We finally want to pull the trigger & go Solar

[SauRoNZA]

So after all the advice we got yesterday we have been considering this type of system above, with the exception of either a single smaller battery to start with - or, reduce the panels to 12 (but acknowledge what others have advised about prioritizing panels over batteries rather) I realize its not ideal but will allow us to buy the hardware and hang onto it while we have a little more motivation to put away for the installation a bit later. Pricing looks much better than when we looked 3 or 4 years ago and it seemed out of reach at 250k, I don't how fast that can change with current world affairs but would hate to let current prices slip and find it has doubled again when we ready

12 certainly makes a lot more sense than 4 and at 600W panels is more juice than I have overall so you’ll be styling especially if they are all north facing.

But really it also depends on your current usage so maybe you can elaborate on that, because chances are this is the sweet spot and you don’t really need more.

Do you plan to put the geyser on there? Stove/oven? Any other big draw surprises?

 

[W@P]

I basicly have been running this since Dec 2021. I just had 16 x 420w panels.

My whole house runs on the inverter. 2 x 200L geysers. One running from 10:00-12:00 and the second one from 12:00-14:00 kind of thing. My base load is about 900-1000W throughout the night. I can run multiple inverter aircons at the same time, etc. I did not have to change any of my patterns or behaviour wrt electricity consumption.

Batteries were set to run down to 40% SOC at night, so I used to go over to Eskom at around 01:00 at night.
I added 6 x 590W panels last week. And I replaced the hubbles with 2 x Deye SE-F12, 12kWh batteries.

If you can oversize the system, that leaves some headroom for when you later add an air conditioner, pool pump, or something.

 

[BLG]

Yes we north facing which is a bonus and our roof definately has the real estate - So I was initially of the impression it would be silly to put things like the oven/stove and geyser on there but I am getting the feeling that the more the merrier which is where the bigger savings come in since you get to run more off the solar side - although I am still trying to wrap my head around how "early" one can start cooking to avoid using battery at night lol - I mean geyser, dishwasher and washing machine no problem we just change our schedule to ensure minimum draw at night

 

[Tomtomtom]

We only have 80K at the moment, if we looking at 40K for installation we going to need to hold off for a bit which is disappointing as we felt we were so close last thing I want is a small loan that will negate any savings on electricity via the panels, so bit of a catch 22

I realize its not ideal but will allow us to buy the hardware and hang onto it while we have a little more motivation to put away for the installation a bit later.

Don't do that. Why run through your warranty while it just sits?

So you have 3 day outages, but you have a generator already correct? Keep that. It's not economically sensible to try to use batteries (with or without solar) to cover that length of outage -- that's basically off-grid, which should be considered a hobby project for fun, not an investment in the sense of putting your money to the best possible use.

If you are looking for to make the money go furthest then you need to shrewd about when to stop. The ROI on the first R10-15k (geyser MPPT) is huge - it's a 2- or 3-year payback. The ROI on the last R 10k can be very low, worse than leaving your money in a savings account.

Most people are in favour of a wham-bam one-shot install of the biggest system you can afford because of the overheads. But I think it can be better to do it in two parts, if only because you don't know up-front what remains after you've invested the first R 10 or R 20k. In my case, having put my geyser on solar a couple of years ago for R 12k (an easy DIY job), I re-run the numbers now and then and it still doesn't make sense for me to do a full system. What little remains of our grid consumption now means the payback is just too long vs. investing the money elsewhere.

If we'd done an 8 kW system and put the geyser on it back in 2022 I would know no better, but I dodged a bullet. The money not spent has grown 50-80% by now.

 

[B-1]

We only have 80K at the moment, if we looking at 40K for installation we going to need to hold off for a bit which is disappointing as we felt we were so close last thing I want is a small loan that will negate any savings on electricity via the panels, so bit of a catch 22

You are close and you could get a smaller system installed but honestly I'd say make sure you get a decent size inverter.

Something like:

Phase 1:
10-12kw inverter R33000
5kwh battery R15000
6000w panels R18000
Install R30000
R96000

Up to 900kwh saved a month but realistically budget for 300-400kwh due to single battery

Phase 2:
2x 5kwh batteries R30000
6000w panels R18000
Install R20000
R68000

Up to 1800kwh saved but realistically 600kwh+ due to limited batteries.

Phase 3:
3 more batteries
R50000

Up to 1800kwh saved realistically 1200kwh+

 

[Tomtomtom]

You are close and you could get a smaller system installed but honestly I'd say make sure you get a decent size inverter.

10-12kw inverter R33000

No, this is why I'm saying be careful about when to stop.

Electricity usage is very non-linear: there's a base load of 100-500 W that is constant 24/7 (fridge etc.), but then you might have a few hours at 1-3kW (geyser), only a few minutes at 5-8 kW (oven + kettle), and maybe a few seconds every few days above 8 kW.

When you provision to supply 12 kW, the amount you pay over an 8 kW inverter, let's say R 10k, is barely generating any value. Over 10 years it may only have done 10 hours of work.

If that's fine by you to avoid tripping the inverter once and learning what not to do then great, but for most people that's the definition of a white elephant. A real waste if you spent months saving that money. It's just you can't see it because it's all part of the same oversized unit.

 

[B-1]

No, this is why I'm saying be careful about when to stop.

Electricity usage is very non-linear: there's a base load of 100-500 W that is constant 24/7 (fridge etc.), but then you might have a few hours at 1-3kW (geyser), only a few minutes at 5-8 kW (oven + kettle), and maybe a few seconds every few days above 8 kW.

When you provision to supply 12 kW, the amount you pay over an 8 kW inverter, let's say R 10k, is barely generating any value. Over 10 years it may only have done 10 hours of work.

If that's fine by you to avoid tripping the inverter once and learning what not to do then great, but for most people that's the definition of a white elephant. It's just you can't see it because it's all part of the same oversized unit.

They have two households though. The main house and also a flat. That means its more likely for multiple things like microwaves, kettles etc to run at the same time.
I have a 8kw sunsynk with 2 geysers, electric stove/oven and its fine but I'm running close to the limit so if there was a flat as well I'd go up a little in inverter size.
The 12kw inverter also has 3 mppt controllers which gives more future PV options.

 

[geezer]

Hahaha, thats generally how it goes. Sure as hell is much easier to spend money than to make it.

Being on a pension definitely limits your spending.

 

[Lupus]

This all depends on what you are running at night and a universal answer simply isn't possible.

My baseline at night is anywhere from 400W-800W and I have 20kWh of battery and just barely make it when trying.

BUT I run 2 x Fridges and a Deep Freezer along with an enterprise network stack and a server as well as my Geyser through the inverter and while the geyser turns off at 19:30 that is still eating a lot of battery this time of year.

What you should rather ask is what electricity you are using at the moment you could shift to day time when it's all free. Stuff like running your dishwasher at 10:00 in the morning instead of overnight etc.

My opinion is that you shouldn't worry too much now about being "Eskom free" the battery is there to save you during load shedding, later down the line you can add more batteries to reduce your reliance on Eskom.

And no, COC doesn't care about the batteries just the panels.

View attachment 1905538

BUT I run 2 x Fridges and a Deep Freezer these won't use much? Why do people think fridges and freezers use a lot of power? At most these would be 1.5 units a day on hot days with people opening and closing them, so two fridges and a freezer would be 4 to 5 units a day, less then a geyser uses in an hour and a half.
What is making it so you're barely making it is the geyser, rather look at something more efficient. I've got 20kWh of battery and most mornings I'm at 50% and I have a base load of 300 to 500, which has been higher since the new inverter which actually seems to include it's usage in the figure unlike the old Axpert.

 

[BLG]

excuse the vrot pic, I thought this might help - we on prepaid and i got these stats from the panel

 

[Lupus]

Let's put it this way - will a system with let's say 10 to 12 panels and a single 5kw battery see us through the night, and into the next day where the Solar will again provide sufficient power to charge up the single 5kw battery and power a few items while doing so? That would be ideal and shift the priority to spending on panels over batteries which can be scaled out later if required ( i am hoping a COC isn't required everytime someone wants to add a second or third battery?).

Why 10 to 12 panels? What is your load over the course of a day, what are you wanting to power? For that battery you'd need to have a base load of 300w for the entirety of the night, starting to take into account solar yields start to dip around 4pm and only start coming again around 7am.

 

[BLG]

The days where you see 19 units are where we turn the geyser off via Tuya Smart Life App, the days where there are 30 units used is when we do the Washing and very sparing usage of the tumble dryer - last week was a good week, we can and have seen 30 - 35 units in a day

 

[Lupus]

The days where you see 19 units are where we turn the geyser off via Tuya Smart Life App, the days where there are 30 units used is when we do the Washing and very sparing usage of the tumble dryer - last week was a good week, we can and have seen 30 - 35 units in a day View attachment 1905706

19 units with the geyser off? What do you run everyday? How large is the family? Do you have a pool pump running?
You'd need this

8KW MPPT Deye Load Shedding 2x Dyness 5.12 KWh Backup Power Combo Kit

8KW MPPT Deye Load Shedding 2x Dyness 5.12 KWh Backup Power Combo Kit HYBRID INVERTER SOLAR KIT COMBO Inverter Specifications: The Deye 8kW NEW GEN Single Phase Hybrid Inverter (SUN-8K-SG05P1-EU-SM2) combines power and efficiency in a smaller, more compact design, making it perfect for modern...

solarwarehousesa.com

With 16 600w panels minimum to cover your load, the batteries will probably not last you through the night if you don't manage load better.

 

[Lupus]

Around R20-25k since you aren't buying the stock from the installer. Maybe ask them to do a comparitive quote.

I'm sure you know a friend or 3 that has solar that can recommend their installer.

With fewer and fewer installers the estimates I got last year for my new system was R40 to 70k for installation.

 

[BLG]

19 units with the geyser off? What do you run everyday? How large is the family? Do you have a pool pump running?

We are 6 (3 kids 3 Adults) - Nope no pool, Oven/Stove, Dishwasher runs in the evening, Fishtank 24/7 - Laptops, extra 27inch screens (we both work from home) so loads of Coffee - TV, lights, the kids have gaming PC's (they do chow a bit maybe 600W each depending on the games) My Dad lives on the property he has his own Geyser, Microwave, fridge and TV

 

[B-1]

Let's put it this way - will a system with let's say 10 to 12 panels and a single 5kw battery see us through the night, and into the next day where the Solar will again provide sufficient power to charge up the single 5kw battery and power a few items while doing so? That would be ideal and shift the priority to spending on panels over batteries which can be scaled out later if required ( i am hoping a COC isn't required everytime someone wants to add a second or third battery?).

Don't worry about getting through the night. Focus on reducing electricity costs for phase 1.
If you do have times when the grid goes down for a week or two you braai, don't use the oven and take short showers but you can still manage.

You can easily save the 3kwh per shower or 5kwh for a bath by having the geysers on a timer.
Thats 270kwh a month on its own for 3 people. Then add some base load, computers, kettle microwave, vacuum cleaner etc used in the daytime and you have a decent chunk the PV panels can save you.

 

[Lupus]

Nope no pool, Oven/Stove, Dishwasher runs in the evening, Laptops, extra screens (we both work from home) - TV, lights, the kids have gaming PC's (they do chow a bit maybe 600W each depending on the games) My Dad lives on the property he has his own Geyser, Microwave, fridge and TV

And you're using 19 units without washing and geyser wow. Old dishwasher? What gaming PCs do they have? Mine at peak hits around 550w, sure it's only a 9700x with a 9070. Unless the TV is 75" or an OLED it's probably sipping power, lights LEDs barely use anything nowadays. Laptop even gaming ones hit 240.
Your dad does he turn off his geyser or let it run?

 

[Lupus]

Don't worry about getting through the night. Focus on reducing electricity costs for phase 1.
If you do have times when the grid goes down for a week or two you braai, don't use the oven and take short showers but you can still manage.

You can easily save the 3kwh per shower or 5kwh for a bath by having the geysers on a timer.
Thats 270kwh a month on its own. Then add some base load, computers, kettle microwave, vacuum cleaner etc used in the daytime and you have a decent chunk the PV panels can save you.

You don't actually need to have the geyser on a timer, generally the geyser will only run when it's been used, even during the day it will only run a short period just to warm itself backup again, setting it at a reasonable temprature will keep this low as wel.
People do report savings with turning off their geysers mainly due to shifting their requirements and load without even realising it, when you keep the geyser off for an extended period of time and turn it back on before bathing or showering you're just moving the demand closer to your actual time of use, but you'd still essentially use the same amount of power. Unless of course you're single and shower like once a day.
I know, I had my geyser and element on a monitoring device for a year and never turned it off, it used the same amount as when I switched it off in the evenings, only reason I switched it off on the solar was to save battery at night and shift the load. Now with the heat pump the only reason I turn it off at 10pm and turn it back on at 6am is the sound it makes when it runs, don't want to disturb the neighbours just in case they can hear it (hum like an aircon). Even the heat pump only runs a few times a day, at 6am after the 5:30am showers, then again at about 11am just to get back to temp, this is 15 minutes and so on.

 

[BLG]

And you're using 19 units without washing and geyser wow. Old dishwasher? What gaming PCs do they have? Mine at peak hits around 550w, sure it's only a 9700x with a 9070. Unless the TV is 75" or an OLED it's probably sipping power, lights LEDs barely use anything nowadays. Laptop even gaming ones hit 240.
Your dad does he turn off his geyser or let it run?

Dishwasher is around 7 years old, maybe not the most economical of models - I blame the coffee machine haha (in all seriousness we don't even bath everyday, if we did we'd see figures in the 40's I am sure)

 

[Lupus]

Dishwasher is around 7 years old, maybe not the most economical of models - I blame the coffee machine haha (in all seriousness we don't even bath everyday, if we did we'd see figures in the 40's I am sure)

I think a proper energy audit is needed, see what uses all your power as well. Cause when you're on solar you need to be a little more conscientiousness of demand.