How do you measure Solar Output to system

[hpeer]

Originally Posted by Steve O

My original question was meant to be more about how do I measure what do my solar panels contribute to the battery bank on a daily basis? It would seem that a new more sophisticated controller might be in order. Any suggestions for a reasonably priced one with monitoring of amp hours?

I was not looking to shut the boat down and drain the batteries to see what they could do.

That’s what I was trying to answer. Something simple. Are they working?

[john61ct]

Originally Posted by hpeer

IMHO if you want a simple Go/No go test it is enough to see that the voltage on the input (panel) side is higher than on the battery side. How MUCH the difference should be is another matter I would like to hear opinions on.

Other than that there are so many variables and losses as to make definite evaluative measurements somewhat difficult.

My panels are advertised at 310 watts but have a “typical” (or equivalent weasel word) of about 285 watts
Line (resistive losses)
Connector losses
Dirt on panel
Shadows
Angle of sun
Transmisitivy of atmosphere
Can all conspire to reduce your output.

Then, if like me, you have a wind generator the panel controllers will be tracking somewhat above the wind gen output. Maybe.

It gets a bit complicated.

But if your panel/controller input voltage is somewhat above the output voltage, consistently over a range (say 12.5 to 12.8) then it’s probably working OK.

THOUGHTS?

Again, this does not pertain to the OP, which IMO has been answered, pending OP asking for more specifics on solar controllers with that feature, standalone AH counters and/or bank monitoring.

To address the side issues you raised, standard "nominal 12V" panels usually output 18V or sometimes a bit more.

This is suited to PWM SCs, which just discard higher voltages than the minimum they need, say 4-5V over charging output.

MPPT controllers maximise their increased efficiency with higher voltage panels, 36+V is normal for "nominal 24V" panels, grid-tie house panels can get up much higher.

For further discussion, start a new thread as again, nothing to do with the thread topic.

[john61ct]

Originally Posted by Steve O

It would seem that a new more sophisticated controller might be in order. Any suggestions for a reasonably priced one with monitoring of amp hours?

The newer Victron MPPT line that includes the dongle bluetooth functionality is low priced for smaller units, let you view logs on your phone.

Nothing wrong with multiple SCs, even one per panel for optimal shade handling.

[boatpoker]

Originally Posted by Steve O

My original question was meant to be more about how do I measure what do my solar panels contribute to the battery bank on a daily basis? It would seem that a new more sophisticated controller might be in order. Any suggestions for a reasonably priced one with monitoring of amp hours?

I was not looking to shut the boat down and drain the batteries to see what they could do.

See Post #17

[stormalong]

Originally Posted by Steve O

My original question was meant to be more about how do I measure what do my solar panels contribute to the battery bank on a daily basis? It would seem that a new more sophisticated controller might be in order. Any suggestions for a reasonably priced one with monitoring of amp hours?

I was not looking to shut the boat down and drain the batteries to see what they could do.

See post six.

I am using an old Cruising Design battery monitor just on the solar. It is a single battery monitor. I also have a dual battery version on the whole electrical system. I am sure that if you shop around you will be able to find many equivalent monitors today.