we’re on a campsite where we have a permanent pitch. I’ve installed an off-grid system with shore power in the equipment shed here.
Everything is working really well, and I’m self-sufficient most of the time.
My question is: how can I configure the MultiPlus-II so that it charges the battery to around 40% from shore power when the battery is low and there is no sun?
At the moment, it starts charging at 20% and then stops again shortly afterwards. It charges at around 500 watts, which means the relays are constantly switching back and forth. That’s obviously not ideal at night, as it disturbs the neighbours.
The system consists of a MultiPlus-II, a Cerbo GX, two MPPT controllers, a 24 V 100 Ah LiFePO4 battery and five 200 W solar panels.
That doesn’t change anything, so it will keep switching back and forth at 40%.
It’s supposed to discharge down to 20%, and if there’s no sunshine at night or during the day, recharge via mains power to around 40%—but how
do I set this up?
We have a fridge/freezer here that runs all the time, as well as the Wi-Fi router.
Most of the time, we manage without shore power, but when we’re here and it’s cloudy, the battery is occasionally flat in the morning (my wife drinks a lot of tea, and we need hot water too).
And when the relay keeps switching, which isn’t exactly quiet, it does get a bit annoying.
don’t let the AC input keep switching off and set the charging voltage lower accordingly!
That works brilliantly with an ESS configuration, but at a campsite you can’t just connect it as an ESS, even if you’re not feeding power back into the grid!
I always set it up so that the grid was switched on at a certain SOC, and then switched off again after the battery had been charged via PV and exceeded a certain SOC; otherwise, I couldn’t use any of the solar power! Hopefully, that will change next year!
Actually, your off-grid system with shore power is a contradiction in terms.
With a true off-grid system, you would have to charge your battery using an additional charger to achieve genuine separation. That would also be easier to regulate.
I know it’s not a proper off-grid system. Victron units were actually designed for applications like this, only my system isn’t on the water/in a boat.
I asked the owner of the campsite whether my system was okay like this, and he said yes.
I’m just not allowed to use ESS; feeding electricity into the grid is prohibited.
It wouldn’t make any sense anyway, since the meter would count the electricity fed into the grid as consumption.
We have several campers here with balcony solar systems who wondered why they had such high consumption.
Every now and then, I connected an external charger to charge the battery.
Why not set up an ESS with zero export and set the grid setpoint to, say, 10 or 20 watts? Then surely nothing will be fed back into the grid. The batteries will be discharged down to the minimum SOC, after which power will be drawn entirely from the grid. As far as I know, no relays click during the transition.
I’m not allowed to do that because it could feed electricity into the grid, even if it’s only a few watts, and the operator doesn’t want that. There must be a way for the MultiPlus to charge the battery to, say, 40% and then disconnect from the grid again. It basically does that already, but as configured, once the battery reaches 20% it only tops it up by around 600 watts and then disconnects again.
And the campsite operator has a control terminal in his office that shows him who currently has ESS enabled on the site? Or does he come by every day and check the settings on your MultiPlus?
Not now, though—you don’t have to abuse his trust. If it doesn’t work out the way I imagined, it’ll just stay as it is; it only happens a few times a year anyway.
Hello, I would try to solve this as follows (I have the exact same situation on my boat)(in line with what DirkW suggested): use the relay of the Cerbo GX as a start-stop for a generator, but the generator is actually the shore power that you can switch on and off based upon parameters, such as SoC or a certain load. It is a bit complex but has been done by several others. You can do some research on this community.
Shortly it comes down to the following: To make this happen, you connect the relay of the Cerbo GX with wire to one of the aux connections on the Multiplus. now follow 2 important steps, 1 is program the Cerbo Gx and 2 program the Multiplus with an assistant to ignore the shorepower (AC Input2).
Programming the Cerbo GX is as follows: In Remote Console under Settings, go to Integrations, go to Relays and set one of the relays to Genset start/stop. Go back to main screen of Settings and choose devices. At the bottom of the menu it says now Genset. In Genset switch Autostart functionality on and go to Settings, go to Conditions and enable Battery SOC and AC load. Click on Battery SoC and you can now set your personal preference for at which SoC you want the shore power to switch on and off. Go back and click on AC load, you can now set a personal preference for at which AC load (for example at 800 W) you want the shore power to switch on and for how long (that way when you boil water for tea, it does no unnecessarily drain the batttery).
To program the Multiplus do the following: Through the VRM portal you can download the settings of the Multiplus and change them with the Victron VEConfigure. In VEConfigure make assistants as seen in the attached screenshot. Upload the changed configuration file to the Multiplus through the VRM portal.
In VRM go to Dashboard and click on Controls. Switch on Autostart. You can also do a timed run (switch the shore power on for example for 2 hours).
It should now work (if everything was done correctly). Your batteries will be charged by the solar panels and when the SoC goes below the set minimum SoC, the shore power will switch on and keep charging your batteriestill the set maximum SoC. When you are present at the site and you use a heavy load over the set AC load, the shore power will also start charging the battery till the set time.
You can of course tweak this to your personal preference or by experience over time. You can also in Victron Connect or VRM switch the shore power manually on and off to charge the battery or you can switch it on for a certain amount of time. Good luck.
