Hello, first post and excited to join this community!
Disclaimer - I do not intend on installing this system alone, I will hire a profesionnal. I am determined though to understand every detail of it, design it and be able to discuss it with my installer.
My goal is to basically to install a split-phase, grid-tied system with ESS and Solar that will act as backup power in case of grid failure and be able to use as much solar and ESS power as possible to offset utility costs.
My questions are:
I understand that in split phase I’ll use 2 multiplus II each providing 110v. If I were to use 2 48/5000/70-95 models, I could provide up to 95 amps. My challenge is that I want to include all circuits in this system which amounts to 200 amps (including heat pump).
Am I wrong in wanting to include all circuits? I want to ultimately become energy independent and therefore build a system that can include heat pump, water heater…
How could this technical be achieved with the multiplus?
Will I be able to configure the system to prioritize power in the following order:
daytime, sun is charging batteries, grid powers the house
Once batteries are full use solar over grid to power the house
Once sun is down use batteries over grid to power house
It will pass through 95A from the grid to your panel, the inverted output is 5,000VA, or 4,000 Watts, which is 32 Amp (at room temperature). 200A would require more than 6 in parallel and a very very large battery.
I’ve been toying with a system to keep the core of our house running during an outage. I hate hearing our 22kW NG generator run all night to keep a few nightlights on and the refrigerator running. Big loads like the HP, AC, electric range, etc could be powered by the generator on demand. Running several tons of AC from batteries seems impractical to me. My holdup is our only clear sky is 300ish feet from where the batteries would live.
Thank you, the math makes sense and I agree with you. My challenge is that ultimately, I’d like to run the entire house without grid reliance whatsoever. I want to do that over time because of cost but if that’s the goal, how you’d you recommend I tackle it?
There is a lot to learn before taking on a large project like that. First step would be to define the actual needs before designing a solution. If you truly need 200A at 240V, that’s a hefty 48kW system. Battery storage requirements for any length of time would be huge, the amount of solar to power and recharge that system would also be very large.
Victron has plenty of reading materials, datasheet, manuals and even more on the Victron Professional site. I started with a small RV project. Single inverter, communicating battery, solar, genset, display, Node-RED, several integrations. It’s been an adventure.
110 Volts that’s 22kw, still a large ess system.
Start small..what you really want on the ess like refrigerator, network, some lights on one 8 kw mp, after some time if you still like it ad 2 more 8kw mp and batteries for a 3 phase system.
For grid connected setup, you need to be sure Victron equipment can be legally connected to the grid in your area.
For example in North America, for grid parallel setup (ESS), a lot of grid operators require 1741-SB certification. Unfortunately, Victron only has few units with the “basic” 1741 certification. So, ESS is not allowed. Only back-up can be done with the basic 1741.
So, I recommend you to do your homework regarding your utility first before spending a lot of money.
Thank you everyone, I definitely have a lot of homework to do and unfortunately not an unlimited budget!! On the 1741-SB certification, does this apply to any ESS mode or only when feeding current back to the grid?
@nick - I am starting to setup an emporia vue 3 to monitor my circuits and gather relevant data!!
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
9
An Emporia Vue 3 is a great place to start. That’s what we recommend to customers, too. There might be an electric utility out there that would allow you to run ESS with Victron, but I have yet to find one. What the other folks said is true: you cannot deploy a Victron ESS system in North America and be code compliant, pass an inspection, and get an interconnection agreement from the utility.
If you are willing to NOT use ESS, then you can use a Victron system. However, if you want full-house backup then you will need four MultiPlus-II 48/5000 or four Quattro 48/5000 120V units. See here: Self-sufficient home in NE Ohio | Off-Grid Power Systems Scroll the pictures and you will see four Multi’s and 16x Pytes V5° batteries.
This system is attached to the grid, but only uses the grid as a backup for when solar + battery isn’t sufficient. It CANNOT sell excess energy back to the grid (legally).
I LOVE Victron products, but they simply aren’t suited for whole-home backup in North America. Myself and many other Victron dealers have complained for years about this, but Victron seems to be satisfied with the RV and marine space here or off-grid stationary systems.
The installation I linked above was the last grid-tied Victron system we installed and will install any time soon. Check out the Sigenergy Sigenstor. It’s an excellent product and much better suited to your needs, in my humble opinion. If you have questions about the Sigenstor then please email me offline. I already feel rude recommending a non-Victron product on their community forum
What you describe in Ohio is my use case, I am not interested in selling any current back but to use the grid as backup if when solar/batteries are not enough and potentially charge batteries during certain low peak hours with the grid and reuse during high peak (unless of course solar is available).
Based on my reading so far, there are ESS configurations allowing that if I am not mistaken.
Would this setup pass inspection? Also an important aspect of my project is that I want a small base setup allowing me overtime to grow towards a larger and ideally fully off-grid setup (years from now).
OGPS
(Ed @ Off-Grid Power Systems - offgridps.com)
11
Hi. There are several points to mention I think. AHJ’s typically won’t allow a downgrade in service if you remain connected to the grid. So, if you want to insert a system between the meter and your main load panel (breaker panel) then you need to pass through the entire 200A. I don’t know if this is specifically called out in the NEC, but it doesn’t matter if the AHJ’s require it then it’s required. Check with your local building department if they require electrical permits and ask them. There’s a good chance you will be asked to maintain the full 200A @ 240V feed, in which case you will need the four inverters (at least) that I mentioned to have enough transfer switching capability to pass through OR utilize an external transfer switch with .S99 firmware to do it. 240V 200A transfer switches aren’t cheap and you might as well just buy four 5kVA inverters. If I am wrong about this please let me know because I’d like to be wrong
Second, you can make ESS work but I can’t recommend you do it, especially if you have a twitchy utility that monitors for any backfeeding. There will ALWAYS be some level of backfeeding in an ESS system, even if it’s just for short periods of time. Using an external grid meter can help with that, but it’s still not cool with the utility.
You don’t need ESS to use the grid as backup. You can program the inverters themselves using the Virtual Switch and dedicated ignore AC function in the inverter firmware or use some simple NodeRed flows to add the ability to create controls that are presented directly in the Victron GUI. You will need VenusOS 3.70 or beyond for this. We do this for a number of our customers. For example, you can set a slider to ignore AC input until the battery SoC reaches a low water mark and then allow AC (for charging) until you reach another threshold. It’s easy to adjust. And, if you know a storm is coming, set those sliders to keep the battery at a high SoC in case the utility goes down for an extended period of time and PV production will be low due to the storm.
In short, ESS is terrific and I wish we could deploy it. But, it’s much easier than it was just two years ago to work around some of the limitations so long as you accept that you cannot feed back into the grid, and hence, can’t enter into net metering agreements. The UL1741 certifications will at least tell the utility and inspector that your setup won’t kill a lineman by backfeeding the grid. Based on our experiences, the utility is likely to want a lockable, blade-style AC disconnect between the meter and your service entrance so they can lock out any potential for backfeeding. They don’t typically utilize those disconnects, but our utilities around here still require them.
