Hi all. I am helping setup a small PV/BESS microgrid for a 42-unit apartment block in South Africa. Not an impoverished community—but nevertheless a price sensitive one. To manage fair usage, we need to:
Assign a battery capacity quota to each unit i.e. total battery capacity/42.
When running on battery, meter each unit’s usage.
Notify units as they draw down on their quota (e.g. at 75%, 50%, 25% capacity)
Cut units off if they hit zero on their quota.
I have established that it is technically possible, and the hardware involved need not be complicated—we are likely to go with a combination of simple smart maters and contactors in our existing metering room. However we need the software to enable the above functions, plus ideally some automatic meter reading, maybe one day differential tariffs, etc.
It seems like OpenRemote is capable of this. Is that the case? More importantly: is it capable of being set up to do the above by someone well-informed but not a coder, such as myself, or alternatively at reasonable cost by a professional? We are trying to limit both upfront and monthly costs.
Thanks for description of your use case, very interesting! This is definitely possible with OpenRemote, and also by a non-developer if the connection to the battery and meters is straight forward.
Two things I can think of now that could complicate this case:
How to deal with the battery recharging (when not completely empty, to not complete full)? When to reset the allowed energy use measurement?
How would you cut off units? Does the meter allow for that or does the battery interface has that as an option?
Your first steps would be to try and connect your battery and meters to OpenRemote. Then you can quickly judge whether you feel comfortable handling this on your own.
The way outages are scheduled there should usually be enough time to charge the battery between usages. However, I think we would set quota as a percentage of battery capacity available at time of outage. And then a rule to disregard brief power restoration (say, <30min). I am however open to suggestions.
We could go with switching meters but I am informed that the ones available locally mostly have proprietary or poorly-documented communications protocols. The options we were looking at were the Honeywell/Elster HS100 or HXE130 and the Landis+Gyr E460P or E460S . If there are established integrations with Openremote then I guess that would make things simple?
The other alternative we found was using a simpler meter with RS485 interface such as from RS, Onesto, Schneider, or Carlo Gavazzi, paired with a 63A contactor, and wiring both to a Raspberry Pi. I have a quote from a developer to build a system from scratch on this hardware, but the monthly cost is prohibitive. We would happily pay for configuration of an Openremote-based system, although depending on the fees we might have to find someone who’ll take Rands.
Installation is being managed by engineers and electricians, so if I had a spec for connecting these devices and battery/inverter to OpenRemote then they could do that for us. Is there something like that I could give to them?
Also ideally we would be able to demo the software side before we install the system. Is there a way for me to set up a demo instance of the planned system?
If I understand you correctly, you would like to supply 42 residential units with electricity evenly in the event of a power failure and be able to switch individual residential units on or off.
In addition, an electricity meter should be used to automatically indicate when a residential unit has consumed the electricity allocated to it.
It’s relatively easy, but why were you offered a raspberry pi? That’s way too expensive.
I can’t speak to the merits of the Pi. Is there a way you would recommend instead, to connect smart meters and contactors to something like OpenRemote?
Depends on what the infrastructure looks like:
electricial control cabinet?
is each residential unit individually electrically fused?
what is the voltage in southafrica?
how high is the fused amperage?