Solar / Battery Storage considerations

I load shift with batteries at 16p per kWh vs 40p kWh so it does seem to make a lot of sense. £3 a day, roughly.

No smart meter though. Despite my provider constantly emailing me to have one, the small print says they don’t have a 3-phase one, so not much I can do.

How are you doing with the second ASHP? Must be much better than the storage heaters.

Very impressed with your lounge and wood burner. Lovely period home.


The second ASHP is great, thank you. We’re using it for DHW as well as a number of new radiators. We now only have two storage heaters left and the pipe work has been put in to replace them with wet radiators as and when we decorate those areas. Getting there! At the same time as the second ASHP, we also installed 2 large cold water storage tanks and some hefty pumps so that our showers are now excellent (we were on unvented mains pressure DHW, which is fine, unless you live on a hill with intermittent cold water pressure issues!).

Our batteries, well, specifically the inverter, has been a bit of a problem, lots of engineers scratching their heads and replacing parts. a representative for the manufacturer was here all day today and replaced a load of stuff, so all now back online. Fingers crossed it’s sorted now!

Thank you for the comments about the house. We’ve been here 6 years and I think we’re probably about 80% through the process of dragging it into the 21st century! These things always take a lot longer and cost a lot more than planned.


November figures

Used 800 kWh
Export 119kWh
Panels 251 kWhp
ASHP 440 kWh
EV 90 kWh

Bill £125 net (imp - exp) inc standing charge.


Can I ask about VAT on renewables in the UK. My understanding is that all renewable are now zero rated - I think that means solar panels, heat pumps, and I believe battery storage and PIR insulation. If this is the case why do outlets like City Plumbing show the VAT?. I’m not buying only looking but if for example I add solar panels to the basket and perhaps an Vaillant air source heat pump it shows the VAT which presumably is chargeable at point of sale (I can’t ring them to check this week) - I would have assumed if the government in the UK is zero rating it should be showing the net rather than gross cost i.e. excluding VAT

Your MCS installer with zero rate. Battery needs doing with solar or at least part of same contract. Likewise heat pump, but BUS grant for first time only.

Best to read the HMG sites for conditions.


Related, has anyone considered a small roof mounted wind turbine? It’s quite windy where I live.

I was looking at a TESUP V7 Vertical Wind Turbine, £800 for 7kW (and not restricted to “sunlight hours). Seems very cheap for the potential returns - too good to be true?

They were being sold widely……even B and Q, think these small roof ones do not stack up in their overall performance.
The only person i know who has a wind turbine is @TimOopNorth who has a “proper” one?

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There were strict rules involving planning on wind turbines. If the ASHP was installed under permitted development the WT may require planning. Listed buildings also.


If it looks too good to be true…

As context, our wind turbine (I think the mast is 19m and the blade 13m) is rated at 11kW and cost us £60k (though they was in 2011). I don’t know what current costs are. I expect if it were possible to generate 7kW from an £800 turbine there would (ignoring planning permission) be thousands of the things all over the place. But I have never seen any positive reports on them - in fact I have never seen any reports on them full stop.

I have done a bit of googling and found very little on vertical wind turbines. There seems to be some negative feedback on Tesup but who knows how representative that is.

With wind the generation rises exponentially with the size of the blade, and small turbines are as far as I know a waste of space.

And I wouldn’t want one on my roof - don’t fancy the vibrations. A key principle is to avoid turbulence, and on your roof there is going to be a lot of that. A nice clean run in for the wind measuring hundreds of metres is what you want. We should perhaps chop some more trees down - the pesky things keep growing!

Here is a photo of ours

Generation has been fantastic the last week - our one third share has been averaging 70 kWh a day


Is that 3 phase ( one phase per share) or a single phase generator?

Three phase, one phase per share


It’s on Amazon with poor reviews. I looked at the videos which give the impression it’s a DIY job but it isn’t. The build quality is an issue and the technical support nonexistent. It probably needs 15km/hour winds. Couldn’t find anything about linking to solar. All things are best done by a professional renewable installer.



Thank you all for your experience and your comments. I guess what @TimOopNorth said rings the most true: if it looks too good to be true… At my age, I should know better!

I have an 8kW solar array and, on a good day in summer, I get 40kW. Significantly more than that from an £800 7kW device definitely made me think twice, hence the question. I have 3 phase at home and do feel like there is the prospect of better self generation, but maybe this isn’t the way.

Grateful for your sage words.


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I hope you mean 40Kwhr rather than 40Kw from your 8Kw array ? Or maybe you did?
I missed 40Kwhr in june by 0.1Kwhr. Still my best days generation ever .

I think you mean kWh :wink:

With combined wind and solar our best in a day is just under 100 kWh I think

Junes best was 60kWh from solar alone (8kWp). This month we had three consecutive days of just over 80kWh from wind (almost no solar)

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I bet like most of you, at the end of every installation year, you look at the figures and make various deductions. So 5 years now completed, and thanks to this thread which showed me how to get exported data from the meter, here are my last years findings:

The amount of solar energy generated this year is “exactly” the same as last year (to nearest KWh)- SPOOKY

We have used 15% less gas this year than last - I can only put this down to turning the Heat Only Boiler stat down to its minimum (allowing Solar to boost HW to above 60degrees).

My Solar diverter diverted 1,478KWh (£428) to hot water and an electric fire. :blush:

5 years of installation now equates to a savings of 75% of the cost of the Panel Installation. Another year in current hight energy rates should then cover cost fully.

I exported 2,248KWh to grid (48% of generated). This would be the figure that had I had a battery, I may be able to use myself. In the height of the summer, I still wouldn’t be able to use all this, but for argument sake if I could, a battery would only save <£470 a year. Don’t think it makes financial sense to get batteries yet, and more likely an EV would take up this slack.

CO2 reduction 4.6Tonnes

Overall very pleased, as I’m sure all of you are.

Chart shows where the generated energy went:


Mine went operational at end of January 2023. Most exports at just below standard rate with Octopus Flux.


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Up and running yesterday.

All we need now is some sunshine… and maybe batteries.


If you’re saving around £450 a year with a battery, assuming a life of 10 years (possibly a bit low?) then doesn’t that suggest a cost of £2-3k for a battery would be a worthwhile use of capital?