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When does it become viable to install solar power


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I am getting a lot of customers complaining about massive monthly electricity bills in excess of R8000 per month (R96 000 per year)... for a 3 bedroom house ... with a pool and garage ... sounds a bit over the top ... we are busy with an investigation ... most people dont understand how their electricity bill works ... with estimates and actual reading etc.

My bill for example ... I had a R9000 credit until March this year ... at the moment my utiltiy bill is sitting at R36780.05 debit ... they decided to read my meter in Feb this year ... the last time they read it was in May 2016 

What is the average consumption per day? For some it could be 10 kw ... others 30 kw.

Lets take my house as an example ... using an avg of 23 kw per day at the current Ethikweni tarrif scale 4 @ R1.9714 

for 31 days = 713 kwh

713 x R1.97 = R1404.61

Lets look at a R8000 bill 

8000 / 1.97 = 4060.91 kwh 

130 kwh avg per day. 

The reason i started this thread is to determine when it will become viable to install solar ... considering a huge percentage of people are now working from home ... which will increase you electricty consumption ... looking forward into 2021 ... it might be smart to start linking house together to reduce wasted electricity feeding back into the grid. 

We all know that panel prices are becoming more affordable ... batteries are still too expansive ... so a grid tie inverter with a few panels on the roof ... starts sounding affordable .. a little careful planning and you could get your meter to stop or at least slow down to a stroll. 

I would be interested to hear your thoughts? 

 

 

 

 

 

 

 

 

 

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Hi I am busy installing a 8kw Sunsynk Hybrid Parity (Super) Inverter which allows you to divert the excess power to non essential loads in a split DB without feeding back to the grid or changing

When does it become viable?  In short my answer is it never does.  But: - The larger your electricity use the larger your system need to be thus your return on investment stays similar - It doe

You don't say where you are, but no matter: We should all know where our meters are and read them. Even if you don't read the same day as the municipality you can check your bill, see the read date an

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Lets say we decide to work from home ... which will result in an increase in kwh consumption.

This changes the norm ... you get up in the morning make breakfast and head to work ... house sits empty all day ... but when you decide to work from home ... your electricity consumption is going to increase depending on what you plan to do.

My wife is going to work in the study and bake during the day ... daughter at her desk in her room and me in the garage manufacturing product.

Lets say our current avg consumption is 23 kwh per day for 31 days = 713 kwh total per month at the new 2020/2021 rate of R2,09 per kwh = R1490.17.

Now we start working from home ... kettle for coffee is used during the day ... dishing are being washed ... geyser is switching on more often ... some lights will be used ... computers/screens etc ... machines operating in the garage ... 10 x ft lightings on ...etc etc etc.

Not only the elctricity will increase ... but now our water and waste water rate will increase ... properties rates have increased ... so the old R2500 - R3500 Utility bill is now gona look more like RR5500 - R6500 per month ... avg to R6000 x 12 months = R72 000 per year ... its got my attention.

 

Time to start looking into cost savings ... starting with the elctricity and how to reduce the monthly cost.

From what i have read ... A verery basic startup system with backup is gona cost around R55 000 ... this would include a battery.

Lets start with what i actyually need ...

Solar panels - a starter kits which can be expanded as the budget allows ... taking into considertion ... the voltage and the capacity they can produce. 

Grid tied inverter - no need for backup at this point ( i have a simple backup system in place for esesential items ... not ideal but it works for load shedding)  ... taking into considertion ... this is not going to be designed as an off grid system ... purely to reduce the electricity bill per month and definately not to feed back into the grid.

Battteries are not required at this point ... however they will be considered in the future.

To start ... the easiest way to determine my consumption without outlaying extra capital or connecting additional metering or logging equipment ... I have started taking a pic of my meter reading at the same time everyday ... I plan to start taking a pic at 7 am when we start work ... at 4.30 again to calaculate the consumtion during the day ... I could just get a unit like an owl and link it ... but at this point its just more money wasted. 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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When does it become viable?  In short my answer is it never does.  But:

- The larger your electricity use the larger your system need to be thus your return on investment stays similar
- It does not become more viable the more electricity you use
- If you install it yourself you can reduce the cost and get better savings for your investment
- People with a large monthly fixed fee and low cost per kwh and low usage (some farmers) can save a lot with solar
- If you can move a large portion of your load to daytime use and use a system without batteries then you can probably have a cost effective system
- I do not think an off-grid system can be cheaper than eskom due to the larger size you require and batteries to cover overnight loads.
- An 'undersized' system which is used as a cost saving system without batteries for backup can be viable. Such as a grid tie inverter with solar panels.

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21 hours ago, isetech said:

We all know that panel prices are becoming more affordable ... batteries are still too expansive ... so a grid tie inverter with a few panels on the roof ... starts sounding affordable .. a little careful planning and you could get your meter to stop or at least slow down to a stroll. 

Problem with grid tie is you have to pay the monthly fee to the municipality to be allowed to give them power. And if you want to feed back it actually mean you have to over-spec your system to enable enough PV for feed back.

Grid tie could be an option but the regulations and extra charges on a bill scares me away for sure, I think a pre-paid meter that won’t give you surprises at the end of the month with a off-grid system that works with no reliance on Eskom just make more sense for someone who wants to save on installation and monthly cost.

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1 hour ago, isetech said:

Lets say we decide to work from home

This was a big factor during the hard lockdown. I experienced a big jump in usage with wife and kids computers running almost 24/7, luckily I installed a slightly bigger inverter from the beginning, although I’m slightly under specked on PV and batteries but it had that extra capacity to add as funds become available. The money I saved at the end of a year I put back into more solar, so that way it’s almost like not digging out extra cash every year for expansion every year just uses the saved funds. My biggest portion of savings came from a 200Ltr EV tube high pressure geyser that I installed myself, that is at least R600+/month that I can through back into solar every month.

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27 minutes ago, Pietpower said:

When does it become viable?  In short my answer is it never does. 

The problem is we are basically forced by the utility company to install solar, that’s if you want some sort of order and planning in your life.  If you have kids studying online where you pay massive school fees and they fail due to power outages it becomes very viable to have solar. 

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1 hour ago, Gerrie said:

Problem with grid tie is you have to pay the monthly fee to the municipality to be allowed to give them power

not necessarily. We have an option in the CoCT to remain on the normal tariffs and fees with a grid tie system if we agree not to feed in. 

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21 hours ago, Gerrie said:

The problem is we are basically forced by the utility company to install solar, that’s if you want some sort of order and planning in your life.  If you have kids studying online where you pay massive school fees and they fail due to power outages it becomes very viable to have solar. 

A generator is more viable for loadshedding power outages.

Inverter and battery backup is nicer but costly.

Solar with batteries is best of both worlds.

Grid tie inverter might be viable compared to eskom costs but does not provide backup.

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12 hours ago, Tariq said:

I had an all in one prepaid meter, but CoCT changed it to a split prepaid meter, according to the technician who installed the meter, it has some sort of anti feed in built in !!!

The split prepaid meter is a bit of a pain.  With an inverter installed it interferes with the inside prepaid unit and sometimes it struggle to communicate to the outdoor unit.  You run out of eskom power without knowing it.  When out of power I am disconnected from the outside unit and can't recharge. Have to plug my meter in at the neighbour to recharge again.

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My thoughts are not to install any batteries in the beginning ... my consumption in the evening is minimul a couple lights ... TV and the router .... and i have a 12 VDC system in place for load shedding.

With everyone at home ... the day time usage is the killer  ... washing machines ... geyser ... kettle for coffee ... lights ... computers ... single phase machines in the workshop (the workshop is separated from the house with its own sub DB) 

Before lockdown it was the other way round ... the house was empty all day and the bulk consumption was in the evening ... and a huge battery bank would have been reuired ...  it has turned completey the other way.

Looking at the price of solar panels ... i was thinking if for example i installed 2/3/4 etc and add onto it as I can afford to. 

I dont want to charge batteries for backup ... purely slow the meter down during the day ... for example ... if my day time useage is 30 kwh ... i want a system which produces 30 kwh of power. 

Please excuse my ignorance as i am not familiar with solar systems .. hence the silly questions. 

 

 

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1 hour ago, isetech said:

My thoughts are not to install any batteries in the beginning ... my consumption in the evening is minimul a couple lights ... TV and the router .... and i have a 12 VDC system in place for load shedding.

With everyone at home ... the day time usage is the killer  ... washing machines ... geyser ... kettle for coffee ... lights ... computers ... single phase machines in the workshop (the workshop is separated from the house with its own sub DB) 

Before lockdown it was the other way round ... the house was empty all day and the bulk consumption was in the evening ... and a huge battery bank would have been reuired ...  it has turned completey the other way.

Looking at the price of solar panels ... i was thinking if for example i installed 2/3/4 etc and add onto it as I can afford to. 

I dont want to charge batteries for backup ... purely slow the meter down during the day ... for example ... if my day time useage is 30 kwh ... i want a system which produces 30 kwh of power. 

Please excuse my ignorance as i am not familiar with solar systems .. hence the silly questions. 

 

 

Day vs night usage.  I thought my night usage was low and all the equipment run daytime but later realised it is about half of the total. One reason is the long duration you are not generating solar power (+- 14 hours). For me about 7-10kWh. You might use the same at night but more in the day so your percentage night time use will be lower.

Re the 30kWh daytime use it would not be possible to match a system exactly without batteries.  Say you have 3kW of solar panel then some instances you will require more than 3kW and draw the balance from the grid or other instances you will use much less and 'lose' the available solar power.  With batteries you can draw from the batteries when power usage is more and charge batteries when you produce more than you use.  But it would probably be cheaper to install a larger system saving on battery cost and just losing the extra power.  You can also play around with load control to say switch off the geyser when you run the dishwasher.

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42 minutes ago, Tariq said:

the new split pre-payment meter has a 9 volt battery and also, keypad unit needs to be connected to a non essential socket ( as per the technician who installed the unit ) , have not had any problems so far

Do these meters allow you to push power back from the inverter to try and equalise the grid feed, or is this still the type that will end up tripping. 

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You don't say where you are, but no matter: We should all know where our meters are and read them. Even if you don't read the same day as the municipality you can check your bill, see the read date and then when you compare to your own records you should be in the ball park.

City of Johannesburg customers can mail in photos of their own meters (these must include the meter's serial number) and they will use those as provisional readings until they get around to reading (you can do this with water as well). 

I think we can do a bit to control our billing. Don't run your geyser until the water is unusably hot is one example. Don't burn lights in rooms you aren't using etc.

But people aren't always rational. I don't expect anybody to be happy about load shedding, but I know folks whose response is to turn on EVERYTHING in their house the moment the power is restored just to show Eskom who is who. Their general attitude is that they will burn electricity just because they can, so you can imagine what their bill is like. 

Anyway, to start answering your question: One should get one's consumption under control first, and you should know what your consumption is because the more you use the bigger the solar system you will require. 

Finally, how does one justify it?

When I got my system my back of an envelope calculations suggested that after 7 years I would break even and it would be all joy from there on (my consumption was and still is under 500 kw/h per month). I am not so sure now, but that depends on increases in years to come. This is looking just at what I do pay, what my system cost and what I would have paid without solar. But there are softer issues too and people will weigh these differently.

  • most of my property still has power through a Joburg 4 hour load shed, in fact it can go longer than that. All we lose is the swimming pool and the appliances in the out buildings.
  • because of that our fridge and deep freeze are always on so we don't lose the contents and have to claim from insurance (driving our NCB up) or go and repurchase
  • security systems always stay up
  • yes, we could have got a generator. But I have no interest in disturbing my neighbours in the wee hours, and the so-called silent generators need a lot of servicing.

And you know, even just being able to watch TV and have a cold beer or a hot cup of tea makes a difference during load shedding. That's worth something, though exactly how much it's worth will vary between families.

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not sure if you are talking about feeding in to the grid, or the 20 odd watts that are used to stop feed-in, these new meters are for non-feed in grid tied systems, and i have not had any problems with tripping, a bi-directional meter has to be used if you want to feed in to the grid and the council charges YOU around R12,000 for the meter

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16 hours ago, Tariq said:

I had an all in one prepaid meter, but CoCT changed it to a split prepaid meter, according to the technician who installed the meter, it has some sort of anti feed in built in !!!

i wonder what the real reason was why the CoCT has changed your existing prepaid meter 🙂. I am not aware of any one way prepaid meters who credit you (spinning backward) when you feed in.  

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3 hours ago, Tariq said:

not sure if you are talking about feeding in to the grid, or the 20 odd watts that are used to stop feed-in, these new meters are for non-feed in grid tied systems, and i have not had any problems with tripping, a bi-directional meter has to be used if you want to feed in to the grid and the council charges YOU around R12,000 for the meter

There's something similar in Jhb. I don't export. My system could but my meter doesn't properly handle the small amount exported to try to zero the meter each day, and more importantly (for me) I'd have to pay for a new meter and go onto a tariff with several hundred rands of flat fees each month. I'd need a Koeberg to make it pay.  My gut feeling is that municipalities for some reason don't want to encourage solar, or at least systems that feed back into the grid.

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10 hours ago, Pietpower said:

The split prepaid meter is a bit of a pain.  With an inverter installed it interferes with the inside prepaid unit and sometimes it struggle to communicate to the outdoor unit. 

I experienced this problem because I normally run completely off-grid during the day, so my prepaid display in my home would be fed from solar power during the day when my system switch over to solar, and that caused lost comms with the outside meter at the utility kiosk. I ended up moving the prepaid display to my utility main breaker that now works very nice as it is illuminated when Eskom is on and when it is off I know there is no Eskom power.

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14 hours ago, Bobster said:

There's something similar in Jhb. I don't export. My system could but my meter doesn't properly handle the small amount exported to try to zero the meter each day, and more importantly (for me) I'd have to pay for a new meter and go onto a tariff with several hundred rands of flat fees each month. I'd need a Koeberg to make it pay.  My gut feeling is that municipalities for some reason don't want to encourage solar, or at least systems that feed back into the grid.

My gut feeling is the same. Why we can't get clarity on these issues is amazing. The industry produces sophisticated grid tie inverters to assist with distributed power generation. Yes, this does become a problem when there is a massive uptake in these systems (mostly driven by incentives) but there's no way this can be the reason here in SA. 

Maybe the authorities are paranoid about something that might happen one day??

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