Category: solar

So…my site has actually been live for 11 months now, but there has been a bunch of stuff that needed fixing after initial energization, so the six monthly maintenance thing happened a bit later. If you are asking ‘does it really need maintenance every six months?’ the answer seems to be yes. I pushed back on this, as I thought it was overkill, but have been talked around. if I owned 10 solar farms, I’d totally let one have maintenance every year or 18 months to see if it was worth it, but with a single asset I likely shouldn’t risk it.

Anyway, I just got the first report. Its VERY long and detailed. Its a 90MB PDF file, if that helps contextualize it. Here are some highlights:

Firstly, google have updated their data and there is now a proper google maps image! They add little points on the image to tell me where stuff was spotted that might need fixing, or keeping an eye on:

In general the summary of the report is this: “The inspection of the site and inverters, and testing of the DC circuits, found generally positive results, although some minor issues were identified – details in the report.” – Which is very good news because frankly so much stuff stressed me out as it was built I really could do with a few long sustained periods of just simple revenue generation from it. I think I will be at least 68 years old before it breaks even, but as long as it eventually does, I’ll be ok with that. This was not a money making scheme for me.

The report has a huge number of photos, including some cool ones. Here are ones that might be interesting:

Checking for hotspots on some panels with a thermal camera:

Checking the DC cables going from strings to inverters still look ok:

You get before-and-after pictures showing that the fans on the inverters have been cleaned. I visited one hot day when the fans were really going for it. I could hear them from 30 feet away. Each inverter is 80-100kw output, so the fans are working pretty hard sometimes. I’m not sure these really need cleaning twice a year, but we have only had one winter so far. Maybe super stormy and muddy weather will be way worse.

There are pages and pages of testing data like this table, which makes sense if you are an electrician, but from my POV its just nice to have a historic benchmark for this stuff so if anything fails we can look back and see what went on:

You also get thermal pictures of all the isolating boxes for the inverters to check there is nothing scary going on inside them:

They also get taken apart and cleaned. I think that might be a bit overkill too. Its tricky. On the one hand, what do I know? on the other hand people who service stuff always have misaligned incentives with regards to what is ‘essential’. If I had a hundred million pounds, I’d buy my own solar farm installation and maintenance company and then I’d know…

There is a ton of other stuff but I will spare you thirty pages of before-and after pictures of plastic boxes that got cleaned, or the many pictures of slight patches of rust on the edges of some supporting frame struts. I guess its good evidence that it was done thoroughly, with a lot of time spent looking for problems. Rather annoying an inverter was left OFF for half a day by error during all this, which happened to be a fairly poor generation day anyway, but that was annoying…

In any case I’ve decided to stick with the same company for the medium term carrying out these checks. At some point we will have a full years of proper generation and I can look at stats and muse as to how well or badly things are doing. I *think* its performing about as expected, which is good enough for me. I just hope the price I can sell the power for does not collapse!

I haven’t blogged about the solar farm for a little while because to be honest there has not been much to report (which is good! this is supposed to be a very stable low-maintenance project!) but I thought I would briefly update the blog to mention communications upgrades and a new PPA.

The site has multiple means of communication, because we need to be able to connect to, and monitor the CCTV cameras, we need reporting from the meter that actually determines how much we get paid (which is reported by a neutral 3rd party who charge a frankly comical amount just to read a single number every 30 minutes and report it), and we also need (or rather we like to have…) reporting from each inverter on the site to tell us the status of each inverter, and indeed each string. When I share the really cool charts and breakdowns with a ton of data, thats from the inverters. This measures DC power, at the inverters, before its converted and then sent some small but noticeable distance along underground cables to the site substation containing the site meter. Because some power is lost in conversion and transmission, the two meter readings are not the same.

Anyway… all of that stuff has to communicate off-site somehow, and its all routed through an aerial on the top of the substation. Its a bad aerial, and it uses a mobile phone connection which sucks. The site is somewhere quite remote and mobile phone coverage isn’t that good. As a result, often the signal is below 25% strength, and we get gaps in the data. The final generation readings are always there, but losing ‘sight’ of the plant is no fun, so we recently had all that comms stuff upgraded. The site now has a constant 48-49% signal strength which is good to see. This cost me unexpected money, but coincided with a maintenance check so the costs of sending people to site were not included.

In other news, we have signed a 2 year PPA (power purchase agreement) again with Ovo. That starts in November and runs out in November 2027. At that point we may stay with them, or switch if anyone offers a higher rate. One of the perverse things about owning a power station is that prices change every 30 minutes, but when you agree a price, it will then be fixed for years. Its tricky, because you are basically watching a fluctuating stock-ticker like price, but where you have to MANUALLY email people to ask for new quotes, and then pick your moment. There are services that offer more visibility into price trends, but I can’t afford them really… You can get 1 year, 2 or 3 year PPAs. I chose 2 years as the 3 year price looked pretty low :(.

And to be honest the actual ‘energy’ price part of it is only about 65-70% of what you get paid anyway. Some of it is benefits accrued through being a remote site, or a site where extra generation is beneficial, and some of it is discounts for having consumption near generation (so you put no strain on the distribution or transmission lines). Basically if you can find a site on some remote island with tons of local businesses and houses needing more power, then go for it. Anything to avoid upgrading the transmission network, apparently! How exactly you are supposed to guess those value pre-build is beyond me. There are probably expensive consultants, or you have to know who to ask and how to ask it.

Price-wise we are roughly the same as we were for our first year. Its… ok. Its not going to make some huge ROI, but its not losing us money either. I did actually pay out some actual company dividends for the first time (OMG), although it will be another few months until I can look at proper accounts and do a real analysis of whether or not we make enough in profits to make that an annual thing… I think larger sites have way better economics.

If you follow this blog a lot, you will know that we actually started generating power on our solar farm in October 2024, but there was some downtime in November, and then more downtime in December due to an extreme storm damaging the site (we lost 10 panels, since replaced), so we didnt have a straight six months of data until yesterday.

Also, because of the way solar is generated over the year in the UK, you want either jan-june or july-dec in order to extrapolate. The output of solar panels is basically a bell curve, peaking mid year, so once you have six months of data, you can make an educated guess (but only a guess) about the whole year. Just who shallow or steep that curve is will depend on a few factors, but in general I think that improvements in panels has flattened that curve a bit. Lots of technical changes to panels mean that they are more tolerant of ‘partial shade’ than they used to be. Handy in a cloudy country!

So how much power have we generated in six months? well its…. 766,739kwh. (766 MWH). So we can assume that if this is a typical year, that would mean 1,533MWH in a year, or 1.5 gigawatt-hours. Enough to run the average TV for 1,700 years. Or enough to fill a large electric car from empty 19,000 times. In some ways this seems a lot, but how does it compare to what we expected?

Well it depends… If I dig up the oldest email about the sites initial plan, the assumed generation output was just 957MWH so this sounds amazing. That was then changed to 1,245MWH it was later changed to 1,347MWH . The final setup for the export meter seems to say that the expected output is 1,339MWH. So the actual expectations are all over the place, but all below the current value. I THINK that we had a very very good April, and that is skewing the results. If we hit 1,400MWH in the year that will be very pleasing. It is too early to really be definitive about whether or not this means that the farm makes a profit. I would be nervous of judging that without a full year. Especially as a maintenance contract is still not signed yet.

In other news…

You may have read posts by me banging on about REGOs. A REGO is a Renewable Energy Guarantee of Origin certificate. When you generate a single MWH of power from a renewable source, you can tell a government regulator (ofgem), and they give you a certificate. There is no subsidy, but you can sell them. Who buys them? Companies and energy retailers who want renewable energy. To be able to sell your power to customers as 100% renewable, you need to buy REGOs to cover all your energy. There is an open and competitive market for REGOs, and currently they are worth £10-£15 per MWH. Thats equivalent to 0.1 to 0.15 pence per unit of electricity, no not a lot from a consumer POV. Like most companies, we have our REGO sales ‘bundled’ in with the PPA (Power purchase agreement) we have with the company who buys our power. In this case OVO Energy.

Thats the theory. In practice, this process is HELLISH. It genuinely feels like ofgem have been told to make the process of getting accredited as impossible as they can. The amount of bureaucracy, inefficiency, radio-silence and pickiness over the grammar and punctuation in every piece of text in every document required in order to qualify is beyond insane. I applied as SOON as was possible (your site has to already be generating, which is stupid as hell), and it still took SIX MONTHS to basically have a form processed and accepted. We even had to argue basic maths with them, such as arguing that 400+500 = 900, and not as they claimed… 810.

Anyway, that insane process (which reminded me of the DNO legal process, which reminded me of the planning process….etc) is finally complete, although not without a formal complain to ofgem about it. And I will not bore you with the details, but suffice it to say that obviously they are still arguing about it, and saying its not right, even though they have approved my site, and approved my output data, and credited me with the certificates which I have lready sold. Its insane beyond words.

And actually the entire process is a colossal waste of time, because there are already a network of organizations who entire existence is simply reading meters and verifying that they are accurate, and reporting that data online. I am charged about £250 a year for this ‘service’ (the real cost is likely under £1, its just a meter). Now ofgem could trivially just connect to the databases for those independent companies, read everyone’s data automatically, and credit the REGOs without any human interaction whatsoever. And as for verifying that the data really is renewable, the people who 100% absolutely independently KNOW what equipment is connected, are the DNO (Energy distribution network operator). There are a handful of meter readers, and a handful of DNOs, and this would be easy…but NO! Lets set up a torturous six month minimum process that involves websites that crash, tons of paperwork, complicated rules and processes and a staggering waste of everybody’s time. Because thats the UK energy industry. Are you surprised your bills are high?

So yeah… its been interesting.

I am HOPING that within a month, I will have stopped getting irritating emails from ofgem, I will not get any more letters about lawyers and leases, from one set of lawyers to another (I would love to jettison the entire profession into the sun at this point), and have a maintenance agreement signed.. and then finally I will be able to basically forget about the farm, apart from enjoying checking the stats!

I do still LOVE the fact that I built it, and own it though. Its awesome :D.

Because we happened to be (vaguely) in the same part of the country, we decided to go pay a quick visit to the solar farm. Its been energized for about 8 months now, although there have been 2 periods of downtime for some work since then, so we still do not yet have a nice clean 6 months of data to extrapolate from. Also I had my drone with me to take ‘finished farm’ pictures :D.

The situation with the farm is that it is 99% finished. There is some tree planting to do (one of the planning constraints), which will have to wait until later in the year, and also it has a problem regarding shutdown. When the site loses power (due to a grid outage), it then does NOT come right back online automatically, which is frustrating. It should, and its back to negotiations between the construction company and the DNO as to why this doesn’t work yet, and fixing it.

From my point of view, there are also two other things that are still *not done* yet. These are, to get a maintenance contract in place (we are still waiting for quotes from fire suppression system inspectors) and also to get ofgem to finally accept that this is indeed a solar farm. That last point is especially irritating, but I finally think, 8 months after switching on that we are close to the end game on that one. The bureaucracy is insane. Why they need to know how many panels are on each string of each inverter is beyond me. The DNO didn’t even care about this, and we connect this kit to THEIR network… As a reminder, this is so we get accredited to produce REGOs, which are certificates to prove a MWH of power was renewable. You can sell those certificates for about £10 each to companies who want to claim their power is 100% renewable.

Anyway…

Its always pretty cool to see the site, and remember that I actually own it! I love my 10 home solar panels, so going to see the other 3,024 is pretty cool. I was surprised just how NOISY inverters are in summer. I assume this is active cooling, as we were there early afternoon in June. If you think your home inverter for your panels never makes a noise, thats likely because its a 4kw one, and 100kw ones have way more juice flowing through them. I think I could hear the inverters from about 15 feet away.

Broadly things were ok, I was VERY happy to see how clean the panels are, 8 months into energization and probably a year into mounting, so this bodes well for minimal cleaning costs. How grubby panels get really depends on circumstances. This is a livestock field, so crop dust is not constantly blowing near them, which probably helps. I did encounter a bunch of things that I had to complain to the construction company about. I guess its just like having builders come work on your house, but 100x bigger in scale. I really hate that side of the project, but it comes with the territory. It was also good to meet up with the landowner, who is a great guy, very understanding, and a great ‘man on the ground’ who can tell me about any problems directly without it being filtered through a third party.

One of the main reasons I wanted to take a look again was to try and get better drone pictures, as last time the site was not 100% finished and my drone had software issues (DJI apps suck!). This time it worked, and I took some, as you see, but it was pretty windy. Being on a hilltop does not help, and I braved the ‘LAND DRONE IMMEDIATELY’ warnings as long as I could, but they are obviously not pro level snaps :D. I also found one broken panel, from when the site suffered storm damage, which shouldn’t be left there really. It was interesting to see a folded and broken solar panel though. You don’t see many of those.

Overall I’m happy, the site is generating nicely in summer. the end of this month will be when I can do a proper financial analysis, as the output mirrors around midsummer so 6 months data gives me a great yearly prediction. I really want it to break even!

A few days ago I got the latest invoice/statement showing how much I was paid for the solar farm, generation in January. The grand total is…

£3,716 + VAT

For those from other countries, VAT is basically sales tax. I get paid the VAT by the people buying my energy (OVO) and then I have to pay it to the government each quarter. Its all quite tedious. Interestingly, the VAT is 20%, which is different to the rate for home power purchasing. Its irrelevant anyway, because I basically just earn interest on it for 3 months before I give it to the government, so I tend to just ignore it in any calculations. Any interest earned will be in my awful cater-allen company account which has an interest rate that is comically low. UK business banking is one giant rip-off.

Anyway, lets dig into that payment a bit more because to break it down. The full details are as follows:

Electricity output:	£2,540
DUoS Benefit:	£667
DUoS Costs:	£-13
Transmission Loss Passthrough	£28
Distribution Loss Passthrough	£511
Admin Fees	£-24
Before VAT	£3,716
VAT	£743
Total for January:	£4,459

Its a complex mess isn’t it? Also it has not included REGOs yet, because I am STILL going back and forth over the minutiae of my application with ofgem. I kid myself this latest batch of questions they have will be the last and that I will finally get them. Plus the ofgem REGO website is about to be completely re-implemented, and I have ZERO faith that they will not just ‘accidentally’ delete my application so far in the inevitable chaos.

Frankly the whole system should take a tenth of the people and the time, but here we are :(

Worryingly, I have no idea how precisely the four entries under ‘electricity output’ get calculated. I assume this is fixed based on where my site is on the distribution (DNO) and transmission (National Grid) system, but I am not sure. My power is almost certainly just used very locally, so I probably don’t use the transmission network at all (hence the £28 rebate?). I likely use very little of the distribution network either, hence the £511. My best guess is that if I was an offshore windfarm 100 miles from the nearest town, that Distribution loss would be actually negative?

The DUoS stuff is a complete minefield of complexity. Best explanation from grok as to how DUoS can be a benefit to me:

Triad Avoidance: By generating during peak demand periods, you help reduce transmission network charges (TNUoS), which benefits suppliers and can result in payments or incentives for you.
Avoided DUoS Costs: If your generation offsets local demand, it reduces the DUoS charges that suppliers would otherwise pay, potentially increasing the value of your electricity in Power Purchase Agreements (PPAs).

Triad avoidance? Hold on, was that not a sci fi kids TV show? How are the triads an issue? Or is it Japanese mafia? Whats going on? Its actually even more complex:

Triads are the three half-hour periods of highest electricity demand on the transmission network each year, typically occurring between November and February.

You will be thrilled to know that my ‘Triad avoidance benefit’ for January was £0, which is why it was not included. Confused yet? You should be. I am, and I literally own an energy company. Anyway, out of interest the DUoS benefit in January was 17.9% of my total(pre-VAT) payment. I just checked December’s statement and it was 16.69%, so its not even fixed. Are they really calculating the flows in and out of each part of the distribution network on a daily basis and adding up how much ‘my’ power used it? Interesting…

In other news we finally got our second home battery installed! we now have 19kwh of home storage. In winter this does not make a vast amount of difference, because our 9.5kwh one already covered mots of our peak usage, so we could load-shift to off peak (the car charges off peak anyway). However in summer this means that on those crazy days where we generate 20kwh of power we can store all of it, even if we are away or not using any power that day.

The last summer we did actually end up with *too much* power, and had to fiddle with car charging to avoid exporting it to the grid (which we do not get a marginal export fee for, as we are on the old feed in tariff). Also we did it because I like the idea of being as resilient as possible.

We also managed to get a cable running from the battery upstairs to the living room and a new double socket installed there, amusingly next to a triple socket, so it looks like we are addicted to power sockets :D. Anyway, those two sockets are the ONLY ones that will work in a power-cut. We couldn’t power the whole house because our inverter is only 3kw, and this was the next best thing.

Its not exactly off-grid living, but being able to charge laptops and phones in a power-cut, or with an extension lead, still run the router and TV and a coffee machine will be nice :D. We paid £3,900 to have the second battery installed and the sockets fitted.