Recycling of PV panels article

[Krill]

Is that the calculator that can play "As the saints go marching in"? If so, I think my dad has one of those lying around somewhere...

[nowty]

Not quite as old but a good excuse to present the 1980's calculator joke if your of that age.

[Mr Gus]

This is where feedback from "St Barnabas chapel" with his early modern Yingli's would be good. (you just know he's been monitoring them) ..wasn't he in Northumberland or Ireland?

Ah well.

[Mart]

Regarding degradation, I had a small argument (me, shirley not!) with a bod on the MSE forum. He wasn't happy about a chat us PV'ers were having, and suggestions that generation (back then, around mid to late 2010's) cost about 7p to 8p/kWh.

I'd produced a spreadsheet, based on a 25yr repayment mortgage, to reflect the opportunity cost of buying PV, and to avoid any arguments about paying via cash, or loans. I based the interest rate on 2%pa, to reflect lost interest in a cash account. I also 'assumed' 0.5% degradation, but netted it off against inflationary rises in income (leccy savings). I popped in an extra £1k to the outstanding debt after yr 12 to reflect a new inverter. Then found a monthly repayment that brought the balance to zero after month 300 (year 25). Lastly, 12x the monthly payment, divided by annual generation, gave me the cost per kWh. Easy to duplicate the spreadsheet and apply different variations of size, cost, interest rate etc.

So, the PV critic, who was a massive RE fan, praising all moves to a cleaner economy, but also attacked domestic PV every time for being too expensive, did his numbers, and presented a detailed report 'prooving' the cost was more than 10p/kWh.

Sorry for the waffle, I'm getting there.

So I read his post, and pointed out a few errors.
1. He used a much higher cost of install, as he claimed our cheaper figures, and those being found by folk asking for advice on the forum, must be using cheap and inferior equipment - false assumption.
2. He told us it was unfair for there not to be an increase in household insurance costs, so he added one!
3. He told us we were wrong not to clean panels, but as we'd all told him we didn't, he'd only add a professional clean every two years.
4. He said a £1k inverter would only last 10yrs, so added a £100pa cost to the 25yr period, an additional £2,500. I pointed out that he was double counting the first 10yrs, as the inverter was part of the install cost, or he was including years 26-35, and needed to also add the PV generation. He told me I was wrong, and stuck with the additional £2.5k.

5. And now we get to the fun bit. He said that degradtion would be approx 1%pa, and proved it by including this 2012 report:

Photovoltaic Degradation Rates — An Analytical Review

I pointed out that the ~1% annual degradation given in the report is based on all types of PV, and all ages tested including pre 2,000, and post 2,000. I then pointed him to the annex which shows that post 2,000 mono-silicon shows a degradation rate of 0.36%pa. I also pointed out that there was a significant improvement from the pre 2,000 figure of 0.47%, and since we were now well past 2,000, we might be able to assume a further drop. But regardless, thanked him for confirming that my 0.5% figure was somewhat pessimistic.


Sorry for the old story, but it was fun, and I was surprised how low degradation appeared to be. For my systems now 11 & 12 yrs old, I've yet to see any drop in performance. I'm not denying that there's any degradation, but I'm genuinely shocked to not (yet) be able to see any downward trend line in annual generation.

Obviously weather, and annual fluctuations help to hide annual differences, but I'm sure I'd get a gut feeling if there was a noticeable drop, so it must be less than 2% or 3% (over the 12yrs) to not yet be noticeable, which I do find quite remarkable.

I wonder if the 'poor' solar weather in the UK, is somewhat gentle on PV panels? But really have no clue.

[Mr Gus]

Just tried to listen to the series linked (world service on the bbc)

It will not let me access the program without a log in (despite the "maybe later" option that usually works.

It does however allow instantaneous play if you click download, presumably it wishes to make a point & log data on us.

[marshman]

__

[Mart]

Hiya, no those numbers look OK. The discussion, took place aroundthe time that costs per kWp install were falling to around £1/Wp for installs of about 5kWp or bigger. Obviously, smaller systems, and older ones, like ours, were a higher cost.

The guy, in question, was a supporter of wind, and large scale PV, but would trounce the economics of domestic PV at every opportunity. In the discussion we had (as at that time), there were loads of installs confirming the prices we (the PV'ers) were suggesting, but he was adamant that those prices were only after haggling (yes, we were encouraging those asking for advice, and giving their quotes, to shop around), and must be based on cheap components that wouldn't last long - a weird assumption.

My sister was lucky and got a large install 10.3kWp in late summer 2021, so she avoided the price spike as demand for pV went up, as leccy prices rose, and also benefitted from the lower cost per Wp as you go bigger.

So I dug out the old spreadsheet and popped in her numbers of £8,600, 1% interest rate, 10.3kWp and 9,500kWh pa estimate. It gave me a unit cost of 4.79p/kWh. Changing it to 2%* (trying to reflect cash accounts for monies readily available for use) it comes out at 5.03p/kWh. But in their first year they actually generated 11,000kWh, as there house is quite exposed and atop a small ridge, so good winds, I believe. So upping the gen to 10,500kWh (just to keep some margin), gives 4.55p/kWh. [Edit - their export rate is 5.5p/kWh.]

Back when this 'dispute' took place, some folks with better minds than I came out with similar figures (for a new install at that point in time), also at 7-8p, but the other guy (no PV) was insistant on his numbers and the 10p/kWh. He also stood rock solid that if an inverter costs £1k and lasts 10yrs, then the cost is £100pa, refusing to accept that the first 10yrs (£1,000) are included in the install price. [Just that single issue, of £1,000, accounts for nearly 1p/kWh difference, based on a 5kWp system, 4,500kWh pa, over 25yrs.]

Fun times.


Edit - *Probably haven't explained this well. In such 'arguments', critics will point to the lost interest of capital spent on PV. This is actually a fair point. But often then try to argue for the benefits of having the monies available, and also interest rates reflecting longer term periods. Obviously you can't have a longer term, higher int rate, and also be available, hence comparing to lower interest rate easy access cash accounts.

Going back to when we get PV, your ~£12k, and our ~£11.5k, it's probably fairer to compare to higher saving rate accounts. But by the late 2010's (without wanting to appear crude) ~£5k was more likely to be from lower interest rate cash deposits.

No idea if that makes sense, obviously I'm condensing several weeks of discussions, and multiple pages of posts into too small a space, so to speak. And if the systems last longer, say 30-50yrs, then it only gets better. But I suspect it may actually be worth upgrading PV panels before that, as their output has risen so much, certainly since 2011/12 when we got ours.

[marshman]

No that makes sense, I kind of assumed you were talk "historic" circa 2010 installs.

[Mart]

Your self use point is really important.

I apprecaite that I'm moving this thread away from the recycling point, but in my defence, the surprisingly low degradation, does lift the economics, and thereby reduce the need to scrap and recycle.

So, the old arguments of PV farms being cheaper and more efficient than small demand side PV misses many points. And I raise this, as the bod in question, was not alone in 'picking on' small demand side PV.

Yes, a PV farm has a lower CAPEX, but this ignores the fact that demand side PV typically has lower (very low) OPEX. The main one being the lack of any land cost (rent, lease, or opportunity cost, if you own the land) since our roofs have no real alternative income potential. Also, unlike wind, PV doesn't have any significant economies of scale with regard to the technology. Yes, there are economies of supply/bulk purchase, but the panels are typically similar. Whereas a 4MW wind turbine, will have many advantages over 1,000 4kW turbines.

But the real gain for demand side PV, is that it competes against a mix of retail and wholesale leccy pricing, whereas a PV farm sells at wholesale. So the savings of self use that you mention, which skews the economics significantly.

I suspect critics of the various types of RE just don't want to see, nor believe, how economicaly competitive they've become, though tbf I don't tend to see as much negativity now, v's the doubts/denial that costs could fall enough, back in the early/mid 2010's ..... and that's before we include the huge externality costs of FF's.


Lastly, just to say I'm not really as boring and anal as this may suggest. I tried to cover all of the costs to negate arguments and caveats. Personally, I'm more in the camp of it looks like a decent saving, then stick the money in, ignore opportunity costs, wait till the initial monies are 'repaid', then enjoy the gravy.

[nowty]

The way I look at it is I card tarted (0% credit card deals) my initial 4kW system (£11.5k in 2011). Apart from having to pay the first 3 months minimum payments on the card up front before my first FIT payment came in, it cost me nothing and no lost interest on capital as not relevant with cheap borrowed money. Debt completely paid off in 6 or 7 years.

All other PV additions (including second FIT system) has been paid for by FITs.

Ripple GF was paid out of 2 years of FITs and by the time KH starts, the FITs and the income from GF will have paid for KH. Ripple DW will be paid off from less than 1 years worth of FITs + GF + KH, so maybe even payed off when DW goes live.

And I'm not even counting the energy savings which were around £500 a year in the distant past, but in the last year the savings have been about £3k.

I still smile when I think of a BBQ I held back in 2012 or thereabouts when some doubtful acquaintances said, "its all hype, you'll never get your money back."

And regards to recycling, every bit of kit I bought and upgraded has been easily sold on for reuse.