Yawn- an energy efficiency, CHP/Air Source/Solar PV question

[Blue Oval84]

Hi all,

Was wondering if anyone could advise about ways to reduce the folk's bills.

The house is pretty big, built in the late 90's, very high quality double glazing, cavity walls filled, loft insulated etc. The boiler however is original.

Combined Heat and Power Boiler - Has anyone got one or seen how effective they really are in real life?

The Baxi website suggests that it produces 6KW of heat, but when demand is increased it goes up to 18KW. This has me confused as the current boiler has a wall mounted thermostat which switches it on or off. This two stage heat thing that Baxi talk about seems to suggest that the boiler is designed to run for longer but at a lower output? This would make sense seeing as from what I can tell it only generates electricity when it's running.

Also, daft question, do they work in a powercut? It would be pretty good to be the only ones in the street who's lights don't go out in a powercut

Solar Photovoltaic - How much do these cost to install, roughly? The Feed In Tariff is very attractive but I have a feeling that it will take years and years to pay back.

Air Source Heat Pump - These seem pretty clever, but onsidering that they cost several thousand to install, might we see bigger savings from the CHP gas boiler instead?

Any other ideas? - Anyone got any other bright ideas about how to get the consumption down? They're currently running at 35,000 KWh of gas per annum and about 6,500 KWh of electricity.

Oh, and in case anyone suggests low energy bulbs, don't bother, they don't like them, only the exterior lighting up the boundary is low energy (as it gets left on all night lol)

[Blue Oval84]

In answer to one of my own questions, CHP boilers don't seem to be much good based on my research.

However, I've done some digging into Air Source heat and it's very interesting, looks quite efficient and could negate the need for the folks to have gas at all (they're on IGT so their gas is not cheap to begin with) Apparently the Feed In Tariff applies to these heaters and pays you 7p per KWh for 18 years. I can't seem to find how this is measured?

Also - what are people's thoughts on this "Reverse Robin Hood" Feed In Tariff policy of using money from everyone's energy bills to pay cash incentives to people who can afford to spend tens of thousands on technology like Solar and Air Source?

I can't afford to fit solar on my house (not that I'm particularly interested as my bills are tiny) but I do find it a little annoying that my bills are going up to help pay money towards those that CAN afford it!

Surely the technology should stand or fall on it's own efficiency rather than been so heavily subsidised by the public?

[caziques]

I doubt very much a CHP will make sense, even if it is 100% efficient you will be generating electricity from gas - while this is probably a lower cost - the electric consumption is only 6500kW hrs a year.

Therefore the gas consumption will go up but the overall cost may come down slightly.

The only device that uses less energy than it puts out is a heat pump, which can be up to 500% efficient.

However a heat pump may not save any money, as the cost of electricity per kwhr is a lot more than gas in the UK - and the overall efficiency of a heat pump depends on all sorts of factors.

Simply fitting a heat pump in place of a conventional boiler won't work.

Will try and write later - business to attend to.

[Blue Oval84]

Thank you for any help you can offer!

I think it's the Feed In Tariff element of the Heat Pumps that interests (and shocks!) me the most. It appears that it may make the pump a much more efficient option for approx 18 years, after which it will have paid for itself in theory!