Many threads have been started on this audio forum around solar power, and I had to ask my self whether it is appropriate to start yet another one? In the end, I decided to go ahead, since:
The next bit goes over some basics that most of you are familiar with, feel free to skip to “Maximising your solar investment through automation and (small) lifestyle changes:” if you’re just interested in the saving and how automation helped me achieve it.
There are many alternatives to solar installations. Let's consider one or two:
1) Generators
I worked from home during covid and still do. This might change, but running a generator was no longer a viable solution for me. I had to run it too much and appliances and garage doors broke when the genny ran out of power. Still, a generator is a good (cheap) solution to the power problem. It is mostly manual though (you have to start it), usually noisy (especially for the neighbour closest to the thing – I am one of those neighbours now) and it uses fuel which is expensive (but still a lot cheaper than a solar solution). <edited>A generator's sine wave seems to be acceptable for most home electronics but the frequency can change a bit based on the load on the generator (I am unsure of the long-term effect of this on electronics). With a generator, the safest option is to have an electrician install a proper switch-over switch. If you don't want to spend that money, please make sure you know what you're doing, the thing can kill you.
2) Battery banks / trolley inverters etc.
These are essentially a battery with an inverter where you can plug devices into. It can be cheap or expensive, probably ranging from R1k to R25k. If you just want to beat load shedding with a couple of devices, this is a good option. <edited> @Orcish75 's reply below contains a bit more detail on this. Also note that the very cheap trolley inverters produce a modified sinewave as opposed to a pure sinewave - this can be an issue with some electronics. From what I can read, mostly those with AC motors will not run as efficient as they should and can get damaged. Fwiw, my own fridge had to be replaced - but it was old so I can honestly not purely blame the genny.
3) Wind / water turbines
These don't seem suitable for domestic purposes but I guess if the wind is howling through your roof permanently then there may be smaller devices that work. The pic below sums up my knowledge of the topic.
Ok, now on to the main meal, solar installations.
I think everyone who has solar, went through a thought process that ranges from having a battery backup for internet and TV through to being fully off-grid many times. This is a natural process as the investment can be quite heavy.
The decision I ended up with, was to reduce my dependency on Eskom as much as possible within my budget. I have managed to reduce my Eskom bill from average R2500-R3500 per month, down to avg R200 – R250 per month with a R207k investment. To get rid of the last bit of dependency on Eskom is expensive RELATIVE to the rest of the solution, but it is much more achievable than I once thought.
If you don't want that type of capital outlay, you can also rent a solar installation with monthly installments. Gosolr is a company you can rent a solar solution from. I like the vision of Gosolr and the fact that they make it affordable for people to have solar, but I hate renting stuff. Also, I don’t believe there is a lot of maintenance in a solar solution, but rental is an awesome option if you don’t want to worry about your inverter breaking or blowing up or whatever. Several other advantages and disadvantages are documented in Kolakidd’s excellent write-up about his Gosolr installation over here: GoSolr 8kW (Large option) install
A typical solar installation uses an inverter, batteries and solar panels.
Inverter
A classic inverter changes electrical current from direct current / DC (that you get from solar panels, batteries etc.) to alternate current / AC that gets used by most devices in a home. The inverters that we discuss here do a lot more - it brings together batteries, solar panels and AC from Eskom in one place and uses it intelligently with many configuration options.
I will not debate the merit of various brands of inverters as I have very little knowledge to support any claim I make. I can only tell you why I chose what I chose (a Deye inverter). The reasons were pretty simple:
Quick note on my understanding of kilowatts: A kilowatt is a thousand watts. A watt (according to Wikipedia) is “ the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3 ”. A watt (according to me) is the amount of electricity that something uses. For instance, my geyser uses 4kW or 4000 watts when it is on. My kettle uses 3000 watts when it is on. Some like my aircon changes the number of watts that it uses based on how hard it is working. An 8kW inverter can handle up to an 8kW load. So, if my kettle and geyser run at the same time, and 8kW inverter can handle the load, but a five kilowatt inverter can not.
Batteries
Lithium-ion batteries are expensive but much better than lead-acid or gel. If at all possible, get them. Go for something mainstream, if you want to understand the differences between <edited - see @Skylar 's comment below> Li-ion and LiFePO4 go ahead – I don’t know, I bought according to spec and price. Most important thing to understand about li-ion batteries is that their capacity is quoted in kWh (kilowatt hour). If a battery has 5kWh then it can provide 5kw for an hour. Or one kilowatt for 5 hours. This is not strictly true though, because there is the concept of depth-of-discharge. In order to prolong the life of the battery, you can’t completely discharge it, my inverter will shut down when the batteries get to 20% (which is standard for that type of battery). Btw, gel and lead-acide have a depth of discharge of 50%, so only 50% of your battery is available.
On the Deye/Sunsynk inverter you set where you want to discharge your battery to. For instance, I keep mine at 40%. This means that my batteries will only discharge to 40%, then it will only use the panels or Eskom. This is to cater for load shedding at night – when the load shedding kicks in my battery will get used and power is back before I get to 20%. Once power is back, it will charge my battery back to 40%. This, and a ton of other things, is configurable on the inverter.
Panels
I have 24 panels, each capable of producing 455 kw at best (getting full sun at a good angle. I’ve been told it is a lot of solar panels (too many for my installation). That may be so, but we work from home, my kids at that stage were studying from home – most of my electricity usage is during the day (when that big yellow bulb is hanging in the sky and powering the panels). I love having all the panels – my 10kWh batteries are usually fully charged early-ish in the morning. From there I do what I like. I run the pool heater, aircons etc. that I would not usually do due to cost. Also, they face in three directions so if it is overcast at certain times of day I catch the sun sooner or later.
Shade is an important factor in solar panels. If one of the small cells gets shade, then the whole panel produces nothing (they are probably wired in series). Most popular panels these days are called split-panels – the panel is split into two so if there is shade on the one half, you still get power from the other half. At least, that’s how I understand it. There are other, more expensive ones but if you are reading this then chances are good that you just want bang for buck.
Maximising your solar investment through automation and (minor) lifestyle changes:
As I delved into the options, I decided that I wanted to decrease my dependence on Eskom as much as possible. So, as we chatted through splitting the DB board into essentials and non-essentials, I asked the installer why I can’t have everything run through the inverter. It is an option, but an 8kW inverter is not really enough unless your major consumers of power (geyser, stove) are gas or some other alternative set-up. I had one solar geyser but another electrical one. And an electrical stove and oven, a pool pump with pool-heater and so on. When something is on non-essential, it won’t run when Eskom is down and the power is down (please correct me if I’ve got the wrong end of the stick here). I didn’t want that, as the failing infrastructure, cable theft, hooliganism and karma caused me to be without power for > 24hrs at times. During those times, I still wanted access to non-essentials. So, I decided to stick everything through the inverter and “see how it goes”.
In order to protect the inverter, the installer put in a switch breaker before the inverter so that it trips when the load get too high (he probably made up his mind that I didn’t know what I was asking for – and was right to some extent). So, when my electrical geyser is running, four kw are gone. Add a kettle, that’s another three and poof goes the trip.
I was annoyed that my trip didn’t allow me to make full use of my inverter (it’s a 6amp breaker), but I guess pushing it to 8kW for extended periods aren’t great? I still need to speak to someone to figure out whether having that trip is best practice or not. Nevertheless, so the education started with the family to understand what is getting switched on and how much it consumes.
In other words, you have to “actively manage’ your consumption not to exceed the inverter’s capacity. 90% of people probably don’t want to do this – things should just work and that is fine, but I made the choice to do this in order to use less Eskom supplied power. We also try to cook while the sun still shines and if my wife has a bath in the evening, I know that to shower in the morning will have to wait a bit, or I’ll have to run the geyser early morning (and pay for it).
The installer put a wifi switch (brand is CBI) in front of the geyser. This is really nifty, you can program your geyser to go on at certain times only and know not to switch on other devices at those times. I also replaced my kettle with a smaller, 1kW kettle that takes longer to boil the water, but we are seldom in a hurry and we seldom need more than two cups at a time. Next I bought a 2kW induction plate which we use a lot of the time in stead of the stove top (it peaks at 2kW but for short periods only). My old fridge got damaged with loadshedding and I replaced it, the effect was also very visible when you monitor consumption after hours.
All in all we were doing very well, and I realised that we were using very little kW from Eskom, but paying R600 odd for the line. I switched over to pre-paid and that cost disappeared. Now I was paying only for the kW I used, and they were very few.
Still the issue of the trip switch kept haunting me. If the geyser is on, and you switch on the washing machine, it trips. The washing machine uses very few watts (maybe 400?), except for a short five minute cycle (presumably when it heats up the water) which uses 3kW. It was clear that if I could automatically switch off the geyser when the load became too high, that would be a good win for me, so I started reading about home automation.
I had an app for the geyser CBI switch, and an app for the solar consumption (solarman smart). I also saw that my air-conditioner’s app (Jet-air) looked very much like the CBI switch app. Investigating further I found that they are part of the “Tuya” platform and if you download the Tuya app, you could control and automate both from the same app. Now if only I could find APIs or something that gives me access to the inverter as well, then I was sorted.
A home automation project called “home assistant” grabbed my attention. This promised to integrate dissimilar systems with each other. I started playing around with home assistant and it quickly became apparent that this could work, as there was a plug-in for “solarman smart” (written by a South African, it seems). So, finally I could now switch off the geyser when the inverter load went above a certain value, say 6.5 kW.
The next issue was that “solarman smart” only updates values every 10-15 minutes. I hunted them down and they changed the interval all the way down to 1 min for me, but it was still not good enough. I headed to powerforum.co.za for help. That journey ended in a purchase of the “solar assistant” software (R 800), on a Raspberry Pi, connected to the inverter with a special USB cable (R500). Small money when compared to an inverter upgrade for more kWs. Of course, there’s a world-wide shortage of Pi’s at the moment, but I found one - thanks to this forum and @Contrabass for helping me out!
Solar assistant is great software, and it exposes all the inverter components in home assistant! Now I had real-time access to the inverter values and a platform for automation. What’s even cooler is that you can create your own dashboards in home-assistant (I understand that type of thing is not “cool” for everyone, but it is for me!). It is incredibly powerful and I have but scratched the surface. At the moment, I switch the geyser on in the morning at 8am IF the batteries are over 60%, otherwise wait 30 minutes and check again until it is switched on. If load goes too high, drop the geyser. Wait till load is below 2kW for five minutes, then switch geyser back on. I can also switch aircons on and off based on criteria, as well as lights etc. The only thing that is a pain to integrate so far is my Hikvision camera. Preferably run home-assistant OS (operating system) on a dedicated device (Pi). Running it virtualised on a PC is great to experiment and play with but (apparently) stability is much better with OS.
The image below is a screenshot of my current home-assistant dashboard, from where I can switch stuff on and off. The automations run for as long as home assistant runs.
The bottom line
It is possible to make everything in a fairly large household run through an 8kw inverter, if you automate some stuff with Raspberry Pi’s. This could substantially lower your dependency on Eskom and shorten your ROI drastically. Mine was at about seven years (assuming R3k/month saving and investment of R207k). Add to that the coming Eskom increases (18%), the petrol for the generator, things breaking, the inconvenience, etc. etc. and it becomes a total no-brainer.
The bottom bottom line / stuff that belongs in “open talk” / soapbox
It’s nice for me to not have any power problems anymore. But, the impact on the economy is something that we talk about but I think most of us don’t understand the full extent of it. We are actually up sh!t creek without a paddle. More and more of the payers will go with solar and the non-payers will still need electricity, but they still won’t have jobs due (in part) to the impact of the power crisis. I think we’ll find a way (simply because of the rapid pace of tech advancement in these areas) but let’s hope it’s sooner rather than later.
- electricity is critical for sound reproduction (if you don’t have electricity, you don’t have sound), and,
- we live in South Africa. Not having publicly supplied electricity is a daily occurrence.
- people ask me basic questions, the idea is that this is a useful thread to point them to.
The next bit goes over some basics that most of you are familiar with, feel free to skip to “Maximising your solar investment through automation and (small) lifestyle changes:” if you’re just interested in the saving and how automation helped me achieve it.
There are many alternatives to solar installations. Let's consider one or two:
1) Generators
I worked from home during covid and still do. This might change, but running a generator was no longer a viable solution for me. I had to run it too much and appliances and garage doors broke when the genny ran out of power. Still, a generator is a good (cheap) solution to the power problem. It is mostly manual though (you have to start it), usually noisy (especially for the neighbour closest to the thing – I am one of those neighbours now) and it uses fuel which is expensive (but still a lot cheaper than a solar solution). <edited>A generator's sine wave seems to be acceptable for most home electronics but the frequency can change a bit based on the load on the generator (I am unsure of the long-term effect of this on electronics). With a generator, the safest option is to have an electrician install a proper switch-over switch. If you don't want to spend that money, please make sure you know what you're doing, the thing can kill you.
2) Battery banks / trolley inverters etc.
These are essentially a battery with an inverter where you can plug devices into. It can be cheap or expensive, probably ranging from R1k to R25k. If you just want to beat load shedding with a couple of devices, this is a good option. <edited> @Orcish75 's reply below contains a bit more detail on this. Also note that the very cheap trolley inverters produce a modified sinewave as opposed to a pure sinewave - this can be an issue with some electronics. From what I can read, mostly those with AC motors will not run as efficient as they should and can get damaged. Fwiw, my own fridge had to be replaced - but it was old so I can honestly not purely blame the genny.
3) Wind / water turbines
These don't seem suitable for domestic purposes but I guess if the wind is howling through your roof permanently then there may be smaller devices that work. The pic below sums up my knowledge of the topic.
Ok, now on to the main meal, solar installations.
I think everyone who has solar, went through a thought process that ranges from having a battery backup for internet and TV through to being fully off-grid many times. This is a natural process as the investment can be quite heavy.
The decision I ended up with, was to reduce my dependency on Eskom as much as possible within my budget. I have managed to reduce my Eskom bill from average R2500-R3500 per month, down to avg R200 – R250 per month with a R207k investment. To get rid of the last bit of dependency on Eskom is expensive RELATIVE to the rest of the solution, but it is much more achievable than I once thought.
If you don't want that type of capital outlay, you can also rent a solar installation with monthly installments. Gosolr is a company you can rent a solar solution from. I like the vision of Gosolr and the fact that they make it affordable for people to have solar, but I hate renting stuff. Also, I don’t believe there is a lot of maintenance in a solar solution, but rental is an awesome option if you don’t want to worry about your inverter breaking or blowing up or whatever. Several other advantages and disadvantages are documented in Kolakidd’s excellent write-up about his Gosolr installation over here: GoSolr 8kW (Large option) install
A typical solar installation uses an inverter, batteries and solar panels.
Inverter
A classic inverter changes electrical current from direct current / DC (that you get from solar panels, batteries etc.) to alternate current / AC that gets used by most devices in a home. The inverters that we discuss here do a lot more - it brings together batteries, solar panels and AC from Eskom in one place and uses it intelligently with many configuration options.
I will not debate the merit of various brands of inverters as I have very little knowledge to support any claim I make. I can only tell you why I chose what I chose (a Deye inverter). The reasons were pretty simple:
- My installer recommended it. He has had issues with cheaper inverters and believes Deye/Sunsynk is the most reliable at the price point. He also feels there is an advantage for him to be master of one brand in stead of half-master of many. Note that Deye and Sunsynk are used interchangeably and he supports both – the hardware is identical but the software on the inverters are different.
- The two other installers that I got comparative quotes from, both quoted on Deye/Sunsynk as a preference.
- I am a little sheep. I don’t swim upstream with these type of things and follow the majority unless I find my requirements differ from the norm.
- Note this point is made based on word-of-mouth and not factual research: Lithium batteries come with a battery management system that uses a specific protocol to communicate with the inverter. I was TOLD (this is NOT confirmed) that cheaper inverters don’t always utilise the protocol, but instead rely on factors like voltages to make charge/discharge decisions. I can’t tell you which inverters these are and I’m sure it’s not ALL the cheaper inverters, but I have a colleague whose lithium batteries swelled to almost double their size (that is a bad thing). Feel free to add to or correct this statement.
Quick note on my understanding of kilowatts: A kilowatt is a thousand watts. A watt (according to Wikipedia) is “ the unit of power or radiant flux in the International System of Units (SI), equal to 1 joule per second or 1 kg⋅m2⋅s−3 ”. A watt (according to me) is the amount of electricity that something uses. For instance, my geyser uses 4kW or 4000 watts when it is on. My kettle uses 3000 watts when it is on. Some like my aircon changes the number of watts that it uses based on how hard it is working. An 8kW inverter can handle up to an 8kW load. So, if my kettle and geyser run at the same time, and 8kW inverter can handle the load, but a five kilowatt inverter can not.
Batteries
Lithium-ion batteries are expensive but much better than lead-acid or gel. If at all possible, get them. Go for something mainstream, if you want to understand the differences between <edited - see @Skylar 's comment below> Li-ion and LiFePO4 go ahead – I don’t know, I bought according to spec and price. Most important thing to understand about li-ion batteries is that their capacity is quoted in kWh (kilowatt hour). If a battery has 5kWh then it can provide 5kw for an hour. Or one kilowatt for 5 hours. This is not strictly true though, because there is the concept of depth-of-discharge. In order to prolong the life of the battery, you can’t completely discharge it, my inverter will shut down when the batteries get to 20% (which is standard for that type of battery). Btw, gel and lead-acide have a depth of discharge of 50%, so only 50% of your battery is available.
On the Deye/Sunsynk inverter you set where you want to discharge your battery to. For instance, I keep mine at 40%. This means that my batteries will only discharge to 40%, then it will only use the panels or Eskom. This is to cater for load shedding at night – when the load shedding kicks in my battery will get used and power is back before I get to 20%. Once power is back, it will charge my battery back to 40%. This, and a ton of other things, is configurable on the inverter.
Panels
I have 24 panels, each capable of producing 455 kw at best (getting full sun at a good angle. I’ve been told it is a lot of solar panels (too many for my installation). That may be so, but we work from home, my kids at that stage were studying from home – most of my electricity usage is during the day (when that big yellow bulb is hanging in the sky and powering the panels). I love having all the panels – my 10kWh batteries are usually fully charged early-ish in the morning. From there I do what I like. I run the pool heater, aircons etc. that I would not usually do due to cost. Also, they face in three directions so if it is overcast at certain times of day I catch the sun sooner or later.
Shade is an important factor in solar panels. If one of the small cells gets shade, then the whole panel produces nothing (they are probably wired in series). Most popular panels these days are called split-panels – the panel is split into two so if there is shade on the one half, you still get power from the other half. At least, that’s how I understand it. There are other, more expensive ones but if you are reading this then chances are good that you just want bang for buck.
Maximising your solar investment through automation and (minor) lifestyle changes:
As I delved into the options, I decided that I wanted to decrease my dependence on Eskom as much as possible. So, as we chatted through splitting the DB board into essentials and non-essentials, I asked the installer why I can’t have everything run through the inverter. It is an option, but an 8kW inverter is not really enough unless your major consumers of power (geyser, stove) are gas or some other alternative set-up. I had one solar geyser but another electrical one. And an electrical stove and oven, a pool pump with pool-heater and so on. When something is on non-essential, it won’t run when Eskom is down and the power is down (please correct me if I’ve got the wrong end of the stick here). I didn’t want that, as the failing infrastructure, cable theft, hooliganism and karma caused me to be without power for > 24hrs at times. During those times, I still wanted access to non-essentials. So, I decided to stick everything through the inverter and “see how it goes”.
In order to protect the inverter, the installer put in a switch breaker before the inverter so that it trips when the load get too high (he probably made up his mind that I didn’t know what I was asking for – and was right to some extent). So, when my electrical geyser is running, four kw are gone. Add a kettle, that’s another three and poof goes the trip.
I was annoyed that my trip didn’t allow me to make full use of my inverter (it’s a 6amp breaker), but I guess pushing it to 8kW for extended periods aren’t great? I still need to speak to someone to figure out whether having that trip is best practice or not. Nevertheless, so the education started with the family to understand what is getting switched on and how much it consumes.
In other words, you have to “actively manage’ your consumption not to exceed the inverter’s capacity. 90% of people probably don’t want to do this – things should just work and that is fine, but I made the choice to do this in order to use less Eskom supplied power. We also try to cook while the sun still shines and if my wife has a bath in the evening, I know that to shower in the morning will have to wait a bit, or I’ll have to run the geyser early morning (and pay for it).
The installer put a wifi switch (brand is CBI) in front of the geyser. This is really nifty, you can program your geyser to go on at certain times only and know not to switch on other devices at those times. I also replaced my kettle with a smaller, 1kW kettle that takes longer to boil the water, but we are seldom in a hurry and we seldom need more than two cups at a time. Next I bought a 2kW induction plate which we use a lot of the time in stead of the stove top (it peaks at 2kW but for short periods only). My old fridge got damaged with loadshedding and I replaced it, the effect was also very visible when you monitor consumption after hours.
All in all we were doing very well, and I realised that we were using very little kW from Eskom, but paying R600 odd for the line. I switched over to pre-paid and that cost disappeared. Now I was paying only for the kW I used, and they were very few.
Still the issue of the trip switch kept haunting me. If the geyser is on, and you switch on the washing machine, it trips. The washing machine uses very few watts (maybe 400?), except for a short five minute cycle (presumably when it heats up the water) which uses 3kW. It was clear that if I could automatically switch off the geyser when the load became too high, that would be a good win for me, so I started reading about home automation.
I had an app for the geyser CBI switch, and an app for the solar consumption (solarman smart). I also saw that my air-conditioner’s app (Jet-air) looked very much like the CBI switch app. Investigating further I found that they are part of the “Tuya” platform and if you download the Tuya app, you could control and automate both from the same app. Now if only I could find APIs or something that gives me access to the inverter as well, then I was sorted.
A home automation project called “home assistant” grabbed my attention. This promised to integrate dissimilar systems with each other. I started playing around with home assistant and it quickly became apparent that this could work, as there was a plug-in for “solarman smart” (written by a South African, it seems). So, finally I could now switch off the geyser when the inverter load went above a certain value, say 6.5 kW.
The next issue was that “solarman smart” only updates values every 10-15 minutes. I hunted them down and they changed the interval all the way down to 1 min for me, but it was still not good enough. I headed to powerforum.co.za for help. That journey ended in a purchase of the “solar assistant” software (R 800), on a Raspberry Pi, connected to the inverter with a special USB cable (R500). Small money when compared to an inverter upgrade for more kWs. Of course, there’s a world-wide shortage of Pi’s at the moment, but I found one - thanks to this forum and @Contrabass for helping me out!
Solar assistant is great software, and it exposes all the inverter components in home assistant! Now I had real-time access to the inverter values and a platform for automation. What’s even cooler is that you can create your own dashboards in home-assistant (I understand that type of thing is not “cool” for everyone, but it is for me!). It is incredibly powerful and I have but scratched the surface. At the moment, I switch the geyser on in the morning at 8am IF the batteries are over 60%, otherwise wait 30 minutes and check again until it is switched on. If load goes too high, drop the geyser. Wait till load is below 2kW for five minutes, then switch geyser back on. I can also switch aircons on and off based on criteria, as well as lights etc. The only thing that is a pain to integrate so far is my Hikvision camera. Preferably run home-assistant OS (operating system) on a dedicated device (Pi). Running it virtualised on a PC is great to experiment and play with but (apparently) stability is much better with OS.
The image below is a screenshot of my current home-assistant dashboard, from where I can switch stuff on and off. The automations run for as long as home assistant runs.
The bottom line
It is possible to make everything in a fairly large household run through an 8kw inverter, if you automate some stuff with Raspberry Pi’s. This could substantially lower your dependency on Eskom and shorten your ROI drastically. Mine was at about seven years (assuming R3k/month saving and investment of R207k). Add to that the coming Eskom increases (18%), the petrol for the generator, things breaking, the inconvenience, etc. etc. and it becomes a total no-brainer.
The bottom bottom line / stuff that belongs in “open talk” / soapbox
It’s nice for me to not have any power problems anymore. But, the impact on the economy is something that we talk about but I think most of us don’t understand the full extent of it. We are actually up sh!t creek without a paddle. More and more of the payers will go with solar and the non-payers will still need electricity, but they still won’t have jobs due (in part) to the impact of the power crisis. I think we’ll find a way (simply because of the rapid pace of tech advancement in these areas) but let’s hope it’s sooner rather than later.
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