Just a brief comment about solar panels in the UK and in particular, Ikea. Comments invited.
Recently announced, Ikea in partnership with a company called Solarcentury are to sell solar panel kit.
I feel I should say my piece and then let others come back to me….
Firstly – solar panels in the Northeast of England – someone is having a laugh. Can someone please come back to me and tell me – other than tax-payer-funded subsidised solar which is one of the biggest cons of all time (YOU are paying for your neighbour’s solar installation and getting nothing in return)… I’m just not seeing this.
So the headlines look good – 25 year guarantee on the solar panels – 10 year guarantee on the invertor – 6 year output guarantee – 6 year workmanship guarantee. So firstly, it is will known that solar panels last for decades, so no big deal there. A well made invertor should also last a very, very long time – as with most (well made) solid state electronics. But try as I might, studying the advert, I could find nothing on batteries, without which the solar installation isn’t a lot of use.
I’ve been in Spain for all of this summer so far and we’ve had GREAT weather – and one of the reasons we do this is because summer weather in the North of England is CRAP.
Long-term average, in Morpeth as it happens, not 40 miles from where I live, has a handy statistic… 180 hours of sunshine in May – and that is the BEST. There are 740+ hours or thereabouts in a typical month and so my simple back-of-a-cigarette package math says that in the BEST month of the year, the Northeast spends over 75% of it’s time WITHOUT sunshine.
Let’s take a look at the year in total. 1400 hours of sunshine out of a total of 8760 hours – 84% of the time, there’s no sun. And recall also that unlike Spain, the sun is not overhead in the UK – it is at an angle which limit’s it’s power and accounts for why it is currently cool in the UK and 40c here in Spain as lunchtime approaches.
So while I don’t in any way claim to be an expert on the UK, overall I have many long years of wondering in the Northeast when the hell we’re going to get some sunshine – erm, maybe 60 years experience on and off? Regardless of that, many new buildings are fitted with solar panels (we’re talking photovoltaic here, not hot water) – funded in large part by the public who help contribute to many of these installations even when they DON’T have these panels.
I went to the IKEA site and asked for a quick quote – it asked me for my postcode… I told them about my roof – confirmed I did not need to charge my electric car!!! And suggested I would be home all day. I did my best to provide honest input.
The computer said I would be using 270w panels (15 panels) – that I would save £612 in the first year and with battery storage would save £17,870 over 25 years. The cost of the system would be just over £8k
So 270w each, 15 panels comes to 4KW which would SEEM to just about run our electric heating – if the sun was out – but as we’ve seen and as you’ll see from the Met office figures, when I need the heat, there is NO WAY ON EARTH the sun will put out anywhere near enough energy for anywhere near long enough. Indeed here in Spain I have a 250w panel which puts out about 270w – but back in the UK on test I could never get more than 200w out even with brilliant sunshine pointing DEAD at the sun, not near enough dictated by the root – so I would have guessed that this system on a typical North-eastern sunny day would in reality out out nearer 3KW – not a lot of use for a house that is all electric including ovens.
We simply have to do the maths here – in the very BEST month of MAY, with 180 hours of sun out of 744 hours of sun, we’re looking at an overall output over the 24 hour period… OPTIMISTICALLY 3.5Kw x50/744 = 840w – that’s assuming the batteries they supply will suffice to get that kind of power overnight. Doesn’t sound that impressive but that is the BEST month.
Now let’s look at a typical North-eastern December – and remember the output of the panel will be WAY lower in December – let’s be generous and say 3KW when the sun is out. According to the MET Office that comes to 3×40/744 = 161 WATTS average per hour over the 24 hour period. My FRIDGE FREEZER takes that amount and runs 24 hours a day.
Of course we’re not looking to run everything on solar – but just to subsidise and cut costs.
With standing charges that apply whether you use electricity or not, with such atrociously low levels of sun, certainly in the North of England and with these high costs – I’m sorry – I’m just not buying the claimed savings or anything like it….
Also – it is probably worth asking – this 25 year guarantee on the panels – does that include storm damage- and what if the roof needs work during that time? I’ll bet that isn’t factored in. We get some pretty bad weather in the winter.
Am I missing something? Could these concerns apply to where you live? Stats derived from Met office info.
Nice blog! and it only expressing the experience of solar panels and to share knowledge for the benefits of other. Thank you for sharing your story and a big help to those.
CurlyWurly – Just a comment … to qualify for the contentious Government subsidy, you have to have a minimum energy rating for your house.
Essentially that means you have to have cavity wall insulation, double glazing (soon to be triple), roof insulation, low energy lighting, high efficiency boilers and draft-proofing. We got knocked down a point for having a single tungsten light bulb in the airing cupboard that I had forgotten about … fortunately, we just sneaked in, despite that.
Ah, we got marked down as well because half of our house walls comprise 24″ solid stone (a 200yr old cottage) so no insulation. Afterwards, we added 5mm thick insulation inside, under the wall-paper – it made a remarkable difference, stopping the cold walls generating convection drafts.
By the sound of it, you have a lot of work to do if you want to qualify for the subsidy.
indeed – clocked that about energy rating. 🙁
There also seems to be a limit to how much power you can export back to the grid without needing prior permission. This seems to equate to having a max number of panels of 16 (250kW)
Have you had a look at this?
http://www.currentcost.com/solar-pv/our-solutions.html
I’ve just put some energy meters (from Maplin) on the washing machine and dryer – will be interesting to see how it mounts up!
Wife goes past the dryer every now and then to check if finished. If the dryer completes and she forgot about it, she turns it back on to get it dry again.
The monitor has already shown this costs 10p each time!
Just changing behaviour (with maybe a wifi connected dryer) would save money!
Yes, max normal panel array limit is actually 4kWhp. You can generate more but you have to apply and get permission (and that can take a few months to get an answer, which may be no) – the reason being that if everyone down our road put in a 20kWhp array and then exported it all on a sunny Sunday afternoon, they would dump 1.5MW into the local grid … I suspect it would go pop. But, like all these things, the early users are likely to get a yes, until the local capacity is reached, then people will get refused more than the 4kWhp.
I have an energy monitor but unfortunately, since my panel array is actually on my workshop roof, the wiring is a little scrambled and there isn’t a clean IN-OUT set of wiring so it gives misleading readings (like sometimes saying it is generating negative energy … but then The Universe is supposed to be 90% negative energy so it may be telling the truth!)
One BIG advantage of the silly way the politicians formulated the subsidy rules is that they assume you export 50% of what you generate. So, my wife watches the system and as soon as we start to export enough power, she turns on the dish washer or washing machine or tumble drier – all for free.
This only works whilst we don’t have a smart meter – as soon as we get one, they will only pay us for what we actually export. It will still pay us because they only pay us 4.5p per unit we export compared to the 11+p we pay to import it.
An unusual saving of our array is a 10% reduction in our gas bill, because we have a gadget on the system that detects when we are exporting and diverts power to the immersion heater instead, saving on gas for heating water.
CurlyWurly – I am in the process of cataloguing my Library and just stumbled across a book that may be of interest to you. It is quite old (1977), and American, but most of the basic theory is sound –
Designing and Building a Solar House
Donald Watson
ISBN 0-88266-085-3
OK – a bit off topic – hopefully interesting to someone.
I bought one of these “IAM” devices (made by “Current Cost”)
http://www.ebay.co.uk/itm/Current-Cost-IAM-UK-Pack-of-1-/182325831151?hash=item2a737765ef:g:4awAAOSwUV9WoOYg
These “IAM” devices transmit an unencrypted 433 MHz signal every 6 seconds, which shows the power passing through the mains socket and if you add up all these power “values” over a period, you can work out the total energy used (kWh)
I did try Rflink, but it didn’t work (because RFlink can’t see FSK)
However, I could see each 433 messages via a SDR dongle using “RTL_433.exe”.
Here’s a page if you want to use a SDR dongle to transmit MQTT from this device
Just thought it might prove interesting for someone who wants to measure power draw from various devices and process via Node-red etc
Sorry, missed the 145W in the bottom left corner …
Finally, here is yesterday’s variable panel array performance. The individual panel performance is frozen at 11:30 so you can see the effect of clouds shading different panels differently, with individual power variations from 95W to 126W – very different to what you would get from a single inverter.
I forgot that there is a ‘last 12 months’ display, so here is what the last 12 months looked like. You can read off the monthly production on the scale on the left.
Many thanks John – very helpful for me.
For some time now, I’ve been baffled over how to work out the following
1) Minimum number of panels (Summer) – To cover monthly energy consumption over Summer
2) Minimum number of panels (Winter) – to cover monthly energy consumption for Nov – Feb ( Thanks to your data!)
3) Balance between more panels vs substantial batteries for Winter
4) Use wind power in the energy mix?
5) Price point for all of this
Just for reference, I’ve been measuring my energy usage using “Loop” (which is brilliant). Unfortunately, none of the measuring systems out there work with renewables (as far as I know) – there is definately a gap in the market here.
However, using “Loop” has given us our energy usage profile over a year (which as you can see is ludicrously high). This a great start point for me.
(Yes I know, get better insulation!!)
At the risk of advertising (I’m not part of them), Loop has saved me its cost (£50) many times over, and gives me detailed energy usage metrics forever. It also compares the market for my energy usage profile and recommends which package is the cheapest
With Graph of Gas usage vs Electricity (for the year in KWh)
With graph of Gas usage vs Electricty (for the month in £) with outside temperature
With graph of Electricity usage compared to last year (for the last 3 months in KWh)
With graph of Electricity usage compared to others in your geographical area (for the day in KWh) – You can start off with the “month” view and zoom in to the “week”, you’re interested in, then zoom to the “Day” to find the hours that have the highest usage. For us, this tends to be the washing machine / dryer / electric radiator – Great for realising where the energy spend goes!
CurlyWurly – ouch!
10MWh of electricity and 73MWh of gas in 11 months – is that correct?
That’s not a house, it’s a steel works! 🙂
Seriously that is a lot of energy. I can see why you are looking at alternatives.
“10MWh of electricity and 73MWh of gas in 11 months – is that correct?”
Yeah I know – its a old house
On really cold days in Winter, 2 gas boilers are working flat out just to keep us “reasonably” warm.
The electricity is high because the dryer is on almost constantly. Also one of the gas boilers broke down at December last year and it took a while to get fixed – so we ended up having to use 6 X 2KW electric radiators for quite a bit of time (which boosted consumption of expensive electricity considerably 🙁
What’s really needed is for us to address all areas – from much better insulation, a more efficient gas boiler which is sited better (atm, we have long runs of pipes) to buying more efficient household goods (e.g. heat pump dryer).
Its all about finding where the biggest waste is and trying to address it – in our case we have realised that we need to replace the poor efficiency gas boilers and make sure there is better insulation
It all costs though 🙁
May I ask where in the World you live?
Wales!
Bills work out £300 per month (Gas + Elec) when averaged over the year. It works out as £200 Gas and £100 Electric.
I repeat – Ouch!
I lived in South wales for a few years, had a factory in Tafarnaubach and lived down in the Usk valley in llangyidr – beautiful. But that was a modern house, not your enormous castle with no windows … 🙂
It does sound as though you need a serious batch of alternative technology – ground-source heat pump to try to keep the place warm, a windmill (assuming you have winds like we had), and solar panels with battery back-up.
An expensive exercise. I wish you luck, and if you need any data on the panels and inverters I used, just shout and I will supply it.
Mr Shark – it is the system that comes free with the individual inverters. Each inverter effectively has its own web server inside and reports its performance every 15mins to my router which then forwards the information every half hour to ABB in Italy who store and present all the data. What I showed was a partial screen grab from their website.
CurlyWurley – give me a little time and I will extract the monthly data for a whole year for you. Obviously, summer is better than winter, but you also get variations within those simple blocks. As I said earlier, we have generated 13MWh in three years, so you can get an average from that.
In the meantime, I will post a graph later showing the output for a ‘variable’ day.
Just for interest, I attach (I hope) an image from my panel monitoring system showing its performance on July 17th this year. It generated 24.97kWh that day.
The output of each of the panels can be seen in the grid at the bottom, the intensity of the blue shading changes with panel output giving a neat visual indication of the system’s performance so you see clouds, birds, shadows reducing the output of individual panels without affecting the others, neat.
If anyone is interested, I can post other images showing performance during less favourable conditions to show that effect.
What you use to generate those graphs?
Hi John,
Many thanks for showing the data.
If you don’t mind, could you give an idea of the relative performance over a year (e.g. KWh figures for Jan, Feb…Dec) and also which month was the best and worst?
really like the graph too !
cheers
CW
All Europe is full of solar panels. From north to south, from west to east there are square miles of solar panel. The profit is coming from green certificates, all those companies get green certificates from EU, then they sell them to companies responsabile for pollution (refineries, heavy industry)
This is the only profitable business with solar energy. Selling only the solar energy never return the investment.
To build your own solar filed needs lots of approvals, and it is available only for certain companies.
The EU green certificate program doesn’t accept new members in the last 2 years.
Hello Curlywurly
No, that’s probably right, but after the loan finishes, you still get £1,200 a year saving for the next 15 years – or have I missed something here?
I had a top quality 4kWp system (16x250W) installed 3 years ago. It cost £8k and I was told it would save me £1,200 a year (half subsidy, half savings). I live in North Lincolnshire, just south of Hull. During the first month of operation it actually generated 4kW for about an hour one lunchtime, but 3 – 3.5kW is its usual peak.
It has generated savings of almost exactly £1,200 a year and produced a total of 13MWh in that time. That gives me a payback of 6.7 years, or 13.4 years if you don’t include the subsidy.
Just for the record, the subsidy is an incentive to persuade everyone to start using an initially expensive technology, to kick-start it, and it is available to everyone, and encourage them to take advantage of something that will also help the planet – my system has saved 19T of CO2, as well as saving me £3,600.
Finally, I would echo Ben’s last comment – you get what you pay for. I specified top quality panels from Panasonic (they are hybrids that generate power from diffuse light as well as direct sun, albeit not as much, of course) and individual inverters made by ABB, these stop the entire array switching off when one panel gets shadowed. Also, if I may take exception to your assumption that all electronics will last forever – single inverters are highly electrically stressed pieces of kit, chopping 400v dc at 10A into 240v ac at 17A along with all the transients around the place, and are usually only guaranteed for five years, and that’s usually when they fail as well, if you talk to some installers. My individual ones have 16th of the stress of a single one and are guaranteed for 25 years. And the whole system is monitored by ABB in Italy who tell you if anything looks problematic, but then my own ap. does the same thing.
So, get decent kit, and the numbers work. And they would work even better when reasonably priced batteries are available, but that time isn’t yet, I’m afraid.
John
Hi there
It wasn’t an assumption that all electronics last forever… I’ve been doing electronics since I learned to walk, so I do know it’s limitations – modern stuff does tend to last a long time but your comments about stressed invertors noted. I don’t think my maths was miles out for the Northeast however – and incidentally not everyone can have solar panels. Our last house was a listed building (our current one isn’t) – and had an unlisted flat section. They could not fit on the listed bit – and did not want to know about the flat section.. may have been an isolated example of course. A friend of ours in the same village has also done his research and although he too eventually backed away from photovoltiacs due to our weather, he did fit hot water panels and they seem pretty good. Where I am currently in Spain of course it’s a different matter – the only problem is – the Spanish government here get (in theory) uppity about you fitting solar panels without feeding back into the grid! Madness – http://www.mariscal-abogados.com/sun-tax-on-photovoltaic-systems-in-spain/
Hi John,
Thanks for the metrics – very interesting – a £10K loan over 10 years works out about £1.2K per annum – in other words, no difference in monthly spend (if all things stay the same) – or have I missed something here (other than maintenance cost) and an immediate drop in bills after 10 years??
I would have thought this would be ideal for you
Pete – for when you arn’t in the UK – using the sun on an empty house to earn money while you are abroad 🙂 ?
Pete – did I say something wrong? Why was I deleted? I thought I made a valid contribution, sorry if not.
John
Might’ve been me just being overly sensitive early in the morning – I don’t have the original but I noted something about me “so despising” something and figured it was being insulting – you’ll note that there is very little aggression in the comments on the blog). Apologies if I deleted a valid set of comments… if you have the original, just re-send…..
Hi Peter
Todo the calculation: http://re.jrc.ec.europa.eu/pvgis/apps4/pvest.php# might help.
Enter your location and the roof angles and click on show graphs and show horizen.
Leave the installed peak power at 1Kwp
You’ll get allot of data.
As a rule of thumb if the Total Yearly Energy produced by 1kWp is higher than 800kWh it’s ok todo an installation.
As you can see winter is crap, summer is great. Batteryies are a hobby if you get a fair price for the surpluss power you feed to the grid.
I have done that exact calculation I think 2 years ago when IKEA offered it here (Netherlands). I forgot the exact offer but initially it seemed doable, not great, but doable… and then you do your own calculation and it is crap.
Currently there is a company here that has an offer in which you dont own the panels but it is sort of a mix between them leasing your roof and offering you the electricity, have to get a bit more details abt that
Pete,
It’s actually worse than your rough calcs……..
I bought 4 solar panels from an installer, these were the exact panels that were being installed on mass on roofs here in Southern California.
Being an automation / data guy, I put shunts and volt meters on each and proceed to look at their output power.
Within the first 2-3 days I could see something was not right. They were marked as 250 watt panels, but I was only getting 50 or so watts.
I spent a lot of time checking things at my end, it had to be my fault right?
In the end, we emailed the manufacturer and got a cryptic answer that said the label on the back of the panel was correct.
What did the label say?
You only get the rated output at the rated temperature with the rated illumination.
So, I put temperature sensors on the backs of the panels, ambient air temps and solar radiation meters.
Granted I am in SoCal, it’s hot a lot of the year. So I logged the data and waited.
Over the space of the following 2 years, I can totally agree with the manufacturer.
You get the full 250w’s output only at full sun (summer) when the panels are at 20deg C (winter).
In short. Never.
Thousands of roofs, thousands of people, have paid to have these crap panels on their roofs and while they are getting some power fed back into the grid to offset their bills, they are getting ripped off massively.
I suggest that the panel you have is a good quality one. Indeed, knowing what I do, I went out out and brought two different 250w panels and both of those give their rated output almost year round. (Each of those panels cost as much as the first 4).
You get what you pay for. I can not speak of the quality of the panels Ikea is selling, but I bet they are not what they seem.
(tl;dr The panels are crap quality, divide the output by 4 and do the math again to get closer to reality).
Try this link: http://pvwatts.nrel.gov/
and enter: London, UK
That seems to work.
Yes thanks – I think in fact it was my incompetence the first time – I managed to get Bellingham, Northumberland, UK.
I’ve not really done the detailed math for the north, but I did run a quick calc for London. I would tend to agree with you, the economics just aren’t there.
For interest, there is a relatively accurate, and free, site that you can type in your location and it will pull weather data for the area, add in your basic panel information, in your case about 4kW, accept the other defaults and it will show you generalized monthly solar production numbers. Find it here: http://pvwatts.nrel.gov/pvwatts.php
Typical 25 year guarantees are for power output, and have nothing to do with damage caused by good ol’ mother nature. Good luck getting home insurance on that one!
Thanks Garnet – but that link only seems to cover America.