Solar charge question

[ramsaymike]

Getting ready to install some solar on a 07 Concord 275. Plan is a basic DC only system with 4 x 100w panels and 2 x 6V 200ah batteries. I am a little - well maybe a lot - confused by the charging priority if there even is such a thing. Say my house base load is 100w, the batteries are fully charged and I driving down the road with 200w coming in from the panels. I assume that 100w is being 'deliverd' to the battery but from the solar system, the alternator or split somehow?
Given that I have excess solar over what is required, where does it go?
Hope this makes some sense. Thanks

[pianotuna]

There are 12 volt elements--but the wattage is pretty low. I've been known to switch on the electric water heater if the battery bank is full before solar noon.

[Lwiddis]

Propane is inexpensive. Clouds and darkness don’t interfere with it.

[2oldman]

ramsaymike wrote:
Why not heat water or run the fridge with the unused power?

You'd most likely need an inverter for that.

[ramsaymike]

red31 wrote:
some fancier controller have diversionary loads when the controller is limiting power production, like using excess power to heat water stored in the water heater.

This is sort of thing I was thinking about. Why not heat water or run the fridge with the unused power? It would seem obvious that you would try to maximise free energy. Thanks for the feedback.

[pianotuna]

Solar sends power to the engine in my case.

[valhalla360]

Generally...it just wastes any excess power.

In the boating community, some folks rig up a diversion and send excess power to the hot water heater once the batteries are topped up.

Keep in mind with lead-acid batteries, up to around 80%, you can dump quite a bit of amps into them but as you approach full, that drops off drastically.

[red31]

some fancier controller have diversionary loads when the controller is limiting power production, like using excess power to heat water stored in the water heater.

[ramsaymike]

Well, maybe I should look for other ways to use the available 200 watts - if that is practical or even possible...

[landyacht318]

I can easily tell via my throttle pedal and 5.2 liter v8 engine response, when my depleted battery is gobbling up everything the alternator can make, versus when the battery is full and my solar wattage is partially feeding the Ignition and fuel pump's 12 amp draw.

But record fuel consumption differences, Ain't gonna happen, but each 25amps the alternator makes sucks up one engine HP, so there will be an effect on fuel consumed.

Measuring/quantifying it is another subject. Easier to dimmiss it and drive a bit slower of one is concerned about mpg's

[naturist]

The solar charge controller’s job is to send power to the batteries, but only as much as they can absorb. When they reach full, the controller turns the panels off. They only produce power as long as there is a use for it. Think of a simple circuit, a single light on a battery. Turn the light off, the battery stops providing power.

[Lwiddis]

You could disconnect any charging of the house batteries from the engine but the savings in gas mileage would be minimal...not worth the effort IMO. At least some charging would take place in a night drive.

[time2roll]

You will not save any measurable amount of fuel going down the road by disconnecting the house battery charge circuit.

[ramsaymike]

Right! That makes sense. My interest concerns how to maximise the use of the available solar energy. Why use the energy from the engine when free solar energy is available?

[time2roll]

Generally what ever source is set to the highest voltage will get the privilege of supplying the actual power.

Where does it go? Like when you turn off a light where does the power go? Nowhere.

Anyway not to worry... multiple charging sources will not have any issues.