New build air source heat pump advise please

Martyn1981

GreatApe wrote: »

Thanks I think they were being too conservative or perhaps read the plans incorrectly so I have forwarded on the actual plans and a suggested layout. I figure 10 panels on the south west side and 9 on the north east side should be possible so 5.13KWp using 270Watt Panels or 5.51KWp using 290 watt panels. Would 5.13 to 5.51 WKp of panels be ok on a solar edge inverter?

I have only had quotes with 270 watt or 290 watt panels. Still waiting on a couple of more quotes.

EDIT: OK quote for 19 panels with solar edge inverter: 5.13KWp for £6,565 so £1.28/watt almost the same quote per watt as the £4,200 for 3.24KWp

I think the 3.68kW capped inverter would be OK, the specs say it is good for 5.7kW of DC, and I doubt you'd get much capping with a SSW/NNE panel spread. This way there shouldn't be any problems with the DNO, so that's a plus. You could e-mail Solaredge UK and ask them for their opinion, but they may want the exact panel model to give a really definitive answer.

The price of £6.5k for 5.13kWp doesn't sound too bad, but with scaffolding and low VAT, I'd have thought a bit better was possible, depends how much interest you get from different installers.

5.5kWp for £6k would be nice.

Martyn1981

Martyn1981 wrote: »

I think the 3.68kW capped inverter would be OK, the specs say it is good for 5.7kW of DC, and I doubt you'd get much capping with a SSW/NNE panel spread.

Thinking about it, in high summer when the sun is high, it may 'see' the NNE panels late morning to mid afternoon, so there may be some capping on these days, at those times, and in good weather, but again, I doubt the annual loss will be significant, so probably not worth bothering the DNO, as that will make the job a bit more complex.

GreatApe

Martyn1981 wrote: »

5.5kWp for £6k would be nice.

Yes that is what I was hoping for. If they increase the panels from the 270 watt model to the 290 model and knock £500 off the quote I would be very happy with that.

Oh and earlier you asked if you need to inform the DNO if multiple homes nearby are having PV apparently that is the case or so says one of the quoters

GreatApe

Martyn1981 wrote: »

Thinking about it, in high summer when the sun is high, it may 'see' the NNE panels late morning to mid afternoon, so there may be some capping on these days, at those times, and in good weather, but again, I doubt the annual loss will be significant, so probably not worth bothering the DNO, as that will make the job a bit more complex.

I think you are right a calculator tool says sun will be about 53 degrees up around 3pm in the summer when the south west side is at peak production. This means the north east side will also see the sun however at quite an angle of about 20 degrees relative to the sun.

If I have this correct the south side could be generating at max while the north east side at 34% of max. So 2.7KW + 0.8KW = 3.5KW so still below the max of the inverter.

Martyn1981

GreatApe wrote: »

I think you are right a calculator tool says sun will be about 53 degrees up around 3pm in the summer when the south west side is at peak production. This means the north east side will also see the sun however at quite an angle of about 20 degrees relative to the sun.

If I have this correct the south side could be generating at max while the north east side at 34% of max. So 2.7KW + 0.8KW = 3.5KW so still below the max of the inverter.

Yep you are right in theory, but as always with PV, there are additional factors. So for the sun to be that high (summer) expect air temps to be higher on average, and for wind speeds to be lower than average - summer v's winter for simplicity.

So the panels in the sun, in strong sunlight, will get hot fast, 20secs or so, and performance will drop to about 80%, whilst those in less ideal sunlight (on the face of the panels) might do slightly better (temp wise), but I'm being overly pedantic here as it still works in your favour, perhaps:

2.16kW (-20%) + 0.96kW (+20%) = 3.12kW

Even if we are both wrong, and it does go over 3.68kW, it won't be a significant number of watts, nor hours per year.

My system holds approx 4.2kW on a really good day from about 11am to 3pm, but factor in the large ESE bias on the kWp deployment, and the fact that WNW is quite a bit better than NNE* and I suspect you'll be safe enough with 3.68kW.

*Obviously SSW is quite a lot better than ESE, so not knocking your rooves, just thinking through the comparison and panel size ratios etc etc etc.

lstar337

GreatApe wrote: »

Thanks. It looks like you use very little for space heating maybe just 1000 units a year! How big is the property?

EPC says 73m^2

thirteen1313

Is it possible to buy an ASHP and fit it with a good engineer? It seems the pumps are not that expensive for say a reasonably well insulated 900 sq ft house.. Im concerned that the installation figure is inflated due to the refund received through the heat incentive refunds. Im confused with who really benefits from the deal. I would rather pay for the pump find an installer-job done. Rather not get involved with the bureaucracy. However would this be cheaper or the same???