Solar PV Quote seems excessive

Sterlingtimes

Thank you Insect, Eric, Martyn and Tunnel for your advice.


It was Martyn's and Tunnels combined kWp that got me thinking in contrast to Insects 3.84 kWp.


If I go for 4 kWp with micro inverters then it should be simple to upscale later should I choose to do so.

EricMears

tunnel wrote: »

Probably better to advise people to get the DNO approval for anything over 4k to be on the safe side

To be absolutely safe, you'd need to check with DNO for anything over 3.3 kWp since what they're actually interested in is the exported amps not exceeding 16A and bear in mind that the grid voltage might just be as low as 210V sometimes.


But it's a ludicrous 'rule' ! There can't be many houses with a "Board's Fuse" of less than 60A (and many more with 100+ A fuses) so the DNO must be confident that their cables are safe at 60A (equiv to 13.8kW) and I'm afraid I find it very hard to believe in the concept of a bit of wire that's OK for 60A downhill but dubious at 17A uphill

tunnel

Sterlingtimes wrote: »

If I go for 4 kWp with micro inverters then it should be simple to upscale later should I choose to do so.

It is simple to upscale later but at a cost(i know). If you're seriously considering going large then you'd be better doing it from the off then you have only 1 lot of costs like scaffold, even tho the FiT is lower(about 1p) the costs per kWp become much less making the install more financially viable

Martyn1981

tunnel wrote: »

I'm not entirely sure that's right Mart, my parents couldn't exceed the 4k threshold on an E/W split, i asked about 5-6k of panels with a capped inverter and was told in no uncertain terms that that couldn't happen and that it went on the panel size.
Probably better to advise people to get the DNO approval for anything over 4k to be on the safe side

True, but you asked them first, so gave them the chance to set a lower limit. Pretty certain that if you don't exceed 3.68kW/16 amps at the inverter, and don't ask em first ..... then they have to accept it.

All ludicrous stuff. I'll see if I can get a more definitive answer from some of the sparkies/installers on Navitron, who may have come across this before.

@sterlingtimes - I think the DNO's (certainly WPD) used to have different rules for micro-inverters as there isn't a single inverter to cap, so you might need prior approval if the potential output of the sum of the inverters exceeds 3.68kW. But, WPD's own advice has changed several times since I first started looking at it 2 years ago ..... even more fun!

Mart.

Martyn1981

Martyn1981 wrote: »

All ludicrous stuff. I'll see if I can get a more definitive answer from some of the sparkies/installers on Navitron, who may have come across this before.

Right! Been PM'ing tunnel, and now have some more info from a couple of very helpful installers on the Navitron site:

http://www.navitron.org.uk/forum/index.php/topic,23462.msg273042/topicseen.html#msg273042

Technically, theoretically, in practice, DNO's shouldn't concern themselves with the DC side kWp of a system. Their interest should be the potential AC side kW output.

If the AC side will be 3.68kW or less, or capped, then everything should be fine.

However, who you happen to speak to, and what they know (or don't) that day could mean all sorts of information/advice/instructions from the relevant DNO.

If T's experience is anything to go by, then if a 3.68kW cap is good enough, then probably best not to ask them first!!!!

So, does this help to clarify things ...... probably not a lot, but hopefully just a little.

Mart.