Going from Coal to Air Heat Source Pump and PV's using ECO4 grant scheme

Reed_Richards

matt_drummer said:

Although my solar panels won't power my heat pump when the sun isn't shining the money they generated when the sun was shining will pay for all the electricity my heat pump will need and then some.

It seems to me that you say what I stated was untrue whilst basically agreeing with it!  You agree that the solar panels won't power the heat pump directly in winter and you agree that you will have more solar power than you can use yourself in summer.  As I recall, you have a system which is exceptionally large both in terms of generation, export and battery storage capacity.  And by your account it works very well for you, which is great.  But that's not what you would get under any grant-aided scheme so it's wrong to suppose that the OP will ever be able to do what you do.  

matt_drummer

Reed_Richards said:

matt_drummer said:

Although my solar panels won't power my heat pump when the sun isn't shining the money they generated when the sun was shining will pay for all the electricity my heat pump will need and then some.

It seems to me that you say what I stated was untrue whilst basically agreeing with it!  You agree that the solar panels won't power the heat pump directly in winter and you agree that you will have more solar power than you can use yourself in summer.  As I recall, you have a system which is exceptionally large both in terms of generation, export and battery storage capacity.  And by your account it works very well for you, which is great.  But that's not what you would get under any grant-aided scheme so it's wrong to suppose that the OP will ever be able to do what you do.  

. 

I don't agree with you, I think solar panels and heat pumps (or any electric heating for that matter) go together really well. In fact I think solar panels are good for everybody.

My system is large but the principle is the same for a small setup.

If somebody had a modest 4 kWp system fitted and generated 4,000 kWh a year it doesn't really matter when it is generated and if the heat pump uses it directly or not.

It is still 4,000 kWh of electricity that you don't have to pay for.

You get the benefit of 4,000 kWh of electricity that you either consume and don't pay for or export and save the income for use when there is no solar.

The fact that generation is minimal in December doesn't mean that solar panels don't work with heat pumps as you have the money you generated in June from exports to pay for some of the heat pump use. The solar panels are in effect running the heat pump in December.

You said point blank that solar panels and heat pumps don't mesh well and I disagree.

QrizB

matt_drummer said:

Reed_Richards said:

matt_drummer said:

Although my solar panels won't power my heat pump when the sun isn't shining the money they generated when the sun was shining will pay for all the electricity my heat pump will need and then some.

It seems to me that you say what I stated was untrue whilst basically agreeing with it!  You agree that the solar panels won't power the heat pump directly in winter and you agree that you will have more solar power than you can use yourself in summer.

I don't agree with you, I think solar panels and heat pumps (or any electric heating for that matter) go together really well. In fact I think solar panels are good for everybody.

And you are allowed to think that.

But I agree with R_R; the financial savings from having solar panels are not dependent on having a heat pump, and whatever saving you make from having a heat pumo vs. having a gas boiler are not dependent on also having solar panels.

You even say as much:

matt_drummer said:

If somebody had a modest 4 kWp system fitted and generated 4,000 kWh a year it doesn't really matter when it is generated and if the heat pump uses it directly or not. It is still 4,000 kWh of electricity that you don't have to pay for.

By your own logic, it doesn't matter if the 4000kWh is used in a heat pump. It's still 4000kWh of electricity that you don't have to pay for.

matt_drummer

QrizB said:

matt_drummer said:

Reed_Richards said:

matt_drummer said:

Although my solar panels won't power my heat pump when the sun isn't shining the money they generated when the sun was shining will pay for all the electricity my heat pump will need and then some.

It seems to me that you say what I stated was untrue whilst basically agreeing with it!  You agree that the solar panels won't power the heat pump directly in winter and you agree that you will have more solar power than you can use yourself in summer.

I don't agree with you, I think solar panels and heat pumps (or any electric heating for that matter) go together really well. In fact I think solar panels are good for everybody.

And you are allowed to think that.

But I agree with R_R; the financial savings from having solar panels are not dependent on having a heat pump, and whatever saving you make from having a heat pumo vs. having a gas boiler are not dependent on also having solar panels.

You even say as much:

matt_drummer said:

If somebody had a modest 4 kWp system fitted and generated 4,000 kWh a year it doesn't really matter when it is generated and if the heat pump uses it directly or not. It is still 4,000 kWh of electricity that you don't have to pay for.

By your own logic, it doesn't matter if the 4000kWh is used in a heat pump. It's still 4000kWh of electricity that you don't have to pay for.

I didn't say that.

@Reed_Richards said that heat pumps and solar panels don't mesh together well.

I disagree and think they do.

Perhaps I misunderstood @Reed_Richards. I read his comment as saying that if you get a heat pump it is not worth getting solar panels as they will be of no benefit in the winter when you need them.

It is this that I don't agree with.

I agree with what you have said, that neither are dependent on the other and I'll say it again, I think solar panels are a great idea for anybody that is able to fit them.

Reed_Richards

Every so often someone posts here about buying solar panels and an ASHP together as a "package".  I worry that they have been misled to believe that electricity generated from the solar panels will power the heat pump and it won't, most of the power that my heat pump draws over an entire year comes from the grid, not from my solar panels.  I'm a bit worried that the Eco4 scheme is being exploited by some companies that are more concerned with getting the money for the work than ensuring that the client really gets what they need. 

I do have solar panels, a "modest" 4.8 kWp array, and I have a 6.5 kWh battery.  I got the panels in March 2019 and then I got a heat pump at the end of 2020.  By then I knew that my solar panels generate very little power in the darkest months of winter, by comparison with what they generate in summer.  That's also why it's cold in winter, because days are shorter, the sun is lower in the sky, it's often more cloudy, so we get much less warmth from the sun.  I like my solar panels, have no regret buying them and I have recently moved to an Economy 7 type tariff so now I charge my battery cheaply overnight.

By all means get solar panels.  Use the money you get for exporting "spare" electricity towards your winter heating bills, however your heating is done.  And by all means get an ASHP, they're good for the planet and, although prices fluctuate, their running cost should not be too far off that of gas or oil central heating.

      

matt_drummer

I think we really agree.

With something like Octopus Flux, the exports in the sunny times generate enough to money to pay for imports in the winter when needed.

Although the actual electricity consumed by the heat pump is coming from the grid (or batteries) it is being funded by the summer exports.

I don't think anybody is being misled, the solar panels can (indirectly) power the heat pump in the winter as long as you get paid for exports.

If you didn't have the solar panels the annual energy costs would be higher, all that matters is what is paid out net of exports on an annual basis. The fact that you have to import lots in the winter is offset by the amount exported in the summer.

I just look at my annual electricity use as a pot, it doesn't matter when it is generated because it all either gets used or generates income. 

Therefore, I think selling solar panels and heat pumps together as a package is a great idea.

The only thing that can go wrong is if the export payments when the sun is shining aren't close to the import costs when needed.

If you get export payments and use that money to pay for electricity in the winter then those solar panels are, indirectly, running the heat pump. The export payments probably won't cover everything, that's true in most cases but it will help considerably.

Pec123

Can you get export payments on ECO4? I didn't think you could?

matt_drummer

Pec123 said:

Can you get export payments on ECO4? I didn't think you could?

I don't know.

Do you have some reason why you couldn't?

Are the panels yours once installed?

And you have an energy supplier?

And you own the property?

If the answer to all of those is yes then I cannot think why you would be prohibited from receiving export payments.

Reed_Richards

matt_drummer said:

Do you have some reason why you couldn't?

Are the panels yours once installed?

And you have an energy supplier?

And you own the property?

And do you have a Smart Meter?

You need a Smart Meter to measure the amount of electricity you export so you can get paid for it.  

Pec123

This is the data provided:

Component list:

Item Quantity

*HIB* Longi HiMo5 400W All Black Mono solar panel 10

SolaX X1-3.6T 1ph (inc WiFi dongle) inverter 1

Emlite ECA2 extended cover 1

Label sheet 1

AC isolator - IMO - 20A 4-pole 2

IMO DC isolator 16A 2p 1string 2

Pair of MC4 connectors 4

50m reel of 4mm2 solar cable 1

Fastensol end clamp (30mm black) 12

Fastensol mid clamp (30mm black) 14

Fastensol black end cap 12

Fastensol landscape concrete tile roof hook 4

Fastensol portrait concrete tile roof hook 22

Fastensol rail splice 2

Fastensol silver rail 3550mm 7

Inverter checks

SolaX X1-3.6T 1ph (inc WiFi dongle)

Panels

PV power 4000 Rated AC output 3680

Input 1: 4 *HIB* Longi HiMo5 400W All Black Mono solar panels in 1

strings

Panels Inverter

PV power 1600 W

Open circuit voltage at -10° C 161 V Max DC voltage 600 V

Vmpp at 40° C 120 V Vmpp lower limit 70 V

Vmpp at -10° C 136 V Vmpp upper limit 580 V

Impp at 40° C 13 A Max DC input current 14 A

Max voltage

The open circuit voltage of the solar panels never exceeds the

voltage limit of the inverter.

Max power point range

The maximum power point voltage of the solar panels is always

above the lower limit of the inverter MPPT tracker. The maximum

power point voltage of the solar panels is always below the upper

limit of the inverter MPPT tracker.

Max Current

The maximum power point current of the solar panels is always

below the maximum current for the inverter MPPT tracker.

Input 2: 6 *HIB* Longi HiMo5 400W All Black Mono solar panels in 1

strings

Panels Inverter

PV power 2400 W

Open circuit voltage at -10° C 242 V Max DC voltage 600 V

Vmpp at 40° C 179 V Vmpp lower limit 70 V

Vmpp at -10° C 205 V Vmpp upper limit 580 V

Impp at 40° C 13 A Max DC input current 14 A

Max voltage

The open circuit voltage of the solar panels never exceeds the

voltage limit of the inverter.

Max power point range

The maximum power point voltage of the solar panels is always

above the lower limit of the inverter MPPT tracker. The maximum

power point voltage of the solar panels is always below the upper

limit of the inverter MPPT tracker.

Max Current

The maximum power point current of the solar panels is always

below the maximum current for the inverter MPPT tracker.

Electrical

SolaX X1-3.6T 1ph (inc WiFi dongle)

AC Isolator

A AC isolator - IMO - 20A 4-pole has been specifed for this input

Current

The rated isolator current (20A) is greater than the rated inverter

current (17.6A)

Phases

The isolator is suitable for use on a single phase inverter.

Input 1

DC Isolator

A IMO DC isolator 16A 2p 1string has been specifed for this input

Current

The isolator is rated for a current of 16A, which is more than the

expected maximum current of 14A.

Voltage

At 16A the isolator is rated for a voltage of 600V, which is more

than the expected maximum voltage of 161V.

Cable

10m of 4mm2 solar cable has been specifed

Voltage drop

Voltage drop at maximum power point at 40°C will be around

1.10 V (0.92 percent)

Input 2

DC Isolator

A IMO DC isolator 16A 2p 1string has been specifed for this input

Current

The isolator is rated for a current of 16A, which is more than the

expected maximum current of 14A.

Voltage

At 16A the isolator is rated for a voltage of 600V, which is more

than the expected maximum voltage of 242V.

Cable

10m of 4mm2 solar cable has been specifed

Voltage drop

Voltage drop at maximum power point at 40°C will be around

1.10 V (0.61 percent)