Hi there! new in the community. I have an off-grid cabin in Sweden with a small 800w setup today with an MPPT 100/50.
I just ordered myself 5kwp of panels that I will use as roofing on a firewood shed - and I would like for them to be used for charging my EV with excess solar power (which will be plenty, since we dont run much more than a couple fridges and some LED light when there). We do not plan to run a big battery, just a small one, since the cost will outweigh the benefit (and our budget ;)).
The idea is when we are in the cabin for longer periods, the excess power charged to the EV battery would provide for some real actual range for us, instead of having to rely on public fast chargers. Even at full PV production I expect a full charge to take several days (EV has 100 kWh battery).
From what I can read in manuals, I should be able to do this with the Victron EV charger + RS Smart Solar 450/100 + Cerbo GX. Anyone done this off-grid and can confirm this is possible? My wifes face if I buy all of above and it doesnt work as intendedā¦
Anyone have a better suggestion for what hardware to use? Struggling to understand the difference between Multi RS and RS Smart for my use caseā¦ RS Smart seems to do the job I need at a lower priceā¦
Of course I will have an electrician help install it all, what I need here is āproof of conceptā if you know what I mean.
Knowing the excess power in a victron setup is not very evident for a regular non-coding electrician. It takes some Node-Red programming skills to get all the excess power into a variable load like a controllable EV-chager. I faced the same challenge in an off grid scenario. It is a matter of writing your own code to make it work. What I did was using dvcc to control my batt. charge current to 20A and wrote my own PID controller to reduce that charging current to 18A by adding loads (water heating boiler instead of ev charger).. This during the ābulk charging part of the processā. After that during absorption/float I use a second PID controller to keep the battery to a certain voltage. (lowering the voltage by adding loads). The thing with MPPTās is that they donāt know the excess headroom in solar power and donāt report it to the GX system. You will have to be creative.
Do you happen to own a type 2 mobile EV charger? One with a normal plug on one end? That will work as well you know.
With 5kWp PV I guess that youāll face a maximum of 16A/3.6kW for the charger. On a good day.
The RS6000 is a no brainer for many. A bit expensive, maybe, but no MultiPlus II hum. A third of the MOIi weight, higher efficiency, a good choice for sure.
If budget is a limiting factor. What about your skills? Could you make your own battery, run a RPi instead of a Cerbo? What capacity is āa small batteryā in your book?
We went for the Cerbo GX MKII plus 7ā display. Iām too old / busy for a Rasberri PI. Not to mention that I want it to ājust workā.
Hej Chief! Hehe, I give you a lot of points for trying though :).
RPI is way past my abilities, and also I think Iād just like to run something that really works. My battery right now is a 360 Ah lead-acid :-D. If I can continue with this for a while I am happy, because it does cover all our needs. If not enough, Iāll upgrade to a 5 kWh li-ion (LifePO or whatever). The setup obviously will be grossly PV-biased with very small battery compared to the PV - but the idea was simply to use the excess solar directly on the car. When we are not there, probably a lot of potential will be lost but I am OK with that - or I might install small things like a heat pump, etcā¦
I think the setup with the RS6000 will be correct for me, and as I understand it if I get myself a multiplus II it doesnt have solar input (MPPT) so I will just add more cost to the setup, right?
I do have several different mode 2 chargers, but what I found interesting about the Victron charger is it says in the manual that in automatic mode it will detect surplus PV energy itself and adjust the amps. Now that is exactly what I want, so that it will harvest the full 5 kW when the PVs are working optimally, but also just take out the 2 kW when that is available i.e. late in the day or on a cloudy day. A standard charger will just have one fixed setting. From the manual of the Victron Charger I get the idea it will do this, just need the final confirmation this will also work in a fully off-grid system:
Automatic mode to ensure maximum PV system efficiency
Thanks to the seamless integration of the EV Charging Station with the rest of the Victron installation, it detects when there
is a surplus of solar power and uses this exclusively to charge the vehicle or, if desired, adds energy from the grid to cover
the minimum power requirement, for example, if there is not enough surplus solar power. Note that this mode requires a GX
device in your system and communication between GX device and EVCS enabled. For details, see chapter VictronConnect
setup, configuration and operation [9] and EV Charging Station setup web interface [37].
I
How does it work?
The EVCS will automatically start charging when the vehicle is connected and the following conditions are met:
The current state of charge is above the 'Start charging at backup battery SoC (%) value.
There is enough excess solar power available, with excess solar power calculated as follows:
ā¢ Excess solar power = Total PV production - AC loads (without car consumption) = 1380W (230V x 6A)
In the example above, the Min. charge current (from 6A) value has been set to 6A. The required excess solar
power increases accordingly if a higher value is set for the Min. charge current (from 6A). Please see the chapter
VictronConnect setup, configuration and operation [9] for details on both parameters.
Or, if there is not enough excess solar power available to meet the minimum charge current requirement as per 2., it is
possible to enable the āAllow low excess solar power for auto modeā option. This option supplements the required power
with additional power from the grid to meet the minimum current requirement. See chapter EV Charging Station setup
web interface [37] for details.
I really hope someone can confirm to me this will work! :). Victron has unfortunately not replied to my inquiry sent quite some time ago (a month or so)..
That coding was what I understood would already be included in the Victron Charger software. I think if weāre into coding it all ourselves then I am in too deep water :)ā¦ When I read the manual of the Victron charger, it states the Automatic Mode will do what I need, adjust charging to excess solar - but I need confirmed this will be the case also in a fully off-grid system. Dont need to buy ā¬2-3000 worth of goods for no reason at all :). Unfortunately Iāve gotten no reply to my inquiry with Victron for this - now hoping someone in this forum knows or even better has this kind of setup :).
From the charger manual;
Automatic mode to ensure maximum PV system efficiency
The EVCS will automatically start charging when the vehicle is connected and the following conditions are met:
The current state of charge is above the 'Start charging at backup battery SoC (%) value.
There is enough excess solar power available, with excess solar power calculated as follows:
ā¢ Excess solar power = Total PV production - AC loads (without car consumption) = 1380W (230V x 6A)
In the example above, the Min. charge current (from 6A) value has been set to 6A. The required excess solar
power increases accordingly if a higher value is set for the Min. charge current (from 6A). Please see the chapter
VictronConnect setup, configuration and operation [9] for details on both parameters.
Or, if there is not enough excess solar power available to meet the minimum charge current requirement as per 2., it is
possible to enable the āAllow low excess solar power for auto modeā option. This option supplements the required power
with additional power from the grid to meet the minimum current requirement. See chapter EV Charging Station setup
web interface [37] for details.
This should not be a problem. I charged with 5 Amps this morning. At 08:00 hours. Yes. We do have a 3-phase grid connection, but almost never use it. I turned off the main switch - as a test - and nothing could possibly come in from the grid. Yet it all worked. As expected.
One note. We do have a little bit more PV power available (8kWp) in different directions, and we are happy with it.
There might still be a good reason to do some coding, but that depends on what you want. I get it. Coding may not be your thing, but I have seen people code in Node-RED after a few week. Like it was their job. Itās quite enjoyable as well I must admit. I mean. Problem solving and Fixing issues yourself.
Anyway. We barely use any grid power. Like 25kWh max a month. Usually the result of my coding errors. True. I also make mistakes, but oh man what a joy when you solve a coding issue yourself. Like this morning when I solved a problem, which I myself had introduced
Questions about Victron hardware/installations usually involves a local reseller. They should be able to assist you.
I just checked and weāre at 99% right now. Lowered the Amps so that wifey can run the washing machine and dishwasher. Absolutely fantastic this solar stuff.
In a grid tied system with grid meter the system knows what the excess power is fed back to the grid. And the excess wil be regulated towards the ev charger. In an offgrid system I am not sure all those functions will work properly without any extra automation in node-red. I could be wrong. Chiefsolar did test it for you by disconnecting the grid from his system so thats allready hopefull. And about coding in Node-Red: It might seem simple for me becouse of the many coding languages i allready master. It is not that simple if you have no engineering background.
Steffen, yes this can be done in an off-grid system and with no special programming skills using the EVCS and Cerbo pair, Iāve been charging my Volvo EV fully off grid for over a year and a half now and Iām definitely a non-coding electrician. Some things to know:
The difference between the Multi RS and RS Smart is that the Multi RS combines the inverter and MPPT into one box, whereas the RS Smart is MPPT only - it has a DC output.
EV charging is a large continuous load. When fully off-grid, you will want more inverter headroom than you think. The Multi RS Solar 48/6000 might look fine for your estimated array, but it will likely be running at its limit and from what I can see it canāt be paralleled.
For my home, I initially installed two Multiplus II 5000/48 and a SmartSolar MPPT RS for the array, and the inverters were running so close to capacity I eventually moved half the array to AC coupled on a Fronius to reduce the heat being dumped into my power shed.
Phil - thank you so much - this is really good input - just what I need! Funny that I plan to charge a Polestar - the daughter-brand of Volvo ;).
I fully understand what you are saying and I have thus revised my setup from the Multi RS Solar to instead;
-5 kW of PV panels
-MPPT 250/100
-Multiplus II GX 5000/48
-Victron EVCS
Do we agree I will not need a separate Cerbo GX when I buy the Multi GX?
I guess above setup could keep me charging with up to around 4 kW (limited by Multiplus output and PV input / amount of sunlight).
As I understand, I would be able to scale this system in the future by adding:
-More panels
-Possibly another MPPT
-Another Multiplus II for increased output (not sure I understand if that would add another phase or mean I could charge with sth like 32 amps on one phase (which my car can take luckily), or if Iād add another phase. I am planning on a 1-phase system but could adapt if this is necessary. Is this correct?
Does the Victron EV charger work on both 1, 2 and 3 phases?
Good point, I do want the options in the future since I will surely get another idea next year! A Victron unit with GX in the name is basically a Cerbo GX built into it, right?
And how do the Cerbo GX connect, do I need to buy cables or do they connect via bluetooth? I have an existing MPPT 100/50 that Iād like to hook up for VRM as well so that I can monitor everything from the comfort of my home :).
Four pin Ve.Direct cable for the MPPT and SmartShunt. Ve.Bus (normal RJ45) cable for the Multiplus.I always connect the Cerbo GX (MKII in most cases) via LAN but it supports WiFi as well.
The Victron EV charger works on both 1 and 3 phase configurations.
There is no 2 phase power. But, all our EVs in the US have only two lines input, which can be confusing. I had to do some research to adapt the EVCS to our home, just passing along what I learned for any others that might face similar questions. Here in the US, each home receives a single phase of a 3-phase source at 240v, and we center-tap the transformer to provide a neutral and two legs of 120v, hence āsplit phase.ā
As I understand it, in most of the rest of the world homes receive 3 phase power at 400v, and EVs can either charge line to neutral at 230v up to a certain point of capacity, or at 3 phase for higher charge rates. European EVs have three lines input, using what I think you call āMennekesā plugs, and can charge either on one or three of those input lines.
In your off-grid application, you can configure the system in whatever configuration you choose, but Iād recomend staying 1-phase. You can stack multiple inverters in single phase, itās typically more efficient for a small system. Additional inverters give you more capacity at 230v, and reduce the overall loading on any one inverter.
Phil, this really helps a lot. Iāll keep my system 1-phase for simplicity, luckily my EV (Polestar 4) charges up to 32A / 230V on a single phase so I can fully exploit all PV production.
Thanks for taking the time, next problem is how I solve the temperature issue for the LiFePo battery (no heating in cabin when Iām not there and the winter gets down to -30 C / -20F). I think Iāll just have to take the battery with me when not there. Thatāll be fun too!
Tell me all about your setup! And Iād like to see a picture too if you have. I do understand that the battery will have to support to an extent as EV charging cannot be 100% instantly matched to the fluctuating PV production.
How does it work for you? Do you see a lot of ābufferingā via the battery, or?
Iāll only use my setup when I am in the cabin 1-2 times pr month, so am not too worried about maxing the Multiplus out (5000 VA) but if it becomes a bottleneck Iām quite happy with the feedback I got in this chat that made me change to the Multiplus making my system easily expandable
The best solution for moderating battery temperature for offgrid systems is to go underground. The same applies for water systems as well. Anything that relies on throwing energy at heating the battery (or water) canāt be relied on - when you absolutely need it the most, youāve got the least solar resource available. The earthās ability to moderate temperature, on the other hand, is free (other than the cost of digging the hole).
Bjƶrn I am off the grid in this location, so I donāt think I can use a Fronius? Iāve actually Changed to the MP2 setup for future scalabilityā¦ Or do I misunderstand?
Yeah I know, just wondering about the humidity underground but of course I could pack the battery into some box which is more or less sealed so that would not be an issueā¦ Sometimes I wonder what I got myself into here, this is becoming quite the project . But Iāll love it when itās up and running!
