Hybrid solar panel + hot water

[Tin Tin]

Any one thought about or have installed one of these on a boat, seem like a good solution for heating water rather than using engines or inverters.
https://www.supremeheating.com.au/wp...sheet-v1.3.pdf

[Tin Tin]

A better link https://dualsun.com/en/solutions/sol...water-heating/

[tsell]

https://www.custommarineproducts.com...for-boats.html

[Tin Tin]

Originally Posted by tsell

https://www.custommarineproducts.com...for-boats.html

Thanks, I was searching about 3 years ago and could not find this type of solution
Cheers

[rabbi]

Why not use the existing hardware? Of course only if you have enough electricity and a suitable inverter.

I don't want to stress my batteries or inverter for hot water so first thing I did was replace the factory 1.x kW heating element with a smallish 500w one (Quick Marine 500w element costs 75€).
The old heating element looked worn and it's anode was already gone so it was time to replace anyway.

Initially I used a timer plug to run it on-demand for 1h on the press of a button. The inverter draws about 45 Amps to power it, so running it in 1h chunks sounds feasible to not accidentally drain the batteries.



Since I have a RPi running Victron's Venus Large image with NodeRed I opted for some smarter control:
The Heater is plugged into a Shelly Smarthome plug. The Shelly plug communicates to NodeRed via the MQTT broker available in Venus.

NodeRed switches the heater on if SoC is >90% and no other AC or DC loads are present, but only between 10am and 18pm or if the shore charger is plugged in.
Switches off automatically as other loads come up or SoC drops below 90%.
The shelly is configured to automatically switch off after 1h. Even if communication fails or my code has errors the heater doesn't drain the batteries.


The inverter typically runs 24/7. Even though I could control it from NodeRed I want this under manual control so we use the manual switch.


Bottom line: No special hardware, no messy work, no routing of hoses, no moving parts or pumps, no leaks. Hot water every day for the total cost of 85€ and a day of learning NodeRed.

I have 1kWp of solar, 3kWh LiFePo and a 2kW inverter and this setup doesn't stress anything at all. On sunny days solar will more or less keep up with the load, and the inverter stays cool and doesn't even start it's internal cooling fan.
It should work OK with a setup 50% smaller than ours.


BTW: The same control code will be re-used to run a dehumidifer during winter storage.

[GordMay]

We used a 17 litre Portable Hanging Solar Shower Water Bag [±$10]

[rabbi]

also an option