Solar Power

I live in a 4 bedroom house, with expensive Witbank power (R2.40/kWh now, so higher than the highest rate on @Wenzdayz’s steps) and in this terribly cold July we had heaters on 24/7 and had the highest usage yet at R3500. You’ll easily get your power down.

What I would look at, though, is getting a solar system installed as part of your home loan. It’s a sound financial investment, where you’ll likely pay less for the solar system per month than you do for power, if you structure it correctly… Also, solar doesn’t get tariff increases.

EDIT: Also forgot, I have a Ryzen 1600 working 24/7 as a server, and it did have a bit of a heavy workload in the 1st week of July. My Ryzen 3900 gaming box is also basically on 24/7.


Engineering notation?! Phwoar!

No axis labels?! Boooo! Hiss!


Definitely going to do it. Plan is to install solar once this house is sold.


That’s roughly my plan for ours as well, looking busy with the bond originator this week.


If you do go with solar, then let me know what you go for!


We should start a solar thread. I know @Viper also has a solar setup.


For the new house I’m planning to go 90% off-grid (literally just the oven will be on the grid). The system effectively pays itself off in 5 years, even sooner if you take annual electricity price increases into account and then you get at least another 5 years of free electricity before you’ll need to look at replacing the batteries.
At the moment I have a scheduled prepaid purchase of R1000 set up for once every 2 weeks so we’re basically paying about R2000 a month on electricity. It used to be over R5000 and that was two years ago before the increases. I’ll see how our usage adjusts in summer with the new increases because we tend to use most of our power in summer.

Reason for still R2000-R2500 a month: I have a normal 200L geyser and 2 computers on 24x7 and they do eth mining, although their power usage isn’t much. In summer though we have two aircons running, 1 of them also 24x7 (this house is stupid and unlivable during summer without them).

One of the more important aspects of solar though is north-facing roof space. I’ve designed the new house to have a massive roof facing 100% north just for this purpose. So the house has a bit of a weird bend in it since the house faces north and the garages face north-ish (aligned with the yard).


Are you building your own house @Viper ?

I had a look now at our future new place and I see that luckily it’s mostly facing north. Didn’t even know about that.

Have you planned which solar components you will get?

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That’s remarkably close to what I also said to @Solitude in PM. I like that our calcs come out pointing at the same conclusion!


We had a look at a couple of companies to try and get our complex on a solar grid as well as most of our units are north facing. but the costs involved for a complex is so astronomical its scary.

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Yes. It has been in planning since last year, but things have been going way too slow for my liking. Still waiting for the final plans to submit for approval. I’ve been doing some research in this a while ago and here is what I’m roughly planning.

Definitely looking at a 8kw inverter or otherwise 2x 5kw inverters. It has been somewhat frustrating to pick and choose what to use at the same time. For instance, if the tumble drier or dishwasher is on and you want to quickly heat something in the microwave, then you have to turn the other appliance off first because you’re limited by 5kw usage at a time.
I’m looking at one of these due to their 5 year warranty and they’ll allow me to sell electricity back into the grid once Gauteng catches up with the legislation:

  • Sunsynk 8kw Hybrid inverter
  • Fusion 8kw Hybrid inverter (basically just a rebranded Sunsynk)
  • Fronius Primo 8.2kw inverter

Solar Panels
These are mostly similar in warranty and output, but the ArtSolar Mono Percium panels seem to be the best value for money. Lowest price for about 20% efficiency and 12/30 years warranty. They’re produced locally in Kzn although I hope I’ll be able to get stock by the time I buy. The other brands tend to have lower than 20% efficiency (or they tend to be more expensive for the 20% panels). Some of the other brands also only offer 12/25 years warranty.

This is the most expensive part of the setup, especially when going LiFePO4 and there is a lot of junk on the market. I’ve narrowed it down to 3 brands which I’ll look more closely at closer to the time. The important parts here are the warranty (must be 10 years), the 1C rating and feedback from existing customers.

  • Hubble AM2
  • Dyness 9.6kw Lithium-ion Power Box
  • BlueNova (these are quite cheap and sold/recommended on the SolarPower forum, but don’t know much about them)
  • (Freedom Won is apparently one of the best, but insanely expensive)

At this stage I’m looking at the solar geysers from UberSolar. A highly efficient system that keeps your geyser where it is and just have the tubes on the roof. Geyser will be close to the bathrooms so that hot water is instant from the taps. I’ll also have a gas geyser for the kitchen / washing room since it is on the other side of the house.
I’ve replaced the burst geyser on my rental property with one similar to this and with two elderly people living there, they’re saving about R400 or more a month (their total electricity bill was R638 last month).
For reference, a normal 150L geyser uses 3kwh when turned on and a 200L uses 5kwh.

This is technically not part of solar and only applies because I’m fortunate enough to be planning and building the house from scratch, but I’m going to try and go completely without aircons. I’ll be putting Sisalation in the roof, double glazed windows and then just ceiling fans. If I do put aircons again, I’ll look for the LG Artcool Inverter aircons.


Wow thanks for the impressive post! I appreciate it.

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Sure. Let me know if there are any questions. A good place to start would be your monthly electricity bill to get an estimation of your needs for either saving or going off-grid.

Roof space also determines how many solar panels you can fit to see if off-grid is even an option. You can also have east and west facing solar panels, but then you need two solar panels to generate about the same amount of electricity over the daytime period as one north-facing panel.


Dude i am proud that someone else is going for double glazing. That alone makes a huge difference, the cost is so worth it.

I’m curious to see the layout plans, also be warned all councils are so backlogged, we started a building in 2019, finished it begin this year (huge university project) the council approved the plans about 2 weeks after we handed over the building. It’s the fun part of covid.

They are apparently catching up now.

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Well, when I saw a video of someone putting a heater right next to the outside window and not being able to feel the heat on the inside, I was pretty much sold. Our current house is absolute hell in summer so this is quite important for me and thus included that with long roof overhangs and the sisalation.

Sisalation is a bit of a mission to put in if the house is already built, but we tinted the windows, put insulation on the ceiling (which made it worse) and even replaced the aircons with bigger inverter aircons. There is however only so much you can do if the house wasn’t designed properly from the beginning.


Google sheets was messing me around and then I didn’t bother. :stuck_out_tongue:

You wanted all the units interconnected or each to have their own inverter and panels?

EDIT: Cause I would have liked to get solar panels on the outside walls of my flat. But I’m sure that would kill the efficiency. Also the Body Corporate would probably say no.

We have this one at work now. With about 3kW worth of panels max we get on a sunny day is 2.2kW. Biggest issue is batteries. On those days where its cloudy for 3+ days and eskom loadshedding the batteries can’t keep up.

I like that even though some systems are not on the backup grid they still can run off of the excess power when eskom is running. So the one guy at our office runs his pool pump for free (almost).


Yeah, the batteries are by far the biggest expense. I should have mentioned that while I’m essentially planning to be off-grid, I’ll still be on the grid for backup for those rainy and cloudy days. I’ll look to schedule the system that if the batteries aren’t fully charged by 15:00 or something like that, to start charging from the grid. Will first have to see how the system works when it is live to determine all the settings and what is going to work and what not.


Is your plan to run as much as you can off the batteries, while still maintaining a separate, Eskom “grid”? Will you have separate plug points and wiring for the battery/solar power?

I’m interested in investing into a “solar assisted” setup at home too, as the electricity costs are crazy, and who knows if there’ll be another price hike.


No, the inverter does all of that. The solar panels and the Eskom grid goes into the inverter and you can set the priority from there. i.e. Solar - Batteries - Grid means it will first use power from the panels, then from the batteries if there is not enough sun and then from the grid if batteries are empty. My current system is set to Solar - Grid - Batteries so that we only go on batteries during loadshedding (because I don’t have lithium batteries).
So all the plugs will run through the inverter unless you specifically exclude certain things on your DB to run directly off the grid like the oven, geyser and underfloor heating (which is how my current house is configured).

We did have to adjust our behaviour as well like we try to use the tumble drier and dishwasher during daytime so it runs directly off the sun and in future when we have a pool, the pump will also run during daytime.

If your focus is more on saving electricity rather than skipping loadshedding, a solar geyser might be the best place to start. It can apparently cut your power usage by 30% and it is cheap compared to the rest of the setup. The UberSolar system I’m looking at starts at about R17,000 to convert your existing 150L geyser to a solar geyser and I think it pays for itself at around 2 - 2.5 years, maybe less after the Eskom increases. I’ve heard multiple companies/people say that water heating is the biggest electricity expense in a household. Since I don’t have a solar geyser yet, I can’t confirm that theory myself. As soon as my current geyser pops, I’ll replace it with a solar geyser so that insurance can at least pay part of the cost.


I don’t know much about solar systems (thanks to @Viper that’s changing though), but I will hazard a guess at this one and say definitely, positively, 100% certainly there will be another electricity price hike. :smiley: