Sunsynk data and losses

[Tradie]

We now have a ton of data. Looking at the data recorded for a year:

PV - 10500
Load - 24000
Export - 4000
Import - 18000
Discharge - 164
Charge - 90

Would I be correct in saying that, the bill should be --- the import = 18000 kwh x 2.968265/kwh = R53428.77 for the year. Less the export tariff. the average monthly bill should be approx.. R4452.39 per month.

If there was no PV the bill would be --- the load = 24000 x 2.968265/kwh = R71238.36

the saving for the year would be R71238.36 less the bill R53428.77 = R17908.59

IF the system cost R200 k back in 2023, it would take at least 11 years to get some form of ROI.

Can you calculate the system losses using this information?

Load 24000 kwh - the import 18000 kwh = 6000 kwh used from the solar

Which leaves the 4000 kwh exported, so there was 500 kwh in loses?

To get an idea of how accurate the data collected, we could compare the utility bill to these figures.

[Dave A]

We now have a ton of data. Looking at the data recorded for a year:

PV - 10500
Load - 24000
Export - 4000
Import - 18000

Rounded to the closest 1000?
If yes, then that's one place to look for the bulk of the "missing" 450kWh.
Also worth noting that:
2% of 24 000 is 480, and
2% of 10 500 is 210

Discharge - 164
Charge - 90

The battery charge vs discharge numbers are also questionable. A battery that can discharge more than it is charged?

[Tradie]

Rounded to the closest 1000?
If yes, then that's one place to look for the bulk of the "missing" 450kWh.
Also worth noting that:
2% of 24 000 is 480, and
2% of 10 500 is 210


The battery charge vs discharge numbers are also questionable. A battery that can discharge more than it is charged?

Correct rounded to the closest 1000

We are busy investigating a few challenges on this site, I have just checked, I thought I might have switched them, but I haven't, something I need to look into.

[Tradie]

Some real figures, not rounded and should be zero export.

Total for the year:

PV : 4134
Load : 9567.9
Export : 2.6
Import : 5923.3
Discharge: 1110
Charge : 1310

Total for the month (12):
PV : 445.9
Load: 926.8
Export : 0.1
Import : 522.1
Discharge : 116.6
Charge : 135.3


Totals for a random day:

PV : 15
Load : 29.1
Export : 0
Import : 15.5
Discharge : 4
Charge 4.8

[Tradie]

Let's look at aa total for a month, which would be the most relevant, because it would relate to the utility bill. It would be interesting to see the values compared to the actual bill.

Total for the month (12):
PV : 445.9
Load: 926.8
Export : 0.1
Import : 522.1
Discharge : 116.6
Charge : 135.3


So if the customer imported 522.1 kwh @ a rate of R3.35/kwh (inc vat), the electricity bill should be R1749.04 (depending on how accuracy of the Sunsynk inverter and the location of the CT)

The PV generation, limited by the load during sun hours and the export limitations means he saved PV 445.9 x R3.35 = R 1493.76 this month.

The battery loss 18.7 is not relevant because there is solar, if you dont have solar, this value could start adding during stage 6 load shedding or if there is no solar.

If the system is registered and you have to pay a monthly tariff because you have solar, it might pay to install a smart meter and claim the feedback tariff in an attempt to offset costs.

[GCE]

There will be a difference as the CT's used are not metering CT's and the split CT's supplied with the inverters are also not the best quality
The house load/internal grid load is also a calculated figure with what leaves inverter and what goes past/comes in the CT to grid
I found there was a monthly difference between what prepaid was used vs what the App said
Also if anywhere during that year there was data connection missing or app down then you could have missed units - check it against what is actually on the inverter

Does Durban not have stepped tariffs ? In PE the first 250 Kwh/units is 3.08 next 250kwh is R3.66 and the balance at R 4.05 on prepaid or str credit
What I did as an exercise, is set a sheet up and worked out what it would have been if the house had stayed on prepaid vs using solar - No feedback allowed as I have been waiting for 4 Quad meter which has just been fitted 18months after paying municipality for it

You have also not factored in the annual increase which has not been below 10 % and with them moving step units from first 300 to now first 250 PE effectively had a 16,5% increase for the first 500 units

Most of the systems I double check on are around 4 years ROI with 1x 5Kw battery and 7 years with 3 x 5kw

Now that I have feedback and TOU it looks like I will reduce the bill even further and basically cover units , just pay for availability

[Tradie]

The idea of this thread is more to try help people understand the numbers and get some idea of what you see when you looking at the data on the app, hence the rounding to 1000.

I am not aware of a stepped tariff for Ethekwini, and yes the increase is in July. I cannot comment about people who are connected to Eskom. We only have a couple of customers connected to Eskom. Non of our customers who have registered have had their meters installed yet, they just got a letter stating that they cannot feedback into the grid

"just pay for availability" ... because of the break in load shedding, I had a few customers commenting about money wasted on solar installations, 2 weekends in a row of load shedding and 2-3 day grid failures has certainly changed their view.

There will be a difference as the CT's used are not metering CT's and the split CT's supplied with the inverters are also not the best quality
The house load/internal grid load is also a calculated figure with what leaves inverter and what goes past/comes in the CT to grid
I found there was a monthly difference between what prepaid was used vs what the App said
Also if anywhere during that year there was data connection missing or app down then you could have missed units - check it against what is actually on the inverter

Does Durban not have stepped tariffs ? In PE the first 250 Kwh/units is 3.08 next 250kwh is R3.66 and the balance at R 4.05 on prepaid or str credit
What I did as an exercise, is set a sheet up and worked out what it would have been if the house had stayed on prepaid vs using solar - No feedback allowed as I have been waiting for 4 Quad meter which has just been fitted 18months after paying municipality for it

You have also not factored in the annual increase which has not been below 10 % and with them moving step units from first 300 to now first 250 PE effectively had a 16,5% increase for the first 500 units

Most of the systems I double check on are around 4 years ROI with 1x 5Kw battery and 7 years with 3 x 5kw

Now that I have feedback and TOU it looks like I will reduce the bill even further and basically cover units , just pay for availability

[Tradie]

I did review the reading on all the sites, the values for discharge are generally less than the discharge, however, there are numerous reading which have a higher discharge than charge indicated. I think it has something to do with the PV charge and the fact that the site was off grid for more than 30 days. The values were totals for 2024. Looking at the totals values for 2025 discharge is 104 and the charge is 116.

The battery charge vs discharge numbers are also questionable. A battery that can discharge more than it is charged?