Adding a new Solar Array - existing 10kWp FIT in place

[Ferdinand]

I'm currently working up a project for a new veranda on the S-facing side of my house, to 1) provide shade for rooms that overheat, 2) create a car port in front of the garage, and 3) possibly to incorporate an office / study on the front of the lounge.

 

Currently I have a (2015) 9.93 kWp grid-connected solar FIT install, which is approx 8kWp East facing and 1.9 kWP West facing. It si a simple array with no batteries or divert devices.

 

The veranda could add approx 45 sqm of S facing nearly-flat roof.

 

In the past I have wondered about moving some of my East-facing solar to the roof of the new veranda - it was laid out with that as a consideration.

 

But given that that would cost (guestimate) £2000 to move, and the neighbour on the East side is considering removing his questionable huge 100 year old horse chestnut tree that overhangs my house / part of the solar array, I am toying with the idea of leaving it as it is and installing a new array on the veranda roof.

 

I already have a report suggesting that the tree is risky, and it is probably worth me contributing to the cost of removal.

 

For background, can anyone advise me if I am going to hit any elephant traps thinking about this:

 

1 - Is there a hard limit for domestic solar connection to the grid at 10 kWp? Would I run into regulatory trouble trying to boost that to say 16 or 17 kWp total?

 

2 - Are there technical issues around integrating an old and a new install? Or can I easily run 2 in parallel?

 

3 - What approach should I consider? An alternative would perhaps be to consider the existing array as an "export" array, and install the new one off grid with a water heating setup and house battery.

 

All thoughts are welcome, as I'm doing my background thinking. I know the solar basics, but I'm wrestling with how to navigate our now more complex environment.

Cheers

 

Ferdinand

 

[SteamyTea]

Are you going to design (size) the veranda (lean to) roof to make it easy to fit PV modules?

 

Probably cheaper to self install off grid and get some thermal and electrical storage, you can get 'islanding' systems that keeps everything easy as normal 230V switching, cabling and rules/regs apply.

Cheapest, and most useful electrical storage is probably an EV, though not sure how easy they integrate into an islanding system.

[Dillsue]

Q1- you need permission from your DNO to export more than 3.68kw so you should already have permission for your 10kw system. If you want to export more, you need DNO approval of a G99 application.

 

Q2- no problem running 2 or more systems in parallel. We have 2. 

 

Q3- its up to you how you configure things and somewhat dependant on what export your DNO will allow, but altering your FIT system is regulated so understand what the rules are before comitting to altering anything

[Ferdinand]

17 hours ago, SteamyTea said:

Are you going to design (size) the veranda (lean to) roof to make it easy to fit PV modules?

 

That would be the intention, yes. Here's the front view from due South. If you look carefully you can see the brick grain change where it used to be a small double fronted 1940s bungalow. One issue is that those 2 front rooms overheat in hot summer.

 

 

 

Lots of designs are possible, eg something in brick with round arches following the front door pattern, or lightweight steel / stainless, or wooden, or even a variety of post and beam. It will need PP, however, as it is forward of the building line.

 

You can see the edge of the 3 panels on the LHS of the big gable. There are another 28 on the RHS of that gable, with the 100-125 year old horse chestnut I would like gone, as it is starting to crack. That protruding branch is directly above the main bedroom.

 

Personally I'm a fan of lightweight structures, so I can even imagine simply using a suitable solar ground based mount put in front - if the aesthetic, engineering, column spacing, panel angle almost flat etc works, or something from a local steel fabricator. I am not even sure that it would need any backing at all.

 

 

https://www.sunfixings.co.uk/roof-type/carport/

 

My dad once made a car port made with one side supported by scaffold poles, which is still there 50 years later. I wouldn't go quite that far. Estate agent distorted piccie below. The lady who had it built for her in 1971 has just passed at age 100, having lived there since. I guess they just wanted something simple which did not intrude - running out of budget?

 

 

17 hours ago, SteamyTea said:

Probably cheaper to self install off grid and get some thermal and electrical storage, you can get 'islanding' systems that keeps everything easy as normal 230V switching, cabling and rules/regs apply.

Cheapest, and most useful electrical storage is probably an EV, though not sure how easy they integrate into an islanding system.

 

Useful thoughts. I think I need a conversation with the DNO as one of my preliminaries.

 

I wonder if I can have 2 systems exporting at once if I go for connected?

 

Cheers

 

F

[SteamyTea]

16 minutes ago, Ferdinand said:

I wonder if I can have 2 systems exporting at once if I go for connected?

It is how micro-inverters work.

[Ferdinand]

8 minutes ago, SteamyTea said:

It is how micro-inverters work.

 

Hmmm. My existing system us fully Solaredge'd thanks to the tree mentioned above. I think that is different (?)

 

F

[Ferdinand]

Interesting - speaking to the company for the carport piccie above, the product is not launched yet and they are focused on their commercial install business 🙂 .

 

Interestingly they say the minim roof angle is 5 degrees, which is roughly what I would want - my way to do the aesthetics would be to have the roof shallow such that the panels cannot be seen from the front - even at verands roof height.

 

F

[SteamyTea]

11 minutes ago, Ferdinand said:

Interesting - speaking to the company for the carport piccie above, the product is not launched yet and they are focused on their commercial install business 🙂 .

 

F

While raising venture capital no doubt.

[Ferdinand]

16 hours ago, Dillsue said:

Q1- you need permission from your DNO to export more than 3.68kw so you should already have permission for your 10kw system. If you want to export more, you need DNO approval of a G99 application.

So a conversation required with the appropriate department.

16 hours ago, Dillsue said:

 

Q2- no problem running 2 or more systems in parallel. We have 2. 

 

Useful - so I should be able to go grid-tied on a new say 6kWp install, if DNO decide there is capacity in the network to take it, without affecting the existing FIT.

And I can stuff neighbour's mouth with a small amount of gold to get him to act on the tree rather than having to bugger about moving panels.

16 hours ago, Dillsue said:

Q3- its up to you how you configure things and somewhat dependant on what export your DNO will allow, but altering your FIT system is regulated so understand what the rules are before comitting to altering anything

Cheers.

 

F

[Dillsue]

17 minutes ago, Ferdinand said:

Useful - so I should be able to go grid-tied on a new say 6kWp install, if DNO decide there is capacity in the network to take it, without affecting the existing FIT.

Yes, if youre getting deemed FIT export payments, as all your FIT payments are based only on the generation meter reading. If youve opted for metered FIT export payments(SEG) then youll need to meter your FIT and non FIT export separately.

[Ferdinand]

28 minutes ago, Dillsue said:

Yes, if youre getting deemed FIT export payments, as all your FIT payments are based only on the generation meter reading. If youve opted for metered FIT export payments(SEG) then youll need to meter your FIT and non FIT export separately.

 

I've been on deemed 50% export since 2016.

 

But I am just swapping to Octopus Agile Outgoing (Export Meter MPAN just approved), which will presumably mean separate metering when I take the next steps in the future and fit a second array..

 

F 

[Dillsue]

3 minutes ago, Ferdinand said:

 

I've been on deemed 50% export since 2016.

 

But I am just swapping to Octopus Agile Outgoing (Export Meter MPAN) just approved, which will presumably mean separate metering when I take the next steps i the future.

 

F 

Yep. Speak to Octopus and let them know youre plans. If you have the new system MCS installed then I think youll be able to run all your export from both systems through a single meter, but check with Octopus. Dont forget to speak to your DNO first as its all hypothetical until they give the go ahead.

[Ferdinand]

Here's another one. They seem to be around.

 

[Ronski]

Minimum recommended angle is 10 degrees so the panels can self clean when it rains, this is stated in one of the solar panel manufacturers install guide.

[Ferdinand]

15 minutes ago, Ronski said:

Minimum recommended angle is 10 degrees so the panels can self clean when it rains, this is stated in one of the solar panel manufacturers install guide.

 

The 5 degrees was from the manufacturer, unprompted - I just asked for the minimum angle.

 

But I'll check in more detail of course.

[Ronski]

I couldn't find the minimum installation angle, until I stumbled across it in the JA Solar installation manual, section 4.2 tilt angle.

 

https://www.google.com/url?sa=t&source=web&rct=j&url=https://www.jasolar.com/uploadfile/2019/0129/20190129030921131.pdf&ved=2ahUKEwjJ1bOy_bn6AhUJB8AKHXLRDrQQFnoECBUQAQ&usg=AOvVaw0UQGhaq4Yom726WScCE8_o

 

Edited September 29, 2022 by Ronski