As preparation for building a three-phase ESS, I’m wondering whether it would be possible to publish the efficiency data for the new MultiPlus II 4k5 and 6k5 units.
I found those for the older 5000VA model on this website, for both charging and inverting.
The point is that building in some power reserve by, for example, choosing the 6k5 comes at the expense of efficiency at low loads.
Thanks in advance
I don’t think there is a big difference between the “old” 3kVA/5kVA and newer 4k5/6k5.
You assume that the 4k5 and 6k5 are the successors to the older 3000VA and 5000VA models, but is that really the case?
As an inverter, the 4k5 performs just as well as the 5000VA, namely 4000W, but as a charger it falls considerably short, at 55A compared with 70A. The 6k5, on the other hand, performs almost like the older 8000VA, both in terms of output power — 6kW versus 6.4kW — and as a charger, at 100A compared with 110A. Its standby consumption is also virtually the same, at 28W.
What interests me most is the performance at low loads, i.e. below 300W, with 500W as the maximum. The periods when the ESS would have to deliver a high output for longer are approximately 11kW in summer, to charge the car using solar power, and around 3–4kW in winter, when the heat pump is operating at full power.
The Netherlands will probably move towards variable network tariffs (not to be confused with dynamic electricity tariffs) in order to shift energy consumption from peak hours to off-peak hours. You would then need to be able to charge a lot within 5–6 hours in order to drastically reduce the power used during peak hours.
Hence my interest in the low-load behaviour of the new devices.
Elsewhere on this forum I asked for the efficiency curves of the new MultiPlus II 4k5 / 6k5. Perhaps it would be possible to integrate this kind of data into the Toolkit? You select an inverter, then enter the charging/discharging power, and the Toolkit gives an indication of the expected efficiency or losses.
This could be useful for selecting the right inverter, but also for determining the required cooling capacity. The enclosure manufacturer Rittal, for example, has a calculator on its website where you first select an enclosure, then enter the ambient temperature, etc., and the expected heat dissipation of the equipment in the enclosure. This allows you to select fans or anti-condensation heaters online.
Example: RiTherm