July. New tariffs kick in in Johannesburg. I bought my minimal amount of prepaid electricity today. Last month (old tariff) I got 62.5 units. This month 55.5 (should be just enough) so it's now 3.06 inclusive on the bottom step of the tariff for pre-paid electricity. Unless you are registered as an indigent person, in which case the first 350 units are discounted.

The cheapest post-paid unit is now 3.04 inclusive. Though because it's post-paid that probably won't show in this month's statement.

1069 on fixed fees for a 60A post-paid domestic single phase connection.

Die wet van die Transvaal

Tshwane 2025-07 to 2026-06 prepaid, single phase, 60amp, for comparison?

The tables from the middle to right, were to get a understanding of average hourly consumption, based on units purchased per month.

For example if you only buy 100 units a month, your hourly avg consumption would be 137 watts per hour, maybe enough to operate one or two residential, energy efficient fridges?

And sadly the increases will continue, and the people who actually pay Eksdom for the power will decline - death spiral!

• Crying in Capetonian @ R3.91/kWh, and R4.75/kWh after the first 600kWh

Luckily I only bought 800kWh in the last 12 months.

Edited July 17, 2025Jul 17 by Paulcupine

There are some advantages to living in the sticks in Richards Bay! Most months I now buy less than 100 units.

Jul-25
R/kwh
R 1.91	Cost for 50
R 2.43	Cost for 50-350
R 3.43	Cost for 351-600
R 3.59	Cost for 601-1500

I am on postpaid and my kWh rate is 2.27. This is with the new charges. I use a little less than 200kwh a month (only geyser) so it’s quite cheap. My fixed charges are 1181 though. Not worth it for me to go to prepaid personally. I’m just focused on building up my system to go off grid. Geyser I’m taking care off next year and I haven’t touched the grid since I added more panels in April. Winter I’ve been completely off grid.

31 minutes ago, Denns said:

I’ve been completely off grid.

Way to go. 👊

Show me yours, I'll show you mine. All before VAT. NMBM.

Can't complain about the monthly basic charge of R117.7

Can't complain about the Off-Peak R1.92/kWh.

Can't complain about Standard-time R2.94/kWh.

Peak energy is a less fun R8.56/kWh. I've used 10kWh so far this month at that rate/time, which was unavoidable.

On 2025/07/20 at 8:28 PM, GreenFields said:

Peak energy is a less fun R8.56/kWh. I've used 10kWh so far this month at that rate/time, which was unavoidable.

I find the idea of TOU fascinating just from an optimization point of view. Surely at that crazy high rate it makes sense to charge your battery beforehand (even from grid) and use only battery during peak times? If you can minimize peak usage then you must have close to the cheapest electricity overall cost. TOU makes the most sense to me in terms of encouraging good grid behaviour but obviously the major issue is the cost of infrastructure (meters and monitoring etc) to implement it.

1 minute ago, JaseZA said:

I find the idea of TOU fascinating just from an optimization point of view. Surely at that crazy high rate it makes sense to charge your battery beforehand (even from grid) and use only battery during peak times? If you can minimize peak usage then you must have close to the cheapest electricity overall cost. TOU makes the most sense to me in terms of encouraging good grid behaviour but obviously the major issue is the cost of infrastructure (meters and monitoring etc) to implement it.

I have a Tier based system. 0 to 500kwh of usage is 2.27/kwh, 500 to a 1000Kwh is 2.64/kwh. Very good for me since my usage is 200kwh and under BUT the way you put across TOU makes it very appealing for people with a decent battery storage system to do as you say. I guess people on solar shouldnt fight eskom too much then with the TOU system. Just charge in the off peak hours.

4 hours ago, JaseZA said:

I find the idea of TOU fascinating just from an optimization point of view. Surely at that crazy high rate it makes sense to charge your battery beforehand (even from grid) and use only battery during peak times? If you can minimize peak usage then you must have close to the cheapest electricity overall cost. TOU makes the most sense to me in terms of encouraging good grid behaviour but obviously the major issue is the cost of infrastructure (meters and monitoring etc) to implement it.

The point of TOU tariffs is to encourage what you call "good grid behaviour". Really to get users to reduce their usage during peak hours.

I have family in Spain, where TOU tariffs are common. They do things like use the timer on the dishwasher so that it runs at 2am which is the cheapest time for electricity. Folks have to save money, and TOU tariffs allow a win win situation whereby the grid is less heavily loaded at peak times and the customer can save.

I already do most of my heavy lifting during the day when I have PV power. My battery also gets charged, and the reality is that I can run the house off of the battery during the evening and morning peaks. Eskom currently define the morning peak as 6:00 to 8:00 and the evening peak as 17:00 to 20:00.

38 minutes ago, Bobster. said:

The point of TOU tariffs is to encourage what you call "good grid behaviour". Really to get users to reduce their usage during peak hours.

I have family in Spain, where TOU tariffs are common. They do things like use the timer on the dishwasher so that it runs at 2am which is the cheapest time for electricity. Folks have to save money, and TOU tariffs allow a win win situation whereby the grid is less heavily loaded at peak times and the customer can save.

I already do most of my heavy lifting during the day when I have PV power. My battery also gets charged, and the reality is that I can run the house off of the battery during the evening and morning peaks. Eskom currently define the morning peak as 6:00 to 8:00 and the evening peak as 17:00 to 20:00.

With that much PV I will be surprised you touch the grid at all. I only recently added 2 more panels but even with 3.25Kwp (rather than the 4.55KWp now) I hadnt touched the grid.

Paying R3.37kw/h in Cape Town with a monthly R340 connection charge

4 hours ago, Denns said:

With that much PV I will be surprised you touch the grid at all. I only recently added 2 more panels but even with 3.25Kwp (rather than the 4.55KWp now) I hadnt touched the grid.

There's many a day when I could run the whole property off of PV, with the proviso that I don't exceed 20A. It depends on my appetite for changes. EG no electric lawnmower. EG varispeed pool pump.

As it is I have to spend R400 a month on prepaid power because of the way COJ apply thd fixed fees on those meters. That gives me 50 something units per month. It gets to a point where saving more will cost me more than I could save.

33 minutes ago, Bobster. said:

There's many a day when I could run the whole property off of PV, with the proviso that I don't exceed 20A. It depends on my appetite for changes. EG no electric lawnmower. EG varispeed pool pump.

As it is I have to spend R400 a month on prepaid power because of the way COJ apply thd fixed fees on those meters. That gives me 50 something units per month. It gets to a point where saving more will cost me more than I could save.

Without a fixed charge I will get through this month with less than R80 for grid use. Last month it was just over R100. I only have 3kWpv. Happy to see more production than use even on a bad PV day like today.

It would make no financial sense to add more battery power even if I have a few hours of wasted PV.

3 minutes ago, Scorp007 said:

Without a fixed charge I will get through this month with less than R80 for grid use. Last month it was just over R100. I only have 3kWpv. Happy to see more production than use even on a bad PV day like today.

It would make no financial sense to add more battery power even if I have a few hours of wasted PV.

I am choosing to add more PV than batteries due to cost and ROI. I am always left with 80/75% of my battery every morning and the lowest I’ve seen is 65% if the day is mostly cloudy. This was with a Pv of 3.25KWp.

It’s been 2 weeks now with the 2 addition panels totalling 4.55KWp and I’m consistently at 75% battery capacity in the mornings as the batteries are fully charged the day before despite the cloudy weather. Very good for my GEL battery bank whose lifespan depends primarily on the DOD.

I am going overboard now and adding more panels to hit 6KWp. This will push my generation to a bit over 3x what I need to meet my house energy demand. It can go to waste, I don’t care. Panels are so cheap that it makes little sense not to. If I can ensure the batteries are always charged I don’t need as big a battery bank.

Edited July 22, 2025Jul 22 by Denns

12 hours ago, Bobster. said:

As it is I have to spend R400 a month on prepaid power

Or completely cut the connection to the grid. If I were on a farm then maybe. Here in suburbia I think it makes a property less attractive when it comes to selling. Any prospective buyer would have to consider the cost of reconnection. Also I have heard, but can't verify, that City Power are charging for disconnection.

Beyond all that, we have a multi-day overcast spell in Johannesburg right now. Yesterday my battery did not get to 100% SOC. This is unusual for me because I have always had my system programmed to charge from the grid if necessary from 15:00 to 16:00. Since I beefed up my panel arrays I have less need for that, and now I have it turned off to see if the system will get me through this spell and then recharge once we get bright weather again. But I like to have that grid connection as a last resort. It costs a lot of money to go 100% off grid, to know that you can't use the grid ever, under any circumstances, and to be sure that you have enough generating power.

Most of my roof space faces E & W. Maybe if I had space for more than half a dozen panels facing North - and the cash - I'd beef my system up but would I have the intestinal fortitude to go all the way off the grid? Hmmm...

23 hours ago, JaseZA said:

I find the idea of TOU fascinating just from an optimization point of view. Surely at that crazy high rate it makes sense to charge your battery beforehand (even from grid) and use only battery during peak times? If you can minimize peak usage then you must have close to the cheapest electricity overall cost. TOU makes the most sense to me in terms of encouraging good grid behaviour but obviously the major issue is the cost of infrastructure (meters and monitoring etc) to implement it.

This is how I manage it - solar-charging and top-up charge from grid by day, running off battery during peak times, and shifting as much load as I can to off-peak and standard time slots.

Compared to the off-peak price of power it becomes less economically viable to install more panels or batteries, so I've settled on remaining grid-interactive, and then being able to cover loadshedding with basic amenities.

The problem is just that I've got a small 5kWh battery and 5kW inverter, so it's easy to either drain the battery making dinner, or exceed the power rating of the inverter and then draw in from the grid, but the cost still doesn't justify making changes.

Metering is in place as I've had grid-tie since 2015, using GPRS communications to the municipality, so that's barely an afterthought by now.

Here in suburbia I think it makes a property less attractive when it comes to selling. Any prospective buyer would have to consider the cost of reconnection. Also I have heard, but can't verify, that City Power are charging for disconnection.

Reconnection is about 12k if i remember well. If you decide to stay at your house for at least 3 years the cost covers itself. Disconnection is 1.2k (at least thats what i saw when I looked at the site the other day). All of these get easily covered with the savings from not paying the fixed charges. But you have a very valid point, cutting the grid makes sense if you know you will stay at your residence for a long time. I only just bought my house last year and we decided we will stay there for the next 10 to 20 years. Ideally till we retire so the money spent on going offgrid will be recovered easily.

I also self-installed since I am an electrical engineer and the entire system cost me just under 40k to do. I will get all my money back in just under 2 years. If I cut the grid, the 1.2k in fixed charges will pay for taking the geyser off in a year. ROI is very good.

I also hear some people would prefer an offrid home due to the rising costs. You might not have to spend on the reconnection at all if things keep goin this way.

Edited July 23, 2025Jul 23 by Denns

25 minutes ago, GreenFields said:

This is how I manage it - solar-charging and top-up charge from grid by day, running off battery during peak times, and shifting as much load as I can to off-peak and standard time slots.

Compared to the off-peak price of power it becomes less economically viable to install more panels or batteries, so I've settled on remaining grid-interactive, and then being able to cover loadshedding with basic amenities.

The problem is just that I've got a small 5kWh battery and 5kW inverter, so it's easy to either drain the battery making dinner, or exceed the power rating of the inverter and then draw in from the grid, but the cost still doesn't justify making changes.

Metering is in place as I've had grid-tie since 2015, using GPRS communications to the municipality, so that's barely an afterthought by now.

Gas is your friend. I get away with 2.5/3kwh of battery usage at night because of gas. We have a 9kg bottle and it lasts us about 5 months (299 to refill). We have those kettles that whistle and do our water boiling with it, cook every 2 days give or take mainly because we dont like the trouble of doing it everyday. Dishwasher and Washing machine are scheduled using connectlife app to run during the day. Pool pump etc also during the sun.

Battery only runs the TV (75 inch one that draws a bit over 200W), lights, router and my Desktop I play games on at night. Laptops for the kids. Microwave gets used here and there but its negligible, same with fridge. I only have a 3.6kw inverter but we work around the power draw by only running one big power user at a time. Dishwasher, toaster, washing machine, microwave and air fryer are only used one at a time. Was a simple enough habit change. Barely inconveniences anyone.

21 minutes ago, Denns said:

Gas is your friend. I get away with 2.5/3kwh of battery usage at night because of gas. We have a 9kg bottle and it lasts us about 5 months (299 to refill). We have those kettles that whistle and do our water boiling with it, cook every 2 days give or take mainly because we dont like the trouble of doing it everyday. Dishwasher and Washing machine are scheduled using connectlife app to run during the day. Pool pump etc also during the sun.

Yep. I have gas for cooking. We had a prepaid meter for some time before getting PV (it's a big saver, even now by my reckoning) and I used to buy 500kWh each mont because then the first 500 units in a month were the cheapest, and we'd usually do about 400kWh a month and so I was building up a credit. So about 13 a day. Is that low? Anyway, if we'd been doing 25 a day then the PV system would have paid for itself quicker.
I think everybody figures the same things out when they get solar - even a solar geyser. You have to make hay whilst the sun shines.

21 minutes ago, Denns said:

Battery only runs the TV (75 inch one that draws a bit over 200W), lights, router and my Desktop I play games on at night. Laptops for the kids. Microwave gets used here and there but its negligible, same with fridge. I only have a 3.6kw inverter but we work around the power draw by only running one big power user at a time. Dishwasher, toaster, washing machine, microwave and air fryer are only used one at a time. Was a simple enough habit change. Barely inconveniences anyone.

Yep. With a 20A limit on the backed up side we had to learn to not turn too much on at a time. Early on our PV journey we had a lot of trips, which led me to introduce a rule for anybody using the kitchen. Is the microwave on? Is the kettle on? Then you can't turn on the dishwasher or anything else until one of them is done. Then once the dishwasher is on you include that in your count and you have to stop at two. It was not that big a deal in the end. We got so good at it that I could move the water heating (heat pump) onto the backed up side, and so when loadshedding was it's worst we could always have a hot shower. Luxury!

For me the biggest benefit of PV for the first few years was that we could live a regular existence inside the house. Our security systems were always on, we always had hot water, always could wash clothes, always had wi-fi (a big deal if you work remotely as I do) and so on. That's worth something, though it's hard to put a rands and cents value on it.

I think all folks with PV go through this process of deciding how to balance their routines and the abilities of their system so that they find a good solution for them. The tradeoff may have been different when there was lots of loadshedding. Continuity was more of a consideration then.

Edited July 23, 2025Jul 23 by Bobster.
can/can't

Lat couple of months, I've hurt quite a bit with drawing from the grid to heat the geyser:

PV production has dropped massively, mainly due to shading. I've added another battery as well which now runs the house through the night after a sunny day, but I should really add 2 more panels so that I have 5 panels per string to get that voltage past the inverter minimum sooner rather than later.

17 minutes ago, Bobster. said:

For me the biggest benefit of PV for the first few years was that we could live a regular existence inside the house. Our security systems were always on, we always had hot water, always could wash clothes, always had wi-fi (a big deal if you work remotely as I do) and so on. That's worth something, though it's hard to put a rands and cents value on it.

I think all folks with PV go through this process of deciding how to balance their routines and the abilities of their system so that they find a good solution for them. The tradeoff may have been different when there was lots of loadshedding. Continuity was more of a consideration then.

Very true. I only wanted to cover loadshedding. 2panels is all I wanted. Then it became a thing of saving on the bill. And now off grid. That’s some escalation in the space of a year on my side🤣

Edited July 23, 2025Jul 23 by Denns

24 minutes ago, Bl4d3 said:

Lat couple of months, I've hurt quite a bit with drawing from the grid to heat the geyser:

PV production has dropped massively, mainly due to shading. I've added another battery as well which now runs the house through the night after a sunny day, but I should really add 2 more panels so that I have 5 panels per string to get that voltage past the inverter minimum sooner rather than later.

A trick I learned from the US guys living in cabins offgrid. Make use of charge controllers. Add a charge controller that is connected to an array that is mounted in an area that gets decent sun.

Also consider a PWM controller if you don’t have a decent area with clear sun the whole day. The advantage is parallel panel connections. Panels in series get heavily affected by shading as your MPPT output is determine by the lowest outputting panel which is the shaded one. PWMs can take Parallel connected panels so even if one is shaded, it doesn’t affect the power from the others.

They are close to enough to as efficient as MPPT if the panel is matched to your system. For 48V for example you can get Jinko 445W panels with a Vmp of 31V or 33V. 2 in series and have 3/4 of those in parallel. The PWM controller won’t lose much efficiency since the voltage is at 62/66V.

They are a bit tricky to find for 48V but they are available. Can add about 2.8kw of panels onto it and help you a lot with generation.

Since you also only use the extra for the geyser, an even better solution is the Geysertech Micro controller. I am getting one for my geyser. I will connect 4 585W panels to it in an area that gets little to no shading. More than plenty to heat up my geyser and its a load my inverter doesnt have to deal with. Works with elements that are 2 to 3kw. There is a bigger one that works on elements up to 4kw. No work needed on the geyser. Total cost will be 10k for me, cabling, panels and the controller.

Edited July 23, 2025Jul 23 by Denns

3 minutes ago, Denns said:

A trick I learned from the US guys living in cabins offgrid. Make use of charge controllers. Add a charge controller that is connected to an array that is mounted in an area that gets decent sun.

Also consider a PWM controller if you don’t have a decent area with clear sun the whole day. The advantage is parallel panel connections. Panels in series get heavily affected by shading as your MPPT output is determine by the lowest outputting panel which is the shaded one. PWMs can take Parallel connected panels so even if one is shaded, it doesn’t affect the power from the others.

They are close to enough to as efficient as MPPT if the panel is matched to your system. For 48V for example you can get Jinko 445W panels with a Vmp of 31V or 33V. 2 in series and have 4 of those in parallel. The PWM controller won’t lose much efficiency since the voltage is at 62/66V.

They are a bit tricky to find for 48V but they are available. Can add about 2.8kw of panels onto it and help you a lot with generation.

My budget solution to solve this, is to shift the entire string up. My geyser is whats casting the shadow, so shifting the string up should solve my problem. My intention is then to add 2 more panels below, landscape, and shift them all the way over to the left.