Dillsue

Reducing load will increase the voltage, so Try that at the times you're getting the problem and see if it clears things up

Get someone who's familiar with doing this to show you where to measure, where to put the probes and which range to select. There's a fair chance of exposed bus bars behind the cover with 400vac on them that have got the potential to kill you and/or spoil your xmas.

If you look at the grid voltages in the snap shots you posted, the L3 phase is up to 252.4vac when your only generating a few hundred Watts, so you're running close to the grid max. Maybe your inverters grid voltage limit has reset to 253vac after the power cut and you're hitting that? If you put a load on that phase, like an electric fire, it will pull the voltage down. Maybe add a kw or 2 of load to each phase when you want to test things

The DNOs max supply voltage is 253vac but your inverter can likely push the house voltage higher before it shuts down. Before our DNO upgraded our transformer mine has in the past run up to 262vac before it shuts down.

They look to be the same panel with 5 watt difference? If that's the case you'll be fine mixing and matching. You can put them on separate MPPT inputs on your inverter if you want to get the last 36watts(5x9) out of them, but you're unlikely to notice the 36w loss if you mix them up For clarity your official approval is almost certainly for your inverter output not the number or capacity of panels connected to it, so don't get hung up on the number of panels you have if other panel configurations would work better for you.

If you're using optimisers and likely micro inverters, you can mix and match panels. We've got 310, 320, 335 and 405 watt panels all on the same inverter. There's a cost overhead, but optimisers have lots of advantages one of which is the ease of alteration/expansion.

Yep it's a G100 compliant inverter that's required to legitimately implement export limitation. G100 is an industry spec produced by the ENA for all DNOs to use . If yours has said they don't trust the spec then they really need to go back to the ENA with their concerns. On the other hand it may only be the view of the the individual you contacted and if you pressed them they would(should) permit export limitation??

Ask them what their own G100 spec is for.

But I wasnt referring to you. I was commenting on Helene who says they've got very limited knowledge. Someone who sees 4 screws on an enclosure when someone experienced says theres only 2 so they maybe going into wrong enclosure. It's nuts to suggest someone with no/limited experience goes into a live enclosure when it can easily be isolated.

Send the designer the photo as that's got 3 phases going in and 3 cables coming out of the back going to 3 isolators....looks pretty 3 phaseish to me. SPEN upgraded our transformer last year to 25kva single phase just for us. If that's 50kva single phase for 4 houses then that sounds relatively underrated for an electrified future......unless it's actually a 3 phase unit. Maybe they've got their records wrong!

Your transformer is already 3 phase????

If you need to ask whether to isolate before removing a cover, there's no question you should isolate before removing the cover.

If they are taking more than is due/agreed, just cancel the DD. They'll soon be in touch and far more amenable to sort things out.

Of course they'll be cock ups but that doesn't make an excessive DD legitimate. Just contact your bank and ask for a refund of the excess over what should have been taken.

If they charge you incorrectly, you get a refund regardless of whether they gave you notice. If you've made a mistake in the meter reading, correct it and get a refund. If they've made a mistake get them to correct it and get your refund. If your bill is £100 they cant give you notice that they are taking £500 and it be legitimate just because they gave you notice. DD is covienient for everyone but the DD Guarantee is there to protect consumers who always have the upper hand

I think the DD guarantee says diffently! If they overcharge you can ask for a refund and they are obliged to give it. Direct debits can be fixed to and taken on a set day to allow consumers level payments over the year. Ours is fixed and taken on the same day each month.

Surely they'll DD the amount specified in your bill and take the DD on the date in the bill so no random sums at random times?

Under G98 you're limited to 16amp per phase. You need to add up the potential export for each phase, its the potential that your DNO is interested in, not what you might actually do. If you add a battery(car or standalone) with its own AC connected inverter then you need to add the potential output from the battery inverter to the potential output from your PV. If the sum comes to more than 16 amp on any phase then you've gone over the G98 limit and need to get permission for the excess over 16amp via a G99 application. If your PV or battery inverter supports export limitation then you can get either or both set to keep your export to no more than 16amp but you still need permission via G99/G100

I think there's plenty of cars including the Leaf that support V2G but there's no bidirectional chargers yet approved for UK use

If you're having a new single inverter then you can theoretically wire your 6 new panels in a single string into the inverter. Is there any shading in the new panel location? You won't breach your FIT payments for adding more panels. You get paid only for the generation attributable to the original capacity. If your original FIT system was 2.5kw(10x250watt??) and you add 2.5kw(6x410watt) then you only get paid for 50% of what your generation meter records. Just let your FIT payer know about the additional panels and they'll sort out the pro-rata payments.

Not to your existing inverter as you'll be overpowering it...3 panels won't give you enough start up voltage, 4 or more will exceed the 1300 watt power input limit

Nice positive take on a hybrid system and music to my ears. Planning on adding a HP next year alongside an LPG boiler and WBS. We select between the boiler or the WBS with 2 port zone valves rather than NRVs so will tie in the HP with another one.

Outside of official trials, AFAIK there's nothing certified in the UK yet for a grid tied system. If the car has V2L for power tools/camping etc then it's been suggested that you could hook up the V2L to a grid tied inverter that has a generator input. The V2L from the car is then seen as a generator. You'd need a separate charger to charge the car.

No requirement to meet any MCS standards....all optional if your not using an MCS installer. Single line schematic is only required at the incoming supply and only needs to show the 240vac wiring so the DNO knows where to isolate. No need to show panel wiring unless you want to. From the installers point of view he seems to have been asked to install kit supplied by the OP. Not sure I'd be slating the installer when he may well have assumed someone else has matched the panels to the inverter. Installer should have raised the issue of lack of G98 compliance though!!

Get the correct inverter to match the panels. With 3 panels on an inverter you'l likely be on the limit of reaching the 120v start voltage, as you've discovered. Put 4 or more panels on one inverter and youll hit the start voltage but be exceeding the max power input of your 1200s so be wasting valuable FIT generation. If you've already got 2.5kw of panels and adding another 2.5kw you'll be well over the combined max input of the 2xSB1200s. You are adding to the system rather than like for like replacement?? You do have the option of reworking your FIT system by changing the inverter and adding the new panels to the larger inverter. As you're making significant changes might be worth discussing with your FIT payer in advance as some don't have a clue....Scottish Power are utterly useless. Hope their CEO is reading this:)