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

Screwdriva

Solarchaser said:

Your total gen was 3985, you used 910.
910/3985 = 23% usage of your generation I'm afraid.

You are going to have to do a lot of solar optimisation if you want the system to pay.

Ah, I see - you're using total generation instead of total consumption. I'm not sure what you mean by "optimization" really, as I already have optimizers installed and use/ charge appliances only during daylight hours?  Even if we doubled our daytime consumption, that would lead to around a £50 net gain per annum. Hardly substantial. 

Particularly worrying, as we have been at home during the entire year, so this is likely to drop, albeit slightly, if we ever go back to spending part of our days outside the home. 

Solarchaser

Yeah usage of what you have generated.
You have offset about 35% of your house consumption with solar.

Optimisation refers to using your washing machines etc when sun is out to increase your 35% offsetting to 50%, but if you feel you have offset all you can, then..... yeah it is what it is

QrizB

Screwdriva said:

I've recently been quoted for solar panels from 3 installers referred by Solarguide. My guidance to these companies was maximum solar power yield per panel for their proposals. The only company to recommend and offer the option of LG Bi Facial 400W panels was a company called Light Renewables.

Great thread OP, thank you for sharing all your info with us.

How did you get on with Light Renewables? I've just got a quote from them for a 3.6kWp system for £3600 fitted, which seems a reasonable price at £1/Wp. They did try to upsell me to a PV+battery system using some slightly iffy ROI figures but I didn't take that bait.

The quote is subject to survey and I don't have a fully itemised parts list yet.

I had two other quotes, one was a similar price but from a Yorkshire-based installer who couldn't do the work until the COVID travel restrictions were lifted and the other (a local guy) was ~50% more.

I've been looking for someone with experience with them and this thread seems the only one on MSE (either that, or my search-fu is poor). From reading this thread, is it fair to say your PV system performance isn't as good as you'd hoped but the install went smoothly enough and everything works?

Martyn1981

Sorry to intrude QrizB, but just to say thanks for that post, as many of us PV fans (fanatics?) have been watching prices fall for a decade, and when they reached around £1/Wp for larger scale installs (let's say 5kWp+), this was fabulous news. To now see that price quoted for a 3.6kWp system is really heartening, and also useful to all of us that try to pass on advice.

Many thanks, Mart.

QrizB

No worries, I was pleasantly surprised too.

The new system isn't for my own residence, I'm putting it on a property I let (my first home, a small semi which I managed to retain ownership of when I moved to a slightly larger family semi 15 years ago). My tenants will see the benefits, they've been with me for 5+ years and I wanted to give them something back.

The roof is well placed, facing slightly west of south and there's no shade, so I'm hoping to get 3600 kWh/yr from it. My rough and rteady estimate is iIf they use 1/3rd instead of paying 15p/kWh (saving £180/yr) and sell 2/3rds at 5p/kWh (earning £120/yr) they'll be better off by £400/yr and it'll pay for itself in 9 years. Not that I'll actually get any of it myself unless I put up the rent (and I won't).

My own system is 9 years old, cost £8500 for 2.75kWp but I got in while the FIT was still paying 45p/kWh. It paid itself off, in cash terms and ignoring inflation, in 2018. Once I'm able to edit my signature I'll put details there.

Screwdriva

Hi QrizB!

If only all of us had a landlord like you at some stage in our lives! 

Light Renewables are excellent at overpromising output but they also supply the best quality components of any installer I was quoted by. Most try to supply the cheapest Chinese panels possible but I pushed LR to supply top of the line LG Bifacial panels and a Solar Edge Inverter/ Optimizers. All with a 25 year warranty. All at their quoted price.

Whatever you do, do not pay in full till everything is installed and running to your satisfaction. I'd insist that final payment of 25% is kept for 2 weeks following commissioning of the system without exception. 

DM me if you'd like a chat? 

Cheers! 

Screwdriva

Exiled_Tyke said:

4. The figures seem woefully optimistic: surely nobody needs to be paying 19p/kWh for electricity? 

In < 18 months following installation, it would appear that even low cost "green" energy companies have been forced to raise their tariffs, like Bulb Energy which is now 18.8p per kWh. Should this trend continue, along with increases in the SEG tariff, the attractiveness of this solar installation continues to make more sense. 

[Deleted User]

Screwdriva said:d

Exiled_Tyke said:

4. The figures seem woefully optimistic: surely nobody needs to be paying 19p/kWh for electricity? 

In < 18 months following installation, it would appear that even low cost "green" energy companies have been forced to raise their tariffs, like Bulb Energy which is now 18.8p per kWh. Should this trend continue, along with increases in the SEG tariff, the attractiveness of this solar installation continues to make more sense. 

We can all play that game. Sadly, the truth is that there are still tariffs around which are a lot cheaper than Bulb; for example, Octopus Go - 14.63/5p per kWh.

Screwdriva

Dolor said:

We can all play that game. Sadly, the truth is that there are still tariffs around which are a lot cheaper than Bulb; for example, Octopus Go - 14.63/5p per kWh.

Let's play that game then, shall we? 

For my post code, Octopus Go is 15.9 p/kWh with a 25p standing charge. Considerably better yes, but I can't sign up for Outgoing Agile if I chose that tariff. I likely won't own an Electric car either (I'm a Classic car guy and don't drive much). 

Given that I export ~75% of the energy produced, it makes sense to prioritize export, which means I have to chose another tariff from Octopus, all of which are more comparable to Bulb's tariff, who I have used for consistency (vs. advocacy).  

Decisions, decisions...

Solarchaser

So I think what you have shown is there are cheaper tarrifs, but you don't want to use them.
Fair enough.