Solar Panels - energy price hikes making them more worthwhile?

shinytop

countryhouse39 said:

shinytop said:

I'm pondering the same as a ASHP user.  However, everything I've read points to savings of a few hundred pounds a year and payback in 15 years plus.  That's not going to make much of a dent in your electricity bill (or mine).  As a heat pump user you might save a bit more in spring/autumn and if you use a lot of hot water you'll save all year round.   

Have you done all you can in terms of radiators/flow temperatures to optimise the GSHP?

I'm not sure we have done all we can to optimise the GSHP as we are not experts in it at all - can you advise how we could do this? 

Apologies if I’m telling you stuff you already know.  A heat pump works least well when it’s cold weather and/or it’s supplying very hot water. You can’t do anything about the cold weather; the HP will be less efficient.  You can give the HP less to do by keeping as much of the heat inside as you can; that’s insulation, double glazing, draft proofing, etc.

On the second point, the HP should be set to heat the radiators to as low a temp as possible while still hot enough to heat the house. If you have underfloor heating that’s good as you should already have low flow temperatures.  If normal radiators then the temps should be in the 35-50 deg C range, depending on how cold it is outside.  As an example, ours are in the high 30s when it’s about 10 outside.  However, your radiators need to be big enough to be able to heat your rooms at low temps.  Our ASHP automatically adjusts the radiator temp according to the outside temp, up to a maximum of 50.  I don’t know how sophisticated your controls are but you should at least be able to adjust manually. If your system has a setting called ‘weather compensation’ or similar then you should use it.  

The other thing to check is your hot water.  50 deg C is plenty and some manage with 45.  The system should be able to program in a periodic blast up to 65 to kill off any nasty bacteria lurking.  If you’re heating your HW to 60 deg plus it’s going to be very inefficient/expensive.

Do you have any idea what your system COP is?  Even if your GSHP is using 15,000 kWh and your COP is only 2, 30,000kWh is a lot of energy. 

 Any more questions please ask.  

Petriix

Martyn1981 said:

countryhouse39 said:

Coastalwatch said:

countryhouse39 said:

re-posting here for more views originally posted in 'energy' ...

We are lucky enough to live in an old house in the Scottish countryside (5bed, 3 reception) and as with many rural properties we aren't on the gas network. The people before us installed a GSHP for the heating and hot water, but they didn't install much in the way of insulation (out house is mostly pre 1900) so we have spent the last few years upgrading the insulation, and we installed some double glazing, but our electricity bills are still high as we use about 18-19000kwh a year...
With both of us WFH and 3 children I don't think we can reduce this much - so as you can imagine the recent massive hikes in energy prices are painful for us. We have been thinking of installing PV panels, maybe solar thermal too, but the possible savings didn't make it seem worth the outlay, however I am thinking that with the rise in energy prices that it will be worth it after all? Is anyone else in a similar situation? is it worth reconsidering so our bills go down? Can anyone advise on the best combination? we have roof space, sadly our south facing roof is also street facing and therefore unlikely to get planning permission for panels (conservation area) but we have a long west facing roof that is unobstructed. Any advise gratefully received

Hi CH, quite a conundrum you've pointed out there which I suspect will only be resolved by researching, obtaining quotes and asking questions on here and elsewhere. I concur with all those posting replies so far.

A west facing roof is good in the summer, as is an east, but in winter, when it's most needed the output would be very limited. Try inputting your location and other info into the link below to give an indication of likely output from any sized solar panel array through the year. If it's definitely a nogo on the south facing roof do you have anywhere you could erect solar panels to face south in the rear of the property?

https://www.google.com/search?client=firefox-b-d&q=pvgis+v5

I've no experience of Solar thermal but believe PV would be a more flexible form of energy as any excess can then be directed to areas other than hot water.

We've nearly 9MW of panels on the roof, which is approx our consumption annually. Unfortunately generation in winter is least when we most need it. It does also cover approx 75 % of our EV  transportation.

Hence we import around 4.5 MW annually.

To assist in offsetting the cost of imports we invested in Ripple Energy's wind farm, which is scheduled to commence generation in December. By doing this the wholesale cost of our energy will be fixed for the life of the windfarm, circa 25 years. Approx 2.5p/kWh, other fixed costs such as energy distribution etc which must also be accommodated in the cost of energy are not affected so no saving can be made on these.

While Ripples first windfarm is sold out they have announced a second, with slightly better returns, so may be worth investigating. Having invested in their first community owned windfarm I then invested further in the company itself.

Along with double glazing, thermal blinds can also be fitted to reduce heat loss and I've even backed these up with 50mm thick sheets of Celotex, cut to fit in the returns of the window spaces. Not used in summer or on mild winter days but popped in place from late afternoon during periods of sub zero temperatures in the darker days of winter.

I tried your link but dont have a clue how to use it! that's interesting about investing in a wind farm - i didn't know you could do this! can i ask how much you invested in the first place to then only have to pay 2.5p/kwh? 

Hiya, the idea behind the Ripple wind turbine is really great, with householders able to take direct responsibility for generating the equivalent of their consumption, or shortfall if they have PV.

Fully Charged just released a video looking at the Ripple idea and their next planned wind turbines:

Share a slice of the wind revolution - RIPPLE ENERGY | Subscribe to Fully Charged PLUS

Thanks for the Ripple info. I've signed up. Didn't realise there's a referral scheme until after I'd done it. I don't think we're allowed to share the link on here. Looks really interesting. 

Meatballs

shinytop said:

countryhouse39 said:

shinytop said:

I'm pondering the same as a ASHP user.  However, everything I've read points to savings of a few hundred pounds a year and payback in 15 years plus.  That's not going to make much of a dent in your electricity bill (or mine).  As a heat pump user you might save a bit more in spring/autumn and if you use a lot of hot water you'll save all year round.   

Have you done all you can in terms of radiators/flow temperatures to optimise the GSHP?

I'm not sure we have done all we can to optimise the GSHP as we are not experts in it at all - can you advise how we could do this? 

Apologies if I’m telling you stuff you already know.  A heat pump works least well when it’s cold weather and/or it’s supplying very hot water. You can’t do anything about the cold weather; the HP will be less efficient.  You can give the HP less to do by keeping as much of the heat inside as you can; that’s insulation, double glazing, draft proofing, etc.

On the second point, the HP should be set to heat the radiators to as low a temp as possible while still hot enough to heat the house. If you have underfloor heating that’s good as you should already have low flow temperatures.  If normal radiators then the temps should be in the 35-50 deg C range, depending on how cold it is outside.  As an example, ours are in the high 30s when it’s about 10 outside.  However, your radiators need to be big enough to be able to heat your rooms at low temps.  Our ASHP automatically adjusts the radiator temp according to the outside temp, up to a maximum of 50.  I don’t know how sophisticated your controls are but you should at least be able to adjust manually. If your system has a setting called ‘weather compensation’ or similar then you should use it.  

The other thing to check is your hot water.  50 deg C is plenty and some manage with 45.  The system should be able to program in a periodic blast up to 65 to kill off any nasty bacteria lurking.  If you’re heating your HW to 60 deg plus it’s going to be very inefficient/expensive.

Do you have any idea what your system COP is?  Even if your GSHP is using 15,000 kWh and your COP is only 2, 30,000kWh is a lot of energy. 

 Any more questions please ask.  

Just to add I'd just drop the weather comp curve a step a day until house is a bit cold then bump it back up to comfort level. Then you'll have found a good limit for your heat loss/emitter sizing.

Patrol

I've had a GSHP in a new build since 2007 and added solar panels this year, so can comment more on the former than the latter.

In terms of optimising the heat pump you may be able to see how many hours the ground loop is on and how many hours the additional heat is on (for my IVT unit I have to go into service mode which allows me to see those settings). Failing that you can probably see on the main panel when each part is on, so real time but no cumulative detail. If you see additional heat is on regularly you might want to try and understand that as it will be costly - additional heat uses 3-4 times the electricity of the ground loop. The two things I did are:

1) Change the time that the ground loop is on before additional heat kicks in. It was set to 1 hour and I was finding that the loop ran for an hour, additional heat kicked in for 15 minutes and then required no heat for 30-45 minutes. I changed it to 3 hours and my additional heat use reduced significantly while the ground loop ran for longer. Overall impact was a significant cost reduction without noticing any difference in heating or hot water availability.

2) Change the interval between hot water hysteresis (heats to e.g. 65c for legionella reasons). I prevaricated on this but changed it from every week to every 3 weeks with no apparent issues. I'd say don't do this unless you are very happy to though.

There is a long forum entry at https://forums.moneysavingexpert.com/discussion/2964222/ground-source-heat-pumps/p1 with all sorts of other useful information.

Although your west facing roof may not give you the best solar performance you may find it helps, and if your heat pump is running in the afternoons + evenings it should mitigate some of those costs.

Spies

Prices of panels and equipment are going up as well, so anyone on the fence about solar, make a decision sooner rather than later! 

Coastalwatch

countryhouse39 said:

I tried your link but dont have a clue how to use it! that's interesting about investing in a wind farm - i didn't know you could do this! can i ask how much you invested in the first place to then only have to pay 2.5p/kwh? 

Hi CH, Our investment in Ripples first windfarm was for 4167kWh's annually, which covered 93% of our estimated annual usage. For this we needed to purchase 1559 Watts share of the 2.5 MW Graig Fatha Turbine. It is anticipated that each Watt purchased would return 2.65 kWh's annually.

Our total for this was £2651 with a ROI anticipated in 14 years, although this is likely to be significantly less if energy prices remain high for any length of time.

As with solar output varying due to different weather patterns the same will occur with a turbine, so precise figures are not possible to predict other than from historical data, which I believe is how pvgis figures are arrived at.

Hope this helps, any questions arising then do ask and I'll do my best to reply a little equicker next time.