Home Automation and setting loads based on battery status and load shedding

Hello Everyone,

Just joined the forum and would like to get some good solid advise. I am in the process of installing a solar system (2x 5kW Sunsynk, 3 x 6.4kW BSL, 24 x410W Canadian Solar), but I have a very old house, so rewiring my DB will add a lot of additional expenses. The purpose for rewiring would be to split my essential and non-essential loads, but it would be cheaper if I replace some with wifi switch breakers and installing smart plugs to manage my demand. I saw a post from @gbyleveldt where he was switching loads based on the battery DoD, etc. What would the best approach be? I was hoping to get all the information into Home Assistant and manage the rules from there. Is Home Assistant the way to go and if it is, what would the best hardware platform be to install Home Assistant on?

Also, would the CBI Astute smart controllers be an option to consider or what would the best wifi controllers be that integrates with Home Assistant?

Welcome @hdupreez

I use a combination of approaches.

In my previous house, I didn’t want the big consumers on the inverter, so the kitchen was purposefully left without backup (because of the microwave oven, the kettle, etc). That meant I had to run an extension cord (neatly in trunking) to the refrigerator, and the Fibre router (which lived on top of the refrigerator).

In my current house, I decided to put the kitchen on backup, because that is something we can manage, and that solves the issue with the refrigerator. But it means the water heater under the kitchen sink (with a 1.5kW element) is now backed up, so the plan is to put a Wi-Fi switch on that.

So it is a bit of a yes/no thing. Would not do it for anything really big (swimming pool pump, geyser, tumble dryer, oven). Would do it for other loads, especially the kind you can manage yourself. Then the Wi-Fi switch is just a way of making it easier to manage.

Thankfully, the loads I mentioned (except the tumble dryer) are generally on their own circuits already.

Node Red or Home Assistant is normally to option to use if you want to go very smart, but then you need to hook everything up witch smart switches which can add up in cost.

If you want to switch off some breakers, you get a little load switch you can put in your DB that can manage loads. They are normally used to disconnect the geyser when the stove/oven is in use and don’t cost much (I think @Phil.g00 had a link to it recently). This is more a is there utilities power or not type of solution and not one depending on how much power there is, but it is much easier and cheaper.

Welcome @hdupreez ! :slightly_smiling_face:

please do not take this as criticism, and knowing that it is always easier spending other people’s money, but with the system you describe I am not sure trying to reduce cost on a proper DB setup by using a R500 wi-fi switch is the best route to go. I think automation is better suited to optimising system efficiency than to ensure trouble-free operation. So, split the DB and then add automation where helpful/needed.

Thanks for the feedback everyone. I do agree that splitting the DB board would be the better way to go and this would essentially split my loads between essential and non-essential. The cost for this is substantially higher because I would need to have single breakers for certain wall plugs, where the norm in old houses is to have breakers for a group of plugs per room - apart from splitting the DB, I would also need to pull in new wires. Secondly, I am not that familiar with the inverter yet, but from the schematics there is a single output for essential and a single output for non-essentials. This would mean that I would not be able to switch of certain non-essentials according to available battery power.

Hi @hdupreez - Welcome!

I had the same issue in a previous house. I ended up pulling more cable just for my essential loads (lights are all essential) to a new sub-DB due to the above issue. It is worked for me.

It’s still perfectly okay to have multiple plugs on the same 20A breaker, as long as the wiring is always suitably protected by the right upstream breaker, and I do believe there are guidelines as to how many plug points you are allowed before you have to start another circuit.

In my experience, things are often already grouped fairly well. The bedrooms tend to be all on the same circuit, the kitchen tends to be on its own already, if you have a Laundry, that usually has its own breaker already, the Garage would normally be on its own circuit (although in my 70s-built house, it isn’t, it’s on the same circuit as the living room).

I remember back in the day when I did a DB (around 2016 I believe), I had to buy some stuff plus a whole day of my sparky’s time. It was around 7k back then and of course that hurt a little… but I was always glad I did it.

if not yet done, look at your own real world electricity use and discuss with your system designer/installer. The question will be what your overall needs/desires are with the system.

Your system suggests 10kW peak power from the inverters and from what I can tell the batteries will likely happily power that too. So if you are unlikely to ever exceed that load (I will need to plug in things from my neighbour to make that happen but you may have multiple geysers, wife that bakes for the basaar, etc. etc) then you at least avoid the inverter or batteries tripping on overload and you could technically connect everything on the essential side (and possibly not rewire anything ).

BUT now there is also the issue of whether you want to minimise use of eskom/municipal electricity you buy then you want to optimise your use of excess solar and self-consumption at night - i.e. run from your batteries. If everything is connected to “essential” then this will be powered from the batteries at night. Again, looks like you have a fairly large battery bank that might see you through the night. BUT what about load shedding and combined bad weather? You and the system designer will need to decide what battery reserve you feel you need.

So, knowing what you can abolutely not go without, goes to essential side so it has battery backup. Things like geysers can go on the non-essential side where they can still benefit from excess solar production during the day. If you live alone with one 2kW geyser and buy all your food prepared you could possibly put everything on the battery backed-up side.

I recently got acquainted with another ZA regulation. As my late father had wired several plugs as a ring circuit using 4mm2 wire. It was also on a circuit where power-hungry appliances were likely to be used simultaneously, so a larger <20A upstream MCB was required.
This can be signed off legally if each plug socket has its own overload protection.
And so it became the first time I saw these:
image

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I had a similar problem in my house with it being very complicated to split the essential/non-essential loads. I wanted more control of the devices and to be able to switch them on/off independently of each other so as to manage the loads better. I have 4 geysers and can’t switch them all on at the same time for obvious reasons.

I use Home Assistant with a mix of both Ewelink (Sonoff mostly) and Smart Life (Tuya) devices.

I use the SMTonoff Din Rail switches for most of my geysers (Ewelink but not made by Sonoff)

I like them because they fit onto a Din Rail and are very compact, they also handle up to 63A
They have settings in the app for high/low voltage disconnects and also over Amperage disconnects.
They are rather expensive if you buy them locally but you can get them for 1/3 of the price of you order from Aliexpress/Bangood etc, delivery usually ±2 weeks from China.

I have a CBI Astute controller as well which I use for one of my geysers (I have 4)
Integration into home assistant is pretty easy, a bit more complicated to get local control of the switch as it all goes via the cloud as default which can be problem if you don’t have internet access for some reason.

My suggestion would be to go with Home Assistant as it is a bit easier to get your head around how it works and will do most of what you can do with Node Red. You can always add Node Red into Home Assistant if you want to do more complicated automations. Home assistant also integrates very nicely with the SUnsynk inverters to pull all the relevant info from them and can also write settings to them for load shedding etc.

I would suggest running it from either an Intel NUC or other similar USFF pc which have a lot more power than an RaspPi and are available second hand at very affordable prices of gumtree etc.

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Thank you very much. The Intel NUC is something I wasn’t aware of. I have a Raspberry PI 4 that I want to configure for now until I have sorted out most of my integration and flows, but will then definitely consider upgrading to an Intel NUC. What processor and SSD size drive would be adequate? I see these devices can get pretty expensive.

Thanks. Yes, the 10kW is more than adequate. At the moment, with some management of energy hungry devices, my max load is around 6kW on average. I prefer the inverters to not run at their maximum throughput. My system has been installed and I am playing around with when to charge the batteries from the grid, but I will probably have to configure two different profiles. One profile for when we have loadshedding to ensure my batteries have enough energy and one for normal operation to limit charging the batteries only using the solar. For the last three days, my average Eskom consumption (based on a max of 50% discharge of the batteries) has been around 7kW per day, which is a massive improvement.

U can pick up a 2nd hand Intel i3/i5 NUC for ± R2K on Facebook marketplace.
Just check the generation of processor and the performance as a newer i3 can outperform and older i5.
Either way they are about 10X faster than a Raspberry Pi 4.

Thanks. Would a Raspberry PI4 with a 256Gb solid state drive be adequate or would you still recommend a NUC? Need to decide if spending R800 for solid state would be worth it or rather just go for a NUC from scratch? What generation of the processor would you recommend?

Hi @hdupreez

Digiblur has a good video on this topic. Doesn’t have to be an intel NUC but they are locally available at usually pretty good pricing second hand. Any of the ultra small form factor PC’s will offer you a lot more processing power than you get with a raspberry pi. I would get as fast as you can for what you are prepared to pay.

To give you an idea of the performance comparison, I found this add on Facebook marketplace for an HP USFF with an Intel i5 processor for R1600

Here is a processor comparison of the i5 processor in the HP vs the RP4 processor

Lenovo have the Tiny PC as well which is also USFF. My advice would be to check the model number of the machine and then look up the processor in it and check the performance on the CPU benchmark site as an older i5 can be slower than a newer i3 processor. I found the Intel NUC’s to be very compact.

Why would you need more power to run HomeAssistant than whan an RPi has?

Depends on how many plugins and integrations you have. Also especially if you doing video, SSOCR etc. Reboots on the pi take ages.