New to this and looking for advice please

[Tinbum]

1) I was told that if I go for more panels I'd have to upgrade to a 3 phase supply as anything over 3.6kW could not be fed into the grid, if I'm not using it, on a single phase supply. Is this not the case? If I am able to have more panels, I will.

Rubbish- its the inverter size that matters. You could put 6kw of panels on a 3.6Kw inverter even more so in your case as your panels are split between E and W.

[nowty]

1) I was told that if I go for more panels I'd have to upgrade to a 3 phase supply as anything over 3.6kW could not be fed into the grid, if I'm not using it, on a single phase supply. Is this not the case? If I am able to have more panels, I will.

Rubbish- its the inverter size that matters. You could put 6kw of panels on a 3.6Kw inverter even more so in your case as your panels are split between E and W.

+1 Agree, most decent 3.68kW inverters for a standard G98 application will take 5kW or 6kW of panels easy, and it’s the inverter power that the DNO cares about.

[JohnW]

1) I was told that if I go for more panels I'd have to upgrade to a 3 phase supply as anything over 3.6kW could not be fed into the grid, if I'm not using it, on a single phase supply. Is this not the case? If I am able to have more panels, I will.

Rubbish- its the inverter size that matters. You could put 6kw of panels on a 3.6Kw inverter even more so in your case as your panels are split between E and W.

+1 Agree, most decent 3.68kW inverters for a standard G98 application will take 5kW or 6kW of panels easy, and it’s the inverter power that the DNO cares about.

Thank you, I clearly have a lot to learn

[Moxi]

Hi John,

Glad you joined, I told you the forum would be helpful.

You can as lots of people have said put five or six kWp of panels on the roof in an east west split but don’t think that because you’ve got xKWp of panels that you will get the same xKWh.

As long as you understand that people are saying fit xKWp to get ykWh more often then that’s ok. The inverter will be rated at a given number of KW and that’s what limits the power you are able to use. If that power available from the combination of panels and inverter is above the legal limit the DNO will allow you (as I said 3.6kW per phase is their default figure) then you need something in place to cap the export to the agreed level. That’s where the greater knowledge of the forum can help.

There’s a lot to discuss for your set so that you get the best system for you and your needs and we definitely need more info than is presently available.

So starting from first principles how much power do you use per 24 hr period and if possible how much of that is daytime compared to night time ?

Are you principally replacing an old slate room and using some pv panels to replace slates thereby making some power as a secondary objective OR are you out to make as much power as you can and planning to get more panels later as either a ground mount or on suitable outbuildings?

I know you’re like me and don’t have a hot water tank but do you have a wet central heating system? What split in electrical energy is between heating water heating spaces and running lights and appliances ?

As you probably read and as JB suggested there’s many answers and many solutions but your solution will be specific to your circumstances and to get meaningful guidance we need to understand your circumstances more and what you want from the system.

Moxi

[JohnW]

Hi Moxi

It's difficult to say what our annual electricity usage will be this year, last year it was >13,000 kW (yes over 13,000!) However, we were running a very expensive 13amp electric Aga, that was a real gas (well electric) guzzler, we got shot of that a few months ago, and replaced it with a more controllable electric range that doubles as a heat source when needed. I think our ongoing annual usage will average 20kW per day more in winter, when the range is used as a space heater, and less in summer. So the pv system will provide less electricity when we need it the most, unfortunately. As we are at home all day, electricity doesn't have a particular peak.
We have no hot water storage, and an external containerised combi oil boiler for heating and hot water, we use about 1000 ltr of oil per year, and we have two wood burning stoves.

As the roof needs replacing, it seemed like the ideal opportunity to combine some, in roof, panels to help reduce electricity costs and offset the cost of installation as fewer slates will be needed.

I don't have the funds to do too much at the moment, so want to get the best I can whilst replacing the roof. In the future, there could be the opportunity to put more panels on a south facing outbuilding.

I'm just trying to realise some ongoing savings whilst replacing the roof and upgrading the insulation.

Should I contact the DNO and ask how much I can install if I maximise panels and not get batteries for the time being?

[Fintray]

Should I contact the DNO and ask how much I can install if I maximise panels and not get batteries for the time being?

You can install as much as you like it is how much you can export that is limited (3.68kW max on single phase but DNO can allow more), a G100 inverter can be programmed to limit the export so you could have 10kW/peak of panels but it will limit the export to 3.68kW.

[Moxi]

Thanks John that packages it more neatly for everyone to contribute.

So the basis of your design is fill the roof with as many panels as possible on an east west basis dc coupled to the biggest hybrid G100 inverter you can get so you can maximise self use by whatever means practical.

John during the day what would you anticipate your maximum kW load is ? As this will indicate the minimum size of the inverter you would ideally need. Ie 3kW 5kW etc and for how long you pull that load.

Fintray / Forum; are all G100 hybrid inverters programmable for export limits and are there any recommendations for inverters ?

Moxi

[JohnW]

Should I contact the DNO and ask how much I can install if I maximise panels and not get batteries for the time being?

You can install as much as you like it is how much you can export that is limited (3.68kW max on single phase but DNO can allow more), a G100 inverter can be programmed to limit the export so you could have 10kW/peak of panels but it will limit the export to 3.68kW.

Hi Fintray, So is it the case that the inverter controls how much is sent back to the grid? For example, if I had an inverter rated at 5.5Wp and the grid would only allow be to export 3.6kW I could have panels capable of producing 5.5kW and the inverter would only export the maximum allowable and somehow stop the pv panels producing more than the grid will accept?

[nowty]

Should I contact the DNO and ask how much I can install if I maximise panels and not get batteries for the time being?

You can install as much as you like it is how much you can export that is limited (3.68kW max on single phase but DNO can allow more), a G100 inverter can be programmed to limit the export so you could have 10kW/peak of panels but it will limit the export to 3.68kW.

Hi Fintray, So is it the case that the inverter controls how much is sent back to the grid? For example, if I had an inverter rated at 5.5Wp and the grid would only allow be to export 3.6kW I could have panels capable of producing 5.5kW and the inverter would only export the maximum allowable and somehow stop the pv panels producing more than the grid will accept?

Yes,

Thats how Nowty Towers operates, but it is a G99 pre-install application to the DNO (if your fitting a large inverter).
This day it was wall to wall sunshine, and note the yellow grid feed in never exceeds 3.68kW because the inverters are throttled back.



Or yesterday, note the generation increase as we returned home and plugged in the EV.

[Moxi]

John,

We need to move next door to Nowty towers!

Today here is been a case of under or in the cloud! so far we have produced 1.5kWh total for the day although its starting to brighten a little and we are forecast some sunny spells around 6 till 9 tonight.

Thanks Nowty - how do you feel about a North South DC interconnector between Gwynedd and Nowty towers?

Moxi