Solar: Panels, controller

[Yellowjacket]

Thank you both. I'd assumed if panels were linked in parallel to a single controller, it would not be able to maximize for both a shaded panel and an unshaded panel. I was surprised how little voltage drop I saw with six cells shaded, but did not measure amps in that situation.

noelex 77, thank you for that very complete explanation. How do separate controllers divvy up the demand from the battery (and running loads)? Is the Victron "local talk" required, or is the system dynamically self-regulating, each panel contributing amps based upon what it's capable of at the 14.6v of your example?

Is there a "system" upper limit of total amps? It would appear that my panels are capable of significant amperage, all in. Is there a danger of over amping battery bank or wire on a bright sunny day, or does absorption capacity rate of battery preclude this?

With that in mind, I suppose my 1.8 Kw of proposed solar might be a bit, just a bit, of overkill. I will have to see how the first three panels perform in the real world of the cloudy Pacific Northwest while driving refrigerator compresor, ancient two-pump WH autopilot, and add in the spec of a water maker.

Thank you again,

~ Erik Dolson

[noelex 77]

Originally Posted by Erik Dolson

noelex 77, thank you for that very complete explanation. How do separate controllers divvy up the demand from the battery (and running loads)? Is the Victron "local talk" required, or is the system dynamically self-regulating, each panel contributing amps based upon what it's capable of at the 14.6v of your example?

Normally multiple solar controllers will play together nicely. When regulating, one controller may be delivering more current, but the batteries only need the required voltage and don’t care if more current is coming from one panel.

However, Victron’s “tail current termination” feature can be immensely annoying in the situation of multiple controllers. Victron need to fix this. There are some manual work arounds, but few owners will bother and they require manual monitoring. The optional device to link the controllers is new. I have not tried this, but it will not all Victron controllers and
user reports suggest a very limited range,so it may not work in some installations.

Originally Posted by Erik Dolson

Is there a "system" upper limit of total amps? It would appear that my panels are capable of significant amperage, all in. Is there a danger of over amping battery bank or wire on a bright sunny day, or does absorption capacity rate of battery preclude this?

This is not normally a problem. If you have a very large solar array and a very small battery bank, you can specify a maximum charge current for the controllers with a simple setting adjustment, but this should not be necessary.

Originally Posted by Erik Dolson

With that in mind, I suppose my 1.8 Kw of proposed solar might be a bit, just a bit, of overkill. I will have to see how the first three panels perform in the real world of the cloudy Pacific Northwest while driving refrigerator compresor, ancient two-pump WH autopilot, and add in the spec of a water maker.

If you have room, more solar is great. Solar panels are super reliable, quiet, generate no heat, and have no maintenance .
Doing without a generator very much simplifies the boat, and reduces the chance you will stuck waiting for repairs. If you can fit enough solar to meet this this goal, it is a very worthwhile aim.

[Yellowjacket]

Your expertise has been extremely valuable, and affirmation of my genset aversion very welcome. I'll keep you posted on how it works out, and share research on the wired communication between controllers. Thank you, ~ Erik