is PV worth it - 9 panels facing west

[Andrew54]

I'm starting to think a PV system just isn't worth investing in for my roof, considering only 9 panels and the roof faces just 18 degrees south of due west.

Another factor seems to be how much of the electricity generated could be used, rather than sold. I'm thinking of it all ways round, but I can't use much power through the day, especially in summer.

Your thoughts please.

 

[Gavin A]

all depends how much you're getting charged for the system really, and if the money is doing anything useful / needed for something else etc.

 

[Andrew54]

all depends how much you're getting charged for the system really, and if the money is doing anything useful / needed for something else etc.

£5,500 no and no.

 

[FB.]

£5,500 no and no.

That's quite expensive for 2.25kW.

Assuming no shading issues from trees, telegraph poles, other buildings etc, and a normal 30-40 degree roof pitch, I'd expect annual generation around 1900kWh.

That'd be worth around £270 per year from Feed-in-Tariff.
About £40 per year export tariff.
Bill savings, assuming 25% in-house usage: £60.
Total annual benefit: £370.

Even assuming 7-8% annual energy inflation and 3-4% RPI inflation that's 10/11-year payback, which I consider to be too long. More than ten years is too long.

However, Gavin's Leeds Solar (he's got a link in his signature) offer 2kW for £3995 (probably £4500 for 2.5kW) and the payback is a respectable 8-years.
Leeds Solar | PV price comparison

I initially worried about having "cheap" Chinese panels (in my case Kinve) but my system has almost completed a year of perfect, trouble-free operation (and exceeded the SAP estimates). I was also offered Sanyo/Panasonic panels at a 30% higher total cost of the system. I wondered whether I should go with a well-recognised brand, but, given the recent downgrading of Panasonic/Sanyo's credit rating to near-junk, even the premium panels may have nobody backing the guarantee in a few years time. The expensive panels only show a small improvement in performance over the lower-cost panels. Some people reckon no difference at all, since 250Watt is 250Watt - it's just that premium panels pack the same power into a smaller panel.

Gavin's a decent, knowledgable chap. If he's not in your area, I suspect that there are others on here who can easily beat £5500 for 2.25kW.

On the subject of payback - my 3.75kWp system, on the old, higher FiT rate of 45.4p, has a likely payback around five years. A fried of mine has a 21p FiT and their 4kW system has a seven-year payback. So an eight-year-payback is not that bad at current heavily discounted prices (compared to late 2011 and early 2012 when solar cost almost twice as much to buy, and had twice as much FiT payments).

 

[balbecdaze]

I think you could definitely get a better price - what part of the country are you in?

 

[Andrew54]

It's a 45 degree pitch roof.

I'm trying to understand your figures FB.

That'd be worth around £270 per year from Feed-in-Tariff. I understand that bit.
About £40 per year export tariff. What is export tariff please?
Bill savings, assuming 25% in-house usage: £60. 25% in-house usage makes sense, but don't we get paid something for the other 75%?
Total annual benefit: £370.

Read more: http://www.electriciansforums.net/p...worth-9-panels-facing-west.html#ixzz2DAcBe9Av

 

[FB.]

It's a 45 degree pitch roof.

I'm trying to understand your figures FB.

That'd be worth around £270 per year from Feed-in-Tariff. I understand that bit.
About £40 per year export tariff. What is export tariff please?
Bill savings, assuming 25% in-house usage: £60. 25% in-house usage makes sense, but don't we get paid something for the other 75%?

Until smart meters are installed in the next few years, it is assumed that half the power is used in-house, and half goes to the grid.
The export tariff is worth about wholesale rates - around 4.5p - for half of what you generate.

In the long term, a smart meter will allow you to be paid precisely, but until then it's assumed to be 50/50 used in-house/exported to the grid.

 

[Graeme Harrold]

If you have an immersion heater, then add Immersun and boost your savings. If you are out during the day, you will heat your water for free. If you dont have tanked hot water add it at the same time and you should be able to have that work done at 5% VAT too....

 

[Andrew54]

Until smart meters are installed in the next few years, it is assumed that half the power is used in-house, and half goes to the grid.
The export tariff is worth about wholesale rates - around 4.5p - for half of what you generate.

In the long term, a smart meter will allow you to be paid precisely, but until then it's assumed to be 50/50 used in-house/exported to the grid.

Sorry I'm still struggling to understand this bit. If 50/50 is assumed, why did you mention 25%. And why did the outfit quoting mention 100%???? You both gave a figure around £40 for the 'export' but you gave a bill saving of £60, they said bill saving of £250.

My present elec meter is very new, and small, is it still not a smart meter? Thanks again, but a bit more explanation would be good.

 

[gizmo]

Last time I had someone round for this, he opened my eyes a little ! Now what he suggested to me I have is a 4kw array, eight panels on the sw side, eight on the ne side ! I pointed out to him that surely that won't give me the best return, and surely I'm wasting my money on the ne side. His reply was the government is paying me an ASSUMED rate, there fore, it could be pitch black and I'd still get my feed in tariff!

 

[Andrew54]

If you have an immersion heater, then add Immersun and boost your savings. If you are out during the day, you will heat your water for free. If you dont have tanked hot water add it at the same time and you should be able to have that work done at 5% VAT too....

Yes I've read up on immersun but not convinced. First we don't use much hot water and second it seems rather expensive if it doesn't last many years.

 

[balbecdaze]

@ gizmo !!! where to start ...:6:

 

[balbecdaze]

The only assumption is, as FB. says, that 50% of the electricity you generate is exported. FB. was using the 25% usage figure to calculate your electricity bill savings.

Your FiT is paid based on a reading from your generation meter, which shows exactly how much energy you have generated.

 

[FB.]

Sorry I'm still struggling to understand this bit. If 50/50 is assumed, why did you mention 25%. And why did the outfit quoting mention 100%???? You both gave a figure around £40 for the 'export' but you gave a bill saving of £60, they said bill saving of £250.

My present elec meter is very new, and small, is it still not a smart meter? Thanks again, but a bit more explanation would be good.

Only a few houses have smart meters at the moment. While it is theoretically possible that you have one, it is extremely unlikely. I don't know anyone who has a smart meter, nor anyone scheduled for one any time soon.

I'll elaborate a bit on where the gains are coming from.

Inside my house is an electicity meter attached to the solar inverter. It is the same model as is out in my meter box.
This "generation meter" records what the inverter pumps out - sitting between the inverter and my consumer unit (fuse box).
Until smart meters are fitted, the only meter that matters is the generation meter.

If I had just had my array installed, I'd get:

1. Feed-in-Tariff:
14.4p for every unit generated, according to the generation meter. 14.4p x 1900kWh = £273.60.

2.
4.5p for half of all units generated, under the assumption that half was used in-house and half went to the grid. Until smart meters are fitted, this is used as an approximation. When smart meters are fitted it will measure precise two-way flows and if all of your power gets exported you'll get 4.5p x 1900kWh = £85.50, but for the next few years it will be assumed to be 50% export, so you'll get £42.75.

3.
If I generate 1900kWh and use it all, at a value of 12.5p per kWh, that's "worth" £237.50 per year in bill savings.
In reality it is almost impossible to use it all due to either not needing the power, or the variability from minute-to-minute on days with a mixture of sunshine and cloud.
If you think you're not likely to use as much of the power, it is probably fair to assume 25% in-house usage, so that £237.50 of potential gains drops to £59.38 of actual gains if you only manage to use 25% in-house.
So the company assuming that you'll use all the power are being very optimistic. It's almost impossible to do so due to the erratic nature of solar generation.

 

[FB.]

The only assumption is, as FB. says, that 50% of the electricity you generate is exported. FB. was using the 25% usage figure to calculate your electricity bill savings.

Your FiT is paid based on a reading from your generation meter, which shows exactly how much energy you have generated.

Yes, I was using 25% in-house because the opening poster said "....I can't use much power through the day, especially in summer...."

So I thought it would be fair and realistic to assume 25% in-house (if nothing else the fridge will use a few hundred Watts of power on-and-off during daylight hours).

Personally I've been using about half of the power in summer and about three-quarters in winter. But I am at home a lot of the time and can take advantage.

 

[TedM]

Last time I had someone round for this, he opened my eyes a little ! Now what he suggested to me I have is a 4kw array, eight panels on the sw side, eight on the ne side ! I pointed out to him that surely that won't give me the best return, and surely I'm wasting my money on the ne side. His reply was the government is paying me an ASSUMED rate, there fore, it could be pitch black and I'd still get my feed in tariff!

gizmo, I really hope this person you had round was not a PV installer.

The 'assumed' part of the Feed in Tariff is the 50% export. But that is 50% of what your system generates as metered. If your system does not generate anything then you will get paid zero plus 50% of zero.

 

[MicraShed]

I too had a bit of a dilemma regarding the do I or dont I luz £5000 on a 2.5kWp system on a SSW roof....
I did and was amazed at the output and generation during the summer months and moreover the difference it made to the electricity consumption.
Im looking at about £600/year in terms of FiT and money off my energy bills, but a lot depends on the way that you use the generated power for the latter.

Simple changes within the home, putting the wahing machine and dishwasher on only during daylight hours and not at the same time, the same with the electric cooker, switching to cooking more in a slow cooker (130w/hr) making sure that things are "off" rather than on "standby"
This graph shows this year vs last year energy consumption off the Norweb Federation, my PV system went live in July, though we had already made some lifestyle changes in the summer months which seem to be reflected in the June consumption data (LED lighting, smart switches etc).

Prices for PV installs do seem to be coming down, my friend paid £9000 for a similar install 12 months before ours and of course is on the 40-odd pence FiT, we paid £5000 an are on the 21pence FiT, now that the FiT has dropped again I expect the prices to have shrunk a little more.

Re: The Immersun, we have one and whilst this month has been disappointing (see "its dropped off" thread) it makes a blinding difference to hot water generation and I am confident that next summer I will be able to shut off the GCH completely...

 

[Gavin A]

Last time I had someone round for this, he opened my eyes a little ! Now what he suggested to me I have is a 4kw array, eight panels on the sw side, eight on the ne side ! I pointed out to him that surely that won't give me the best return, and surely I'm wasting my money on the ne side. His reply was the government is paying me an ASSUMED rate, there fore, it could be pitch black and I'd still get my feed in tariff!

Please do not even consider buying from this company - this is total garbage.

it can be worth doing ese / wnw splits, but generally only upto around 10-15 degrees off west / east, as the production levels drop off too far beyond that point to usually be sensible, unless you've got massive onsite day time energy consumption.

 

[Worcester]

@FB The Export is DEEMED at 50% (for =< 30kWp) i'ts written in the legislation. Just becuase smart meters COULD read export, there is nothing in the legislation to allow them to change to measured export.for your FiT payment.

 

[Graeme Harrold]

With the immersun, crank the thermostat up higher to increase storage capacity and if required for safety get a thermal balancing valve fitted on the tank outlet.....

 

[Worcester]

Since Installing our Immersun at the end of August we've saved / not exported / diverted / used 539kWh (depending upon what you want to call it)

 

[FB.]

With the immersun, crank the thermostat up higher to increase storage capacity and if required for safety get a thermal balancing valve fitted on the tank outlet.....

Is an Immersun worth it, for 1900kWh per year?
Especially if the water can be heated by gas for half the cost.

Not to mention the possibility of the Immersun not making use of the power because the water may already be hot, or on the numerous days with heavy cloud cover the Immersun may not be able to kick-in much, due to the system not reaching the 100W surplus output threshold.
In reality, I would expect 50% to 75% utilisation from Immersun, with 25% to 50% unable to be used because of the above.

That makes for a several-year payback. Will Immersun prove to be reliable, or will it be just as unreliable as most modern electronics, which have a lifespan of about five years?
A lot can happen in several years - Sharp and Panasonic/Sanyo currently teeter on the edge of administrators taking control due to high debts and low profits or even losses.
Only a few days ago, Panasonic/Sanyo was downgraded to a creditworthiness rating of "junk", and Sharp were similarly downgraded a few weeks ago.

 

[Worcester]

And your PV alone is a MUCH longer payback, if you add in the Immersun it reduces the overall payback time. Especially if as we are - on oil.

For real world results vs gas, see the posts by Brian Wright22 starting around here: PV immersion heater proportional control


​

 

[TedM]

@FB The Export is DEEMED at 50% (for =< 30kWp) i'ts written in the legislation. Just becuase smart meters COULD read export, there is nothing in the legislation to allow them to change to measured export.for your FiT payment.

Actually the legislation says that deeming only applies if there is no registered export meter in use. So if the supplier registers the SmartMeter for export as well as import then the readings from it would have to be used for calculating FiT export payments and the deeming would stop for that particular installation.

I would expect most, if not all, suppliers to register any SmartMeters they install over the coming years for both import and export where there is existing microgeneration on site. Assuming they get their act together and don't fit SmartMeters that are not capable of measuring export - which has already been happening.

 

[Simpsod1]

I too had a bit of a dilemma regarding the do I or dont I luz £5000 on a 2.5kWp system on a SSW roof....
I did and was amazed at the output and generation during the summer months and moreover the difference it made to the electricity consumption.
Im looking at about £600/year in terms of FiT and money off my energy bills, but a lot depends on the way that you use the generated power for the latter.

Simple changes within the home, putting the wahing machine and dishwasher on only during daylight hours and not at the same time, the same with the electric cooker, switching to cooking more in a slow cooker (130w/hr) making sure that things are "off" rather than on "standby"
This graph shows this year vs last year energy consumption off the Norweb Federation, my PV system went live in July, though we had already made some lifestyle changes in the summer months which seem to be reflected in the June consumption data (LED lighting, smart switches etc).

Prices for PV installs do seem to be coming down, my friend paid £9000 for a similar install 12 months before ours and of course is on the 40-odd pence FiT, we paid £5000 an are on the 21pence FiT, now that the FiT has dropped again I expect the prices to have shrunk a little more.

Re: The Immersun, we have one and whilst this month has been disappointing (see "its dropped off" thread) it makes a blinding difference to hot water generation and I am confident that next summer I will be able to shut off the GCH completely...

I had the same dilema but with a east facing roof and £6k on a 3.25kw system - we took the plunge and to be honest have never regretted it.

We are on target to hit 2450KW for our first year earning us £560 in FIT payments, our electric savings will be around £140 per annum (and we already had low energy lighting everywhere - even the cooker hood)

It takes a bit of effort to maximise savings - have washing ready for sunny days etc, but just having the panels promotes a mindset that in itself is a more effiecent one!

 

[Worcester]

@Tedm I'm going to start a new thread on deeming as it could do with discussing in light of your contirbution.

 

[Danlow84]

The best way to know if your going to get a good deal is by having a free roof survey as then they can give you accurate facts and figures so you would know exactly how long your return on investment would be and how much you would be looking to save and make.IF anyone interested in free no obligation roof survey then get in touch.

 

[Danlow84]

Also in regards to panels for hot water then if your wanting any more info in regards with thermo dynamics ill gladly help as unlike a lot of companies we actually provide a panel that runs of atmosphere and doesnt need to go on roof it works 24 hours a day all year long and works in any weather condition and actually works better in the rain so perfect for our climate

 

[Andrew54]

The best way to know if your going to get a good deal is by having a free roof survey as then they can give you accurate facts and figures so you would know exactly how long your return on investment would be and how much you would be looking to save and make.IF anyone interested in free no obligation roof survey then get in touch.

Oh, I'm on with a couple of surveys Danlow, but it's still a tricky decision. They cannot give me accurate figures as to how much of the generated energy I can use myself - it depends on my lifestyle. And they can't accurately predict how many years payback makes sense - will I still be alive in 13 years time????? (I'll be 59 next month).

So please don't lie to me by saying you can produce accurate facts and figures, it comes down to opinions and guesswork.

 

[Andrew54]

Also in regards to panels for hot water then if your wanting any more info in regards with thermo dynamics ill gladly help as unlike a lot of companies we actually provide a panel that runs of atmosphere and doesnt need to go on roof it works 24 hours a day all year long and works in any weather condition and actually works better in the rain so perfect for our climate

"a panel that runs of atmosphere" ?????????????????????????????????????

 

[Danlow84]

I bull you not if they know how much you normally spend on your electric bills and they know what size system best suits you they could and should give you facts and figures to the penny and also the exact time period for your return on investment and dont be put off by your age i know people in there 80s that still buy panel systems.were are you based yourself?also yes the thermodynamics systems we use run off the atmosphere in any temperature down to -15degrees so works all year long to provide people with constant hot water and also only one panel needed.

 

[zeljuga]

Space shutle in black .It ments runs out of Earth atmosphare to infinity.

 

[Danlow84]

I can assure you they run of atmosphere they extract the heat from atmosphere day and night 1panel can provide a family of 4for hot water all year round.check out our website solarstyleuk.com or inbox me for a further chat

 

[FB.]

I bull you not if they know how much you normally spend on your electric bills and they know what size system best suits you they could and should give you facts and figures to the penny and also the exact time period for your return on investment

Exact amounts are not possible - not least because we don't know what the price of electricity will be in five years time, nor do we know what inflation will turn out to be, from which the FiT rats are annually adjusted.
Also my electricty usage habits will change over the years.

We can make a guess, but the further out the guess the more prone to random variation it will be, and, most likely, in 25 years time we can all look back and laugh at just how inaccurate some of the projected rates of return turned out to be.

My post #4 on this topic is probably a realistic and unbiased estimate, based on observations from my solar array and the arrays of many others (I am not in the business of selling solar so I can "tell it like I see it").

 

[Danlow84]

True in regards to rising energy bills but a sap calculation will give you accurate figures at current rates but all it means if energy bills rise again it just means the more money you would save and with the pv panels some people have even noticed them working off moonlight

 

[SolarCity]

True in regards to rising energy bills but a sap calculation will give you accurate figures at current rates but all it means if energy bills rise again it just means the more money you would save and with the pv panels some people have even noticed them working off moonlight

Moonlight? If this is true then I'll eat my own jaw and post a video of it on YouTube.

 

[Danlow84]

It all depends if its a full moon and posistion of moon as pv panels run off light not just sunlight so if moonlight strong enough it works and this isnt a fact we use to sell them this is what we have been told by customers who already have them fitted.

 

[SolarCity]

The only way I can even consider a system running off moonlight is if there was a huge amount of panels on a very small inverter - which would, of course, be pointless.

My offer of self-cannibalism remains.

 

[Danlow84]

Im not saying it works well but it does generate something.but the thermo dynamics do work very well in either day or nite

 

[SolarCity]

I've no doubt some photons are actually reacting with the panels and producing a tiny amount of potential energy but it needs to produce a certain voltage high enough to kick the inverter into life which is surely unlikely in moonlight?

 

[Danlow84]

As i said we dnt mention it in sales pitch its just what we have been told by our existing customers

 

[FB.]

Moonlight? If this is true then I'll eat my own jaw and post a video of it on YouTube.

The sparky who did mine said that especially during the late-2011 rush, he sometimes had to continue working after dark, and that in moonlight there is a trace of electricity flowing from the panels (as you'd expect; any light on the panels counts), but, of course, it's far too little light and electricity to meet the startup requirement for the inverter.

My inverter goes to sleep at dusk and no matter how big or bright the moon, it has never powered-up, nor even flickered its status LED's as it does when the power-up sequence begins at dawn.

 

[SolarCity]

Yeah, and I'd imagine that the difference in terms of light reading between dusk and a nice bright full moon is pretty much colossal.

 

[Danlow84]

The people i spoke to said obviously it wasnt enough to shout about but it generated some electric and then obviously some income from fit

 

[SolarCity]

Fair enough that you don't mention it in your sales pitch but believe me, there are sales people all over the country that will use it in in theirs. And reading about it on a forum like this is all the information they need to back up this claim.

 

[Danlow84]

Well we are a very reputable company and with our surveys we dont send any kind of salesperson we send a qualified surveyor and if it aint guna benefit people we will tell them it wont benefit them

 

[FB.]

The people i spoke to said obviously it wasnt enough to shout about but it generated some electric and then obviously some income from fit

Any generation during moonlight - if any; mine have never powered-up at night - would be so tiny as to not be worthy of factoring into account. More significant would be factoring in the effect of bird poo impairing panel performance during daylight.
So before counting the number of full moons, I'd count the number of sparrows, starlings, blackbirds, doves and pigeons who use your panels to practice their aim when there's no washing on the line.

 

[SolarRoofSols]

The people i spoke to said obviously it wasnt enough to shout about but it generated some electric and then obviously some income from fit

If it aint enough to kick start the inverter then there is nothing going to the generation meter, therefore no fit benefit. be careful about making claims like this without any hard evidence (i.e. seeing it for yourself). If you have seen it yourself, then we want to know what panels and inverter you are using!

 

[Danlow84]

As i said it isnt something we claim as a company its just what our customers have told us in feedback