Solar Panels

[NealebParticipant @nealeb]

An interesting paper but spoiled by them conflating two different variables – panel orientation, and bifacial/monofacial panels. Bifacial panels will outperform monofacial in any orientation, all other things being equal, as they use reflected light reaching the back of the panel (as I understand it). A useful result but nothing to do with orientation.

I do not know what they were comparing their vertical panels with. Their test system was on a flat roof; a typical 35deg or so system would be more prone to weather damage as they say on a flat roof but how does that compare with a typical modern panel setup on a pitched roof?

The thing I found most interesting was that vertical panels make more use of diffuse daylight so better results in winter, for example.

[not done it yetParticipant @notdoneityet]

If you wish to rely on diffuse light, buy multi-crystalline panels.  Cheaper but less efficient than mono-crystalline silicon panels of the same output under the standard lighting conditions to which solar panels are tested.

[Adrian R2]

On Adrian R2 Said:

I was quoted around 20K for an installation some time in the mid 2000s, we did not proceed with it.

Mind you I have probably spent that on grid power since so maybe I should have done.

All these ROI calculations are hard over long periods as they don’t consider what else you could/would have done with the cash meantime. Stuffed under the mattress you are likely better off, properly invested possibly not.

What got me interested in PV’s was a couple of nearby domestic installations around 2008 – 2010, both costing around £11k. Prices dropped at that time so by the time I went ahead in 2012/3.  I saved a few £k.  Perhaps I should have acted sooner to get the higher FIT payment, although still very generous compared with the SEG after 2019(?).

As for ROI, I agree, a difficult thing to calculate if everything is taken into account.   It has worked out okay for me, but not a spectacular return like some of the advertisements for solar panels and batteries might have prospective customers believe.  My initial investment was repaid in less than 9 years, based solely on FIT payments.  Trying to work out what I was actually using while the panels were generating was near impossible.  Happy to accept the 50% FIT estimate.

 

 

[Adrian R2Participant @adrianr2]

In retrospect FIT was very generous (keep quiet if you have still it lest the tax payers revolt) but arguably served its purpose in kick starting the UK solar market. You have reminded me that not wanting to be dependant on a government subsidy was one of the reasons why we didn’t go for it then.

It is good to see increasing amounts solar being installed on new builds now, the marginal extra cost of doing it at construction time should make the ROI much better for owners.

[not done it yetParticipant @notdoneityet]

FIT payments for early adopters were generous – to encourage them.  Those payments, although now lucrative were needed to cover the high initial cost – the usual inflated installation costs due to government ‘carrots’.  There were limited numbers of installers, back then – and many of those were unreliable companies out for a quick profit, then disappear.

The number of early adopters, on generous FIT payments, is a drop in the ocean on today’s electricity costs.

Same as grants towards, EVs and heat pumps.  They kick start the industry – and not a lot more, these days.

[VicParticipant @vic]

We’ve recently received a quote and the estimated payback is 8 years. We selected a more expensive modular AI battery with integrated inverter and the package also included a gateway so we can run off the battery during a power cut. With cheaper/fewer options the payback period would have been somewhat quicker. The supplier also stated that the figures are based on the average increase in energy costs over the past twenty years. Recent rises have been considerably higher and this is expected to continue so this could further reduce the payback period. As I believe I may have mentioned though, our main objective is to reduce our bills including running our new EV.

[Vic]

On Vic Said:

We’ve recently received a quote and the estimated payback is 8 years. We selected a more expensive modular AI battery with integrated inverter and the package also included a gateway so we can run off the battery during a power cut. With cheaper/fewer options the payback period would have been somewhat quicker. The supplier also stated that the figures are based on the average increase in energy costs over the past twenty years. Recent rises have been considerably higher and this is expected to continue so this could further reduce the payback period. As I believe I may have mentioned though, our main objective is to reduce our bills including running our new EV.

What they never include in their payback calculations is the lost earnings on the invested capital during those 8 years. Invested in a conservative index  fund or yhe lke at 10 per cent PA, your invested capital will double in 6.5 years. But if that capital is sitting on your roof, you don’t get that. So it will take a very long time to recoup that lost earnings on your power bills.

 

[NealebParticipant @nealeb]

I think that just about sums up the national situation – there is no financial incentive (in fact the opposite) to move to renewable energy when we can still suck fossil fuels out of the ground and burn it to release CO2 but get cheap energy. Any move to renewables mean investment now for long-term gains – and why should we have to pay when other countries aren’t? And what about those who can’t afford to invest now?

It parallels the situation in which EVs are best suited to town dwellers – less pollution/noise, etc – but are least likely to be able to use cheap home charging, so where’s the incentive?

Bit of a b****r, really…

I’ve voted with my feet. I bought my first EV 6 weeks ago, and the PV panels and battery will be installed in June. Probably won’t see a “payback” in my lifetime on either, but the car is the best I’ve ever owned and I look forward to my electricity company giving me money rather than vice versa. As I heard on the radio recently, you don’t use “payback period” as a criterion when updating your kitchen. But neither renewable move is a one-size-fits-all solution, just one that pleases me.

[IdlerParticipant @idle1]

Yes, I’ve travelled in quite a few EV taxis when abroad and they are very nice and smooth and quiet to drive in. The drivers swear by them for both economy and reliability. For me, an EV would make sense at home because I’ve  never driven my current petrol car more than 20 miles from home in the 11 years I’ve owned it. Thats what motorbikes, trains and planes are for.So an EV could be next.

What I’d really like is a system where I could charge the EV from solar in  the day time, then use the car’s  battery to power the household at night, down to a preselected point to keep x amount of range in the battery for driving the next day. Tesla was talking about this some years ago but I have never seen it actually offered.

[Idler]

On Idler Said:

What they never include in their payback calculations is the lost earnings on the invested capital during those 8 years. Invested in a conservative index  fund or yhe lke at 10 per cent PA, your invested capital will double in 6.5 years. But if that capital is sitting on your roof, you don’t get that. So it will take a very long time to recoup that lost earnings on your power bills.

We spoke about this earlier. Payback on our investments hasn’t been very good. But even if it had been there’s tax to pay on it. I actually think they did include it though. They also mentioned the increase in property value. All in all the figures looked good to us.

 

[Idler]

On Idler Said:

Yes, I’ve travelled in quite a few EV taxis when abroad and they are very nice and smooth and quiet to drive in. The drivers swear by them for both economy and reliability. For me, an EV would make sense at home because I’ve  never driven my current petrol car more than 20 miles from home in the 11 years I’ve owned it. Thats what motorbikes, trains and planes are for.So an EV could be next.

What I’d really like is a system where I could charge the EV from solar in  the day time, then use the car’s  battery to power the household at night, down to a preselected point to keep x amount of range in the battery for driving the next day. Tesla was talking about this some years ago but I have never seen it actually offered.

Our new EV is smooth, quiet, has good handling and is nippy. Once the panels go in it’s going to be very *cheap to run. The Battery we choose has AI and the built in inverter first sends energy to the house, then tops up the battery then the car. You can of course charge the car any time you like though.

*For the naysayers, yes, we could have kept the old car another 20 years 🙄

[Michael GilliganParticipant @michaelgilligan61133]

Interesting stuff, Vic

Please keep the progress-reports coming.

MichaelG.

[NealebParticipant @nealeb]

The PV system I am getting uses the Sigen battery and inverter/control system. That also has “AI” as an operating mode which can, it appears, and with the right mystic incantations and settings of a whole bunch of parameters, do things like optimise charging from the grid at cheap rate, using battery or PV to supply domestic needs, and sell back to the grid. Be interesting to see how it works.

I’m still not convinced that PV has anything to do with EV charging, though, when it’s cheaper to charge overnight (presumably helping mop up a glut of renewable power) and sell PV-generated power back during the day when demand is high. In effect, the supplier is renting your battery capacity to help manage loadings.

The Sigen system is also capable (or so I read) of using vehicle-to-home charging, so that the car battery comes into play. Given that the car battery is an expensive item and possibly less aimed at very frequent charge/discharge cycles than the static battery, I’m not sure about that. Yet, anyway. There are not many cars around that support this mode of operation either. Again, not yet.

Another aspect to explore is the interaction between an AI battery management system and dynamic supply pricing, which I believe might be possible. Even more opportunity to optimise return on investment but at the cost of much more effort needed to set up. Again, this might become the norm one day. The domestic user can be part of the half-hourly electricity wholesale market.

Every so often, I look at the car I am driving and wonder what my father would have made of it. He quite literally could not cope with all the technology in his Morris Minor (he never did find out what the manually-dipping interior mirror could do) so faced with a steering wheel that alone has more controls than the old Minor altogether, and where you log in rather than turn on the ignition… So the PV management possibilities would have been way beyond his ability to cope. I wonder how many people today have the same problem?

[John HaineParticipant @johnhaine32865]

Well my 80 year old brother is on his 4th electric car and third solar PV system and seems to cope. Probably at one extreme but having grown up with the technology does help.

[Martin King 2Participant @martinking2]

Hi all,

I have only just discovered this thread and here is my 2 cents worth!

We have had solar panels now for about 10 or 11 years on our 4 bed detached house which faces just west of south. No shading at all.

The installation with a top end Fronius inverter cost a tad under £10k and we got the index linked FIT payments which started at around 50p if I remember correctly. The deal is for 25 years.

Installation was trouble free and has worked perfectly ever since.

The system payed for itself in about 6 years and as the indexed payments have gone up we are now getting about 78p per unit.

The lowest quarterly check we get is about £250 and in the summer we get about £1100; approx £2.5k per annum.

Works for us! 15 years to go!

We have just added a Hypervolt charger for our VW ID3 and that works well using “Smart” charging on off peak juice.

The actual solar does not make a huge difference to car charging as it is only 4kW max. just tops up a bit on a nice day,

We have thought about a batter like a Powerwall but I cannot seem to make the numbers work at our age?

Cheers, Martin

[Robert Atkinson 2Participant @robertatkinson2]

Since the FIT scheme closed to new installations in 2019 the information is of little value regarding new installations.

[VicParticipant @vic]

We’ve had the Air Conditioning on every day for the past couple of weeks, and still exporting energy to the grid. 😊

[Idler]

On Idler Said:

On Vic Said:

We’ve recently received a quote and the estimated payback is 8 years. We selected a more expensive modular AI battery with integrated inverter and the package also included a gateway so we can run off the battery during a power cut. With cheaper/fewer options the payback period would have been somewhat quicker. The supplier also stated that the figures are based on the average increase in energy costs over the past twenty years. Recent rises have been considerably higher and this is expected to continue so this could further reduce the payback period. As I believe I may have mentioned though, our main objective is to reduce our bills including running our new EV.

What they never include in their payback calculations is the lost earnings on the invested capital during those 8 years. Invested in a conservative index  fund or yhe lke at 10 per cent PA, your invested capital will double in 6.5 years. But if that capital is sitting on your roof, you don’t get that. So it will take a very long time to recoup that lost earnings on your power bills.

 

I would be interested in these conservative index funds as my current Aegon fund is not paying anywhere near 10%, please advise.

Thanks,

Tony

[John HaineParticipant @johnhaine32865]

If your capital is sitting in a bank it is subject to inflation which you have to subtract from the interest.  5 – 7% is probably the best real return you could get.

[An OtherParticipant @another21905]

I installed a solar panel system about 6 years ago because where we live, the local supply was somewhat irregular. As a consequence deriving an income was not relevant, and my main target became getting a ‘useable’ power supply at a reasonable price. The intention wasn’t to supply all our needs, and this eventually came down to supplying some lighting, and running things such as a TV and computer/router. (evenings with no power dragged!).

We have a roof facing SSW, so this was fitted with 4 x 280 W panels. There is no provision for feeding power back into the ‘grid’ where we live, so the panel output is fed to an MPPT controller, which controls the charging of 2 x 150Ah LiFePO4 batteries. Connected across this is a 24DC to 235VAC true sinewave Inverter. Recommended maximum battery discharge current is 100A, so I should have 2.4kW available.

The original inverter I used was capable of 3 kW, so fitted pretty well with this, but the inverter was later changed to a 7kW true sine wave type (because I had one!).

The current load in use is 8 LED light bulbs (say 60 watts), two computer/monitors (total 170 Watts), a TV (125W) and occasionally two electric fans, at around 60 watts the pair, with a few other small items, so a total load of around 500 watts – obviously this load is variable and intermittent depending on whats in use. I also want to add two refrigerators to this load, after I re-design the thermostatic controls for them, (another story) which will add about 150 watts intermittent load. I also soon learned that electric motors can be problematic on solar systems, due to the high inrush current (so my lathe and mill won’t run on it – yet!

Power distribution is via a ‘solar-dedicated’ socket network to make connections, to avoid switching, and allow us to use the solar system independently of the local supply.

I experimented with running an electric kettle on this system (2 kW), but this clearly pushed the batteries to the discharge limits, and I didn’t want to damage them, so this will wait until I can add more battery capacity. Initially I used 4 x 24V 120Ah lead-acid Gel batteries, which were a complete waste of time and money – they lasted 2 years, before they failed to hold a charge (with the correct controller settings) – I suspect this was aggravated by high temperature conditions, but the LiFePO4s seem much better, and have built-in control for all ‘over-driven’ conditions.

Basically the system is simply ticking over during the day, charging batteries, and its main use is in the evenings or overnight. During Summer we usually have more than 10 hours strong sunlight during the day. Nonetheless, this system has cut our electricity bills by approximately 50% – this varies depending on usage, but at least it is a saving – I’m hoping this improves as I add various items to the system.

This obviously has reduced capacity in winter, but so far, over 5 winters, it has supported the basic ‘lights +TV’ successfully, and kept the batteries charged. (They have a 10-year guarantee if used correctly)

Other items remainng in the house using the usual 230V supply are the kettle, a washing machine, a microwave and about another 8 LED lamps – these are all intermittent loads, but the washing machine and kettle are too great a load for the system as it stands. The microwave and more lights will be added to the system when I can get a roundtuit.

I live in Eastern Europe, and all the equipment was sourced online for a total cost around 2300 Euro. My saving is about 50 to 60 Euros a month, so perhaps 4 years to cover the cost.

I appreciate my usage case is really only “daytime charging/night-time load”, but at least we don’t have to sit in darkness (The local electricity supply is not good!). Perhaps this may encourage other users?

Incidentally, from May to October, we have as much free hot water as we can use from a solar water heating system, and free boiling water from a sun-tracking parabolic reflector heating system – it is free – the water comes from our own borehole.

 

[Author]

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