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Goodday I need a backup system to help with loadshedding in South Africa. White extencive testing and monitoring I have found that I would NOT excead a max total of 1550w. 98% of the time I only need 300-400watts. My question is would a pylontech us3000c run safly on a multiplus II 48/3000 sins my absalute max watt requiredment is only 1550 compaired to the battery nominal of 1775? Want to use a multiplus 3000 to future proof system Thank you
Ideally you want 2 x US3000c installed.
The battery is not sized for the load, it is sized for the inverter minimum requirement. Then increased if storage needs are greater.
So 2 batteries is future proof.
We installed a US3000C, 48V 3000 MPII and Cerbo GX on 22 May 2023. Our devices are as follows:
Office - 1 x 24" LCD (+-35W - switched off during loadshedding if PC not in use), 1 x 850W PSU PC (on 24/7 to run backups); 1 x 24" LCD (+-35W), 1 x 450W PSU PC (LCD and PC usually off during loadshedding); router, power adapters for phone/printer.
Kitchen - 103W fridge, radio, 9W LED (when we're in there), PSU for alarm.
Lounge: 1 x 9W LED, 1 x 150W incandescent for the ambiance (I left it in after I realized replacing it with an 8W LED was unnecessary), 1 x old-school CRT TV
The first week, or so, we swopped the 150W incandescent for the 8W LED during loadshedding and closely monitored our consumption. Now we just leave it in.
Interestingly, our consumption is far lower than we thought it would be:
We use approximately 10-12% battery capacity per hour, recharging within +-2 hours. After 4 hours loadshedding we've gone down to 56% battery capacity. When on AC we no longer run the kettle (2,400W), microwave (1,000W), heater (1,000W) and standard loads (260-480W) at the same time as the system then switches to inverter to make up the balance. We just switch off the heater if we want to boil a kettle, or use our 650W ' loadshedding' kettle.
Our battery is charged at 10A and the maximum current draw is set at 37A. Based on these settings we can draw around 1,700W from the battery during loadshedding. Two batteries would be better, but with a little discipline, one battery is enough. You'll be fine with one US3000C.
If you haven't already, get the Cerbo GX, it will also allow you to monitor the system, upgrade the firmware etc. The Pylontech BMS will then interface with the inverter via the CAN port (get the correct CAN cable from Victron, I learned that the hard way).
Oh, and don't believe those that claim your monthly electricity bill will become "astronomical", we've been keeping daily records since our prepaid meter was installed almost eight years ago, there has been no increase in our monthly power bill.
