"GBM" wrote in news:5vvzg.53527$Uy1.48756
@read1.cgocable.net:


"Geoff Schultz" wrote

You can get elements that have both 120V AC and 12V DC feeds. See
http://www.svhotwire.com/divert_loads.html


That's great, but:
- how is the water temperature controlled? Temperature should not exceed
49C to prevent scalding (used to be 60C)
- Once water reaches maximum temperature, what do you do then?

Seems to be of limited value if engine is also used to heat water. Our hot
water gets up to about 45C after an hour of motoring at low speed. It is
self limiting because of engine thermostat.

GBM

I would say that if you have large enough panels to worry about this, then
you should use the controller in PWM mode. Solar panels don't require a
load. Wind generators do. I use 1 controller for both.

In real life I rarely have problems with the batteries being completely
charged while cruising. I only have 2 panels that output 68W *peak* each.
The only time that I have the luxary of fully charged batteries is when it's
been blowing 15-20+ for a day or two and my wind generator is cranking.

Remember, this is a boat and there's no one-size-fits-all solution. You can
always buy a resistive load such as the one at
http://www.svhotwire.com/divert_loads.html, but then you have to do something
with all of that heat. I can always find something to do with my "extra"
power such as making more water and washing down something on the boat.
Don't go crazy solving a problem that probably doesn't exist in real world.

-- Geoff