Nothing like leaving it to the last minute! Couple of PV questions...

Temrael

Hi all,

We've been thinking about PV for some time but only just realised the FiT is ending! We've had to get our backsides in gear but I think we might be nearly sorted.

We've had a quote from a well respected local company for 14 x Jinko 290w panels and Solis inverter for just under £5k which seems about right. The quoted output is 4.13kWp.

Our house is just a few degrees off east/west and so we're looking at putting a string of 6 panels on the east side and a string of 8 panels on the west. The installer has one last available installation slot for us later this month which he's pencilled us in for.

We've got a small 3 bed detached house and electric vehicle. My wife and I are starting to work from home more now so hopefully this will be a good way of using the electric produced as we can pop the laundry/dishwasher/car on then. We might look to add battery storage later, but not for a while I think.

We've had an EPC check this morning and are just waiting for the results of that. I think we'd only proceed if we're a D or above really.

A couple of questions I'm hoping you guys might be able to give pointers on. I just want to confirm my understanding really before we go ahead (depending on the EPC)...

a) Our energy supplier is Tonik (we switch around) and whilst they have a FiT license, they apparently only provide it for customers that they've actually installed solar for. Am I right in thinking we can simply apply to any of the big FiT licensees (e.g. EDF) and get setup on FiT with them as it's totally separate from our supply arrangements and they're obliged to take us on so long as we meet the FiT criteria?

b) Does anyone have any recommendations of which suppliers to use/avoid for the FiT? They all pay the same rate so presumably we should just be selecting one based on customer service/billing? EDF sound ok, is there any reason to go with someone else?

c) I was worried about the deployment cap for the FiT. Looking at it here though it looks like as of last Friday they were less than 10% through the sub 10kw PV cap for this quarter, with only a few weeks to go. So even if there's a last minute rush there looks to be little likelihood of the cap running out? Is that right?

d) Any thoughts on the Jinko panels? They are 17.72% efficient apparently which seems to be at the lower end but they are cheaper than those from LG etc. They come with some wizardry called "Maxim Integrated" which allegedly helps turn off individual cells if they are soiled with bird poop or something. Sounds very clever but I'm not sure the extent to which it helps in practice.

e) Given that we'll ideally use over 50% of the energy we generate, I think the same number of more efficient panels would not only push the install price up but also make it less likely we'd hit that 50%. Any thoughts on that trade off?

f) Any other gotchas we might not have thought of?

Any contributions would be much appreciated. We've done a fair bit of reading but it's all been a bit of a rush and I just want to make sure I'm not getting anything wrong.

Thanks!

mgbond

a) you can use any.


I'm sure your aware but although your system can produce over 4kw, only 3.6 (I think) will make it out of the Inverter as it is capped unless you apply for permission to supply more.


but (especially) as you have panels spilt across 2 roofs then you will probably never it that 4kw anyway so this is why its best to go for a bigger system. So on low light days you can still produce more.


Mine is a 6kw system and is split like yours my max I could generate at one time is just over 5kw but as I have had it agreed then all of that will be usable as my inverter does not cap it.

Zarch

Just for info, I have 17 x 300w panels (5.1kw) across a variety of orientations connected to a 3.68 inverter (the max without needing DNO permission).

As mgbond says, its unlikely all the panels will work at their maximum being pointed in different directions. And whilst I occasionally hit 3.68, most of the time I don't. But i'm still benefiting from having more panels.

My advice is more is better if you can afford it. It especially helps during the winter months when you're struggling to cover base-load on some murky days. If you're WFH and trying to fill up an EV then more is surely better?

PS. I'm with EDF for FIT and no problems so far. Payment is swift and via BACS.

Temrael

Thanks mgbond.

Yep just sat here the house seems to use around 250w so I was working on the assumption that we wouldn't often get much above 1kw usage and so therefore a real world peak of about 2kw might work well.

I see your point about producing as much as you can in low light conditions. I'll see if the installer thinks it might be worth upping the panel spec a bit.

Temrael

Thanks Zarch, unfortunately my EV will mostly not be here in the day (the wife gets to wfh more often) but yep on the occasions when we do charge during the day that will obviously take whatever we're producing at the time, and then some!

Zarch

Temrael wrote: »

Thanks mgbond.

Yep just sat here the house seems to use around 250w so I was working on the assumption that we wouldn't often get much above 1kw usage and so therefore a real world peak of about 2kw might work well.

I see your point about producing as much as you can in low light conditions. I'll see if the installer thinks it might be worth upping the panel spec a bit.

Can you fit more panels on the roof? Rather than chasing 30w per panel? Things may have changed in the 6 months since I was pricing things up, but 330w / 350w panels were way more expensive than the 300w I went with.

And to such an extent that I didn't think i'd get the extra outlay back over the course of the FIT.

Also, you stick the washing machine on and even A+++ rated are going to take usage past 2kw-2.5kw. Tumble dryers the same.

Temrael

Ahh I see, that's a good point. We'd be able to squeeze some more on the west side, not sure about the east. I'll ask him

mgbond

most people fit 5kw systems that are capped to 3.68. I had 20 x 300W panels with 3 optimizers and an IBoost for 6.8k.

mre15

I have the Jinko panels fitted as I get some shade from a chimney. Its a cheap mans solar edge but without the monitoring or extra price.

My panels are working very well, often providing more than they are rated.

I also have a Solis inverter, although I have the energy store version which is a hybrid with a battery.
This also works very well, just remember to buy the monitoring wifi dongle to go with it to allow you to see what's happening with an app or online.

Temrael

Thanks all, looks like we're in business!

The EPC check came back as a C which is great (we'll actually be a B with PV) and the installer is going to bung another panel on the back so 6 east, 9 west for around 4.5kWp (up from 4.13).

One thing the installer has left me mulling over is where I want the inverter. He's suggested the loft but I'd naively assumed it had to go in the meter cupboard (where the consumer unit is).

The meter cupboard is located on the ground floor in the middle of the north/gable wall, directly beneath the middle part of the attic. So it's no difference really in terms of the run of cable from the panels to the inverter i.e. we'd come into the house at the same point on wall the only difference is whether it's at attic level or ground level.

What are the pros and cons? Presumably if we add batteries later they ought to live with the inverter, and there would obviously be a lot more room for them in the loft. But do indoor battery packs like a nice stable temperature (the loft gets really hot in summer and properly cold in winter) in which case should we pop the inverter in the meter cupboard in readiness?

I'm happy for the inverter to live out the way in the loft (I guess the generation meter can still live in the meter cupboard?) but I should probably avoid that if that'll complicate adding batteries later.

What do you guys reckon?

mre15

Have you looked at the size of the inverter offered, they are a lot bigger than you might think.
I also don't like the loft as an installation location, mine is in a utility room.

If you are considering batteries in the future then unless you buy a hybrid inverter now they won't actually connect to your inverter. They will have to be AC coupled and therefore will require an additional inverter.