Nic Roets

Yes, that was my first thought. We've had a few multi day outages in the past. All kinds of bad things would happen: Residents would charge their devices in their cars. Then the car would go flat requiring friends to help jumpstart. Or residents would idle their vehicles. Freezers would defrost and food would be lost. One resident ran a generator creating noise and pollution. Right now, the solar system is too small to run all the freezers. But if we have a proven quota system, we may just expand the solar system...

Intro My sectional title apartment block recently installed solar panels, batteries and an inverter. Currently it's a backup that supplies the outdoor lights, the security gate and the private garages during power failures. Due to fragile municipal infrastructure, we're not subject to load shedding right now. When load shedding or prolonged outages inevitably returns, I'm worried that a few residents may overload the system by operating power hungry appliances in their garages. Requirement I'm cautiously optimistic that we can prevent abuse of the system if we can limit each garage to a daily quota (together with a simple over current circuit breaker). Ideally it should be possible to adjust the quotas wirelessly. Are there power monitors on the market that can do it ? I'd like to avoid building a WiFi network that covers all the garages.

The problem with pluglesss extension cords (wiring them directly to the back of sockets) is that it makes it hard to see where the power is coming from. For example if you see two sockets wired together, you may conclude there's no power because you don't see the source. Then you open one and get electrocuted because the power comes through the wall. Looking at the picture of the DB, you may think there's a black wire connected to the live output of the timer switch. But the wire is in fact purple.

I want to know if the wiring in my dad's house is illegal and how I can fix it. See the photos. Can devices be wired to the back of a 4x4 socket ? Can an extension cord with a plug on one end and a socket on the other be fixed (for example nailed to the shirting) ? What about other devices like lights ? Can an extension cord be chained like the built in plugs ? Can a Sonoff Switch be wired inside the DB ? Will an electrician give a CoC for a earth leakage circuit breaker that's 17 years old ?

Ok. I managed to set up that integration on my Pi running HA. Then set up polling of the power sensor at 5 second intervals and got this graph. I guess I'll now be able to write code to shutdown overloaded circuits. It will run on the Pi, so I need to make sure the Wifi is as reliable as possible.

I need a power meter that can allow smaller appliances like TVs or fridges, but shutdown when connected to power hungry appliances like kettles or hairdryers. On the face of it, the Sonoff Pow R2 can do it. But when I tested it with my fridge, the default firmware cannot distinguish between the startup spike of my fridge and a hairdryer (both are of order of 1 kW, but the former is only short lived). Right now, I'm installing the Sonoff LAN controller on my Home Assistant, in the hope that it can configure additional variables on the default firmware. It looks like the Tasmota firmware will work, but I don't have a 3.3 V serial port to reflash my Pow R2. Can someone in Pretoria maybe help me with this ? Are there any other devices that can do this correctly ?

I explained wrong: Here the garages are units that can be sold separately from the apartments. Fortunately the "free" electricity in the garages hasn't been abused too much here. Only isolated incidents of residents with freezers. Most of the residents of this building are decent people. Levies in arrears are negligible. If we run a diesel generator only during outages, the administrative overhead related to billing may not be worth the effort.

In this case, the electricity in the garages already comes from a DB box belonging to the BC. So there is already a precedent for the BC distributing power to exclusive use areas. It is not currently billed. -- In this case allowing individual owners to install solar panels on the roof will be a recipe for disaster. -- How are the generators in Midstream Retirement village managed ?

My mom lives in an apartment building in Faerie Glen. In the last few years there were 3 multiday outages totaling 18 days in addition to load shedding. Residents desperately wants a backup power supply. The trustees are meeting later is this week. Here are some of the ideas I want to propose, but to have any chance, I'll need concrete examples of success stories in South Africa: A. Solar - Because it's so capital intensive, the resource needs to be utilized nearly every day of the year. Given how expensive storage is, it's best to consume the electricity as it's being produced. I see two options: (i) Have smart meters that enforces a quota for very apartment. For example x kWh during the day and y kWh during the night (ii) Have smart switches that switch apartments (or devices) between solar and grid electricity so as to use the generated electricity B. Diesel generator (Preferably the backup power source should be large enough to power the elevator for short periods of time) I see 3 ways of distributing the electricity: 1. Through the wires that currently provides grid power to the apartments. The municipality supplies power to 3 cabinets which contains the 45 meters. I guess it's impossible to obtain permission to modify these cabinets. 2. Installing a set of parallel cables, similar to how UPS power is distributed in a large office building. This may be possible to connect all 45 apartments with only 450 meter of cables and ducting. 3. The body corporate already supplies power to 15 plugs spaced throughout the building. We could manufacture 15 "smart" extension cables that can be deployed during these multiday outages to provide each apartment with one operation socket / Janus coupler. Each extension cable would have 4 x 4 PVC box that houses a 5 A breaker and 3 electricity meters e.g. Sonoff Powr. Given that these extension cables are not permanently fixed to the building, there is no need for a modified CoC. Any thoughts ?

Thank you Louis. I didn't know that some inverters can be paralleled up. This feature makes it possible to start smaller and scale up. Bob makes a good point about having a single breaker in each apartment that can disconnect both all the sockets. I don't know what a suicide plug is. But power to our garages is already supplied by the BC. I once used a bad appliance in my garage and tripped a number of garages in the process. Fortunately the caretaker was nearby and could reset the breaker that I tripped. I foresee similar problems if we have a central battery bank. It's good to discuss things here before presenting any concepts to the owners.

We're a 3 storey building with 45 apartments in Pretoria East. Each apartment get's municipal power, most of them on a post paid basis. Some flats use as little as 200 kWh per month, while other go up to 500 kWh. Some residents are so fed up with load shedding that they are considering buying battery backup systems costing R3,000+ each. I think we need to consider a central battery bank to achieve economies of scale. Then supply one socket in each apartment with reliable power. Installing electrical cables is a major hurdle, but that's our problem. We also have 10+ parking bays getting plenty of sun. We can build car ports with solar panels on top. At this stage, I just want to draft a discussion document for circulation. If we aim to supply each flat with 200 W, then it's 9 kW total. Add some spare capacity then we need 3 x 5 kW of inverters. (R70,000) 18 kWh of battery backup to supply us during 2 hours of load shedding. (R125,000) 10 kW of solar panels (R70,000) 10 kW MPPT (R21,000) 45 power monitors so that we can detect if someone is overloading the circuit and / or bill residents (R18,000). Total R304,000 According to pvwatts.nrel.gov, this system will generate 17000 kWh/Year, saving us R34,000. So the hardware will pay for itself over approximately 10 years. What have I missed ? How realistic is this calculation ?