Zero PV generation allowed by DNO

[scottishjohn]

13 hours ago, willbish said:

Their latest position is that after upgrades have been completed (at their expense) following a 'fit and inform' of 16A per phase, the network can then
support a massive 3.8kWp of PV.

16amp PER phase --that surely means you can run a much bigger array then 4kw,thats 3.8kw per phase --so a total of  11.5kw  ?,onthe prsumption you have a 3phase supply

or am I being thick 

[willbish]

Thanks for the comments. From what I've now read it looks like the G98 regs should/could work in my favour.

I'm thinking to go back to the DNO and say:

"thanks for the increase to 3.8kWp. I will now be installing 6.0kWp split equally between an E/W roof using a G98 certified 3.6kW inverter on a fit and inform basis.
My electrician will send you the correct testing and completion paperwork. If you're not happy come and take a look yourself."

 

@Nickfromwales
No batteries from the outset

 

@scottishjohn
If I had 3 phase, 16A per phase would be ample.

[joth]

10 minutes ago, willbish said:

If I had 3 phase, 16A per phase would be ample.

Out of interest, do you know 3ph is not possible or have you had a quote for getting 3phase installed? It took me 2 days and zero cost to get a quote, so well worth it. (Tip: when the DNO surveyor comes give the the list of things you maybe considering, and they can give a price estimate for each. They can only go away and formally quote for one job at a time, but this was super useful for comparing cost of moving existing meter vs getting a new 3ph feed (for my case this was £1k vs £3k, purely because new feed involves carriageway closure and roadworks)

 

Having said all that, for a split E/W roof your current plan sounds solid so probably not even worth opening this can of worms.

[willbish]

7 minutes ago, joth said:

 have you had a quote for getting 3phase installed?

Yes I had a similar experience, very helpful discussing options and providing quick quotation. £5590 inc VAT at 0% for 3 phase

[scottishjohn]

reading this topic 

so if you have 32amp system and you use a limiting device / invertor to only allow 16amp to flow htrough it to grid--what happens to the other half of what you produce on a summers day 

-what,s the  downside 

i ask this cos in winter when you need most power  the daylight will be worst 

[Ed Davies]

26 minutes ago, scottishjohn said:

so if you have 32amp system and you use a limiting device / invertor to only allow 16amp to flow htrough it to grid--what happens to the other half of what you produce on a summers day 

 

Either you use it in the house or the inverter sees that the export current is approaching 16 amps and stops taking so much power from the panels by taking less current and allowing the panel voltage to rise above Vmpp so the extra power gets dissipated as heat in the PV panels. Obviously, if you've got a good use for it in the house then it's better it goes to that. However, whatever diverter or other mechanism used to control that doesn't have to be one accepted by the DNO if they accept the export limit of the inverter as a backstop.

[scottishjohn]

2 hours ago, Ed Davies said:

 

Either you use it in the house or the inverter sees that the export current is approaching 16 amps and stops taking so much power from the panels by taking less current and allowing the panel voltage to rise above Vmpp so the extra power gets dissipated as heat in the PV panels. Obviously, if you've got a good use for it in the house then it's better it goes to that. However, whatever diverter or other mechanism used to control that doesn't have to be one accepted by the DNO if they accept the export limit of the inverter as a backstop.

sounds like best option is blinds for pv panels in summer

[Ed Davies]

1 hour ago, scottishjohn said:

sounds like best option is blinds for pv panels in summer

 

That's completely pointless. PV panels are fine in direct sunlight if you don't take the energy away, unlike some solar thermal panels. They just radiate away the excess as thermal infrared in much the way that any similar-coloured object left out in the sun would. If the house and the distribution network both don't want the power then just don't take the DC current needed for it. The only “issue” is making sure either the generation or the export (depending on your chosen interpretation of the rules) is limited to 16 A/phase in a manner which is approved by the DNO. I highly doubt they'd accept blinds over the panels, however operated or controlled, for that purpose.

 

Summer isn't usually the time of peak production, anyway. Normally that happens in late spring. E.g., for south-facing panels at 35° inclination near Kirkcudbright the peak month, according to PVGIS, is May.

[SteamyTea]

30 minutes ago, Ed Davies said:

Summer isn't usually the time of peak

Too right.

It is a combination of angles, hours of daylight, ambient temperature and cloudiness.

Though I think my peak generation month is June. Not checked for years.

[scottishjohn]

thats fine then if panels can get rid of the heat without suffering  --just from last reply it seemed that heat build up could be a problem  in panels 

[SteamyTea]

3 minutes ago, scottishjohn said:

 

thats fine then if panels can get rid of the heat without suffering

 

They work ok in deserts, so I think the UK climate poses little challenge.

Now the inverter on the other hand is better off kept as cool as possible, especially if it is limiting output.

I have get to see some decent, public data on inverter life.

[scottishjohn]

1 minute ago, SteamyTea said:

They work ok in deserts, so I think the UK climate poses little challenge.

Now the inverter on the other hand is better off kept as cool as possible, especially if it is limiting output.

I have get to see some decent, public data on inverter life.

maybe that,s the weak spot then  if you have too many panels and restrict it most of the time 

[SteamyTea]

Someone posted up about a new inverter that got rid of the 'magnetics'.

Getting rid of the capacitors is what is needed.

Or at least a simple replacement service pack.