How much money have you actually saved installing solar ?

**Tradie** · 01-Apr-25, 08:09 AM

If you installed a solar system in 2023, I would be interested to see how your ROI is going.

It would be interesting to compare a 5 kw (R100- 150 K to an 8 kw R150 - R250K if installed in 2023)

I did a few calculations using actual data collected from installed units, and the results are rather interesting.

Looking at it realistically (a system with 12 panels) , I would say if all goes well and the price of electricity keeps going at the current rate, and no additional fees are added to the bill, it might just even out the cost in about 12 - 15 years.

Looking at it from a convenience point of view, the value of the system has already paid for itself 10 fold.

However when we look at the amount of grid failures and the duration of these grid failures, the load shedding system is currently just not suitable. Looks like we are going to be be going back to adding generators to keep lights on, or laying out thousands on batteries, which are great if we have sunny days.

**GCE** · 01-Apr-25, 12:10 PM

Not sure how you getting to 12 to 15 years
I have looked at various systems that we have installed and depending on Qty of batteries come in at between 5 and 8 years

Standard 5kw system with 5kwh battery we are seeing 22K a year savings .If I take the 22k and add 10% for increases every year it is 4 years and 100K is saved . We seeing 3K bills come down to R700 and likewise bills that are up at 4K mark down to R700 .
Where bigger battery systems have been installed we see R0 bills coming in but the pay back period inc due to the cost of batteries

**Tradie** · 01-Apr-25, 12:50 PM

Originally Posted by GCE

Not sure how you getting to 12 to 15 years

It's the figure people are using, 10 year warranty for an inverter/battery combo, one of the reasons we only install combo unit with a 10 year warranty. Our oldest unit is only 3 years old, are they going to last 10-15 years, only time will tell.

The last of the older Axpert units that we installed, have been replaced, Many of them have had PCB issues, you hear a bang and puff of smoke and you in for a board replacement, we dont bother anymore, just replace. We only have a few FLA batteries in trolley type inverters, which will be replaced with a drop in lithium battery.

Dont you install Victron units, which batteries do you install?

**Tradie** · 02-Apr-25, 08:24 AM

Bill from the utility - import 707 kwh

707 kwh x R2.97 = R2099.79

The saving would be the PV used plus the PV exported

PV used = PV total less the PV exported

325.7 kwh - 102.1 kwh = 223.6 kwh

223.6 kwh x R 2.97 = R664.09 (tariff rate)

102 kwh x R1.25 = R127.5 (export rate)

Total saving = R664.09 + R127.50 = R791.59 per month

**Tradie** · 01-Apr-25, 12:53 PM

How do you figure out the ROI and savings?

Originally Posted by GCE

Standard 5kw system with 5kwh battery we are seeing 22K a year savings .If I take the 22k and add 10% for increases every year it is 4 years and 100K is saved . We seeing 3K bills come down to R700 and likewise bills that are up at 4K mark down to R700 .
Where bigger battery systems have been installed we see R0 bills coming in but the pay back period inc due to the cost of batteries

**GCE** · 01-Apr-25, 03:11 PM

Originally Posted by Tradie

How do you figure out the ROI and savings?

Take the units consumed for the month - Work out what it would have cost in prepaid without solar - minus what it costs with solar = savings

Have attached a sheet that I used to do a quick calc

**Tradie** · 02-Apr-25, 08:37 AM

Just when you thought, great my system is optimised and my system is saving me R 791.59, this is not an average, it is the best month of the year, then you have to subtract the initial cost of the system, including all other stuff, like registration, the maintenance cost, monthly utility fees.

Total saving for the year R791.59 x 12 = R9499.08 per year (it is less than this but we being optimistic today and it was designed a sa load shedding solution, not focused on ROI)

System cost R120 000.00

R120 000/R9499.08 = +/- 12 years.

**GCE** · 02-Apr-25, 11:49 AM

Originally Posted by Tradie

Just when you thought, great my system is optimised and my system is saving me R 791.59, this is not an average, it is the best month of the year, then you have to subtract the initial cost of the system, including all other stuff, like registration, the maintenance cost, monthly utility fees.

Total saving for the year R791.59 x 12 = R9499.08 per year (it is less than this but we being optimistic today and it was designed a sa load shedding solution, not focused on ROI)

System cost R120 000.00

R120 000/R9499.08 = +/- 12 years.

You are not allowing for a 10% increase per year in Elec pricing which effectively works to an extra 10% saving per year
You would then be looking at between 8 and 9 years

Year 1 9,499.08
Year 2 10,448.99
Year 3 11,493.89
Year 4 12,643.28
Year 5 13,907.60 57,992.83
Year 6 15,298.36
Year 7 16,828.20
Year 8 18,511.02 108,630.42
Year 9 20,362.12 128,992.54
Year 10 22,398.33
Year 11 24,638.17
Year 12 27,101.98

Total 203,131.02
Cost of Purchase 120000

**GCE** · 02-Apr-25, 12:05 PM

On any solar system if it is an over design on PV and especially batteries the pay back period will become longer.

It would be like starting a courier company and having a contract to delver 200Kg's from PE to Cape town every 2nd day - I base my rates on what the market dictates at the moment and then buy a 10 Ton truck for the transport - I am never going to make money , but if I bought a 0,5ton bakkie and did the delivery I could make money and pay off the bakkie

Likewise with solar - If I put up a 60Kw plant that can supply me with +/-360Kwh of electricity every day but only actually use 20Kwh a day , I will never have a savings - If I put up a 5kw plant that supplies +/-30Kwh a day my return with improve and if i stick up 3Kw plant that gives me around 18Kwh per day i will use every Kw and my rate of return will improve compared to the 5kw and definitely the 60kw

In the end - Courses for horses

**Tradie** · 02-Apr-25, 08:14 AM

Lets look at the numbers from the inverter, some figures randomly taken from an inverter

PV - 325.7

Load - 885.7

Export - 102.1

Import - 707

Discharge - 17.7

Charge - 27.3

The PV produced is 325.7 kwh for the month, which has to be split because the exported kwh is a lot less than the used kwh

For example 325,7kwh - 102.1 kwh = 223.6 kwh

The export rate in our hood is only R1.25, compared to the tariff R2.97

Export value - 102.1 x 1.25 = R127.62

the solar used is far more valuable - 223.6 x 2.97 = R664.09

Imported - 707 x 2.97 = R 2099.79

the charge and discharge value

27.3 - 17.7 = 9.6 kwh