Solar PV baseboard heater

We need to develop a 120-240 volt DC space heater.
Use a oven coil.... $35
Use a DC thermostat to control a relay... $35 + $125
Overheat protection... $6

The more I think about what you said... the more obvious it is true...
and the light is really good compared to CFL and early LED lights.

As more and more CLF and incandecent lights get replaced with high light quality LED the percentage of KWH used to provide light will go way down.   Also cooling will go down as well.   Almost every watt going into a lightbulb has to be removed using another watt or so with the air conditioning.  Its a double wammy.

Also LED TVs are replacing CFL backlit TVs and monitors.    Less watts for lights, less watts for TV, less watts for cooling off the heat producing interior loads.  TV in america tend to be on for hour on end.   Its a significant load.

Overall KWH goes down but percentage of that bill for water heater will go up!   Its hard to cut water heater load to the same degree as going from incandescent to LED lighting.    Yes there are ways to conserve but that is not the same as tech making a product 10 times as efficient.

Water heating does not need to be distributed...

Not economic to distribute hot water typically.  Must be locally provided.
No transmission loss...


No arguing ..

That's the best part.   Solar fights are starting to get old and boring.
Easy self install..

Make a kit, sell on ebay.
No regulation..

Until the solar panel nazis implement surprise inspections!
Mostly off the shelf parts...

Yes,  not a custom tank.   Those are wayyy too much money.
No batteries...

Water heater is the battery
Low tech metal tank ...

Go to home depot. I can fit 2 or 3 50 gals in the back of my truck.   Elon Musk can't compete with that.
What could go wrong...

Solar is made for water heater...

If water heating uses 18% of the household energy... just imagine the power of our DC water heater design..

It may be 18% of the residential load now but that percentage I think is very likely to hit 25% or more.

If its PV direct like DC water heater idea the same concepts apply.

Yes.. agree..

Don't need special element (I don't think).    Just use standard baseboard heater.

Except AC thermostat switch and overide is built in

That is easy to deal with.   The thermal override switch is just like the electric water heater ECO.

Just wire (using low voltage wire):   12VDC power supply (+) -----> Power Relay coil contacts ------> external thermostat (if desired) ------> onboard thermostat (if installed) -----> Thermal Override -----> 12VDC power supply (-)

Then wire: (using power wire):  PV (+) ----> Power Relay (NO-C contacts) -----> Heater Element ----> PV (-)

I have onboard thermostats on all my baseboards.   They usually do not trip due to external control but it does make a very good secondary over temp safety.

The external thermostat can be low-voltage type,  usually simple baseboards are wired with line voltage thermos.

Other thoughts:

1) You could easily have one, two or even three baseboards wired in series to allow great amounts of downshifting during low solar input to maximize yield.   If they are in the same room its like multiple elements in a water heater heating up a single thing (one room).

2) PV DC baseboard heater isn't nearly as useful as the PV DC water heater.   Sometimes you just don't need heat but you will always need hot water.  The hardwired nature of the PV DC baseboard heater means its hard to shunt that extra power elsewhere.