February 8, 20233 yr Greetings all Hope you can assist with something. Excuse my ignorance, I am new to this. On the edge of getting a 8kw system installed, two 5kw batteries and 8x 545w s/panels, the idea being to cover load shedding and reduce utility bill, with a view to maybe being off grid far in the future. The issue I have is that I want to power two outbuildings on the system, each of which have a geyser and stove. Installer has said I need to have separate systems for each, but I can't believe that is right. Firstly I would think at worst, it should be possible to lay a second power cable to each building to provide a essentials power supply and a non-essential power supply. This would be a pain as it would mean digging up driveways etc. But would it not even be possible to set up a remote switch on the circuits of the out buildings to simply cut those stove and geyser circuits when there is no utility supply? or when battery power gets below a certain level? I understand that sunsync is bringing out a remote switch shortly that can work from their inverter, and I can't think that it could not be programmed to cut out geyser and stove circuits. Your thoughts? Edited February 8, 20233 yr by Belix
February 9, 20233 yr 23 hours ago, Belix said: The issue I have is that I want to power two outbuildings on the system, each of which have a geyser and stove. Installer has said I need to have separate systems for each, but I can't believe that is right. I don't believe separate systems are absolutely required, but they are prudent. Most installs have the geyser on the non-essential side, and for a reason: pretty much anything that has an electric heating element is going to impose a non-trivial load on your system, so usually geysers and electric stoves are not backed up. If the geyser has a 3kw element and that element turns on, then that is 3kw extra load. Either it will be power from PV that won't go into your batteries, or it will be power that has to come out of your batteries. 3kW for an hour = 3kWh = 1/3 of your useful battery capacity. You want to run two of them... Go with the installer's recommendation at first. If it seems you have sufficient spare capacity, you might try running the geysers once a day, on a timer, and see if the system still gives you protection against load shedding. Preferably with down graded elements. There will be grumbling, but you have to sell the idea that you can have hot water on demand OR protection against load shedding, but not both. Or use gas/solar heated geysers. Even a heat pump is better than an element (I have a heat pump, it runs twice a day and is on the backed up side of the DB). Almost anything is a better bet than a conventional electric element. Stoves - forget it. 2 geysers can maybe be managed with timers and lower powered elements. Stoves there is just no way. They don't get backed up.
February 9, 20233 yr Belix, I had the exact same issue. Cottage and main house. Solved it without running new cables. I installed an ATS in the main house that changes over the cottage power from Eskom (63A breaker) to inverter supply (5A breaker). In the cottage, I installed a WiFi contactor that disables stove, geyser, and all other heavy loads. Sonoff smart scenes manage the contactor. During loadshedding, any accidental high power draw from the cottage (eg kettle) trips the 5A breaker. ATS: https://e-glow.co.za/products/copy-of-ats-toq5-63a-ac-2p-230vac-tomzn?_pos=2&_sid=e789640cc&_ss=r WiFi breaker: https://e-glow.co.za/collections/smart-wifi-controllers/products/wifi-smart-controller-63a-kwh-timer Works like a charm!
February 9, 20233 yr Sonoff have a product called the "loadshedder". Geewiz also sell the same thing, it is installed in the main dB with both eskom and inverter connections needed, then at loadshedding it triggers a "scene", and all linked devices switch off/on as you set it. You could install a single smart breaker (must use ewelink) with a high amp rating for the entire 'non essential' circuit, or one for each device separately. Note, you will need reliable wifi wherever the smart breakers are installed. It should switch devices off within a few seconds of loadshedding. Edited February 9, 20233 yr by abd7
February 9, 20233 yr https://www.geewiz.co.za/sonoff-products/187936-sonoff-load-shedding-detector-kit-with-instructions.html
February 10, 20233 yr Author Thanks for the replies, I was thinking of something along those lines... I'd found this https://www.bidorbuy.co.za/item/5785690 ... gIFMvD_BwE to trigger and this to "switch" https://www.geewiz.co.za/smart-plugs-sw ... gKlcfD_BwE which use Tuya (i'm not familiar with Tuya or EWELINK. Is there a preference of one over the other). Wifi quality could be an issue, I'll need to see how to improve it too.
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