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

“Given that I have excess solar over what is required, where does it go?”Yes, you are over the benchmark one solar watt per battery amp hour. However, on overcast/cloudy days you’ll be happy with those extra two panels. Excess goes no where. The controller determines what the batteries will accept and doesn’t pass any additional juice.You’ll love your solar system.

ramsaymike wrote: I assume that 100w is being 'deliverd' to the battery but from the solar system, the alternator or split somehow?I'm not familiar with your coach, but are you positive the alternator charges the house? Theoretically, the charging source with the higher voltage will overtake the other.As for where excess power 'goes', I'm not sure. My best guess is it's dissipated as heat in the controller. Another guess answer is it acts like a battery.. no draw, no power.

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.

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?

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

Solar charge question | Good Sam Community

16 Replies

pianotuna
Nomad III
Mar 02, 2020
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
Explorer II
Mar 02, 2020
Propane is inexpensive. Clouds and darkness don’t interfere with it.
2oldman
Explorer II
Mar 02, 2020
ramsaymike wrote:
Why not heat water or run the fridge with the unused power?
You'd most likely need an inverter for that.
ramsaymike
Explorer
Mar 02, 2020
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
Nomad III
Mar 02, 2020
Solar sends power to the engine in my case.
valhalla360
Navigator
Mar 02, 2020
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
Explorer
Mar 02, 2020
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
Explorer
Mar 01, 2020
Well, maybe I should look for other ways to use the available 200 watts - if that is practical or even possible...
landyacht318
Explorer
Mar 01, 2020
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
Nomad
Mar 01, 2020
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.