Antony

It seems 45° C is what it does.
got this from https://www.specifile.co.za/news/bosch-thermotechnology-the-bosch-solar-kit/
"
Using the Bosch Solar Kit means you can connect your existing hot water installation to either a solar water heater with gas back-up or only add a gas back-up to an existing electrical geyser without having to purchase any special solar appliance.
It avoids unnecessary on/off cycles as well as accidental scalding at the tap by ensuring that hot water is supplied at 45 degrees, irrespective of whether the incoming water was too hot or too cold, by pre-mixing the water.
It optimises your solar water heater by ensuring you have hot water, but will avoid unnecessary gas ignition due to a unique bypass function, which allows the water to bypass the gas water heater all together if the water is already hot enough."

1kW 12V trolley in stock at Geewiz
https://www.geewiz.co.za/new-items/188334-rct-megapower-pure-sine-1000va-inverter-trolley-1x-100ah-battery-4-hour-battery-life-kit-1000w.html

Om te meet is om te weet.  I agree with others here that you should measure before you spend.  I ran one of those Efergy meters in my house for about six months before installing anything.  Once you have a handle on your consumption - what's what, what can change and what cannot - you will be far better placed to buy appropriately.
While one could go for a system that is backup power only with grid charging, remember that you then only have costs.  Batteries don't save you money and every kWh that goes into them you only get part of a kWh back.  PV panels are both the cheapest part of your system and the only part that makes you money. 
The 2kW worth of panels I put in a little over three years ago have generated 10MWh of energy.  They have already paid for themselves and part way for the Fronius they're connected to.  A little over two years ago I added another 2kW of panels and those have already generated around 7MWh.  Once the panels have paid for themselves, they start paying for the rest of your system - at least that's how I see it.

Firstly, try and see if you can get that 30kwh per day down. Try to analyse where it is all going and then see where you can cut down. Maybe (for a common EG) you are running your geyser unnecessarily hot.

I say this because:
1) I think most people can make a savings on their bill without serious compromise
2) To maximise the PV system's benefits, you will need to do as much "heavy lifting" as possible during the day to make the most of the free power
3) If you can reduce that figure you can either reduce the size of your PV system or back up more with the same system.

You won't save unless you can reduce your consumption and/or have PV. If you carry on as usual and don't have PV, you are storing power for later use, and because of losses in the system, you will actually pay a little more. Once you have PV you get some free power in the daylight hours, and you can charge your battery if there is sunshine but no grid.

This is a long term investment. When I bought my system (I don't have the skills to do my own install), I figured a 7 year payback. I don't think that anymore. That doesn't mean I have regrets, just that I have had to adjust my expectations. This is doing the simple accounting of what I didn't pay on the meter. There are other benefits that are harder to put a price on: always having the lights on, always being able to open the garage, not losing the contents of the freezers, always having the security systems, always being able to read, use a computer, or watch TV, not having to check load shedding schedules when inviting friends around, etc. These are all valuable, even if harder to express as rands and cents.

Finally, check what tariff you are on. I recently heard stories about people who have installed PV and didn't see the expected nice round number on their bill under the heading electricity. They thought that Eskom was punishing PV users, but the reality is that they were on a tariff which had a fixed component per month for the connection and the costs that go with that, and that doesn't fall away even if your consumption from grid is zeo.

Yes from the 1st model that needed an external small charger like 12V 2A at R100 the design evolved to include the 15/24V for POA equipment. The one in the link is a great unit for the price. I got one for a friend more than 2 years ago and then it was available in 2 sizes. The lower storage was good for about 2 hrs but I went for the larger one with double the storage. Mine was the one sold by Geewiz.
Interesting to see that the OP adds a auto transfer switch when on a low budget. That unit can nearly buy a 100Ah lead acid battery but then one must do manual switching which I would rather do if Rands need to be stretched.

I swear, I was going to say that same thing (more or less), but held back thinking folks were looking for a full-on system. Anyway, have to concur, you don't need much to run a couple of 5W LED lights or have internet, I got by for a long time on a 150W modified-sine-wave car inverter, a cheap 2A charger and a couple of 7AH alarm batteries.
Personal take, once you start looking at running a fridge and one or two extra plugs, but only one major appliance at a time, the (barest of bare) minimum is probably a pure sine-wave 3kVA 24V Genuine Axpert PWM inverter/charger with 2x 120Ah Lithium 12V batteries, just charging from the grid with no panels, and no intention to expand. Estimated cost R20K for main parts. 
One step lower, the Axpert VM2 1200VA/1200W 12V with a single lithium 120Ah battery could be around R12K, but then it's mainly for LED lights, TV, PC, wifi, and no major appliances.
But speak to an installer first.

Keeping Internet going a simple mini UPS designed for routers can keep the WiFi going. No rewiring or cutting. Straight plug router DC into the UPS. The UPS has a DC ug at either end. Larger on the UPS side than the router so you cannot connect is wrong. External 220V charger from wall socket to charge the lithium battery inside the MINI UPS. About R650
For lights a cheap China intelligent charger to a 12V lead acid battery will see you through if LED lights. The key is for LS not to discharge for days without charging.

I have one of those that I linked above, it is enough to power my mikrotik router and fibre router, and I have tested it, runs for about 4 hours no prob. And charges up again in about 4 hours so should make it with stage4 loadshedding, maybe not stage 6 though.
You do not need a charger for it, its builtin

They have tried this 3 years running. 
2019 the city said it was edited into the budget after sign off and then did not impose the surcharge. 
2020 it was proposed then dropped as a part of a packet of relief measures. 
2021 proposed again with some twists. No surcharge where average property value for the neighbourhood was under a limit and the homeowner opted for a 20A main breaker. First 150 units per month would be increased at half the %age increase Eskom got. This was all dropped for reasons not explained. No surcharge, but also no discount so everybody gets the full 15% increase. 
Run the numbers. At present it is still cheaper to be on prepaid, especially if you don't draw a lot from  City Power. You pay more per unit, but all the fixed fees fall away. Even with the R200 you could still save. 
BUT
1) there is a cost for switching and you bear that (City Power will give you a quote for this) 
2) for a couple of months you are going to be feeding the meter and paying off the arrears on your post-paid account. 

Awesome post! Promoted.
Jay

Thanks for the comments and putting me mind at ease that I haven't overcapitalised here 
My neighbour has a borehole and I have the solar... I can feel a trade exchange coming on.
 
 
 

Hi all
Thought I’d introduce myself and take you through my current experience with solar. We have moved into a new house and the family is big - 8 people and the electricity bill was getting completely out of control - in winter we were doing in excess of 80kW per day. I live in Johannesburg and City Power’s tiered electricity costs hurt bigger households. Borrowed money out of the mortgage at 7% interest and figure I can make the money back with interest.
I didn’t do enough analysis up front, but just decided to go with
8kW Deye inverter
18 x 540W JA Solar = 9720W 
3 x 4.8kW LifePO4 (80% DOD) 
The whole household and two cottage are on 4(!) solar EVT geysers. I bought these first and then got more ambitious. In retrospect, I’m wondering whether they I needed them with proper timing (not running all at same time) - maybe I could have got away with just using the solar panels to heat the water (see load graphs later). We have LEDs and gas stove.
Bought the whole set up from SolarAdvice and their installers did a great job, no complaints.
They flicked the switch on on Monday. I think my night time load is a problem because we don’t get through the night - mostly because the household still thinks cooking is for night time. We have a fish pond pump that may be an issue.
It’s a bit desperate to see all the power after 12pm going to waste because COJ doesn’t want our electricity or won’t pay for it. And I can’t see it on the graph as it has nowhere to go, so I don’t know the potential... Natural answer is to spend more money on batteries. 
Also some lifestyle changes required.
I’m setting the battery to discharge to 25% leaving 5% for early morning load shedding.
My questions
Have I sized the solar too large? It made sense to me to max out the inverter.  How bad is winter in Johannesburg (% difference in solar production in your actual experience)?  Were the solar geysers a waste of money? I feel I should have got these second and not first as everyone says... I see geysers as batteries (rather poor performing) as they store energy for later use I’m thinking of allowing the excess solar power I have during the day to contribute to the heating of water, to guarantee max temp at sunset. Anyone doing this? What is the current situation with grid tied in Johannesburg with City Power. Does it exist? Anyone done it and is it worth it? What should I do with this extra electricity from 12pm-5pm? Bitcoin mining? I will attempt to answer these questions over time on this thread, but appreciate any input.
 
Typical sunny day in JHB

 

It came with the geyser in the evacuated tube box, I think it can also be purchased at electronic shops.

@AntonySo after trying two depths of heat trap loops (150mm first, then 600mm on both inlet and outlet), they really don't seem to work much (if at all). After the heat traps, the next iteration was to install a flap type NRV (horizontally positioned so the flap would close under reverse flow conditions) on the pipe which flows from the panel to the hot side of the geyser. I expected that ALL of the thermo-syphoning was going out the top of the geyser and the flap-type NRV would sort the problem. To my surprise the thermo-syphoning continued and when I had a close look at the data it was clear that it was going out of the cold side of the geyser up to the panel during the night (by this stage I had installed a temperature probe on both the inlet and outlet of the geyser). Some posts suggested a spring type NRV on the cold side, but I was not convinced because during the day the water has to flow in the same direction as the thermo-syphoning would go at night. But to my surprise it stopped the thermo-syphoning - I guess the spring is just strong enough to stop the little pressure 'bursts' which characterize thermo-syphoning - but not strong enough to prevent the pump flow during the day. For the fist time the panel temperature dropped well below the geyser temp for the whole night!
So my experience is that you need two NRVs - one on each line, but the cold side one has to be the spring type. Probably worth trying before re-piping 😰. Just be careful to get the NRV directions correct so you don't end up with a closed loop 🥵
FYI - Below is a graph of the data when the thermo-syphoning was happening out of the 'cold' side of the geyser. The blue line is panel temp, the grey line is geyser hot side temp and the orange line is geyser cold side temp. The more regular 'up-and-down' of the orange line from around 23:00 is the small bursts of pressure that thermo-syphoning produces as it forces the hot water along and it is replaced by cold water. Overall you can see that the panel is hotter than the geyser during the night and they all have the same downward trend indicating the heat is being bled out of the panel.

@RyanF, would you mind doing an illustration of what you did (ie where spring type and non-springtype NRV is). I have the exact same problem and the heattrap the plumber put in doesnt work, just like your findings has illustrated.

See it became a home automation topic now 🙂
Agree with the smaller element in the geyser.
I maintain 400W to 550W during night time, without having a timer on geyser. (it has a blanket, and inside greenhouse... so I guess its not getting cold), We just 2, but when someone bath, we share the water... else we shower. Heaters are managed like a dictator. Everything LED Dishwasher, AirCon., Washing, Drying,  Fridge / Freezer, even oven is INVERTER type, low energy.
(Oven is Siemens, it uses normal 16A plug, stove top is gas,
Dishwasher only have water water line, so that internal heating is not required) Espresso machine (screw the energy... everyone should have a little pleasure) PC, switch it off when done (my media server and NVR is on a intel NUC - it uses less power than PC)

And the last one, that may have a huge response. Learn form the people in Europe. If you work from home, do not sweat a lot, and wipe your ass thoroughly, there is no need to have long showers each night 🙂 For the younger crowd.... this will also teach you not to have sex 10 x a day 🙂

Refrigeration is often overlooked or ignored when looking for energy savings.
 
Cleaning the condensor and/or improving air circulation around the fridge can reduce the energy it consumes by 20%... or a lot more if it's a commercial underbar type fridge. Ive seen up to 40% energy saving with condensors being cleaned on commercial underbar units. Even domestic fridges have small condensor fans sometimes, check they're working and dust free.
Check the door gasket for damage and replace if necessary, also angle the fridge slightly backwards so the door has a better tendancy to close on its own.
Use your cellphone to check the internal lights switch off when the door closes.
If you fridge or freezer needs manually defrosting do so regularly, don't wait until there's thick ice built up inside it. If it needs defrosting more than once every couple of months check the door gasket and the door hinge adjustment. I've seen old fridges where the plastic washer in the hinge has broken and fallen out causing the door to drop down about 5mm and leave a thin air-gap along the top of the gasket when the door is closed and most people wouldn't be tall enought to notice this.
Check the temperature isn't set too low, if it is then thermal losses through the insulation become excessive. Don't use glass door fridges unless you really have to, they have higher thermal losses through the door than a regular fridge. If the fridge feels cold on the outside of the cabinet or it has areas on the cabinet where condensation forms, assuming the internal temp is correct then get rid of it (preferrably check it with a thermal camera if possible). Always buy a fridge with a minimum of A++ energy rating. I've also seen chest freezers where the thin aluminium internal liner has become damaged by frozen food being dropped inside it, this led to the foam in the base area becoming water logged and losing its insulation which in turn meant the compressor was running 24/7.
Locate fridges and freezers in a cool and ventilated room without direct sunlight.  I've seen a 30% energy saving where domestic fridges were in a small room with polycarbonate roof and direct sunlight from big windows and they were moved to inside the garage where it was much cooler ambient temp. This will also enormously  improve the compressor lifespan.
There's an urban myth that says it's not good to turn fridges off. I'm guessing it's because if a fridge has a slow gas leak it might leak quicker if the fridge isn't running. Ignore it, if you have a fridge that's empty don't leave it on to unnecessarily consume energy; rather run one full fridge than two half empty ones. On the one in a thousand chance your fridge does have a gas leak it will already be highly inefficient and needs fixing or replacing anyway so you've got nothing to lose in the long term.

Another sneaky one that could get you is lighting. If you don't already have LED lights everywhere, then switching to LED lights could reduce your nighttime consumption significantly. When we moved into our current home, the previous owners had put in 100W halogen lights all over for some reason. The first thing I did was replace them with LEDs.

late to the party but brought my own drinks so will hang around in the parking lot...and in the spirit of "give a man a fish blah blah... but teach him to hot wire a car..."
EDIT: @Darrenf noticed I bombarded you previously with my rambling, you are welcome to ask for more clarification/explanation 🙂
Don't worry about total household consumption since you only want to power a couple of very specific things.
Ideally get some form of power meter (about R500 from what ever your flavour of online shop)... .or less ideal check each "appliance" for the label that shows you the power rating (like a 2000W kettle).... or search online for general estimates since many appliances don't actually list the power rating (my TV does not... but I checked my 47" (OLD school, not OLED) TV, AV amplifier, android TV box thingi, and B315 router all combined average about 125W).
Add all the various power requirements up and you will probably not even pass 500W (but if possible check your own numbers). So you could probably get by with a 500-800W inverter.
Now multiply the total power requirement by hours you want to power it for. 4h * 500W =2000Wh - this is technically how much energy you will need from a battery to power these things. Because energy conversion is not perfect and to allow some extra room, add an efficiency factor of 80%.... devide the 2000Wh by 0.8... 2000Wh/0.8 = 2500Wh will be a safer number to work with.
Here is where things can seem to become too technical but soldier on...., batteries will specify their voltage (12V, 24V, 48V most common) and their storage ability (in either Amp hour (Ah) or Watt hour (Wh)). Lithium batteries often specify the capacity in Wh and lead acid batteries in Ah. So how do you decide if a given battery will be "big" enough? Lithium just compare the Wh numbers. For lead acid (like the adds posted in this thread) take YOUR Wh number and devide it by the listed battery voltage. The first add has a single 12V 100Ah battery. So...2500Wh/12V = 208Ah. You will need a 208Ah 12V lead acid battery to power 500W for 4 hours - so a single battery like the one add will not be enough since it is a 100Ah battery. You can connect two 100Ah batteries in parallel then you will have a 200Ah but still 12V battery, so two of  those batteries might be needed (or maybe two 60Ah batteries?....read on first).
The second add says it comes with 2 batteries.... but if you check the specifications you will likely find that the inverter works on 24V (the two batteries are connected in series), so you have a 100Ah 24V battery (even though it is made with two 100Ah 12V batteries).... will the 2 batteries be big enough?... 2500Wh/24V = 104Ah... so this is closer.
BUT lead acid batteries do not have a very long total life before they "break" if you tend to use more than 50% of their capacity. So if looking at lead acid battery systems you will make life simpler if you take your power requirement and double it from the start. 2500Wh * 2 = 5000Wh.... 5000Wh/12V~400Ah.... or 5000Wh/24V~200Ah. So whether you go with 12V or 24V you will need at least four 100Ah batteries (or eight 50Ah batteries or two 200Ah batteries). Lithium batteries will generally let you use about 90% of their capacity but lithium is heavy on the pocket (depending how you do your sums)
I attached an excel sheet which can help you play around with some numbers. Change the battery voltage and time (in red font) as you need/want and add your appliances+watts in the yellow columns to the list. Since this is about load shedding you should also look at things lile time available to recharge the batteries (the sheet will show you how much time you need depending on the charger capacity to recharge the battery). Use at own risk (do not use it to make calculations to power grandma's iron lung)
Any of the mentioned systems should meet your inverter requirement but I suspect you will end up with a flat battery often and/or have to buy new batteries after a couple of months.
The "off-the-shelf" solutions can generally be made up cheaper by just combining everything yourself. I would personally not install the Axpert inverter laying flat though (like in the add)... pretty sure the unit thermal regulation was designed around a vertical install. If you can change a plug on a toaster you should be able to make up a system - especially for your listed needs. If not comfortable doing that - no shame in that (and stay out of the DB!).
Another option to the miriad of "ready made" UPS type systems that you can look at in your budget is something like a DIY victron multiplus 12/800 inverter charger (R8500-9500) combined with a second life Mecer 200Ah/2500Wh 12V lithium battery (R6400-R7500). Add a victron Mk3 USB cable (R1200) so you can make some changes to the inverter settings from a laptop. Get a battery place to make you up some 25mm2 cable with properly crimped lugs, add a fuse between battery and inverter, put it on trolley in a box (make sure the battery terminals are at least covered) if you want and you should have the lightest, least intrusive system that should meet your power needs in terms of inverter power, fast enough charger for most load shedding scenarios, and with a bit of careful load management your total storage capacity should be enough.
The axpert type systems definitely are lower cost and simpler (no extra cable/laptop needed for changing settings) and you have a screen to see what is happening. Especially the 3000W inverters give you more options to power something like a kettle if you really need to (not gonna do that with a 800W any inverter). The axpert type systems also generally add the option out of the box that you can add solar panels later without needing any other bits than solar panels, solar cable and solar fuse/disconnects.
If you think/gamble that load shedding will only be around now-and-again for a day or two and you want to keep this grudge purchase as cheap as possible, then also consider just battery, a separate smallish inverter and a loose battery charger. (keep charger connected to battery, when load shedding comes around, hook up the inverter... when load shedding goes away again for 3 months... put inverter in cupboard). Here you will just lose out on the automatic/"seemless" switch over when load shedding happens that you get with the axpert/multiplus type systems.
If going axpert type system - try and make sure it is an original voltronic produced inverter (quality and support on the clones seems somewhat iffy).
last thing... Just a note on having any system next to the TV... all these systems contain fans that switch on at least when charging the battery at a high rate and possibly when powering the load... you could find that it bothers you if right next to the TV.
whoop-whooop...that's the sound of the police... off I go..
LoadShed_Calc.xlsx

I fact I actually worked out that running a genny during load shedding to power the basics is by far more expensive than having a decent standby.
Petrol (or diesel for the Hulux guys) is far more expensive to run the genny than the grid power needed to recharge the batteries of the standby. AND IT'S MUCH QUIETER! 
Although the initial cost may be more than a decent generator, you will breakeven sometime, especially with the guaranteed amount of load shedding events is SA. 😉

For maximum power display on Hexing press 869 + enter

I fact I actually worked out that running a genny during load shedding to power the basics is by far more expensive than having a decent standby.
Petrol (or diesel for the Hulux guys) is far more expensive to run the genny than the grid power needed to recharge the batteries of the standby. AND IT'S MUCH QUIETER! 
Although the initial cost may be more than a decent generator, you will breakeven sometime, especially with the guaranteed amount of load shedding events is SA. 😉

@Ninja Girl what inverters do you currently have? Will you be moving them with you?
 
the reason why I am asking this is that 
1. a pylontech US3000 is around R20000
2. A good inverter of 5kw is also around R20000 If you buy a Mecer it is around R12k 
Is the rest of the cost the installation, this sounds very steep, The Instalation and wiring and COC should not be that high. It will take a good electrician about half a day to split your DB and wire the inverter and batteries. At R500/ hour that is R2k plus say R2k for the certificate which is very high, plus around 2-3k for material depending on the distance from battery to db. I know people on this forum is going to kill me but charging more than R10k for a basic instalation is raping the customer. 
The extra money could buy you another US3000
just my 2c

And that place is here, that is why the active guys are here as well, to help the newcommers reach their dreams.   

Perhaps, but there should be place for everyone trying to become less dependent on the grid.
The number of 'active' guys should be happy with the discussions since they dominate the forum. What about the guy (who doesn't have the money required) who wants a simple system to mitigate power outages?