Hi Guys

Anybody maybe have a solar return of investment calculator they be willing to share please?

Thank you

Simplistic ROI Calculation

Total System Cost ÷ Cost of Electricity ( per unit cost per kWh ) ÷ Annual Electricity Usage ( Total units per year in kWh ) = Estimated Payback Period

This excludes any fixed charges your provider may add.
Does not factor in yearly price increases of units.
This simply provides a snapshot at the current prices.

Edited November 5, 20232 yr by WannabeSolarSparky

10 minutes ago, WannabeSolarSparky said:

Simplistic ROI Calculation

Total System Cost ÷ Cost of Electricity ( per unit cost per kWh ) ÷ Annual Electricity Usage ( Total units per year in kWh ) = Payback Period

This excludes any fixed charges your provider may add.
Does not factor in yearly price increases of units.
This simply provides a snapshot at the current prices.

According to the above formula and based on today's price per KW, my ROI is 5,5 years. Prety much what I anticipated when decided to install solar. My estimate was 6 years.

Three more years and system will be paid off.

Price of system ZAR 100,000.00

Price per KW/h 2.12

Yearly consumption 6800 KW/h

 

 

2 minutes ago, Antonio de Sa said:

According to the above formula and based on today's price per KW, my ROI is 5,5 years. Prety much what I anticipated when decided to install solar. My estimate was 6 years.

Three more years and system will be paid off.

Price of system ZAR 100,000.00

Price per KW/h 2.12

Yearly consumption 6800 KW/h

 

 

Yip, most correctly sized solar systems should ROI in 5 to 7 years

1 minute ago, WannabeSolarSparky said:

Yip, most correctly sized solar systems should ROI in 5 to 7 years

Just now, my small system 12 X 410 W panels pushing 4 KW of power from PV beautiful sunny day.

 

1 hour ago, Voltageza said:

Hi Guys

Anybody maybe have a solar return of investment calculator they be willing to share please?

Thank you

Keep a spreadsheet. The price of your system is fixed.

Each month calculate what you would have paid for the total amount your house used using the current tariffs apply. Then deduct your actual cost to Eksom/municipality and then you can calculate the savings for the month. And THEN you can caclulate what % of the total outlay you saved that month.

You could project that to get a point at which the system has paid for itself but
1) You usage doesn't necessarily stay the same. When I got this system we using about 13kWh per month on average. (This already limited what I could save in a month). But these days we average about 10.2 kWh per month (awareness, new, more efficient appliances, LED lighting throughout the house). Because of the stepped tariff in Johannesburg we would use less units per month, and come in at the bottom step of the tariff, so our savings has declined.

2) The tariff will increase year on year. So it nothing else changes, you will recover a great percent of outlay each year.

My pay back point is looking pretty distant at the moment, but as I often say, this is based on only what we save at the meter. There is also the continuity of life style, things like not losing the contents of the fridge. This is worth something to, though it's harder to put a rands and cents value on it.

I initially calculated 7 years. But I now don't expect to make that.

6 minutes ago, Bobster. said:

Keep a spreadsheet. The price of your system is fixed.

Each month calculate what you would have paid for the total amount your house used using the current tariffs apply. Then deduct your actual cost to Eksom/municipality and then you can calculate the savings for the month. And THEN you can caclulate what % of the total outlay you saved that month.

You could project that to get a point at which the system has paid for itself but
1) You usage doesn't necessarily stay the same. When I got this system we using about 13kWh per month on average. (This already limited what I could save in a month). But these days we average about 10.2 kWh per month (awareness, new, more efficient appliances, LED lighting throughout the house). Because of the stepped tariff in Johannesburg we would use less units per month, and come in at the bottom step of the tariff, so our savings has declined.

2) The tariff will increase year on year. So it nothing else changes, you will recover a great percent of outlay each year.

My pay back point is looking pretty distant at the moment, but as I often say, this is based on only what we save at the meter. There is also the continuity of life style, things like not losing the contents of the fridge. This is worth something to, though it's harder to put a rands and cents value on it.

I initially calculated 7 years. But I now don't expect to make that.

@Bobster. My calculations are pretty accurate, see dashboard of the last 2 years of my system. I'm saving an average of 15 Kw/h per day, I average 21 KW/h home consumption 15 KW/h from PV and 6 KW/h from grid. I think that my ROI will be less than 5 years.

ROI is a nice indicator if and when future costs are ignored.
And future costs will include maintenance due to failures and also the inevitable battery replacements.
To me it's just a "feel good" justification.
My primary motivation remains independence and available power when the SOE fails it's tax paying citizens.
Any savings in monthly costs are a bonus which I appreciate more than whatever ROI numbers I can come up with..

1 minute ago, zsde said:

and also the inevitable battery replacements

This one I never really worry about as the technology will always progress faster compared to "using up" the battery.
Replacement costs may end up a bit higher with inflation but what you get in terms of storage capacity will most likely double if not more over the next 10/15 years when your replacements are due.

11 minutes ago, Antonio de Sa said:

@Bobster. My calculations are pretty accurate, see dashboard of the last 2 years of my system. I'm saving an average of 15 Kw/h per day, I average 21 KW/h home consumption 15 KW/h from PV and 6 KW/h from grid. I think that my ROI will be less than 5 years.

@Bobster. With my custom-made monitoring system, I archive everything possible from my PV, inverters and battery. I've used almost 2 MW from my battery. see dashboard of the last two years of my LBSA 5 KW battery.

9 minutes ago, zsde said:

ROI is a nice indicator if and when future costs are ignored.
And future costs will include maintenance due to failures and also the inevitable battery replacements.
To me it's just a "feel good" justification.
My primary motivation remains independence and available power when the SOE fails it's tax paying citizens.
Any savings in monthly costs are a bonus which I appreciate more than whatever ROI numbers I can come up with..

@zsde My feelings exactly, the savings are the cherry on top of the cake, however, it nice to know that sooner or later we will recover the investment made to beat LS.

1 hour ago, zsde said:

ROI is a nice indicator if and when future costs are ignored.
And future costs will include maintenance due to failures and also the inevitable battery replacements.
To me it's just a "feel good" justification.
 

Yes. The best I can hope for is that my system gets paid off just as the battery starts declining. But that's not as expensive as a new system, so I would still be saving 

1 hour ago, Antonio de Sa said:

@Bobster. My calculations are pretty accurate, see dashboard of the last 2 years of my system. I'm saving an average of 15 Kw/h per day, I average 21 KW/h home consumption 15 KW/h from PV and 6 KW/h from grid. I think that my ROI will be less than 5 years.

Shoo. Either the unit cost of electricity is high where you live, or you got a very good price on your system. 

15kWh saved per day is 5745 kWh per year. Say 2.50 per unit is R13700 per year. 

Hi guys. 
thanks for everybodies input. 
 

I need however need the calculator more for quoting purposes. To give a customer a idea on how much many he is gokmg to save. 

4 minutes ago, Voltageza said:

Hi guys. 
thanks for everybodies input. 
 

I need however need the calculator more for quoting purposes. To give a customer a idea on how much many he is gokmg to save. 

Well use the calcs above and you'll be able to do that

Edited November 5, 20232 yr by madness_za

5 hours ago, Voltageza said:

Hi Guys

Anybody maybe have a solar return of investment calculator they be willing to share please?

Thank you

If you have to use 2 times the current battery size your return would move a few years longer. 

There are so many variables to take into account. Not all systems are equal. 

2 hours ago, Voltageza said:

I need however need the calculator more for quoting purposes. To give a customer a idea on how much many he is gokmg to save.

This is what I use - it's free and does very professional proposals.

https://www.opensolar.com/

20 hours ago, zsde said:

ROI is a nice indicator if and when future costs are ignored.
And future costs will include maintenance due to failures and also the inevitable battery replacements.

Hmm, provided you reach your ROI before future costs then it is really not bad. It means the system has paid for itself and you have enjoyed the benefit of having backup power for free.

Those who use more electricity are more likely to reach their ROI sooner, ie. those who are always in the higher Eskom tier (over 600kWh per month), even with their solar system as it's currently around R3.96 per kWh then when including VAT.

Let's say someone averages a reasonable and achievable 25kWh per day from their PV, 750kWh per month equates to R2 970 savings per month or approx R35.6k savings per year. If the system cost R150k, would be paid for in less than 5 years. Obviously the weather varies and winter leads to lower production and not everyone uses a lot of electricity during the day so lots of factors to consider as well however I feel we could comfortably say in the above example it would be paid for in 5 to 6 years and I would hope batteries and inverters last this long without issues.

1 hour ago, PsyCLown said:

Hmm, provided you reach your ROI before future costs then it is really not bad. It means the system has paid for itself and you have enjoyed the benefit of having backup power for free.

Those who use more electricity are more likely to reach their ROI sooner, ie. those who are always in the higher Eskom tier (over 600kWh per month), even with their solar system as it's currently around R3.96 per kWh then when including VAT.

Let's say someone averages a reasonable and achievable 25kWh per day from their PV, 750kWh per month equates to R2 970 savings per month or approx R35.6k savings per year. If the system cost R150k, would be paid for in less than 5 years. Obviously the weather varies and winter leads to lower production and not everyone uses a lot of electricity during the day so lots of factors to consider as well however I feel we could comfortably say in the above example it would be paid for in 5 to 6 years and I would hope batteries and inverters last this long without issues.

Based on actual figures by a lot of members we do see that 25% or more of daily production is not used. In order to store it battery cost goes up a lot. This will then move the pay back a few years on. As you indicated if you can use the during the day yield the pay back much shorter. 

Interesting point about the size of the system. I tend to think if the use is low like 10kwh a day its easier to get a shorter pay back. This is also very system specific. 

I run mostly with my string inverters and my back up use with about zero power outings outside LS means my battery side I need about 1kWh a day. I forum member I know is using his Sunsynk without battery. His pay back was about 2y3m and DIY so his cost was only for equipment. 

I myself have a R23000 system equipment only generating about 13kwh a day in summer. 16.8kwh yesterday. 

Back up side I have no data on and excluded as it is used for convenience with limited PV being 1x420W panel only. Before this panel I charged from the grid. 

6 minutes ago, Scorp007 said:

Based on actual figures by a lot of members we do see that 25% or more of daily production is not used. In order to store it battery cost goes up a lot. This will then move the pay back a few years on. As you indicated if you can use the during the day yield the pay back much shorter. 

Interesting point about the size of the system. I tend to think if the use is low like 10kwh a day its easier to get a shorter pay back. This is also very system specific. 

I run mostly with my string inverters and my back up use with about zero power outings outside LS means my battery side I need about 1kWh a day. I forum member I know is using his Sunsynk without battery. His pay back was about 2y3m and DIY so his cost was only for equipment. 

I myself have a R23000 system equipment only generating about 13kwh a day in summer. 16.8kwh yesterday. 

Back up side I have no data on and excluded as it is used for convenience with limited PV being 1x420W panel only. Before this panel I charged from the grid. 

I agree with you 100% in my case, after about 11:30 AM, my battery is fully charged, 200 liters 3 KW geyser done, the system goes in to idle mode, I could Easly generate +_ 10 KW/h.  

46 minutes ago, Scorp007 said:

Based on actual figures by a lot of members we do see that 25% or more of daily production is not used. In order to store it battery cost goes up a lot. This will then move the pay back a few years on. As you indicated if you can use the during the day yield the pay back much shorter. 

Interesting point about the size of the system. I tend to think if the use is low like 10kwh a day its easier to get a shorter pay back. This is also very system specific. 

I run mostly with my string inverters and my back up use with about zero power outings outside LS means my battery side I need about 1kWh a day. I forum member I know is using his Sunsynk without battery. His pay back was about 2y3m and DIY so his cost was only for equipment. 

I myself have a R23000 system equipment only generating about 13kwh a day in summer. 16.8kwh yesterday. 

Back up side I have no data on and excluded as it is used for convenience with limited PV being 1x420W panel only. Before this panel I charged from the grid. 

100% This is often the case for most houses, a few things use PV and then the system sits idle until they are back home and by this time the PV production is usually quite low. Chances are a house like this uses a lower amount of electricity and ROI would be higher I feel.

 

It is easier to be off grid if your electricity usage is on the lower side, I am not sure about ROI with a lower electricity usage. The first 600kWh which Eskom charge is quite a small amount.

Looking at my Eskom invoice, if I were to pay for the connection fee & only use 600kWh per month I would only be paying R1835 per month. Any kWh used above this would mean an additional R3.96 per kWh as the first 600 kWh is at a lower rate.

 

600 units a month works out to 20 units a day, not a large amount. I could be wrong, but such a household would likely go for a smaller system (5KW inverter, single battery, fewer panels). So the system cost would be reduced, but how much power is being used during the day vs at night in such a situation?

Chances are it would be the battery being charged from PV (if set as such) and I doubt they'd even have their geyser on the inverter as it seems majority of people with a 5KW inverter do not opt to have their geyser added to the inverter. I would be surprised if they were able to consistently get 7kWh or more per day which would lead to 210 units a month which equates to R525.96 per month or R6311 per year. ROI of over 12 years.

 

If you were to go and ask a company to quote on such a system, I would estimate costs to come in around the R80k - R120k mark.

Additional savings could come from using the battery at night, but then you run the risk of not having battery when loadshedding hits.

 

 

If we were to reverse the situation, take the same system and put it into a household where consumption is higher and more electricity is used during the day chances are you would reach your ROI sooner.

You may not save a big percentage of your monthly Eskom bill but you would likely end up saving a decent per month and therefore achieve a quicker ROI time.

That same system could be generating 15kwh to 20kwh per day in a house with higher loads and higher electricity usage. Perhaps a house which uses 40kWh per day.

Even if we work on 15kWh per day, that's 450 units a month and now we work out the savings on the higher tariff of R3.96 and we're saving R1782 per month and R21.3k per month. ROI of 4 to 6 years.

 

With that being said, the smaller system in a house which uses more power may struggle a bit and might not necessarily be the right fit for that house. Loadshedding might still be an issue, especially with the higher stages. Won't be able to easily run everything off the inverter or would need to manage when various appliances and equipment is used to ensure you do not exceed the limits of the inverter.

 

That is my view, however it can vary greatly between each situation and every household would use electricity differently and for the average house hold, consumption during the day will always be on the low side as everyone is at work.

10 minutes ago, PsyCLown said:

100% This is often the case for most houses, a few things use PV and then the system sits idle until they are back home and by this time the PV production is usually quite low. Chances are a house like this uses a lower amount of electricity and ROI would be higher I feel.

 

It is easier to be off grid if your electricity usage is on the lower side, I am not sure about ROI with a lower electricity usage. The first 600kWh which Eskom charge is quite a small amount.

Looking at my Eskom invoice, if I were to pay for the connection fee & only use 600kWh per month I would only be paying R1835 per month. Any kWh used above this would mean an additional R3.96 per kWh as the first 600 kWh is at a lower rate.

 

600 units a month works out to 20 units a day, not a large amount. I could be wrong, but such a household would likely go for a smaller system (5KW inverter, single battery, fewer panels). So the system cost would be reduced, but how much power is being used during the day vs at night in such a situation?

Chances are it would be the battery being charged from PV (if set as such) and I doubt they'd even have their geyser on the inverter as it seems majority of people with a 5KW inverter do not opt to have their geyser added to the inverter. I would be surprised if they were able to consistently get 7kWh or more per day which would lead to 210 units a month which equates to R525.96 per month or R6311 per year. ROI of over 12 years.

 

If you were to go and ask a company to quote on such a system, I would estimate costs to come in around the R80k - R120k mark.

Additional savings could come from using the battery at night, but then you run the risk of not having battery when loadshedding hits.

 

 

If we were to reverse the situation, take the same system and put it into a household where consumption is higher and more electricity is used during the day chances are you would reach your ROI sooner.

You may not save a big percentage of your monthly Eskom bill but you would likely end up saving a decent per month and therefore achieve a quicker ROI time.

That same system could be generating 15kwh to 20kwh per day in a house with higher loads and higher electricity usage. Perhaps a house which uses 40kWh per day.

Even if we work on 15kWh per day, that's 450 units a month and now we work out the savings on the higher tariff of R3.96 and we're saving R1782 per month and R21.3k per month. ROI of 4 to 6 years.

 

With that being said, the smaller system in a house which uses more power may struggle a bit and might not necessarily be the right fit for that house. Loadshedding might still be an issue, especially with the higher stages. Won't be able to easily run everything off the inverter or would need to manage when various appliances and equipment is used to ensure you do not exceed the limits of the inverter.

 

That is my view, however it can vary greatly between each situation and every household would use electricity differently and for the average house hold, consumption during the day will always be on the low side as everyone is at work.

Valid points but due to variables. One 5kW inverter cost over R20 000 being full hybrid. Then you can now buy a 6.2kW inverter for R7000. Generation of PV higher from the cheaper unit. Not using averages but a specific install. 

Then the user level can make a big difference. Many evenings and night time I don't even use my inverter. It depends greatly on user profile. My routers are running from battery 24/7. Stream content and normally not to the TV. Being 2 people it is 10 times easier than when you have kids around. 

If 10x550W panels at R20 000 and R7 000 for inverter with a R25 000 battery is quoted at R120 000 I guess get another quote. 

We have seen a number of installers getting out of solar due to low margins. Had a chat to a client that mentioned his order book dropped from 20 installs a month's down to 5. Too many fly by night guys around. 

1 minute ago, Scorp007 said:

Valid points but due to variables. One 5kW inverter cost over R20 000 being full hybrid. Then you can now buy a 6.2kW inverter for R7000. Generation of PV higher from the cheaper unit. Not using averages but a specific install. 

Then the user level can make a big difference. Many evenings and night time I don't even use my inverter. It depends greatly on user profile. My routers are running from battery 24/7. Stream content and normally not to the TV. Being 2 people it is 10 times easier than when you have kids around. 

If 10x550W panels at R20 000 and R7 000 for inverter with a R25 000 battery is quoted at R120 000 I guess get another quote. 

We have seen a number of installers getting out of solar due to low margins. Had a chat to a client that mentioned his order book dropped from 20 installs a month's down to 5. Too many fly by night guys around. 

Yes, although costing is based off the usual / typical installation quote with what is common... Or perhaps what was common which Deye / SunSynk inverter, JA or Canadian Solar Panels, Batteries well that varies a lot but typically not the very cheap ones.

 

That was at least my experience when I was shopping around for quotes and when I wanted to try and finance it via a bank or go with one of the companies that does offer finance or rent to own. You are extremely limited by suppliers as well as the equipment the yare able to provide and even the installation options (one company told me they are not allowed to parallel inverters. So being single phase my only options were 5KW Sunsynk or 8KW Sunsynk...)

 

One could go for a much cheaper inverter and battery option (we are now seeing some decent batteries at really good prices) and we all know the price of panels have come down a lot this year.

 

I can fully believe the number of installs have been reduced - quite a few companies are not willing to offer the cheaper products and these fly by night installers do sometimes under price the bigger guys and I feel the amount of people installing systems has reduced.

There was always going to be a boom with loadshedding and as loadshedding got worse. I feel we have already experienced that, we are now heading towards the end where majority of people who are able to install a solar system have already done so.

3 hours ago, PsyCLown said:

Those who use more electricity are more likely to reach their ROI sooner, ie. those who are always in the higher Eskom tier (over 600kWh per month), even with their solar system as it's currently around R3.96 per kWh then when including VAT.

Yes. We were low users (averaging about 13kWh per day) before switching to solar. I hadn't thought about it at the time, but that was always going to mean a long paypack period. Now, for reasons I can guess at but don't know, our consumption is down to about 10 a day. So what chance do I have?

Anyway, I remember that at Technikon we got the difference between being involved and being committed. Think of bacon and eggs for breakfast. The hen is involved but the pig is committed. And I am now committed to my PV system.

35 minutes ago, PsyCLown said:

Yes, although costing is based off the usual / typical installation quote with what is common... Or perhaps what was common which Deye / SunSynk inverter, JA or Canadian Solar Panels, Batteries well that varies a lot but typically not the very cheap ones.

 

That was at least my experience when I was shopping around for quotes and when I wanted to try and finance it via a bank or go with one of the companies that does offer finance or rent to own. You are extremely limited by suppliers as well as the equipment the yare able to provide and even the installation options (one company told me they are not allowed to parallel inverters. So being single phase my only options were 5KW Sunsynk or 8KW Sunsynk...)

 

One could go for a much cheaper inverter and battery option (we are now seeing some decent batteries at really good prices) and we all know the price of panels have come down a lot this year.

 

I can fully believe the number of installs have been reduced - quite a few companies are not willing to offer the cheaper products and these fly by night installers do sometimes under price the bigger guys and I feel the amount of people installing systems has reduced.

There was always going to be a boom with loadshedding and as loadshedding got worse. I feel we have already experienced that, we are now heading towards the end where majority of people who are able to install a solar system have already done so.

In my opinion ROI is also depended on how one runs the system, I for one only use battery for load shedding and occasionally run it for about 6 hours nighttime when my house load is about 1 Kw. I run my system on SUB and only charge the battery from PV. I don't mind using about +_ 5 Kw/h from grid on a daily basis.

My average house daily consumption is +_ 21 KW/h usually 15 KW/h from solar and the remainer from grid.

That amounts to +_ 150 KW/h. a month in my municipality rates on prepaid meter = R350.00. 

I have the data to prove it. Last three months.

Edited November 6, 20232 yr by Antonio de Sa