question

@David Campbell

Firstly, have I got this broadly correct?

Short answer : NO

You may want to first spend some time on reading docs and watching presentations on the Victron web-site ...... Factor 1.0 rule applies to AC-coupled solar (AC-OUT1, not AC-IN), 16 kWh batteries and only 1.6 kWh solar ? etc.

Once you have done that, more useful questions/answers are possible.

Thanks for your message. Not sure why I'd thought it was AC-IN.

So instead, I would connect the micro.inverters to the Multiplus AC-OUT. That makes more sense.

Does the generator simply connect to AC-IN, and then I just set up the multiplus to charge from AC-IN?

I gather that if there is excess power from the micro inverters beyond what is being consumed by appliances then this will automatically be used by the Multiplus to charge the batteries too?

Anything else obvious I'm missing?

Thanks,

David

@David Campbell

I think you may find that you can't use the genset at the same time as the Enphase is producing. I doubt Enphase would recommend it either, even with a Multiplus in between them.

You may even want to set up a relay system to prevent it happening inadvertently.

I've been offgrid for years, and frankly wouldn't even consider installing a setup like that. Too clumsy, and fraught with the possibility of unstable ac. I run my genset whenever I want as well, set up to give dc solar priority if it's producing at the same time.

That's interesting. I'm talking about purely using the generator to charge the batteries. For example I could buy a 48v charger, connect that to the generator and batteries and presumably have no issues.

The Multiplus is a charger / inverter. Assuming I switch off features such as Powerassist, I wonder what the issue would be?

Just further to this, I've found a Victron schematic which appears to show the precise setup I'm trying to achieve:

https://www.victronenergy.com/upload/documents/SLD-Multiplus-II-AC-PV-and-gen-off-grid-2019-05-21.pdf

The problem is the schematic has no accompanying explanation, but it does appear from this that such a setup would be possible.

Hi Jonn,

Thanks for your help. I should have been clearer... this is not to run a home, but simply a system to power various items of portable equipment on a mobile site where there is no grid connection. The site is attended and currently we simply run the generator for a few hours whenever the batteries are running low. This doesn't need automating or anything clever, and the current setup works absolutely fine and has done so for a year.

The only thing I'm trying to do is augment the current setup so that the batteries also receive a charge from solar. (There are various reasons why micro inverters suit this application for us much better than a traditional solar DC system - involving setup time, the distribution of the panels, wiring lengths etc).

As you said, Victron don't seem to provide much in the way of information, but from reading their various guides it looks like one needs to -

- Connect generator to AC-IN (and set up as we have currently an appropriate charging current)

- Connect micro inverters to AC-OUT

- Install PV Inverter Support assistant and set up frequency shifting

There do seem to be some pitfalls but from what I can gather things should be ok if:

- The 1:1 rule is respected with respect to the PV inverter. In my application we are only talking about 3 or 4 panels so this is not an issue.

- You don't run the generator when the batteries are fully charged (or to be safe don't run it unless they need charging). This is no problem as we don't do it right now either.

I guess I'm just going to have to go-ahead with this and try it in practice. It is a shame that Victron don't supply more comprehensive guides for such an install.

David

@David Campbell when you will run the multiplus2 with frequency shifting on the enphase, you need a special profile from enphase for that. I Have running a Victron 3phase system with Multiplus2 10kVA here in Germany on Grid and on the AC-Out I have 52 IQ7A with frequency shifting. And last but not least, when the electricity suplier will reduce the power to the grid, they give me 4 Signals for reducing the IQ7A.

Juergen

Hi everyone,

I also have the same problem Off grid house (mountain high isolated house) with already mounted 3Kwc Enphase system and the grid is out and for long ( for > 2 years probably berore being rebuild ). I need then to go completely off grid. There is some info here and there on the site but I still crave for a clear presentatio of a system by one of you as to avoid mistake and minimize costs. Can you help ?