Which wattage of inverter to pick?

[SolarNoob]

Hi looking for some advice, I’m planning around a 5kWh pv array and am getting mixed messages re inverter size.
i’ve been quoted for a standard 3.6 hybrid solis, but am concerned about clipping.
should I be?
It seems not that long ago undersizing was the norm, but I can see a 4.6khw solis hybrid with the same start up voltage of 120v so would that be a better solution?
it seems to me a better match to a 5khw pv array?
any advice much appreciated.
cheers

 

[binky]

Bigger is better, inverter efficiency could drop to as low as 70% when undersizing was fairly normal, now they don't drop below 93% and run at around 97% efficient most of the time.

 

[Berserkerboy]

Will your DNO allow it? Mine insists I can only connect up to 3.6kw.

 

[SolarNoob]

Thanks for your replies , so a 5kw array and a 4.6khw inverter would be the norm nowadays?
my DNO (Scottish power) I’m told will be ok with this, obviously G99 and apparently a two month wait..

 

[binky]

Thanks for your replies , so a 5kw array and a 4.6khw inverter would be the norm nowadays?
my DNO (Scottish power) I’m told will be ok with this, obviously G99 and apparently a two month wait..

that will be fine if you can't get a 5kW inverter.

 

[SolarNoob]

that will be fine if you can't get a 5kW inverter.

So you‘d recommend matching the pv array to the inverter?
is that the norm these days trying to find out what others are recommending any why for new install.
cheers

 

[binky]

Yep, panels are +ve tolerance, so you always get a bit more than planned, and certain weather events can boost output for short periods of time. There's also a cultural thing to consider. German panels do exactly what they say they will, Chinese panels just about do what they are supposed to on a good day, and Japanese panels normally over perform, because they don't like to disappoint people. You rarely see Japanese panels these days, but a 2.8kw array I installed a few years ago actually peaks at nearer 3kw.

 

[SolarNoob]

Thanks for that, it seems from all the quotes I’m getting are using JA panels, wonder if that‘s just because of availability?
so might be settling for;

16 x 410w All Black JA Solar panels
10kwh Puredrive Battery
6kw Solis Hybrid Inverter
K2 Tile roof mounting system
Eddi Hot Water Divertor
Bird Protection

 

[glenns]

Will your DNO allow it? Mine insists I can only connect up to 3.6k

That'll be the export limit but you could have a larger inverter. I've gone for the 6kw Solis Hybrid for a few reasons but I'll have to limit its export to 3.6kw.

Not a big deal as I don't really want to export anything at just 5ppkw.

 

[binky]

JA panels are fine, and more available than other brands. My preferred panels are Q Cells, but getting these isn't easy at the moment.

 

[Gian]

Will your DNO allow it? Mine insists I can only connect up to 3.6kw.

Which network company is this. We are with spenergy and I was granted 8kw system ok it cost £380 for that pleasure. I would go back and try and find the person who actually deals with that area of tech as many call centers work off a script. New inverters now come with grid export limiter built in as well .

 

[binky]

Which network company is this. We are with spenergy and I was granted 8kw system ok it cost £380 for that pleasure. I would go back and try and find the person who actually deals with that area of tech as many call centers work off a script. New inverters now come with grid export limiter built in as well .

It varies a lot by region, how many other people have solar in your area, and how old the network is in your area. It also varies by whoever deals with your application, one fella I've had regular dealings with was a jobs-worth, his colleagues were very helpful. No DNO can't really say no to a grid limited inverter, and to be frank, with no FiT, it's fairly irrelevant these days anyway.

 

[SolarNoob]

That'll be the export limit but you could have a larger inverter. I've gone for the 6kw Solis Hybrid for a few reasons but I'll have to limit its export to 3.6kw.

Not a big deal as I don't really want to export anything at just 5ppkw.

So as your inverter is limited to 3.6kw did you have to only fill in a G98 instead of a G99? And if so did your DNO accept this? I’ll be in the same position.
thanks

 

[glenns]

So as your inverter is limited to 3.6kw did you have to only fill in a G98 instead of a G99? And if so did your DNO accept this? I’ll be in the same position.
thanks

Yes G98. My DNO is UK Power Networks and have been very good (so far), they have an entire portal for low carbon applications. They wanted the G100 cert (for export limiting) and G9X (ENA Test type cert) for the equipment, a site plan, photos of the consumer unit, main fuse and meter and a diagram of the proposed installation.

This was my first time putting anything like this together but having read plenty of posts on here it was pretty easy to figure out and get everything together. Was approved in lass than a day, now just waiting for everything to arrive so we can install and commission.

 

[Berserkerboy]

Which network company is this. We are with spenergy and I was granted 8kw system ok it cost £380 for that pleasure. I would go back and try and find the person who actually deals with that area of tech as many call centers work off a script. New inverters now come with grid export limiter built in as well .

South West Power. We live out in the sticks in a cwm of 4 properties. One of the other properties has 16 panels, so I assume 4kw with a 3.6 inverter put in at the start of FIT. We have 3.6kw of panels using microinverters. The transformer is a small unit on a pole. This is what SWP are saying would need to be upgraded if I needed to feed back any more. I guess they're worried about elevated voltages, especially if the other 2 properties install solar.
Presently waiting on a response on a G100 application to allow battery storage with an AC coupled inverter.

 

[binky]

South West Power. We live out in the sticks in a cwm of 4 properties. One of the other properties has 16 panels, so I assume 4kw with a 3.6 inverter put in at the start of FIT. We have 3.6kw of panels using microinverters. The transformer is a small unit on a pole. This is what SWP are saying would need to be upgraded if I needed to feed back any more. I guess they're worried about elevated voltages, especially if the other 2 properties install solar.
Presently waiting on a response on a G100 application to allow battery storage with an AC coupled inverter.

the transformers do not like being backfed more than 30% of their capacity. There is a possible way around this, submit applications for the neighbours at 16A, this may then force SWP to upgrade the pole transformer for free.

 

[Berserkerboy]

Ah, that will explain it. Hopefully, from my point of view, the G100 application will be accepted and I'll not have to go any further. I can't see that there will be any argument from them as I don't want to export, with no FIT or SEG, and will set up the inverter accordingly.
They're taking an inordinate amount of time to reply though, as they claim they're inundated. .

 

[binky]

Ah, that will explain it. Hopefully, from my point of view, the G100 application will be accepted and I'll not have to go any further. I can't see that there will be any argument from them as I don't want to export, with no FIT or SEG, and will set up the inverter accordingly.
They're taking an inordinate amount of time to reply though, as they claim they're inundated. .

After years of being in the doldrums, demand for solar has gone crazy, so they are no doubt lacking staff to process applications

 

[Berserkerboy]

Application accepted by Western Power yesterday. Phew!
Yeah, I'm sure you're right there Binky. I'm getting lots of requests for advice from people who know I've installed solar.

 

[hiddenhippo]

Yes G98. My DNO is UK Power Networks and have been very good (so far), they have an entire portal for low carbon applications. They wanted the G100 cert (for export limiting) and G9X (ENA Test type cert) for the equipment, a site plan, photos of the consumer unit, main fuse and meter and a diagram of the proposed installation.

This was my first time putting anything like this together but having read plenty of posts on here it was pretty easy to figure out and get everything together. Was approved in lass than a day, now just waiting for everything to arrive so we can install and commission.

Hi there. I've pretty new to the forum, as in <24 new. I'm in the process of trying to understand how to submit a DNO to UK Power Networks and noticed you mentioned a "portal for low carbon applications." Just wondering whether you might be able to clarify where this is. Currently finding it a challenge to complete the A1.1 document, as I plan to remove an AC inverter and replace with hybrid. Thanks