(1-Phase house + 3-Phases workshop) on shared batteries
A friend of mine came to my shop with a drawing (see attached below) saying: "Install me this!" I'm not sure if the design is improvable (or even feasable) and I couldn't find any info about that in the forum.
Customer's desired result:
House in a remote area, so totally off-grid
Two 1phase inverters for the house
Water boiler connected to Smart-Load port
One 3phases inverter for the workshop (seldom used)
Emergency diesel generator connected to GEN port
Two batteries (10/15kWh each) shared by the house and the workshop
The main idea is "When SOC is low, the workshop can be disconnected and the generator starts" What can I reply to the customer? Can we share the batteries between two different inverter sets (house and workhop)? Thank you Carlo
The desing makes sense, but there are other options that give simular fault tolerance and mixed single and 3 phase option at lower cost and with simpler setup:
For 3x single phase Inverters configured in 3 phase confgurations providing both the single phase house load and 3 phase workshop load.
All inverters use BMS via the Master inverter
There is no technical reason to also have sepearte single phase inverters in addition to the 3 phase configuration as this setup can supply both the single and 3 phase loads.
As this is a off grid configuration the generator can be connected to the Grid ports
The Smart Load can use the Aux port on the master Inverter.
With this setup the main fault tolernce options are:
One inverter fails:
The remaning 2 inverters can configured in single phase parallel configuration
The genarator can be connected in single phase to one inverter
Two inverters fail:
The remaning 2 inverters can configured in single phase parallell configuration
The genarator can be connected in single phase to one inverter
Three inverters fail:
The genarator can be connected directly to the consumer loads which would give both single and 3 phase power
The key to designing the solution so it works as intended is good understanding of the loads used by both the house and the workshop.
The battery configuration also need to factor in the maximum power that needs to be drawn from them in the worst case.
With the generator conncted to the Grid ports it can also be configured to provide additional passtrough power when needed.
If the maximum load per phase is for example 5kW per phase for both the workshop and the house loads there are 2 options:
3x 5kW Inverters in 3 phase configuration
6x 3.6kW Inverters in 3 phase configuration and each phase having 2 Inverters in parallel providing 7.2kW per phase.
Although the 6x 3.6kW setup provides better fault tolernce options there is higher inverter internal power use as each inverter consumes ca 60w.
Regards