Solar Panel installation basics

Reed_Richards

mcn99 said:

Currently my electricity bills are quite high. I have 2 areas that are heated by electricity plus we have a number of computers running 24h.

If these are home/office PCs they will most likely use 500 W or less.  The power requirement goes up if you have a dedicated graphics card but that is most frequently used for computer gaming.  A monitor might consume up to 100 W but presumably is not on for 24 h.  Anything that is on for 24h is poorly-matched to solar panels.

mcn99

I think i have discounted the idea of batteries at the moment its just too expensive to justify, and i suspect with the amount of research being done on battery technology, the cost will quickly reduce. I also think in the future we may be using 2nd hand ev batteries, so for this installation i will give them a miss and try to keep installation cost to an acceptable level. I may revisit this in a few years.

Useful information on 20% of power being average from setup, I knew the power rating of panels was theoretical and in ideal conditions, but thought it was more than 20% average.
  
if i do go for 6kw and just put in a 3.6 diverter, how much power would in reality would i be throwing away ie is it worth splitting it to ensure i can use power in ideal conditions, or is it going to so rare that i am producing over the standard feed  its just not worth it.

Next week plan to phone up a few local suppliers, and see what they propose, so i just want to have some basic understanding of the limitations of these installs.

[Deleted User]

Hexane said:

Dolor said:

Your installer will submit the appropriate paperwork and you will pay c.£350 for the DNO to review your proposed installation.

I paid nothing for the DNO to review my installer's proposed installation, although I'm not in southern Scotland. Ultimately the DNO agreed a 6kW export limit at no extra cost.

I suspect you did. It would be hidden in the quote. All DNOs raise charges.

Meatballs

With DNO applications, can you ask your installer to tack on an extra 3kWh/5kWh for future battery capacity rather than repeatedly send and pay for more applications? 

Hexane

[Deleted User] said:

Hexane said:

Dolor said:

Your installer will submit the appropriate paperwork and you will pay c.£350 for the DNO to review your proposed installation.

I paid nothing for the DNO to review my installer's proposed installation, although I'm not in southern Scotland. Ultimately the DNO agreed a 6kW export limit at no extra cost.

I suspect you did. It would be hidden in the quote. All DNOs raise charges.

Well, the charge my DNO tried to raise was asking for over £1000 for permission to connect a 6kW generation system. (So that they could make "checks".) When I said no to that, they agreed to do it for free instead.

The installer was willing to fit the same hardware for the same price regardless of whether they asked the DNO for permission or not. Of course, maybe it's all part of their business ("hidden in the quote") but they seemed a lot more up-front, as I saw it, than the larger companies that turned up on-site to promise much less realistic on-site usage and returns, and also to claim that installing a system of more than 4kW peak was "impossible".

(In other words, they couldn't be bothered asking the DNO, they preferred just having a one-size-fits-all approach even if the customer - me - wanted more. That's how to lose my business.)

arty688

Am I right in thinking no matter the size of your array if you limit the export to 3.68kw you don’t have to apply to the dno just inform them? If so then how much ch will you actually be loosing as how much ch generation over that level will you get?

JKenH

arty688 said:

Am I right in thinking no matter the size of your array if you limit the export to 3.68kw you don’t have to apply to the dno just inform them? If so then how much ch will you actually be loosing as how much ch generation over that level will you get?

I think you might find that will differ from one DNO to another. Not all accept export limiting devices or at least did when I was enquiring. 

QrizB

... and a 3.68kW inverter connected to 6kW of panels, for example, usually won't need permission while than a 6kW inverter plus export limiting device connected to the same array might well do.

Another option is to have a DC-coupled battery, like @Reed_Richards does. Any excess over 3.68kW can be diverted to charge the battery, then allowed out again when the solar output falls. (I don't know exactly how RR's system works but its's something like that.)

arty688

look looking at the WPD website it looks like there is a fast track system.

• A G59 Fast Track application process has been developed for single phase installations that comprise ER G83/G98 compliant generation (e.g. solar PV) rated up to 16A and ER G83/G98 compliant energy storage rated up to 16A fitted with an ER G100 compliant Export Limitation Scheme that restricts the export to 16A per phase or less. Further information on the G99 Fast Track process is available here.

Unfortunately the link on the here doesn’t work…

Martyn1981

arty688 said:

Am I right in thinking no matter the size of your array if you limit the export to 3.68kw you don’t have to apply to the dno just inform them? If so then how much ch will you actually be loosing as how much ch generation over that level will you get?

Hiya, I think there are two sides to that. The simple one is yes, if you have an inverter that restricts/limits output to 3.68kW (or a system size under 3.68kW), then the installer notifies the DNO after the install (within 28 days I believe).

The more complicated answer, and linking in to your next post, is export limitation to 3.68kW, rather than inverter output. I was avoiding mentioning this whilst reading along, but since you've spotted it, it's really interesting, and as per your post will require installing kit that has been approved by your DNO (G100 compliant) to prevent export exceeding 3.68kW*. So approved AC side batteries, V2G (vehicle to grid charging infrastructure) etc.. That way the inverter can produce more than 3.68kW if the system is larger, but gets restricted when the kit sees the export rising to 3.68kW.

*Or a higher pre-approved limit.


Doesn't help you today, but I assume that in the future, grid tied inverters may come almost as standard with export monitoring to cap generation, rather than just 3.68kW at the inverter. The crucial thing though for DNO approval, isn't just that they monitor and manage, but that if they fail for some reason, they still can't exceed the limit. My application for a V2G trial a couple of years ago was declined, because the kit the company was using was supposed to prevent excess export in the case of a failure, but it hadn't yet been tested and certified, so therefore wasn't (then) G100 compliant, and therefore the DNO said NO as my property didn't have enough export 'headroom' after taking my PV export permission of 5.9kW into account.

[Edit - That might not make much sense, so just to clarify, there's no reason why you'd want to export from a vehicle and all your PV at the same time. The issue was (for the DNO), did the V2G have the appropriate kit/guarantee, that it wouldn't and couldn't export from the vehicle in error, resulting in a total export beyond that which they felt the local infrastructure could manage. M]