Author Topic: The cost-effectiveness of solar panels  (Read 8753 times)

Wowbagger

  • Sylph
    • Musings of a Gentleman Cyclist
The cost-effectiveness of solar panels
« on: 02 March, 2017, 01:11:11 pm »
I have been thinking about getting pv panels on my roof. Our energy bills are eye-watering - a big house with a 98-year-old occupant takes a lot of heating in the winter. I thought that anything we can do to reduce our bills would be a good idea.

I had an estimate from Solar Century, who work with Ikea. I think they are reputable, but I asked a local man to give me another estimate for comparison purposes. I'm still waiting for him, but the SC estimate was for a bank of panels to be fitted to the eastern side of our roof. The ridge runs NNW-SSE, so those panels would be pointing a few degrees N of E - not ideal. The roof has quite a shallow pitch, so that wouldn't be a problem in the summer. The other side has a chimney which would cast a shadow over the panels for much of the afternoon so I assume that is why they have ruled that out.

In a nutshell, I don't think the returns justify the expense. Their estimate if for about £5800 with an estimated annual return (based on a who load of variables like government capping which they are in no position to predict) of 3.86%. That means that I would be in my late 80s before it had paid for itself, if I or it haven't conked out first.

I think if such a scheme were viable we would be amongst the households who would likely to benefit most: we run two electric cars and cover about 19000 miles a year. That's approximately 50 miles per day, or about £1.25 in electricity costs (in reality, less, as we don't do all our charging at home). I can't see us maintaining that sort of mileage for much longer - a good chunk is dedicated to looking after grandchildren and in a couple of years I expect that to reduce dramatically.

So we have decided not to go ahead with the installation. We already buy our gas and leccy from Ecotricity, who claim that everything they supply is 100% renewable. That means that a bank of solar panels on our roof would do nothing to aid the environment and little to reduce our bills. I wonder then - if we can't justify solar panels, who can?
Bach without a doubt.

Kim

  • Timelord
Re: The cost-effectiveness of solar panels
« Reply #1 on: 02 March, 2017, 01:31:55 pm »
How much of that changes given a more optimally oriented roof?

Do you have scope for more insulation?  That might be a better investment...
Careful, Kim. Your sarcasm's showing...

Re: The cost-effectiveness of solar panels
« Reply #2 on: 02 March, 2017, 01:35:12 pm »
- if we can't justify solar panels, who can?
People with large, south-sloping roofs.

Orientation makes a *massive* difference (this statement is based on living on a boat where I recharged my battery from a PV panel).
<i>Marmite slave</i>

nicknack

  • Hornblower
Re: The cost-effectiveness of solar panels
« Reply #3 on: 02 March, 2017, 01:40:37 pm »
- if we can't justify solar panels, who can?
People with large, south-sloping roofs.
That would be us then.
We got ours about 3 years ago and I reckon they'll be paid for in another 2 or 3 years.
There's no vibrations, but wait.

Dibdib

  • Fat'n'slow
Re: The cost-effectiveness of solar panels
« Reply #4 on: 02 March, 2017, 01:47:13 pm »
I've no idea about solar panel efficiency, but

So we have decided not to go ahead with the installation. We already buy our gas and leccy from Ecotricity, who claim that everything they supply is 100% renewable. That means that a bank of solar panels on our roof would do nothing to aid the environment and little to reduce our bills. I wonder then - if we can't justify solar panels, who can?
(emphasis mine)

Even if all of Ecotricity's generation is renewable, you feeding a little extra renewable energy into the grid - or, if you're storing it to use yourself, sucking out a little less - would still increase the renewable:non-renewable ratio for everyone else. A tiny, probably just token, difference but a difference all the same.

Unfortunately as you say, whether it makes financial sense is another question.

Re: The cost-effectiveness of solar panels
« Reply #5 on: 02 March, 2017, 02:01:19 pm »
We know a few people with pv.   The key is to have a south facing roof within 15 to 20 degrees of south.   The efficiency of the newer panels is improving but it will be a few iterations yet before we can justify a few panels on the ESE side. of our NNE ridge.   People we know will have paid for their installations in terms of reduced bills as well as feed in in less than a decade.   A very reasonable return if you ask me.

I'm looking into installing a home storage battery in the next year or so to charge overnight on cheap rate and then to run the house on it during the day.   Our daily usage easily allows for this except in extreme circumstances.   We already do our laundry overnight to save on unnecessary expenditure.

We are a low consumption household but I will install pv if and when they become viable.

Re: The cost-effectiveness of solar panels
« Reply #6 on: 02 March, 2017, 02:03:44 pm »
- if we can't justify solar panels, who can?
People with large, south-sloping roofs.

Orientation makes a *massive* difference (this statement is based on living on a boat where I recharged my battery from a PV panel).
Exactly. My roof is, to my regret, unsuitable. The only part where the extra weight wouldn't be an issue (according to the builder who renovated & insulated the dormer, taking care to keep down the added weight) faces ENE & is partly shaded by chimneys.

If I look out of a window on that side of the house I see a row of WSW-facing, bigger, unshaded roofs, some of which have solar panels, currently in full sun. None of the houses in that row have solar panels on the other side. I wonder why?
"A woman on a bicycle has all the world before her where to choose; she can go where she will, no man hindering." The Type-Writer Girl, 1897

Dibdib

  • Fat'n'slow
Re: The cost-effectiveness of solar panels
« Reply #7 on: 02 March, 2017, 02:09:13 pm »
I'm looking into installing a home storage battery in the next year or so to charge overnight on cheap rate and then to run the house on it during the day.   Our daily usage easily allows for this except in extreme circumstances.   We already do our laundry overnight to save on unnecessary expenditure.

It'll be interesting to see how you get on with that, and how conversion/storage losses and other inefficiencies balance against the lower rate at night. Either way, it'll be (FSVO) more environmentally friendly, as so much of the overnight baseload power is from nukes rather than gas.

Wowbagger

  • Sylph
    • Musings of a Gentleman Cyclist
Re: The cost-effectiveness of solar panels
« Reply #8 on: 02 March, 2017, 02:44:39 pm »
How much of that changes given a more optimally oriented roof?

Do you have scope for more insulation?  That might be a better investment...

I think the roofing issue is one that has been adequately covered by others.

Yes, I think we could insulate our house better. I think there's a case for triple glazing as we live beside a very busy road, albeit on in which the traffic is usually slow-moving. The loft doesn't have as much insulation as is recommended, but I like to be able to walk across it whilst still being able to see the rafters. In the past, we have had snow on the roof for longer than many nearby houses, and one year the ball-valve on the cold water tank froze. I had to leave the hatch open a fraction of an inch to allow warm air to thaw it!

We have had the outside-facing walls of one room lined with insulating plaster board. I think that has been very effective and I would like to do other rooms, but the waiting time for our "good" builder is quite a few weeks. We want to do a lot more of the house like this. These boards keep out the damp as well as the cold.
Bach without a doubt.

Kim

  • Timelord
Re: The cost-effectiveness of solar panels
« Reply #9 on: 02 March, 2017, 02:48:25 pm »
one year the ball-valve on the cold water tank froze. I had to leave the hatch open a fraction of an inch to allow warm air to thaw it!

Standard solution to that is no insulation under the tank, and plenty above and around it.  Has the bonus side effect of keeping the dead pigeons out.
Careful, Kim. Your sarcasm's showing...

Re: The cost-effectiveness of solar panels
« Reply #10 on: 02 March, 2017, 03:16:23 pm »
I installed a DIY thermal system in 2009 when I took early retirement and within 6 months I was so impressed with the output that I invested in PV. I was told that I would recover the cost of installation in 8/9 years and the final yield on the investment was predicted at 14%. I reckon I'll break even next year and then have about £1250 p.a. income from them untill they're 25 yrs old (payments are indexed linked).

Have a look at http://www.navitron.org.uk/forum/ where there seems to be lots of knowledgeable people some of which have EV's, and you will get an idea of the going rate for instalation, and maybe a chance to visit a local instalation.  Are you sure about Ikea? http://www.theguardian.com/environment/2016/feb/08/ikea-quietly-stops-selling-solar-panels-to-uk-householders
One thing to consider is how long you will live and don't forget to put it in your will!

Re: The cost-effectiveness of solar panels
« Reply #11 on: 02 March, 2017, 03:19:31 pm »
We have two types of internal insulation and they both work very well and I would recommend either.

The first is the insulated plasterboard that Wow speaks of.   We have that in two rooms and the change, especially in the bedroom that has been converted to a bathroom is very impressive indeed.

The second is multi layer foil.   Basically we have a two product installation which has an outer multi layer foil and foam blanket which is set against the brick or plasterwork and has a built in vapour barrier, held in place with 3x2 stud type framework which has the second product which is honeycombed foil and foam, again with a vapour barrier, laid between the studs and drywalled over.  This is proving to be extremely effective too.   

I would recommend either.

I'm looking into installing a home storage battery in the next year or so to charge overnight on cheap rate and then to run the house on it during the day.   Our daily usage easily allows for this except in extreme circumstances.   We already do our laundry overnight to save on unnecessary expenditure.

It'll be interesting to see how you get on with that, and how conversion/storage losses and other inefficiencies balance against the lower rate at night. Either way, it'll be (FSVO) more environmentally friendly, as so much of the overnight baseload power is from nukes rather than gas.
 
At the moment we buy our electricity from Good Energy so we should not be buying nuclear directly.   I appreciate that it is all mixed together.   :)   We have a dual rate tariff which doesn't seem to be listed now.

 

Wowbagger

  • Sylph
    • Musings of a Gentleman Cyclist
Re: The cost-effectiveness of solar panels
« Reply #12 on: 02 March, 2017, 03:20:55 pm »
- if we can't justify solar panels, who can?
People with large, south-sloping roofs.
That would be us then.
We got ours about 3 years ago and I reckon they'll be paid for in another 2 or 3 years.

Can I ask - what was the feed-in tariff set at for you?

This is from our estimate:

Quote
This system performance calculation has been undertaken using estimated values for array orientation, inclination and shading. Actual performance may be significantly lower or higher if the characteristics of the installed system vary from the estimated values.

We have estimated some of the factors that affect this quote. We will carry out a full on-site survey at your home before installation commences.

Your total annual return is calculated by combining:
• the income you receive from the Feed-inTariff* made up of:
– the generation tariff - you earn a fixed income for
every unit of electricity your solar generates – the export tariff - you earn an additional fixed
income for every unit of electricity you sell back to the grid - deemed at 50% of generation
• the savings you make on your electricity bill.We have estimated that 41% of the generated electricity is consumed**.

Our feed-in tariff is estimated at 4.91p.
Bach without a doubt.

Re: The cost-effectiveness of solar panels
« Reply #13 on: 02 March, 2017, 03:22:06 pm »
That's the current rate.   It has been far more generous in the past.   

Re: The cost-effectiveness of solar panels
« Reply #14 on: 02 March, 2017, 03:34:59 pm »
Mine is now a little ove 50p/kw!!!!!!!!!!!!!!  But instalation prices have dropped dramatically and for a long time 8 yrs remained the normal payback time.
- if we can't justify solar panels, who can?
People with large, south-sloping roofs.
That would be us then.
We got ours about 3 years ago and I reckon they'll be paid for in another 2 or 3 years.

Can I ask - what was the feed-in tariff set at for you?

This is from our estimate:

Quote
This system performance calculation has been undertaken using estimated values for array orientation, inclination and shading. Actual performance may be significantly lower or higher if the characteristics of the installed system vary from the estimated values.

We have estimated some of the factors that affect this quote. We will carry out a full on-site survey at your home before installation commences.

Your total annual return is calculated by combining:
• the income you receive from the Feed-inTariff* made up of:
– the generation tariff - you earn a fixed income for
every unit of electricity your solar generates – the export tariff - you earn an additional fixed
income for every unit of electricity you sell back to the grid - deemed at 50% of generation
• the savings you make on your electricity bill.We have estimated that 41% of the generated electricity is consumed**.

Our feed-in tariff is estimated at 4.91p.

Wowbagger

  • Sylph
    • Musings of a Gentleman Cyclist
Re: The cost-effectiveness of solar panels
« Reply #15 on: 02 March, 2017, 03:54:25 pm »
Given that we pay Ecotricity 13.6p for every kwh we consume, 4.91p is niggardly, to say the least. There was also this on the estimate:

Quote
Every quarter, the government will cap the number of installations that qualify for the Feed-in Tariff. If the cap is reached, your system will be placed in a queue for the following quarter’s tariff. If this happens, your annual return will be lower. We will keep you updated on how much has been used up during any given quarter. We cannot guarantee the tariff you will receive.
Bach without a doubt.

Re: The cost-effectiveness of solar panels
« Reply #16 on: 02 March, 2017, 04:00:46 pm »
When the feed in tariff was at its most generous firms were bleeding the public for all they could get in terms of cost of new installations. These capital costs have now plummeted in line with the reduction in the tariff. Don't forget to factor in a new inverter every 15 years or so and the cost of cleaning the panels. Also keep an eye out or nearby trees. It is something I will still consider doing in the future perhaps when re-roofing.
Get a bicycle. You will never regret it, if you live- Mark Twain

nicknack

  • Hornblower
Re: The cost-effectiveness of solar panels
« Reply #17 on: 02 March, 2017, 04:04:18 pm »
- if we can't justify solar panels, who can?
People with large, south-sloping roofs.
That would be us then.
We got ours about 3 years ago and I reckon they'll be paid for in another 2 or 3 years.

Can I ask - what was the feed-in tariff set at for you?


Our generation tariff is 15.32p
Our export tariff is 4.91p
There's no vibrations, but wait.

hellymedic

  • Just do it!
Re: The cost-effectiveness of solar panels
« Reply #18 on: 02 March, 2017, 04:56:48 pm »
I think Quisling has posted positively about solar panels previously.

Re: The cost-effectiveness of solar panels
« Reply #19 on: 02 March, 2017, 05:05:13 pm »
Our roof is basically E-W. We got solar panels installed (8 on the slightly south facing side, 7 on the other) in October. The Generation tariff is 14.something and the export is 4.something. It cost just over 6 grand (our house is 3 storeys, so we needed extra scaffolding).
We have a website that we can see how much power we have generated today/last 30 days/forever. It's at a total of 299kWh, but it's been much better (106kWh) over the last 30 days - I think it's just longer days and some sunshine that's driven it up. We use an iBoost to divert electricity into our immersion heater, and since we've had the system we've rarely had to turn on the hot water at all - I hope that in the summer the gas boiler will stay off for weeks or even months at a time.
The total repayment time if you believe the salespeople is just over 7 years - I think it will be the other side of 8, but the FIT is for 20 years, and the panels have a 25 year guarantee (though the inverter guarantee is only 12 years they are only £600 or so), so a few months here or there makes little difference. It has also inspired me to seriously think about an electric car.

Battery storage systems to store electricity generated from PV systems are nowhere near economically viable right now though IMO.
 

Wowbagger

  • Sylph
    • Musings of a Gentleman Cyclist
Re: The cost-effectiveness of solar panels
« Reply #20 on: 02 March, 2017, 05:53:13 pm »
- if we can't justify solar panels, who can?
People with large, south-sloping roofs.
That would be us then.
We got ours about 3 years ago and I reckon they'll be paid for in another 2 or 3 years.

Can I ask - what was the feed-in tariff set at for you?


Our generation tariff is 15.32p
Our export tariff is 4.91p

We have been offered 4.11p & 4.91p. Those figures are valid to 03/2017. Is the government planning to scrap them all together? Their policies seem to be designed to prevent people taking up renewables.
Bach without a doubt.

Aunt Maud

  • Le Flâneur.
Re: The cost-effectiveness of solar panels
« Reply #21 on: 02 March, 2017, 06:14:06 pm »
If you have a decent sized garden, a ground source heat system might be worth looking into.

caerau

  • SR x 3 - PBP fail but 1090 km - hey - not too bad
Re: The cost-effectiveness of solar panels
« Reply #22 on: 02 March, 2017, 06:15:50 pm »
Without the feed in tariff they're not cost effective at all, for anyone, pretty much under any circumstances (from what I heard at a conference about solar cells by experts on making solar cells).  They said themselves that to be viable as an industry they really must be independent of state subsidy.  Though this was an academic conference, they may sing a different tune elsewhere.


With the feed-in tariff they're great for my mother who loves hers - though I'm not sure she's really broken even, she's mostly just being an eco-warrior I think.  If you can get one of those contracts where you don't actually have to pay for them, you just lease your roof space then personally that's what I'd do.
I tried to in fact, but it turned out I had a 'difficult lender' so *they* gave up on us.
I'm soon moving my mortgage to another lender so I may try again...

It's a reverse Elvis thing.

Kim

  • Timelord
Re: The cost-effectiveness of solar panels
« Reply #23 on: 02 March, 2017, 06:16:12 pm »
If you have a decent sized garden, a ground source heat system might be worth looking into.

Or you could cover it in south-facing solar panels....
Careful, Kim. Your sarcasm's showing...

Aunt Maud

  • Le Flâneur.
Re: The cost-effectiveness of solar panels
« Reply #24 on: 02 March, 2017, 06:22:16 pm »
You could set them in a parabola to concentrate the suns rays, so you can get a nice tan or cook chicken, if chicken's your thing.