New system for storing solar and a bit of ESS

Q&A and troubleshooting
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Iam thinking of buying a new system to store solar.

Some ESS would be nice, thinking about 30% minimum battery storage for an emergency.

The other 70% would be for storing solar and using that in the house.

System below would do, i can have the multiplus behind a 3x16A group. I do not want my whole house behind a multiplus.

But the Mulitplus has a very specific ACout, does this mean i can charge the battery, but only the ESS part of my house can use the stored solar energy? Or does that battery energy also go out the ACin part?

At some point i will have more solar than the battery can hold, does that go to the grid in this system?

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The very first requirement for the proper planning of an Energy Saving System (ESS) is knowing your own load profile. What is your annual electricity consumption, what are your peak loads, and how long do they last?

In the vast majority of households, a single-phase system is perfectly adequate. However, it also depends on the country and its regulations. In Germany, the maximum permissible load imbalance between the phases of the power grid due to PV (photovoltaic) is 4.6 kW, which is why single-phase systems are limited to this. But this is usually perfectly sufficient, and even overnight charging of an electric car is possible.

I always recommend not skimping on either the installed PV capacity or the battery capacity. Both are now so inexpensive that saving money isn’t worthwhile. The additional cost of a 16 kWh battery compared to, for example, a 10 kWh battery is recouped simply through the significantly higher number of charge cycles of the larger battery. The larger battery can then be operated down to a remaining capacity of perhaps 50%, while the smaller one needs to be replaced at 80%.

The solar surplus from, for example, 10 kWp can easily be fed into the grid using a 4.6 kW inverter, provided the battery is large enough to buffer the surplus and feed it in at a later time (e.g., at 1 kW continuously throughout the night).

I would primarily feed the solar power directly into the battery via Smartsolar charge controllers and only use a microinverter to cover the house’s base load.

With 10 kWp of solar power, a MultiplusII-6k5 inverter, and a 16 kWh battery, a four-person household in Germany can easily cover 80% of its annual electricity consumption. And if you need to charge two electric cars every night, then upgrading the battery to 32 kWh is sufficient.

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Yes if you use a grid meter after your grid entry, feed in from ac in is possible, so pv on ac out, dc pv and or battery power will power everything on ac in side as long as there is grid power

If grid fails and you have nothing on ac out you will not have any backup power

Surplus pv will also feed grid if grid feed in is allowed in your country or grid provider

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I Should have given more information, i live in the netherlands. This means my meter does not care on which phase i charge or uncharge as long as the sum is near zero.

My roof is filled up with PV, the infeed will not go through the MP, so no changes there.

I would like 3xMP3000 of power(3x2,4KW), so i can charge my car at 7KW, remainder goes to the house. Also it can store all the PV energy the house does not consume. ( a single MP6500 will blow my mainfuse)

1: Is there a setting to power up only one MP3000 if there is little consumption to get maximum efficiency or do they always charge/uncharge at the same level?

@TomBerger, you are right, more battery will go a long way and also make sure the system works longer without replacing batterys, i was thinking of more than 20KWh. I have many days my infeed is in excess of 20KWh and the car will take it all in the evening.

2: Does anyone have any advise on brand or type’s of battery 48V i should look into?

3: Can i program the victron to charge/uncharge the battery between 30/100%?

My daily program will be the battery fills up with solar so my meter shows zero KWh, after dark the battery uncharges down to 30%, after that iam a normal consumer until the sun comes up again. 4: Any advice on the meter is should install near my main switch?

5: Does anyone see problem with this setup?

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Look at NKON.nl. They offer a 32 kWh battery with Seplos BMS and active balancer, fire extinguisher and heater below 3000 €. A 16 kWh battery without heater and fire extinguisher is available for around 1300 €.

Yes, of course

Really? In the Netherlands? I guess they have similar house connections like here in Germany.

With 7 kW charge power you can carge you EV with 84 kWh every night. Do you really need that much?
The average daily driving distance of a German car is less than 40 km, and an EV would need less than 8 kWh to recharge that. I would always use only single phase 230V charging at home. Most EVs can charge a maximum of 2.3 kW single phase, which would allow for charging for 200 km every night.

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You dont have to power one multi, if you set it up as ess the system will do that itself, they run as 3 phase with different power in/out put

I would recommend an em 540 as grid meter or a v3p from victron both are fast

I have pylontech batteries (4x us 5000)

You can take a look at my system in my profile

I have a 3ph 25a grid connection, 10kw dc pv and a 3ph mp 5000 system powering almost my whole house, running fine for a few years now

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In NL we have 3x 25A so a 6k5 unit can be to heavy, unless you limit grid feed in

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Victron’s “German Grid Code” limits the 6k5 to 4.6 kW which is allowed for single phase feed in.

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The speed (= data rate) of the grid meter is rather irrelevant since we have a limit for change of 400 W/s here in Germany. I use a Shelly 3EM as a grid meter because my victron system is at the other side of my house and so I needed data transfer over Wifi. But even with the Shelly I have unwanted grid feed in of much less than 1 kWh per week.

I have no doubt that your system is running fine. But I am quite sure that your system would run just as fine with just one single phase MP5000. You probably spent much more money than necessary.

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I was just giving some advice to a fellow dutchie :blush:

Grid meter speed does make a big difference in system response, NL is not limited on grid feed in speed

1 5k multi is too small to run a whole house if you want to be as much grid independent as possible (net zero) you cant even cook electric on one

But every household is different :blush:

What works for one doesnt mean it works for someone else!

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I wouldn’t go for 3 x Victron Multiplus II 3000 inverters, but at least. At the absolute minimum. Opt for 3 x 4K5. Preferable 3 x 6K5.

Yes. For a 3 phase 25A grid connection as well. Thing is. The 3000 has a limited capacity and runs inefficient at high(er) loads. Even the MP II 5000 will run into this inefficiency, but is a more solid choice (compared to the 3000).

And yes, your grid meter is still nulling the phases. Until 2028. That is when the new electricity law comes into play. With 15 minutes grid time blocks to charge customers. Making it more cost effective to use power at certain cheaper times, with a higher price for other time periods. Possibly even effective in 2027 already.

Also. Summertime isn’t a problem, but winter time is different. Then you’ll end up charging your EV from the grid and , hopefully, not from your previously grid charged batteries.

Money wise. I see nkon.nl being named here, and they sell the 6K5 for €799 which to me for customers is a bargain that is future proof.

Also. Never fool out on thin wiring and using battery cables in the same colour!

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A single MP II 5000 would run way less efficient. Especially when you need to charge your batteries overnight from the grid. With a dynamic contract, the times blocks with lower prices can be rare, and that is when you want to charge fast. With 3 inverters that can also be done more efficiently.

Not to mention that with an EV, heat pump / boiler and electric cooktop… things will get very limited.

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I strongly disagree. A three-phase installation has significantly higher standby losses. And for 99.9% of all households with DESS (Dynamic Energy Storage System), charging from the grid at a maximum of 4 kW is more than sufficient. Or do you really have a daily consumption of 100 kWh?

The limit will be 4.6 kW only in the event of a power outage. I had not a single event of a power outage in the last 20 years.

How often and for how long do you have a household load of more than 4.6 kW? Again, this value is more than sufficient for the vast majority of households, and the additional costs of a 3-phase system cannot be recouped through the rare and short periods with a household load exceeding 4.6 kW.

In my case (I live alone), I cover 80% of my annual electricity consumption, including my heat pump, electric water heater, frequent cooking and baking, and a constantly running computer and TV, with a single-phase MP2-3000. And that would even be sufficient to charge an electric car with average mileage overnight. A 1phase MP2-5000 would only increase my self-consumption by 50 to 100 kWh per year, and the resulting savings wouldn’t even cover the slightly higher cost of the MP2-5000.

I maintain that a single-phase MP2-5000 easily meets the needs of 99% of all households. The prerequisite is a sufficiently large battery, especially if you plan to charge one or two electric cars overnight.

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Yes, a single MP2-5000 is definitely too small to power an entire house. But who wants that anyway? Is your goal really near-complete energy independence?

99% of households can cover a full 80% of their annual electricity consumption with a single MP2-5000, including heat pump, hot water, and electric car, electric cooking and baking. To reach 90% coverage, you’d have to invest just as much again for those extra 10% as you did for the previous 80%, and that will never be economical, and it’s definitely not sustainable either.

A single MP2-5000 can continue to power all your critical loads during a power outage, including lights, refrigerator and freezer, radio and TV, computer and internet router, and even the stove for cooking.

No one is stopping you from achieving that last bit of energy independence through extremely high and uneconomical investments, and in very rare cases, that might even make sense. But it’s certainly not a recommendation for everyone.

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It is A. the limited/short period of time when you can charge your batteries from the grid at lower prices. Taking RTE and battery costs into account. And B. charging at full blast is a well know and proven Round Trip Efficiency killer. Same for lower charging power. Also bad. The Victron data is somewhere available.

So it’s not like we use 100kWh a day, but on winter days we use something like 40-50kWh (without charging an EV). And in the summer when airconditioners are running all days long, we use something like 20kWh without EV charging. Just our induction cooktop can take up to 11kWh on turbo stand. Usually only takes about 7kW but it can do much more. And we need warm water as well.

I mean. Some people here have eight 16kWh batteries, in the winter it takes a while to charge. And I’m not even speaking about fully charged here.

With 3 x MP II 6K5 we can handle anything that comes on our way. Grid loss is something else. Same here. Almost never happens. But when it hits us, we couldn’t care less. Everything will run like normal. And that for at least 9 months a year.

Not to mention C. We are not allowed to feed anything into the grid , and thus we use as much energy in summer time as possible. The rest is stored for bad weather and charging your EV at a later time.

No. It’s not like everyone needs something like this. But we do. To each his own of course. Whatever it is that you want/need.

P.s. main fuses here are 35A

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For the vast majority of people, myself included, dynamic electricity tariffs are simply not worthwhile, and therefore they don’t use them at all.

The typical four-person household in Germany has an electricity consumption of just under 10 kWh per day, and this 10 kWh could easily be replenished during short periods of low electricity prices. But most people with Victron systems cover almost all of their electricity consumption with solar panels for eight months of the year anyway. So why bother with a dynamic electricity tariff?

To achieve an advantage that is unattainable for most people, you spend a lot of money that you can never recoup. A three-phase MP2-5000 system costs about €2,000 more than a single-phase one. How do you ever expect to recoup these €2,000 in additional costs with normal electricity consumption?

No. Such a system is only a sensible option in very rare cases of unusually high electricity consumption.

And some people build nuclear bunkers in their gardens. That’s not the norm, and it’s not advisable. But if you think you need it, then go ahead and build it. But please, please, don’t present your view of the world as the norm.

Yes, you probably can. But not everything that can be done is advisable, or even economically sensible and sustainable.

With my single-phase MP2-3000 system in Germany, I completely cover my electricity consumption from the beginning of March to the end of October, including my heat pump, hot water, cooking, baking, etc. I only have 5.4 kWp of solar panels installed. My annual electricity consumption is just under 3,000 kWh, and my solar yield is almost 6,000 kWh per year. What could a three-phase system offer me that I couldn’t with my single-phase one?

And yes, here in Germany I can feed my surplus solar power into the grid and receive 8 cents/kWh for it, which amounts to €240 per year. But that’s peanuts compared to my savings from self-consumption, which total around €580 per year. With my PV system costing only €3,500, it pays for itself in just over four years. Without the feed-in tariff, it would take six years.

Kant’s categorical imperative always applies: You are free to do anything as long as you do not infringe upon the freedoms and rights of others. So you are even allowed to build an economically unsustainable ESS. But please, please, don’t consider yourself the center of the universe and recommend your uneconomical system as the standard for everyone.

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@TomBerger thanks for your view and input.

@dekkerdek your drawing pictures a 3 phase inverter is that the current or future situation? You also have a 3 phase grid connection? Are you on a dynamic electricity plan or do you want that in the future? For whatever applies to your situation. Possibly to avoid additional costs to feed in excess PV.

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Multi plus 4.5k only 650 euro, here in the Netherlands (that’s including 21% tax)

Ideal for your 3x25A grid, i think one big battery is best, no fuss about 4 battery bms working together or not, nkon 32kwh as mentioned before; 3500 euro tax included.

With 3 phase you charge with 165A maximum, in 3.5 hours you charge the 32 kw battery from 15% to 100% or 0.26C for for many many battery cycles.

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One thing that I would like to add is that the higher standby usage mentioned by Tomberger can be solved by using ‘Charger Only’ and/or ECO mode on the inverters. The former requires you to use the MK3 but that is something you’ll need anyway to setup a 3 phase configuration.