Average Energy Consumption

Ah, that makes sense

Yes, I had an air to air heat pump, otherwise known as reversible air conditioning, installed seven years ago. It is a dual split unit with a maximum heating output of 5.4 kW. Living considerably south of Inverness the cooling is essential in summer. COP for heating is about 5 at outside temperature above +7 C but drops to about 3 below -7 C as a result of the defrost cycle. With the prevailing wind coming off a mountain range over 2000 m elevation I expected to have to use our wood burner for supplementary heat but it hasn't been used for years.

I would expect more recent models to be yet more efficient.

Russell

Turning to the other side of the coin … I now have a reasonable ‘feel’ for what my modest electricity requirements might be, and it looks like an adequate solar array would fit on the new roof … so I had a look at this [which is what has replaced the Feed In Tariff] : **LINK**

https://www.shellenergy.co.uk/info/terms/smart-export-guarantee/tariff-guide

at 3.5 pence per kWh, paid annually; it seems that there might be better ways to dispose of any surplus electricity produced … perhaps a nice little electro-forming tank for making stuff ?

Does the team have any better ideas ?

MichaelG.

Michael,

All the people that I spoke to about solar PV were agreed on one thing - that I should switch to Octopus once the system is installed as they pay a lot more per kWh for export (and can offer a low overnight price to top up the storage battery in Winter). I haven't done so yet as there are a couple of things to resolve with current supplier.

You do get best value by using the PV generated energy yourself, as it is then backing out full price imports.

The SEG is something the suppliers are forced to do, so is generally at a minimal per unit price.

A further complication that you may not be aware of - even if you have a smart meter which can measure the exports, you won't get paid for any until a new MPAN is assigned, your existing reference number it seems is just for consuming, not for supply! I've now been providing free electricity into the system for several weeks.

With any potential change of supplier - check unit costs and standing charges in relation to your own circumstance.

Thanks for that, David

MichaelG.

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Ref. https://octopus.energy/smart/outgoing/

Edited By Michael Gilligan on 30/09/2023 08:45:04

Hi, How much does all this electricity saving kit (panels,batteries,etc) cost and how much is saved per year ?

Maurice

Just a small point - Michael references Shell Energy, David recommends swapping to Octopus. Apparently Octopus are going to take over Shell Energy in the not too distant future, so I don't know if that will have any effect on their respective feed-in rates.

Rob

Very interesting, and encouraging, Rob … provided the rates move in the right direction.

MichaelG.

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Ref. https://octopus.energy/shell/

Edited By Michael Gilligan on 30/09/2023 12:38:29

Cost very much depends upon, size of array, size of battery (if any) - conventional inverter or multiple micro inverters and any additional equipment. Also how much the installer wants the job.

Savings will depend on array size, geographic location, direction it points, angle of roof, any shading issues, then how much of the generated energy you use yourself, and what tariff you are on.

MCS registered installers all use the same set of assumptions and formula to give 'projected savings' as part of their quotations.

In short - it is fairly complicated.

Hi, Thanks for your reply. I can’t see how it’s complicated , if a person has spent £8000 on kit after a year he should be able to say how much he’s saved.

It doesn’t matter what size batteries or other kit he’s got ,the only thing that matters is total cost and yearly saving, so it’s really very simple.

Maurice

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I don’t know whether this will help or not, Maurice … My brother has a system notionally specified at 4.44 kW and it has a Kodak branded battery with a capacity of 5.12 kWh, and a reasonably fancy controller.

The snapshot that he sent me recently [from North West England] showed this :

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Which tells me that he purchased no electricity that day, and exported too little to mention.

What that would mean to any of us, in our own personal circumstances, is for us to work-out.

MichaelG.

Maurice,

Nobody can guarantee what the weather will be like for the next year at your location (how much sunshine). The 'projected savings' I mentioned are all calculated using approved assumptions that are reasonably conservative.

You could get a free quote from one of the many providers, or I suspect that whoever sets out the calculation method probably makes it all available on line somewhere.

This might be a starting point for working out savings

Use the solar energy calculator - Energy Saving Trust

The results I get from my PV's would suggest that it is possible to predict the amount of "generating weather". Over the 10+ years I've had them the export "income" for has been the same +/- £20/annum. I was also able to work out how long it would be to cover the purchase and installations costs, only out by a couple of months in nearly 8.5 years.

While its nice to be able to do ones bit to save the planet, I want a reasonable return on the investment. I'm fortunate in having the old Feed in Tariff still. The SEG tariff is nowhere near as good, a quick calculation suggests that pay back time would almost double. I probably wouldn't bother with a PV installation now.

I looked in to getting a battery recently, the numbers just didn't add up, I would be using the grid to keep the batteries charged during the winter. Also, £7k will (still) buy a lot of electricity.

As for heat pumps, I can see me going that way when I'm too old to shovel coal in to the solid fuel boiler. But first I will continue with my efforts to improve insulation of the house.