first DIY Powerwall with 64 x EVE 280Ah lifepo4 - help needed

[mike_solar]

Hi All,

first of all what a great forum I have a great time of reading and watching also videos from Andy's off grid garage on how to.
I have received some quote's from commercial installers to place BYD LVL or LVS and I thought it was a bit to expensive since my house uses a lot of power.
Since I like to DIY and I rewired all the AC in my house when I bought it 2 years ago I thought let's do a DIY power wall how hard can it be right

House energy/electrical setup
My house is connected to the dutch grid and has 3 phases rated at 25A each (400V 3P+N) 17 kW power available with TN-S earth supply.
I'm all Electric so no natural gas. we have "normal" electric appliances like wasmachine/dryer/dishwasher/microwave/fridge freezer combo and all LED lights some networking gear and 2 computers.

for the "special" electric appliances we have.

- Air source heatpump boiler for hot water (0,7 kW +/- 3A on heat pump mode "Eco" mode or 3,2 kW in "turbo" mode with electric element enabled)
- Air source heatpump "multisplit AC" for heating and cooling in the main rooms averages 1,2 kW but can go to 3,6 kW (full 16A) on very cold or hot days.
- 2 IR heat panels 0,7 kW each for secondary rooms
- 11 kW induction stove with oven (3 phase device)
- 8 kW jacuzzi that can spike on jets and air blower start (20A 3 phase slow tripping C mcb). of which 3 kW is heating element.

No electric cars for the moment and not sure if we can find a home charger since we don't have a garage.

average yearly consumption is 14.400 kWh, lows in summer around 900 kWh/month and high in winter around 2000 kWh/month.
which low energy days in summer are around 32 kWh and high in winter 60-70 kWh a day.

this is a lot of energy but consider the house is over 100 years old and previous occupants used around 4000 m3 of gas for heating with old gas heaters AND had a fireplace they used almost daily in wintertime.

the total power of all our devices combined is a lot but on my energy measuring device I see total usage at the net meter of around 4000 watts and 7000 watts on average in a winter period. and no circuit breaker has ever tripped from overload. highest measured peak from usage over the last year is 14.000 watts (at a time we used the jacuzzi).

Solar

Of course we also have solar, consisting of 2x AC coupled SMA sunny tripower 8.0 on which 3 strings are connected on both inverters with a total of 34 panels are connected with 15.190 Wp orientation to the south -7 degrees and 35 degrees array and 2x 10 degrees.

yearly production is around 8.000 kWh for inverter 1 and 4.200 kWh for inverter 2 combined: 12.200 kWh
I've seen peaks of exporting around 13.000 watts on moments of very low self consumption and optimal production.
so probably I'll fit another 3 panels in the 35 degrees string in the ground mounted garden string.

Battery

after watching some video's from Andy's off grid garage, I ordered 64 prismatic EVE 280 Ah batteries.
Which I would like to connect in 4 parallel strings of 1P16S so every cell is monitored.
the batteries should arrive from China around mid April.
all cost included shipping/customs/vat e.t.c. I averaged around $119/kWh which I think is as close to $100/kWh as it will be for a while.

Goal

- my goal is to be self sufficient "off grid" as often as possible. According to my calculations this should work for like march till somewhere in oktober.
- in wintertime when power is more mission critical because of early darkness and heat depending on electric I would like to have a % of battery capacity for power outages. and still charge the battery a bit with the surplus solar we have at some moments in the day.
- in the near future I also consider changing my contract to flex rate so I can charge the batteries (in wintertime) when power is cheapest.
- whole home backup so the wiring would be

Main grid point -----> 3x C25 mob ---> 17M YMVK 4x6mm2-AS ground cable --> subpanel in workshop behind the house with 2x solar inverters (batterie's would fit here) --> 22M YVM 4x10mm2-AS ground cable back to house --> subpanel with all the circuit breakers for the house).

Wishes

- I'm thinking of 3x SMA Sunny Islands 8.0H-13 because it would exactly fit my needs for power. and It matches my solar inverters which I'm happy about.
- I see also a lot of Victron, that could also be an option although more expensive (multiplus II or Quattro II).
- BMS needs to work with SMA SI, currently thinking of REC but any recommendations welcome.
- Safety over cost saving.


All feedback is welcome, and thank you all in advance for your advice.

Cheers
Mike

 

[houseofancients]

Welkom hier.... ongeveer hetzelfde verbruik als jij

Welcome here
have no exp. with the SMA's , nor victron
as for bms, may i suggest looking at seplos ?
Their bms's are "stackable" up to 16 bms's and do have victron as a supported supplier and they are a major supplier of those bms's
Their bms "talks" pylontech, so i suppose if your inverters are compatible with pylontech, the bms should be able to communicate

 

[Quattrohead]

Make sure your inverters can be programmed to not export too much if any of your battery stored energy during the summer, you would be pissed to have "sold" it to the PoCo during the day then have to "buy" it back at night !!!

 

[mike_solar]

Make sure your inverters can be programmed to not export too much if any of your battery stored energy during the summer, you would be pissed to have "sold" it to the PoCo during the day then have to "buy" it back at night !!!

Right know I take advantage of net metering so the grid is my battery but that will change very soon and with all the solar installed we run into problems that inverters reach 253V and force shutdown.

I guess even with batteries I will make more solar in the summer then I consume and therefore I will have full batteries anyway.
my idea is first charge the batteries full and after start exporting to the grid, which means that in summer I should have a period where I only export power and not buying at all since my usage will match my storage capacity.

anyone experience if SMA Sunny Island can do this?

 

[jules_bike]

@mike_solar that's a similar setup to mine. I have the tripower 5 and I'm about to add more panels. Do to the complexity of French burocracy I can't get feed in so I need to look into batteries. My supplier is recommending a SolaX hybrid inverter which apparently will charge and distribute 3 phase.

I'll be interested to see what solution you go with. 3 phase is quite a pain because it is hard to deal with single phase devices which draw a lot of power, I may be generating enough watts but the afaik the Tripower cannot send all the output to one phase.

Is the aim to put one sunny island for each phase?