7.3 kW Bi Facial Rooftop Panels: ~7 year ROI: Fact OR fiction?

Screwdriva

Finished up July with a near identical 522 kWh (when compared to April and June. May was a record shattering 680kWh). It's looking like this system's 1st annual generation of > 4MWh is quite achievable.

Hexane

"It's looking like this system's 1st annual generation of > 4MWh is quite achievable."
If that level of generation is achieved in the first year, would that mean the 8 year ROI is on track? How do the figures look on self-consumption, export payments and electric bill savings?

Screwdriva

Not looking likely at this stage. Here's more data for the past 7 months below:

Consumption:
A. Smart Meter reading on 1st Jan: 7450 kWh
B. Smart Meter reading on 1st August: 8430 kWh
Total consumption over 7 months is (B-A): 980 kWh
Bulb's Cost per kWh is ~13.5p
Generation:
A. Total generated as of 1st August is 2830 kWh (via Solar Edge)
B. Total exported to the grid as of 1st August is 2240 kWh (via Smart Meter)
Total renewable energy consumed would be (A-B): 600 kWh
Bulb's Payment per kWh is ~5.3p

Based on these, I estimate the system has "earned" ~£200 over the past 7 months, likely because the SEG tariff and our daytime consumption are lower than originally expected.

Screwdriva

Pretty underwhelming August 2020.

Martyn1981

Hiya mate, just a quick warning, keep an eye on your Solaredge system, I'm pretty sure it's giving you 'the finger'!   

joefizz

Screwdriva said:

Pretty underwhelming August 2020.

July and August here in NI were the worst pro rata Ive had since having the panels installed almost 5 years ago. June was only just marginally better.

September hasnt started well either ;-)

Lockdown and clear skies showed what was practically possible earlier this year, just need America to stop flying again to get the kWh up here ;-)

Screwdriva

That's good to know. I guess we're still paying our dues for a superb start to the Summer. On that note, September wasn't much better. 

joefizz

Screwdriva said:

That's good to know. I guess we're still paying our dues for a superb start to the Summer. On that note, September wasn't much better. 

September ended up bang on average here. Interestingly 381kwh and thats for 14 285w panels split 7/7 directly east west and 4 300w panels directly south.
Sep-Feb are the months here with few swings in annual output, last few septs have been 381, 383 and 378.

Screwdriva

joefizz said:

September ended up bang on average here. Interestingly 381kwh and thats for 14 285w panels split 7/7 directly east west and 4 300w panels directly south.
Sep-Feb are the months here with few swings in annual output, last few septs have been 381, 383 and 378.

If I got my maths right, that's a 5.2 kWh system? If so, I suppose I should be more grateful 

joefizz

Screwdriva said:

joefizz said:

September ended up bang on average here. Interestingly 381kwh and thats for 14 285w panels split 7/7 directly east west and 4 300w panels directly south.
Sep-Feb are the months here with few swings in annual output, last few septs have been 381, 383 and 378.

If I got my maths right, that's a 5.2 kWh system? If so, I suppose I should be more grateful 

Its all relative though, living on a cold wet windy rock in the north atlantic does have its drawbacks ;-)
East/West is just because thats where the roof is and the south facing panels have a steeper angle to fill in gaps in output which occur about now. They dont really add too much in peak in summer but double output (such that it is) from about now through to late Feb/early march).
I originally had planned to build the 4 extra on a sliding frame where I could adjust the angle each quarter... ...then realised I'd probably do it once or twice and then either get bored or think that standing on the garage roof mid december with bleeding fingers and swearing at panels covered in snow instead of just paying a few extra quid wasnt the greatest idea I ever had!