Green Building Forum - Solar PV questions + ASHP or GSHP? Tue, 19 Dec 2023 08:17:45 +0000 http://www.greenbuildingforum.co.uk/newforum/ Lussumo Vanilla 1.0.3 Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300405#Comment_300405 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300405#Comment_300405 Thu, 23 Feb 2023 11:00:16 +0000 gustyturbine I've not been here for a long time for various reasons but since I've finished my first self-build I'm now doing another self-build!!
I aim to do things slightly differently this time. Last time I went as far as the budget would allow with insulation etc and a GSHP. It's done well but these days electricity isn't cheap as we know.

I'm in Wales.
I want to install solar PV with micro-inverters. From what I can gather the panels are fairly similar efficiency wise when cost is taken into account. The weakest link is the inverter. That's my micro-inverter thinking so if one fails it doesn't knock the whole system off. So, roof or ground mount? I have land available for ground mount. I think that without PP I'm limited to 3Mx3M so that's too small. I was aiming for 10kWish as we also have an EV. I'm also thinking of battery storage to cover the evenings following charge during the day.
I'm on the coast with 3 acres so I'm thinking my COP on an ASHP might be better than a GSHP considering the milder climate on the coast. It's also cheaper but the ASHP unit may corrode in time due to the salty atmosphere. I'm probably 1/2 mile to the beach.
So many questions. UK climate, triple glazing or double. I'm fitting MVHR. Good window companies that aren't too expensive? UK based?
Many thanks all.
It's good to be back :bigsmile:]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300406#Comment_300406 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300406#Comment_300406 Thu, 23 Feb 2023 11:54:30 +0000 WillInAberdeen
I was surprised how much has changed in 10 years between our previous project house and our current project. We needed to go back and relearn.

Main thing for me is that renewably sourced heat is becoming easily available, so our previous project's focus on heat conservation/insulation/fabric etc is no longer the only consideration. The impact of the build itself is becoming more significant, eg minimise high-impact materials cement/steel/glass.

ASHP tech has improved, is becoming the default rather than GSHP.

We are buying-in renewable electricity rather than building our own, the economics of scale favour GW solar and wind generators rather than kW.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300408#Comment_300408 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300408#Comment_300408 Thu, 23 Feb 2023 16:06:03 +0000 revor Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300409#Comment_300409 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300409#Comment_300409 Thu, 23 Feb 2023 16:21:45 +0000 Jeff B
Revor - I was interested to read your statement: "I was restricted to 3.6kw export but that got raised last year to 5kw". Was that just for your installation or is that a Wales-wide allowance? Also is yours an MCS installation with FIT payments?]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300411#Comment_300411 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300411#Comment_300411 Thu, 23 Feb 2023 17:13:24 +0000 djh The microinverters and the panels I chose both have 25 year warranties, so I can relax. No problems so far and no cleaning needed in nearly 8 years - they still perform well. I know Enphase also sell batteries that will integrate. I believe Tesla batteries will as well. It all depends whether the battery is DC-connected or AC-connected.

I'm not yet convinced batteries are worthwhile in our situation. I own part of a wind turbine instead.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300413#Comment_300413 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300413#Comment_300413 Thu, 23 Feb 2023 17:46:24 +0000 revor Posted By: Jeff BRevor - I was interested to read your statement: "I was restricted to 3.6kw export but that got raised last year to 5kw". Was that just for your installation or is that a Wales-wide allowance? Also is yours an MCS installation with FIT payments?

Think it was my area. I was conscious in the summer of my inverter clipping the export when I could have been exporting up to about 5.5 at times so asked my DNO how much it would cost to get it uprated and they said (same day) up to 5kw no charge more than that a fee of £750 plus a witness test whatever that would have cost. I had to make another application which was basically what had been submitted before with a declaration that the inverter would be set to 5Kw max. And by return got the ok.
My installation is an MCS but do not get fit I am on Octopus Agile and get variable payment which is not good at moment. You need MCS regardless of what export tariff you are on without it you just giving grid free juice. A friend has 17kw roof mounted but the max he is able to export is 8kw the panels are on different orientations but he is also close to a biggish transformer.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300414#Comment_300414 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300414#Comment_300414 Thu, 23 Feb 2023 17:59:15 +0000 Jeff B
I am a "pioneer" as far as MCS/FITs goes, as we had our PV system installed in 2011, hence am on the highest FIT payment regime. As much as I would love to do it, I think it will be complicated (not permissible even?) to try to extend my system to increase the output. Our PV array faces southeast rather than due south and we have a southwest facing roof which catches the sun for the whole of the afternoon in summer and on which I could attach several more panels. I need to check the latest regs but your post has got me thinking!

P.S. Sorry Gustyturbine for hijacking your thread but hopefully this may still be of interest to you of course.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300417#Comment_300417 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300417#Comment_300417 Thu, 23 Feb 2023 22:25:12 +0000 philedge
If youre adding panels on a different facing roof pitch the panels on the differing pitches will effectively be shaded for part of the day compared to the other pitch. To stop the differing pitches affecting each other, they'll need wiring separately each to their own MPPT input or use optimisers/micro inverters.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300421#Comment_300421 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300421#Comment_300421 Fri, 24 Feb 2023 10:13:03 +0000 revor Posted By: Jeff BRevor - thanks for your response. Very interesting. Where is your area, if I may ask? We are in Pembrokeshire.

Anglesey

Posted By: djhI'm not yet convinced batteries are worthwhile in our situation


I was not sure originally whether my investment in a battery was justifiable as a lot depends on what you can get for export, where it would go if not used and not in a battery. The economics keeps changing. Practically all I have produced this year has gone to battery or used and very little exported. What I have been paid is about 15p kwh. Yesterday was a good sunny day 22 kwh generated used a bit, filled the battery which lasted from sundown to 9AM this morning and 11kWh was exported. At a bought in cost of 35p and export of 15p the electricity is better in the battery. Also being a sunny day yesterday the solar gain was enough that we did not need heating on other than a wood fire in our lounge stove.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300428#Comment_300428 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300428#Comment_300428 Fri, 24 Feb 2023 18:04:19 +0000 djh Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300462#Comment_300462 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300462#Comment_300462 Mon, 27 Feb 2023 08:37:31 +0000 gustyturbine I think then in reality I need to get the 10KWp ground mount, hydrid inverter with battery if permitted in Ceredigion. I'll then go for ASHP as I'm near the coast and it's milder generally and it has lower install costs compared to GSHP. I'll also install MVHR as my last build needed it really and I'm not building a home to be as airtight as possible then whacking extractor fans and trickle vents in again. It's madness. All of the above whilst insulating as best we can. I'm also installing a log burner as I don't believe in relying on the state anymore to provide anything the way the world is these days. Secondary form of heat is essential and the PV should help.
Thanks.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300464#Comment_300464 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300464#Comment_300464 Mon, 27 Feb 2023 10:04:04 +0000 philedge
With 10kw of panels youll need planning permission for a ground mount system over 9m2, I beleive. Unless you want to restrict what you export to 3.68kw you probably need to speak to your DNO to see what export restrictions you have, before you comit to any generation/export capacity or configuration.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300466#Comment_300466 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300466#Comment_300466 Mon, 27 Feb 2023 10:52:16 +0000 Peter_in_Hungary Posted By: philedgeIf youve got the roof space I think youd be better roof mounting what you can as youve got longer exposure to the sun and less chance of winter shading, unless the ground mount is on the side of a hill.

With 10kw of panels youll need planning permission for a ground mount system over 9m2, I
But with ground mount you get to install at the optimum angle and direction which is unlikely on a roof, also ground mount provides a bit more output in the summer due to better cooling (air flow) than roof mounting - but PP may be a pain - so a few things to think about between a ground or roof array.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300470#Comment_300470 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300470#Comment_300470 Mon, 27 Feb 2023 12:49:19 +0000 Jeff B Posted By: philedge@Jeff b. OFGEM changed the FIT rules a few years back allowing FIT accreditted systems to be altered so you can now increase generation, add batteries, change components etc. Down side is youll still only get paid FIT for the original registered capacity so if you go from 4kw to 5kw you only get paid for 4/5 of what you generate and export. If your existing inverter can handle extra DC input its a cheaper way of adding extra capacity compared to a second system, but......

If youre adding panels on a different facing roof pitch the panels on the differing pitches will effectively be shaded for part of the day compared to the other pitch. To stop the differing pitches affecting each other, they'll need wiring separately each to their own MPPT input or use optimisers/micro inverters.

My existing system already uses microinverters. Because it is facing south-east, the output drops off dramatically after about 2.00pm. This is when a south-west facing add-on system would take over. I had some data from a small PV panel (the type you would use on a caravan) which I mounted temporarily on the south-west facing roof back in May 2020 and there was a good output from 2.00 pm right through to 7.00 pm. Unfortunately I have lost the data but I remember it was quite impressive.

The existing 21 panels have a nominal output of 180W each, so theoretical maximum output would be 3.78kW but in reality the highest figure ever achieved was 3.05 kW (approx 150W per panel). On the south-west facing roof I would be able to fit 4 panels (it's much smaller than the main south east facing roof), with modern panels of say 250W output each, then a bit less than 1.0 kW should be possible. As the total output would still be within the original 4 kW "limit" do I need to inform OFGEM or whoever?]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300474#Comment_300474 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300474#Comment_300474 Mon, 27 Feb 2023 14:18:11 +0000 philedge
You'll do well to find new 250 watt panels. Mainstream size of current panels seems to be 350 watt upwards]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300477#Comment_300477 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300477#Comment_300477 Mon, 27 Feb 2023 16:54:22 +0000 djh https://blog.spiritenergy.co.uk/homeowner/adding-more-solar-panels

AIUI the microinverters talk to one another and/or their monitor gateway thingy so as to limit their output to the 3.68 kW limit. I sometimes see my generation 'flat-topping' in summer, instead of following a smooth curve.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300482#Comment_300482 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300482#Comment_300482 Mon, 27 Feb 2023 19:34:00 +0000 philedge Posted By: djhThere's what looks to be a reasonable guide athttps://blog.spiritenergy.co.uk/homeowner/adding-more-solar-panels" rel="nofollow" >https://blog.spiritenergy.co.uk/homeowner/adding-more-solar-panels

There's a couple of things that stand out as not being quite correct! If youve got a 3.68kw/16A limited inverter your first port of call to see if you can add panels is the inverter manual, not the DNO. Our 16A limited inverter currently has 4 kw of panels attached but it can have up to 5.4kw of panels attached and still retain its 16A output limit, so no DNO involvement. I assume that a 16A limited micro inverter system can be expanded in a similar way??

The guide says you can't alter a FIT system but that's not been the case for a while.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300486#Comment_300486 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300486#Comment_300486 Mon, 27 Feb 2023 22:33:34 +0000 Jeff B Posted By: philedgeAFAIK your "limit" is whatever the installed capacity declared on your MCS cert says. Anything over that and you're supposed to notify your FIT payer.

You'll do well to find new 250 watt panels. Mainstream size of current panels seems to be 350 watt upwards

Even better, I'd only need 3!]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300492#Comment_300492 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300492#Comment_300492 Tue, 28 Feb 2023 10:44:17 +0000 Gareth J
As you have space, I'd consider building a separate shed/carport with the exact pitch(es) you want to maximize winter output, which if you're hoping to power heating will have a pitch/pitches geared towards winter production, rather than total production. Corrugated tin roofs are very easy to fix panels to.

Regarding the location and ashp, is the humid environment likely to cause more icing up, and therefore defrost cycles, despite the relatively mild temperatures? I don't know either way but could imagine it's a possibility.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300497#Comment_300497 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300497#Comment_300497 Tue, 28 Feb 2023 11:23:34 +0000 djh Posted By: philedgeThe guide says you can't alter a FIT system but that's not been the case for a while.Is there a good explanation of the current rules somewhere?]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300504#Comment_300504 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300504#Comment_300504 Tue, 28 Feb 2023 13:38:33 +0000 philedge Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300510#Comment_300510 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300510#Comment_300510 Tue, 28 Feb 2023 16:08:50 +0000 djh
"This document is intended for owners, or potential owners, of Solar PV and wind installations
with a Declared Net Capacity (DNC) over 50kW up to a Total Installed Capacity (TIC) of 5MW"]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300515#Comment_300515 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300515#Comment_300515 Tue, 28 Feb 2023 18:58:44 +0000 Gareth J Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300518#Comment_300518 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300518#Comment_300518 Tue, 28 Feb 2023 21:06:41 +0000 philedge
And these FAQs- https://www.ofgem.gov.uk/environmental-and-social-schemes/feed-tariffs-fit/generators]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300521#Comment_300521 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300521#Comment_300521 Tue, 28 Feb 2023 23:06:15 +0000 Jeff B
"Can I extend the capacity of my installation?

You can modify your accredited installation to either increase or decrease its capacity as long as the total installed capacity (TIC) of the installation and any extensions does not exceed 5MW (or 2kW for micro-CHP). 
However, you cannot receive FIT payments in respect of electricity generated from any additional capacity unless the extension was commissioned before 15 January 2016".

This is the closest reference I can find on this topic. It still doesn't really answer the question if by adding extra PV panels, does this affect the need for notification if the total generating capacity does not exceed the original specification?]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300530#Comment_300530 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300530#Comment_300530 Wed, 01 Mar 2023 09:31:53 +0000 philedge Posted By: Jeff B It still doesn't really answer the question if by adding extra PV panels, does this affect the need for notification if the total generating capacity does not exceed the original specification?
Not quite sure what you mean by original specification? AFAIK the definition of your capacity is whats registered on the MCS database which hopefully is the same as on your MCS cert. Seems that any deviation from that figure should be notified]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300532#Comment_300532 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300532#Comment_300532 Wed, 01 Mar 2023 10:15:35 +0000 djh Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300535#Comment_300535 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300535#Comment_300535 Wed, 01 Mar 2023 11:46:29 +0000 philedge Posted By: Gareth Jconsidering that it's relatively easy to put a completely separate system in if you want/need to expand. .

If youve already git a typical 4kw system limited to 3.68/16A then adding a second system is subject to G99 application and DNO approval. The beauty of expanding the DC side of an existing inverter is you are free to do as you wish up to the inverters limit.

This was one of the drivers for OFGEMs original consultation on expanding FIT systems, as with rapidly rising prices people were wanting to get more out of what they already had]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300536#Comment_300536 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300536#Comment_300536 Wed, 01 Mar 2023 14:08:29 +0000 Gareth J Posted By: philedge
Posted By: Gareth Jconsidering that it's relatively easy to put a completely separate system in if you want/need to expand. .


If youve already git a typical 4kw system limited to 3.68/16A then adding a second system is subject to G99 application and DNO approval. The beauty of expanding the DC side of an existing inverter is you are free to do as you wish up to the inverters limit.

This was one of the drivers for OFGEMs original consultation on expanding FIT systems, as with rapidly rising prices people were wanting to get more out of what they already had

Good point!

However, G99 with export limitation isn't that tough (well, wasn't a few years ago) wouldn't like to say if it would be more or less of a pain than notifying the FiT side.]]> Solar PV questions + ASHP or GSHP? http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300537#Comment_300537 http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=17751&Focus=300537#Comment_300537 Wed, 01 Mar 2023 15:23:10 +0000 djh