I have solar panels and am thinking about electric heating instead of gas

hentkergareg

This is my first post for ages and I may be in the wrong place for this particular question but here goes! We have 4kw PV solar panels which last year gave us a pay back of nearly £1,900. We have A rated double glazing, cavity wall insulation and loft insulation in a detached 3 bedroom bungalow. We are retired so at home during the day and we also like to be toasty. We wonder whether overall it would be more cost effective to have a wet electric central heating system rather than a gas one bearing in mind the overall costs, ie installation and maintenance. For example, my in-laws live in a modern 2 bed flat (there is no gas) on the second floor with 3 outside walls to the living area, have a wet electric system (Heatrae-Sadia) and their annual running cost is around £800. Their flat has a similar floor area to our bungalow so seems a fair comparison. All advice and opinions welcomed.

Cardew

As you have a 4kWp system, and with a £1,900 return must have had it for 3 years or so, you must be aware of the pattern of generation over the year.


In the season you need heat - say late Sep to early April - you will be aware that the generation on some days can be virtually zero and of course it produces nothing outside daylight hours. So your solar contribution to your winter heating will be minimal.


If you have a hot water tank, and not a combi boiler, then there is some sense in considering a solar diversion device e.g. an Immersun to divert 'spare capacity' to an immersion heater.


But to replace Gas CH with electrical heating would be an extremely bad move.

gazapc

hentkergareg wrote: »

Their flat has a similar floor area to our bungalow so seems a fair comparison.

Two key phrases highlighted. Flats have other heated properties generally above and/or below. Your bungalow will probably have alot more surface area and potentially heat loss.

The problem with PV heating systems is that when you really need it, in the middle of winter PV produces !!!!!! all and buying in standard rate electricity is pretty much the most expensive thing you can do (per kWh) to heat a house. Your PV system will top out at 4 kW max power, your boiler will likely be more like 20 kW + (note power, not energy as this depends on how it has to cycle)

Do look into an immersion diverter, this diverts excess power into your immersion tank, it won't heat your house but will provide you with hot water for much of the year.

I also imagine a cheap option would be to buy a cheap electric radiator and run around turning it of every time you see a cloud appear.

Cardew

It is also pertinent to point out that at present you get payment for an assumed 50% export of generated electricity regardless of how much you use in-house..


It is probable that with the advent of Smart metering you will get paid for what you export. You can get gas around 3.5p/kWh at present, you will lose more than that from your reduced electricity export. i.e. it is better to export it at, say, 4.5p/kWh and buy gas at 3.5p/kWh.

System

If it suits your lifestyle then consider an EV as your next car. I have a 2kWp solar array and, on a sunny day, I just leave the car on a low charge (1.4kWs). Three Hundred miles so far this month and I have used the metered 7kW charger just once - total cost £1.20. Even without a free charge from the roof, my driving costs are about £85 per month less than they were a year ago.

gazapc

I read the £1900 quid as a yearly value, certainly possible if you got the early ~45p/kwh tariff. If I recall the early days had a lower export tariff of around 3p/kwh so a bit cheaper than gas.

macman

£1,900 payback in one year?! Are you sure about that?
Why would you rip out a working gas CH boiler costing about 4p per kWh and replace it with an electric one costing about 12p per kWh? Insanity: they're the single most expensive way of heating a property.
Let alone the capital cost of the new boiler. The maintenance cost of a gas boiler should be the cost of the annual service-around £80 depending on region.

Cardew

macman wrote: »

£1,900 payback in one year?! Are you sure about that?

A 4kWp array can generate around 4,000kWh depending on orientation of panels and location in UK.


Early adopters are now getting around 50p a kWh in FIT and including selling back 50% assumed export, so £2,000pa in subsidy is possible(a subsidy that all electricity consumers pay in increased charges!!)*


Over and above that, the OP can use as much of the 4,000kWh in the house as they can without affecting their payments.


However, as we all agree, the amount of solar generated electricity that could be used during the heating system would be minimal, and never justify ripping out gas CH.


* No criticism is being made of the OP or anyone with solar PV, it is the crazy system that is at fault!

Sledgehead

I get the impression the op is drawing his conclusions re heating capability of his PV arrangement from the FIT of £1,900. Most understand that this figure was intended as a bribe to get people to help the New Labour government fulfill its emissions targets by installing "green" technology. It in no way represents the energy output of these arrays, especially in our high-latitude, cloudy country. So in short, no, this PV array will not heat your place, unless you find a very efficient, cheap, way of storing your summer energy.

I should add that it is a sad reality that the most needy are now paying inflated energy bills because of these ridiculously generous FITs. The OP should think himself lucky that the ire directed at the energy companies has not fallen on those receiving these overly generous FITs. Any move to render such payments realistic would soon result in FIT payments incapable of heating even that flat he refered to.

Sledgehead

Cardew wrote: »

* No criticism is being made of the OP or anyone with solar PV, it is the crazy system that is at fault!

Running for parliament are we? :rotfl:

C'mon, who did he think was gonna pay the extra 40p/ kWh, Santa Claus?