Victron Blue Solar 100/20 with 400W of panels

[cmcardle75]

According to the spec sheet for the Victron Blue Solar 100/20

"If more PV power is connected, the controller will limit input power. "

Does this really mean that provided the short circuit current rating of the panels doesn't exceed 20A and the open circuit voltage doesn't exceed 100V (wiring in series), I can connect loads of solar (i.e. much more than 290W) and just have it throw any excess away? I only want more panels to give me power in marginal conditions (i.e. winter). I don't care if it needs to throw away energy in summer. If it can produce 20A bulk charge to the battery that's more than enough for my needs (TBH, 10A would be fine).

I'd prefer to buy the 100/20 over the 100/30 as I would like to use the load terminals for the compressor fridge (and it's cheaper), but I can fit about 400W of panels up there. Actual array would be something like 7.1A short circuit current at 66V open circuit, so well within the max current and voltage of the controller, but also well over the maximum rated output power in full sunlight.

 

[Two on Tour]

I had this conversation with the guy at 12 Volt Planet a couple of months ago as the extra panels I was adding to our van was going to take the wattage over the upper limit of our Victron SmartSolar 100/20 if the panels achieved their max output by about 10%.
My concern was would the controller be damage if the panels output exceeded it's quoted limits. He had spoken to Victron some time ago about this and Victron had stated that the controller would only see and process the max of 290 watts and ignore the excess over that. The controller would not suffer damage unless the higher that stated input wattage was continuous for long periods.
In my case I fitted an additional Victron SmartSolar 75/15 to handle the new panels

 

[paddymcc]

[
The controller would not suffer damage unless the higher that stated input wattage was continuous for long periods.
[/QUOTE]
That's interesting,I guess you could therefore isolate one of the panels by pulling a fuse up on the roof to avoid that situation?

 

[cmcardle75]

[
The controller would not suffer damage unless the higher that stated input wattage was continuous for long periods.

That's interesting,I guess you could therefore isolate one of the panels by pulling a fuse up on the roof to avoid that situation?
[/QUOTE]

It doesn't mention anything about this on the spec sheet, just that the power is automatically reduced. I'm only talking about 400W nominal or thereabouts. It'll almost never reach the 290W recommended, let alone stay high for long periods! I'm definitely sold on the 100/20, as the 100/30 has no load outputs. Almost tempted by the 75/15. That would be technically within spec and significantly cheaper again. Wouldn't be bothered by the 15A charging limit on the battery.

 

[cmcardle75]

[
The controller would not suffer damage unless the higher that stated input wattage was continuous for long periods.

That's interesting,I guess you could therefore isolate one of the panels by pulling a fuse up on the roof to avoid that situation?
[/QUOTE]

You could stick in a switch to turn off one of the panels easily enough (slightly easier for parallel, but still doable for series).

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[Bobby-gg]

Just a warning about the load terminals on the Victron, and this is from personal experience, not just something that "I read on the Internet"

I first installed my Victron blue solar controller back in early 2017 with a 250w panel on my VW T25, limited space meant that the leisure batteries are under each seat, so the charge controller went under there too.

Had no issues whatsoever until the May Bank Holiday weekend when it was stinking hot, proper not a cloud in the sky hot, arrived at a festival and plugged in the Vango pump to blow the awning up.

Got one tube inflated when the output of the controller switched off, and with wall to wall sunlight I couldn't understand why.

Checking the battery voltages, everything was suggesting that it certainly wasn't low voltage, but after a little googling turns out that the controller would also switch off when it decided it was getting too warm. But checking it wasn't actually getting warm at all, turns out it was a fault within the design of them

Found this out from another T25 owner who also installed one, he is a YouTube'r and has serous long term issues with his in Spain.

I ended up using an external low voltage cut-off direct from the battery supply, and I've never had any issues since.

Don't know if any of the software upgrades since have rectified the issue as mine works as it is.

Just a warning since you plan to use the controlled output

 

[Off da Grid]

I was wondering if it’s possible to split the charge between 2 controllers, as in one cable from the panels split to feed the controllers in parallel.
I would like to put more panels on the roof but it was such a pain to get the cable down to the controller I don’t want to run another set.
I have a 255w panel feeding a votronic duo 350.
ive got room up top to swap the 255w panel for 3 of the newer 200w German panels.
I like the votronic controllers so would want to stick with the brand

 

[autorouter]

The voltage rating is a hard limit, you should make sure the input voltage from the panels never exceeds this. Voltage is specced at 25 degrees C, and voltage goes up when colder. Bright sunshine on a cold autumn or spring morning can be a problem, don't get caught out.

The current (amps) rating is for the controller OUTPUT to the batteries, not the input from the panels. So the 290W limit represents 20 amps at 14.5 volts into the battery. This is not a hard limit, and the input to the controller can be greater, up to 50% extra I think, without damage. Don't forget that even at 290W, if the battery is fully charged the controller will waste all the 290W safely, that's what it's there for.

 

[Raul]

Like autorouter said, you can have more panels safely will handle them IF the input short circuit current is not exceeded. This will be smaller than output of the 20A. And the 100voc limit is met. At 66voc voltage open curent you are safe even at -20C (79v) but do not put to many panels in parallel to exceed the short circuit INPUT. I have a 75/15 for the outside lighting and manages ok two 250w panels in parallel. The reason is because are two different orientations, and can never supply full power. I suspect the 75/15 has a short circuit INPUT limit of 10A. The 100/20 could be 10 or 15A INPUT. The load terminals turns the lights on and of and that’s what was intended and engineered
for, low loads NOT fridge with a surge start. If you whant to do that, then the proper way is to wire a relay to the load terminals and have the relay dealing with the heavy switching. The Big load should be fed from the battery not controllers load output; unless is only a small load like lights. That’s why it goes south, overloaded. Take time and read the manual in detail and you will see clear it’s limitations.