Hi guys,
I am migrating from one country to another. In the other country I will be living for a while in a tiny container while my contractor can start building my house.
From my current country I will build up a power system inside a container that also contains our assets.
Now the local grid company said they can't deliver in time any power. And when my house is finished, I will be going into a house 3x2 MP2 5000 with 4x15kW of LiFePo..
The 3x2 is because my cooking island needs a top of 7.5kW. And it's not an 8000 because if one of the MP2 breaks, I can scale down to 3x1 and order in while I let the MP2 be serviced.
Because I want to be able to run on 3xMP2 5000 my max AC PV should be around 10..12kW.
Eventually I plan to have that with an additional 12kW DC.
So these are the devices I will probably have.
But since the grid is not available, I need power for my builders and I need power for myself. My "cabin" is about 70m away from the building site.
I see four options:
1) I don't care about the builders, they buy or rent an expensive diesel generator and I pay the full price.
This is not something we want to see here, right :-).
2) I split the units evenly, they can run the generator to 1 set of 3xMP2 5000, provided they mainly use less than 4kW per phase, and we turn on the generator on those moments the loads would exceed the 4kW per phase.
On my part I will need the same (2 generators)
3) I split the units evenly. However instead of being fed by the generator, the builders power is fed by 3x3kW over 70m fed from my set. My set is fed from AC PV (when I have time to set it up temporary), DC PV (same) and the generator.
The MP2 set at the builders location should be in plain UPS mode with power asist and charge until 90% or so.
4) I create one 3x2 setup with 60kWh of energy in batteries and a peak capacity of 60A/phase and continuous of 32A/phase.
This last part is a setup that I am personally not ready for and if some of the design or crimping is not good I will have a lot of problems. There is no wait for me to test a full load on a system as big as that with all safety covers off and IR camera to look for the weak spots.
Also it requires a different set of bus bars to mix the inverters with the batteries on the same bar than the normal victron lynx system.
And what is still not clear to me is if a generator on AC-in can be mixed with a PV on AC-OUT.
In the mean time I will probably also have an AC-PV inverter with panels (limited to 1:1) and probably a smart solar with the same power. The panels are near my cabin and not near the building site for obvious reasons. And yes, I will be 24/7 at that cabin, as my real work is 24/7 managing/setting up/making drivers for embedded linux systems, so the cerbo is so nice to have. I digress...
Using 3) I can build 2 seperate setups each totally limited to 32A of in and out, and use (I assume)common 3P+E+N 32A CEE connectors. I have no idea what is normal during house buildings. When it all fails I can switch to 2), however it is hard to switch to 1) because if 3 and 2 fails, it means I (or they) have severely underestimated their peak power needs.
I would buy an extra cerbo just to monitor the 2 separate setups so I know the usage is still within bounds.
Until now I am only talking. So what can you do:
Tell me I am a fool because...
Tell me solution x or y is good...
Maybe AC-PV on AC-out isn't possible with a set of MP2 behind it.
Please tell me that this is all stupid because building usually uses at most 3kW per phase with some inductive peaks.
(I have a shared document with my contractor, and I am actually waiting for him to input his side of the story.)
If I am looking at solution 4, just getting a full 60A cable (16mm^2 per phase and neutral) feed to the construction site is the price of a generator.
Getting a 32A cable is already down to 6mm^2 (using 100m as distance).
And if I feed it really only 12A, cable requirements are really down. And 12A (AC IN)+16A (power assist) is within the boundaries of the MP2 5000, so it should be more than enough for them to work with I guess...
2 battery boxes per setup should keep the load on these boxes way below 1C and charge at at most C3.
So please shoot.
The best thing is that "de groene aggregaat" is probably a few km from here ;-).
Anyway: if this all works great, that would be a real step for me to be off grid. I need power for my work, and the grid at the village I am going to live can be out of power for a few days at a time. I mean, when I arrive I am already off-grid, but in the winter I doubt the PV can support the equipment. And being on-grid for a short time with 3x16A is probably more cheap than a generator. If at the end I have too many MP2 and boxes, I can keep one for experiments and in case of emergency ship them to the local doctor or vet for emergency power.
