Solar cost per kWh

[Speedster]

Best way to measure this is as Achmat has suggested: Total system cost / total lifetime power production.

 

[Scooby_Doo]

You can't generate power which isn't consumed. We'll I guess you can if you load up and ship out charged batteries, but who does that?

Oh right, I am not familiar with how it all works. That clears it up.

 

[Steamy Tom]

Feedback into the grid would make the calculations harder.

What I am getting at is that if you include "wasted" generation which is never consumed (due to over-spec or whatever) into the calculation that could skew the data away from a like-for-like comparison against a grid-consuming customer. If you do include wasted generation your "price per watt" will be artificially lower. Whereas the actual consumed price per watt will be much higher.

ok I got you, theoretical production vs actual production due to consumption, difficult after the fact but would put an interesting spin on it, for anyone running SUB it might make the plunge for more batteries and running SBU more transparent.

 

[AchmatK]

I'm a bit confused. If consumption exceeds production, then shouldn't there be nothing available to feed the grid?

This is what a full pv day looks like. Batteries are fully charged by 12pm but they are used up by 1am the following morning.

This is in summer but autumn and winter my batteries are only fully charged by 3pm so the US very little that is feeding back into the grid.

 

[zeb]

This is what a full pv day looks like. Batteries are fully charged by 12pm but they are used up by 1am the following morning.

This is in summer but autumn and winter my batteries are only fully charged by 3pm so the US very little that is feeding back into the grid.

I presume your meter does not run backwards when you're feeding back as some have mentioned on the forum?
Would be nice to have "credit" available at nights and when conditions aren't favorable.

 

[wingnut771]

I presume your meter does not run backwards when you're feeding back as some have mentioned on the forum?
Would be nice to have "credit" available at nights and when conditions aren't favorable.

It does, good ol' faithful:

 

[W@P]

Interesting. If I have my calcs correct I am sitting at R72.07 per kWh produced.

 

[Harmonic]

Basically the cost to install and all equipment plus any maintenance and upgrade costs divided by the total kWh generated.

You also have to minus the opportunity cost if looking at it from a purely financial perspective. Let's say you spent 100k on your system, putting that into a goalsave instead would net you ~8k in the first year as an example.

 

[Hd7]

Im at R71 for this calc - clearly need another couple years of maintenance free production. Which i guess is what we're all aiming for

 

[itareanlnotani]

Rough calc for me -

130,000k cost
5*365*20 = 36,500, 6*365*5 = 10950 (11 years / 365 days a year) = 47450
R2.73 including storage (10kWhr)


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Also have a newer system that was about 90k (8kw/9.4kw panels). Need to add storage to that at some point.
Not really in use yet.

 

[Speedster]

Rough calc for me -

130,000k cost
5*365*20 = 36,500, 6*365*5 = 10950 (11 years / 365 days a year) = 47450
R2.73 including storage (10kWhr)


----
Also have a newer system that was about 90k (8kw/9.4kw panels). Need to add storage to that at some point.
Not really in use yet.

You're going to have to explain how you got to that calc. Why 6*365*5?

 

[itareanlnotani]

You're going to have to explain how you got to that calc. Why 6*365*5?

I moved.

5 years at location one. 20/kWhr daily usage (4 people in situ)
6 years elsewhere 5/kWhr daily usage (1-2 people in situ) - It's more now, but I wasn't necessarily here for a while, so averaging out over the period.

 

[W@P]

Now you've given me an idea.
I think I need a little charging station outside my gate that my neighbours can wheel their batteries over to and pay with snapscan.

Great idea just not sure how long those batteries would be charging before they find new owners hahaha.

 

[W@P]

Im at R71 for this calc - clearly need another couple years of maintenance free production. Which i guess is what we're all aiming for

Yep of course being maintenance or repairs free for as long as possible would be ideal and would also bring the R/kWh down. However, I just make these calcs for the sake of interest and I like playing with data.

I don't care about ROI and all that. Was never the driving/deciding factor when I got my system. It's for the pure bliss of not having to worry about outages in my area or LS.

 

[Joeboy69]

Agreed but this is not just about ROI.

Having real world data is useful. At my current trajectory I think my cost per kWh will be less than what it would cost to buy from CoCT by the end of 2023.

My wife works permanently from home so trying to factor that benefit into any ROI calculation is not possible.

Reaching a break-even unit cost within 5 years (if I understand the time periods) is fantastic. For some reason I always thought it takes closer to 10 years ignoring the value of the luxury of not having hours without power.

 

[Cius]

It really depends. I will be interested to track and will definitely do so. My system was half installed yesterday. Rest is tomorrow hopefully.
I am hoping to get 12kwh useful energy on average per day for the life of the system (season variability aside), and I expect to have to replace the battery, and do a major repair or replacement of the inverter in the 20 year lifecycle of the system.

Calculating those costs and production my rough estimate is that over the life of the system I would produce 87600 kwh over the 20 years at a cost of perhaps 180K in today's money making my expected cost per kwh R2,05.

This could change drastically if system costs are higher, or if I get less or more average power production and use per day. Only time will tell I guess. I have not actually looked closely at people's production numbers to check if 12KWH per day is reasonable. My panels would produce 3kw per hour at peak efficiency (8x365W panels). Roof gets no shade unless there are clouds.

As mentioned by others it was not done for cost saving so much as to get rid of load shedding. I also viewed it as investing capital to reduce ongoing costs. I hope my monthly power bill comes down significantly which helps me from a monthly budgeting perspective which is also valuable to me.

 

[Speedster]

Reaching a break-even unit cost within 5 years (if I understand the time periods) is fantastic. For some reason I always thought it takes closer to 10 years ignoring the value of the luxury of not having hours without power.

Yeah, by calcs I should be hitting break-even in under 5 years.

 

[AmazeBalls]

Do you factor in both tarrifs, I adjust my "savings" based on production based on 0-600 kw and 600kw+. The savings on my tarrif 2 is where i see the real benefit on my cost per kw. Currenlty sitting at R35 per KW but installed in Nov 2021 with bayback in 7 years

Installation Date		24 November 2021​
Total Solar Cost		R 220 000.00
Effeciency		74%​
Current Saving		R 17 724.57
Payback Yrs		7.24​
Date		17 February 2029​
Average cost per KW- Solar		R 35.70

 

[AchmatK]

Average cost per kWh after June 2022 is R8.54/KWh.

 

[hj2k_x]

Average cost per kWh after June 2022 is R8.54/KWh.

Have you done a post/thread about feeding back into the grid and how it all works? Have I not nagged you about one before?