My Solar quote

[Ferdinand]

OK, @scottishjohn

 

Me >> It is possible now that inroof ie not onroof panels will be as inexpensive as as your roof covering, and so a no brainier.

 

Thee >>

14 hours ago, scottishjohn said:

If not fitting tiles then you surely still need a waterproof surface below them of some sort?

not just the membrane ,which if exposed to uv will fall apart very quickly 

you can get concrete tiles down to £10sqm -

please enlighten me how solar panels are going to be same price as roofing ,

i sort of think that if it was ,then everyone would use  a roof that pays for itself 

 

Solar Panels costing less than a normal roof...

Roof coverings are (as you say) £10 per sqm up to about £60 for slates or much more for something premium (eg copper).

 

Area of normal solar panel is approx 1.65m, based on the one I just measured in my garage.

Cost of a solar panel is from (as quoted here for Wagner Renewables the other day) say £95

Cost of a solar panel mounting kit is from £75 per panel (14 panels £1100 see Ebay), all in.

 

And you are (technically) there, once you have taken into account the fitting costs which are cheaper for solar.

 

And much can be done with eg secondhand panels.

 

For most people it will be a help in justifying the cost of solar (save £xxxx on my roofing), but we are well on the way.

 

Ferdinand

 

[scottishjohn]

33 minutes ago, Ferdinand said:

Roof coverings are (as you say) £10 per sqm up to about £60 for slates or much more for something premium (eg copper).

if you want to fit slates @£60 sqm --why you worried about pv 

you got too much money to waste anyway .LOL

tiles that last 100 years+ --waste of money IMHO

[SteamyTea]

2 hours ago, Big Neil said:

i'd rather it directly benefited someone i knew.

I think the problem with that is the high admin overheads.

The smallest units measurable is 1 Wh.  Now imaging that your smart meter has to transmit that data every half hour (or whatever) to your billing company, who then have to bill the nominated recipient if they are capable of using power at the same time.  If not, then it has to go somewhere else (via billing, not physically).  This, even in an automated system, would be costly, if only in computing power.

Now it could be changed that only multiples of 1 kWh, or about 5p worth of electricity, is the minimum trading unit, but how much would you be willing to pay to get the admin sorted out?

Edited May 16, 2019 by SteamyTea

[AliG]

4 hours ago, ProDave said:

Be careful comparing ROI of solar PV with savings interest rates.  They are not comparable.

 

Put your money in a savings account at 5% interest (please tell me where you can get that) and your capital sits there instantly giving you an income .

 

Put your money into solar PV and your capital has gone.  The ROI might be higher but if it takes 10 years just to get your capital back, then it is not much of an "investment" compared to the savings account.

 

Fair point, I should really have done an IRR calculation. If I do this, the IRR on panels with 25 year life, assumed £1000 inverter replacement half way through, 0.5% a year degradation, generating electricity worth 5% of the initial cost per year and 2% electricity inflation is 3.4%.

 

You would need to earn around 4.3% before tax in a savings account to match this (ignoring the £1000 interest tax exemption) but clearly you always have access to your money.

 

Even if you die the panels are still there generating electricity and have a value, just like your house does. But admittedly it isn't easy to realise this.

 

 

 

 

 

 

 

 

[Ed Davies]

5 hours ago, Temp said:

Some suggest the panels are Canadian?

 

Probably from Canadian Solar, main manufacturing in both Canada and China: https://en.wikipedia.org/wiki/Canadian_Solar

 

[gc100]

So, I just got another quote at 4.5K for a 16 panel 305W system which seems pretty good. However I expect they are expecting a normal roof and not a wooden one so not sure how thats gonna work. This is their calculation attached. 

 

[Jeremy Harris]

You can do your own calculation using PVGIS if you wish.  It's probably what some of the PV companies do anyway.  PVGIS is here: http://re.jrc.ec.europa.eu/pvg_tools/en/tools.html#PVP  You just enter your location, the pitch of your roof, the direction the roof faces and the installed peak power of the PV system and it will give you loads of pretty accurate data on performance.

 

Remember that you'll probably struggle to use more than about half the annual output, as periods of high generation aren't likely to coincide with periods when you can use all that generation.  Despite having an electric car, and an all-electric house, with electric hot water storage, I'm lucky if I can use even half our daily generation; much of the time I'm finding that the hot water system is fully charged, and my car is fully charged, by mid-morning, so excess generation is just being exported to the grid from then on.

[scottishjohn]

14 hours ago, JSHarris said:

much of the time I'm finding that the hot water system is fully charged, and my car is fully charged, by mid-morning, so excess generation is just being exported to the grid from then on.

how often do you have to pay to get DHW?

Is it ever in the best 9months of the year or just in worst 3 months?

 

[Jeremy Harris]

3 minutes ago, scottishjohn said:

how often do you have to pay to get DHW?

Is it ever in the best 9months of the year or just in worst 3 months?

 

 

I started monitoring energy use both on the grid power to the water heating and on the solar power to it last November.  At the moment, just over half the hot water energy in that period has come from from excess PV generation, the rest from the grid.  At  guess, I'd say that it seems likely that we will be around 75% PV, 25% grid over the course of a whole year.

[scottishjohn]

1 minute ago, JSHarris said:

 

I started monitoring energy use both on the grid power to the water heating and on the solar power to it last November.  At the moment, just over half the hot water energy in that period has come from from excess PV generation, the rest from the grid.  At  guess, I'd say that it seems likely that we will be around 75% PV, 25% grid over the course of a whole year.

so maybe your dhw storage is too small then  so you could use all of excess pv ?

I,m not being funny and its easy to have hindsight ,

maybe a combination of sun amp and water storage would be a better use of pv ?

[SteamyTea]

If space is not a problem, I still think a large, say 1000 litre, water tank that is heated by any excess energy is the way to go. That preheated water then feeds the usual DHW system. Water is a cheap form of storage.

Edited May 17, 2019 by SteamyTea

[Jeremy Harris]

2 minutes ago, scottishjohn said:

so maybe your dhw storage is too small then  so you could use all of excess pv ?

I,m not being funny and its easy to have hindsight ,

maybe a combination of sun amp and water storage would be a better use of pv ?

 

We store around two to three day's worth of heat for hot water, so about as big as we can reasonably go.  In winter we're lucky to get enough excess PV to charge that.  If we went for a bigger store than we'd probably end up with higher losses, I think, as there's a balance between being able to best utilise excess PV generation and the heat loss.  If we used hot water for storage, rather than the Sunamp, the losses would be higher.

 

The bottom line is that you can't magic up energy that isn't there, and in winter it's not at all unusual to go a week or more with no meaningful excess PV generation.

[ProDave]

2 minutes ago, SteamyTea said:

If space is not a problem, I still think a large, say 1000 litre, water tank that is heated by any excess energy is the way to go.  Water is a cheap form of storage.

Water is a good form of using excess energy, but only the amount of hot water you actually use.  If you heat and store more than you are using, then in reality all you are going is using that energy as space heating (heat losses from the HW tank) which you probably don't want at this time of year.

 

We have a 300L HW tank, sized so in winter when only heating HW to 48 degrees with the heat pump it is large enough.  That is currently getting to about 65 most days with surplus solar PV and most days the HP is not coming on.

 

Jeremy will have more surplus PV than us because he has a larger array, is further south and I don't think he has any shading problems.  Simply heating more water with the surplus would not actually achieve much.  There might be an argument for that with a weather pattern of one sunny day followed by a cloudy day perhaps so you could store 2 days worth of hot water?

[SteamyTea]

2 minutes ago, ProDave said:

There might be an argument for that with a weather pattern of one sunny day followed by a cloudy day perhaps so you could store 2 days worth of hot water?

That is the whole point, it is not a panacea, just small gains.  In effect raising the temperature of the incoming water by 8 to 10°C could make a difference, especially in the shoulder months.

It is basically what dirty wood burner people do, they have a big burn every 2 or 3 days.

[scottishjohn]

I was really thinking back to his problem of sunamp not charging when he wanted it to and so ending up with  cold showers.

that would suggest you are not  storing even a full days hot water?

as for having excess storage that you cannot heat in winter --just don,t try to in winter have a divert valve 

all these thing s going round in my head 

and trying to balance up front cost with actual real advantage of such .

I am suprised you say only 75% of dhw from pv 

I was getting all hot water and some UFH from my solar thermal for that time  on a poorly insulated house,in comparison  to modern ones.

I take on board the heat loss ,which will go to providing space heating ,sometimes when its not needed --solution is windows that open when it s that hot  for scotland +  dress accordingly .

 

 

 

[Jeremy Harris]

40 minutes ago, scottishjohn said:

I was really thinking back to his problem of sunamp not charging when he wanted it to and so ending up with  cold showers.

that would suggest you are not  storing even a full days hot water?

as for having excess storage that you cannot heat in winter --just don,t try to in winter have a divert valve 

all these thing s going round in my head 

and trying to balance up front cost with actual real advantage of such .

I am suprised you say only 75% of dhw from pv 

I was getting all hot water and some UFH from my solar thermal for that time  on a poorly insulated house,in comparison  to modern ones.

I take on board the heat loss ,which will go to providing space heating ,sometimes when its not needed --solution is windows that open when it s that hot  for scotland +  dress accordingly .

 

 

 

 

That's fixed, and the problem was that we were storing a couple of days worth of heat, but the phasing of when the thing would charge and when we were drawing hot water off was skewed badly by the high hysteresis in the firmware in the original control box.  This resulted in us running out of hot water because the thing hadn't taken advantage of a charging time window.  The new controller seems to start to accept charge when about ~20% discharged, I think (early days, still trying to evaluate exactly how it behaves).

 

BTW, to put the hot water cost into perspective, since last November we've used around £36 worth of grid electricity to heat our hot water.  I doubt we'll use much grid electricity for hot water between now and this November, so at a rough guess I'd say our hot water cost might be around £40 a year.  I can live with that, TBH.

[gc100]

Hi @JSHarris,

 

where could I get more information about your hot water /PV setup - I'd like to get my head into the details to see if its still worth the effort of us without the FIT.

 

Looking at that link you shared with a 6K systems we would generate 4010K a year (attached)

 

Many thanks

[scottishjohn]

every time i look at it comes back the same --you must use ALL the pv and then consider what itwould have cost you same as bought in 

 

so 4010kw x 0.16p per unit =£641.6 per year  you save if you had bought it in -

start adding E7  where buy rate is much lower  and not being able to use it all --calculation just gets worse

tell me if i,m wrong 

 

[Jeremy Harris]

1 hour ago, gc100 said:

Hi @JSHarris,

 

where could I get more information about your hot water /PV setup - I'd like to get my head into the details to see if its still worth the effort of us without the FIT.

 

Looking at that link you shared with a 6K systems we would generate 4010K a year (attached)

 

Many thanks

 

Our system has 25 off black PV panels set into the roof using GSE Integration in-roof mounts.  These are rated at 6.25 kWp and feed a 6 kW Aurora Power One inverter.  Because the maximum power is over the 16 A per phase allowable for connection without consent, we had to get consent from the DNO (in our case SSE) to be able to install this system.

 

I have a home made excess PV generation power diverter, that senses when we are exporting electricity and switches a variable amount of power to the water heating system.  The water heating uses a Sunamp UniQ eHW 9, which uses phase change storage to allow up to about 10 kWh of heat to be stored in a small volume (roughly half the volume of a washing machine).  The heating element in this system is very like an immersion heater, with the same power rating.

 

The Sunamp controller determines when the Sunamp heating element can accept power, and the excess PV diverter can then just heat the element as required.  In winter, when we have periods of several days with little or no useful PV generation, I have a boost time switch, which comes on in the early hours, during the E7 off-peak period, to charge the Sunamp if it hasn't been charged during the day.  This ensures we always have hot water, even during cloudy periods.

 

The Sunamp heats the hot water rather like a powerful combi boiler.  It only heats water on demand, as it has an internal heat exchanger that can deliver over 30 kW to the incoming cold, mains pressure, hot water, delivering hot water at around 55°C.  We have a TMV on the output to mix this down with cold water to about 45°C which we find is about right for hot water from the taps etc.

 

Out of interest, here's the PVGIS plot for our 6.25 kW system, which faces SSW and is at 45° roof pitch (it delivers about 6,000 kWh/year):

 

 

 

[gc100]

6 minutes ago, scottishjohn said:

every time i look at it comes back the same --you must use ALL the pv and then consider what itwould have cost you same as bought in 

 

so 4010kw x 0.16p per unit =£641.6 per year  you save if you had bought it in -

start adding E7  where buy rate is much lower  and not being able to use it all --calculation just gets worse

tell me if i,m wrong 

 

 

For use not not all about financial sense - in fact our whole build does'nt really make sense from a financial point of view ! For us the motivation for PV would be climate impact reduction and lower yearly bills (paid upfront by PV install), and just that smug feeling of generating our own power ? .

 

Edited May 17, 2019 by gc100

[gc100]

6 minutes ago, JSHarris said:

 

Our system has 25 off black PV panels set into the roof using GSE Integration in-roof mounts.  These are rated at 6.25 kWp and feed a 6 kW Aurora Power One inverter.  Because the maximum power is over the 16 A per phase allowable for connection without consent, we had to get consent from the DNO (in our case SSE) to be able to install this system.

 

I have a home made excess PV generation power diverter, that senses when we are exporting electricity and switches a variable amount of power to the water heating system.  The water heating uses a Sunamp UniQ eHW 9, which uses phase change storage to allow up to about 10 kWh of heat to be stored in a small volume (roughly half the volume of a washing machine).  The heating element in this system is very like an immersion heater, with the same power rating.

 

The Sunamp controller determines when the Sunamp heating element can accept power, and the excess PV diverter can then just heat the element as required.  In winter, when we have periods of several days with little or no useful PV generation, I have a boost time switch, which comes on in the early hours, during the E7 off-peak period, to charge the Sunamp if it hasn't been charged during the day.  This ensures we always have hot water, even during cloudy periods.

 

The Sunamp heats the hot water rather like a powerful combi boiler.  It only heats water on demand, as it has an internal heat exchanger that can deliver over 30 kW to the incoming cold, mains pressure, hot water, delivering hot water at around 55°C.  We have a TMV on the output to mix this down with cold water to about 45°C which we find is about right for hot water from the taps etc.

 

Thanks thats very interesting. I'll look into this more. Much appreciated.

[scottishjohn]

If micro generation is going to help save the planet ,then it has to make economic sense or it will never be taken up enough to make sod all difference

[gc100]

Not to get into a discussion about saving the planet, but the reason we are in such a mess is because doing the right thing for the planet has never makes economic sense!!

 

It we all tried more, even with a negative economic element it would make a difference. 

[ProDave]

9 minutes ago, gc100 said:

Not to get into a discussion about saving the planet, but the reason we are in such a mess is because doing the right thing for the planet has never makes economic sense!!

 

It we all tried more, even with a negative economic element it would make a difference. 

But you are pushing sand up hill when you get obstacles like increased VAT rates and having to use an over priced MCS install if you want to claim the pittance of export payments that might be on offer at some point.

 

The way I see it, any competent electrician should be able to install solar PV, with help from other trades re mounting the panels,  at minimal cost and then anyone should be able to claim the export payment.

 

It could even be made REALLY simple with no bureaucracy if these new fangled smart meters recorded your export and simply deducted the export (at the wholesale rate) off your bill.  It would be really simple with  no need for separate export payment contracts.

 

Of course when half hourly billing is introduced, the smart meter would be clever enough to pay you a higher wholesale price for that you export at peak times.

 

Until things like that happen, then uptake of renewables is being slowed by unnecessary expense and unnecessary complication.

 

[gc100]

Yes I agreed. Its totally unacceptable the current status.