Right now, we have some rather strange approximations used for solar water heaters with electric backup where we have jacket insulation with a very specific R-value. These systems in reality are single tank systems, where the backup element is in the top of the tank like this:
The default in ResStock (and I believe OS-HPXML as well) is to assume a two tank system, where there's a separate solar storage tank and then a backup water heater. That's definitely the norm for fuel fired backup on solar water heaters, but not electric backup. At some point we might want to change the way these are specified, but seems super low priority as we have a workaround. I might just specify a name change on the options meant to approximate single tank so no one gets confused, and leave this open as some sort of future not urgent TODO.