Cptnvideo wrote:
"IMO, in order to actually use excess solar capacity, add battery storage capacity so the excess power can be used when needed."
Exactly. That is the correct thing to do.
I completely agree that the idea is to save the energy for later rather than "waste" it. Unfortunately I have no more room on the trailer tongue for more batteries. I don't want to relocate batteries inside as that would require moving to a different battery technology than my flooded lead acid GC batteries. A full battery technology swap is a very expensive alternative. Adding more batteries also requires that I have more solar than needed for my current battery capacity and that I could properly charge more batteries if I had them. Or that I need more of both batteries and solar for my needs. Neither of those situations are true, although admittedly I am thinking of a bit more solar as I explore remote work possibilities.
A heating element adds heat energy to water that I want heated, so it is a way of saving the energy for later as well. All of the daily energy not used for charging and other loads is still being saved in a heat reservoir vs a battery chemistry reservoir. I am disregarding the insulation of the hot water tank and other variables that allow for that heat energy to escape.
To me, the cool part about the diversion load idea is that 100% of solar harvest capacity is used throughout the entire solar day. If a solar charging system is designed to be able to fully charge your batteries, then for a good chunk of time your charge controller is going to be tapering the amps to the batteries. Whether you're using 280 watts of solar into a 200 Ah battery bank or 1600 watts of solar into a 1000 Ah battery bank, at some point the CC begins to taper amps. A heating element diversion load changes this tapering from on/off (use/waste) of the solar input to splitting it between charging & loads and water heater. 100% use, zero waste.
