Solar Panel Guide Discussion

zeupater

Sirlaughalot wrote: »

.... Looking for a good boiler at the moment in anticipation of the winter. The old lady we have owes us nothing and still is ploding on even if it is in an inefficient way. From the quotes we have a new boiler should save us £300 per year so i`m looking at a 5 year payback but is the £300 figure over hyped as well.

SL

Hi

Posted on this recently on another thread related to the Green Deal ....

zeupater wrote: »

Hi Roger

If the average household uses ~16500kWh per year (source - http://www.ofgem.gov.uk/Media/FactSheets/Documents1/domestic energy consump fig FS.pdf ), then raising the conversion efficiency of a 35year old boiler from a realistic ~60%(max) efficiency to somewhere around 90% would save in the region of 5000kWh(30%*16500) per year, which at say 4p/kWh seasonal average would represent annual average savings of around £200(5000*0.04).

Realistically, a boiler exchange should cost no more than £2000, even if there is a substantial amount of work to do (we replaced a substantial floor standing >30kWh boiler with a wall mounted A rated condensing unit a couple of years ago which included modified pipe runs, bypass circuit, brickwork etc. and paid far less than £2k !), therefore, the 'golden rule' should certainly repay over a 10year period as long as the scheme registered installers were not greedy and the scheme finance was low or even interest free ... this is exactly why the scheme is failing, it's not that people don't want to make improvements, it's the scheme design (who'd have thought it !), the expected scheme margins from consumers, coupled with unnecessarily high scheme finance rates .... a 'government supported' enhanced margin to all involved in the supply & finance chains then ...

In summary, both the 'Green Deal' and the 'golden rule' works, but the inherent greed of those tasked with managing the scheme has throttled the scheme .... another case of incompetent public sector employees being driven down a path by a competent private sector driven by vested interests .... the solution then is to sack (yes sack, not promote, move aside or make redundant) the obviously incompetent individuals involved, then tweak and re-launch the scheme based on an aggregated managed contract commercial basis, which includes the finance rates .... it's really astounding that no-one has considered the 'economies of scale' which would apply to a developer should also apply to individual improvements made under this scheme ...

HTH
Z

... if your consumption is around 50% greater than average, then £300 could be in the right ballpark, however, even if you have a house which is larger than average as long as insulation levels are well above average then £300 of savings could be a gross overstatement .... our gas consumption for the past 12months cost under £70 even though the winter was longer than normal .... we did burn about 3.5tonnes (~£225) of logs though ...

HTH
Z

Sirlaughalot

zeupater wrote: »

Hi

Posted on this recently on another thread related to the Green Deal ....



... if your consumption is around 50% greater than average, then £300 could be in the right ballpark, however, even if you have a house which is larger than average as long as insulation levels are well above average then £300 of savings could be a gross overstatement .... our gas consumption for the past 12months cost under £70 even though the winter was longer than normal .... we did burn about 3.5tonnes (~£225) of logs though ...

HTH
Z

Thanks Z,

Last years gas consumption for our home was 21300 KWh . We can replace our heating only boiler gas fitted for around £1500 so it may be worth our while to replace her now was prices are cheaper!

SL

zeupater

Sirlaughalot wrote: »

Thanks Z,

Last years gas consumption for our home was 21300 KWh . We can replace our heating only boiler gas fitted for around £1500 so it may be worth our while to replace her now was prices are cheaper!

SL

Hi

You've probably already thought of this, but in case you haven't ... don't make the mistake of justifying the cost of the more efficient boiler based on poorly insulated fuel savings then justify the cost of insulation later - do it the other way around or together - after all, insulation will be cheaper and have no running cost ....

The cheapest energy you'll ever find is the energy you don't need to use !! ....

HTH
Z

Cardew

zeupater wrote: »

Hi

Posted on this recently on another thread related to the Green Deal ....



... if your consumption is around 50% greater than average, then £300 could be in the right ballpark, however, even if you have a house which is larger than average as long as insulation levels are well above average then £300 of savings could be a gross overstatement .... our gas consumption for the past 12months cost under £70 even though the winter was longer than normal .... we did burn about 3.5tonnes (~£225) of logs though ...

HTH
Z

I don't dispute your figures using both ends of the 'efficiency sprectrum'(i.e. 60% for the 35 year old boiler and 90% for new)

However IMO those efficiency figures are atypical. A 20 year old boiler(still old) might have a figure of 75% and a new condensing boiler will rarely achieve 90% overall.

There has been much discussion about this in other parts of MSE and I posted this:

The Royal Institution of Chartered Surveyors stated recently
:

The average cost of installing one of these modern boilers is £1,720, but saves on average just £95 off people's gas bills."
See:

http://www.telegraph.co.uk/news/ukne...erts-warn.html

Also the old non-condensing boilers tend to be totally reliable; mine in 25 years has needed a thermocouple, and plenty of other posters state similar.

This just isn't true of modern condensing boilers stuffed full of electronics, and a printed circuit board can cost £hundreds. My plumber was telling me that a board went on his own boiler, and even at trade prices it cost over £200.

zeupater

Cardew wrote: »

I don't dispute your figures using both ends of the 'efficiency sprectrum'(i.e. 60% for the 35 year old boiler and 90% for new)

However IMO those efficiency figures are atypical. A 20 year old boiler(still old) might have a figure of 75% and a new condensing boiler will rarely achieve 90% overall.

There has been much discussion about this in other parts of MSE and I posted this:



Also the old non-condensing boilers tend to be totally reliable; mine in 25 years has needed a thermocouple, and plenty of other posters state similar.

This just isn't true of modern condensing boilers stuffed full of electronics, and a printed circuit board can cost £hundreds. My plumber was telling me that a board went on his own boiler, and even at trade prices it cost over £200.

Hi Cardew

Ours was almost 30 years old when changed and starting to show her age a little, the main reason for change being the use of more energy per day just to keep the pilot light running (needed to be set quite high because of open, windy aspect blowing it out quite often) than our daily hot water requirement. ... although the nameplate and instructions detailed the efficiency (kW.t out/kW in) it was when running and didn't include the pilot light, which is likely the case for most ... In our case, Summer efficiency would therefore be closer to 33% than 60% or 70% - and don't forget that our heating season is shorter than most due to the high levels of insulation ...

When changed, although the system had fern0x in it and had been flushed through a couple of times over the years there was still loads of sludge in the heat exchanger, so I'd guess that, even when running, the efficiency was nowhere near what it was when originally installed ....

HTH
Z

Cardew

Hi Z,

With an annual gas expenditure of under £70, the economics of getting a new boiler, regardless of the old boiler efficiency, must be questionable;)

However I was just making a general point on the 'retain old boiler or replace' debate'.

Sirlaughalot

Are there any smart devices like immersun that can divert solar energy produced to specific devices?

Thanks in advance

Martyn1981

Sirlaughalot wrote: »

Are there any smart devices like immersun that can divert solar energy produced to specific devices?

Thanks in advance

You might get replies here, but if not, ask on the generation thread. I think Oscargrouch, Eric Mears and K66 (and others) may be able to help.

The 'intelligent switches' can usually have a secondary device, for when the water tank is full (hot). But most devices won't operate under a variable power supply like an immersion heater.

For 'other' devices Oscar (and others) use opti-plugs or similar, these devices monitor export and you programme each plug for an amount of Watts (I think). So if a device needs 400W, the system monitors export till there is 400W excess, then switches on that plug. You can have several plugs, all with their own limits, and set in an order to switch them on as and when 'spare' power reaches each necessary point.

As you've mentioned before, a blunter tool, is simply to use timer devices, or timers on white goods, and set them to switch on when the weather forecast says the sun will come out (yeah right!)

Mart.

Sirlaughalot

Martyn1981 wrote: »

You might get replies here, but if not, ask on the generation thread. I think Oscargrouch, Eric Mears and K66 (and others) may be able to help.

The 'intelligent switches' can usually have a secondary device, for when the water tank is full (hot). But most devices won't operate under a variable power supply like an immersion heater.

For 'other' devices Oscar (and others) use opti-plugs or similar, these devices monitor export and you programme each plug for an amount of Watts (I think). So if a device needs 400W, the system monitors export till there is 400W excess, then switches on that plug. You can have several plugs, all with their own limits, and set in an order to switch them on as and when 'spare' power reaches each necessary point.

As you've mentioned before, a blunter tool, is simply to use timer devices, or timers on white goods, and set them to switch on when the weather forecast says the sun will come out (yeah right!)

Mart.

Thank`s Mart,

At the risk of probably repeating myself would these other devices be made virtually redundant by the introduction of smart meters?

SL

Martyn1981

Sirlaughalot wrote: »

Thank`s Mart,

At the risk of probably repeating myself would these other devices be made virtually redundant by the introduction of smart meters?

SL

Ooh! That's a tricky question. For myself and anyone with a pre - Aug12 tariff it's an easier decision as the export rate is 3.3p, so it's possible to save money, whereas for installs post Aug12 the export is a much more realistic 4.64p, which is awfully close to gas savings. Don't feel sorry for us, the FIT tariff is much higher and reflects the lower export.

I'm trying to think of uses, for such switches. When our house is coldish, but not quite enough to put the heating back on, I try to maintain temp in two rooms using small leccy heaters 400W + 240W, they don't make a lot of difference, but help keep the chill off. For something like that a simple 'intelligent switch' (one that doesn't modulate the power) would work well. But for you the lost export (post metered export if it ever arrives) would negate most of the savings, though my thoughts are that a small amount of heat in a couple of rooms, is possibly better than running the GCH through the house, even with TRV's on all rads. Not sure I can back that up, just a gut feeling.

Another problem, would be for devices like washing machines and dishwashers etc, since once on, you won't really want them to stop when a cloud comes over. Perhaps the switches or some switches also have 'on only' modes, so they wait for generation to reach a critical point, then just stay on - I don't know(?)

Quick question, a few posts back you said that you had a heating only boiler. How is your water heated, is it by another boiler, or via an immersion?

Mart.