Anyone gone down the max self consumption route?

[Alan Ambrose]

Quote

I went the max panel and inverter route.

 

Size of inverter was partly determined by desire to cover peaks without drawing from grid i.e. kettle, toaster, air fryer all on at same time.

 

This allowed for a large number of panels (24).

 

This was dictated strongly by my (carport) roof size.  I wanted to get it looking neat so fewer panels would look stupid. 24 panels filled the roof really nicely.

 

It also compensated for sub optimal angle and orientation (12 degrees and South West).

 

It also allowed reasonable generation (enough to cover daily demand) in the shoulder months as the panels are badly shaded by trees and the house.

 

All in all we have zero import for 6 months and produce about 25% of demand in deep winter.

 

The array easily saturates my export limit (a measly 3.6kw) so we have alot of potential excess in the summer.

 

One advantage of the big array and inverter in the winter is the charge rate can be really high so you can take advantage of the 2 or 3 hours of sun during an otherwise dull day.  3 hours of good sun is about all I need to top up.

 

 

@Beelbeebub  Yeah, that's pretty much what I want to do for similar reasons. Presumably you had to limit the export in software but had a much larger inverter?

[scottishjohn]

22 minutes ago, Alan Ambrose said:

 

 

@Beelbeebub  Yeah, that's pretty much what I want to do for similar reasons. Presumably you had to limit the export in software but had a much larger inverter?

why are you limited to export volume?

[scottishjohn]

On 06/08/2026 at 08:31, G and J said:

For us and I assume many, maxing the panels on one face of the roof was a no brainer as it saved slate (I’m not a fan of surface mount panels).  

I did look at that but was assured by builder that by the time they GRP that area there would be no savings  and possible problems over time  if not GRP below the panels 

[Alan Ambrose]

>>> why are you limited to export volume?

 

Well the DNO will always limit, even if it's only to 17kW on single phase - it's a risk thing with local voltages apparently. And we have planning permission to cover one roof and the 'cartlodge' with panels.

[Dillsue]

2 hours ago, scottishjohn said:

why are you limited to export volume?

Are you talking about volume/quantity(kwh) or the rate(kw) of export??

 

I don't think anyone in a domestic situation gets limited on the volume they can export but everyone gets limited on the rate they can export as ultimately you'll blow your service fuse if you try and push power into the grid too fast! Most are limited way below the power that would blow their fuse though!

[scottishjohn]

1 hour ago, Alan Ambrose said:

>>> why are you limited to export volume?

 

Well the DNO will always limit, even if it's only to 17kW on single phase - it's a risk thing with local voltages apparently. And we have planning permission to cover one roof and the 'cartlodge' with panels.

yes I knew that one --  unless you get a different export  permit

 16 kW per phase  is what I remember form when I got my 3 phase supply when I asked how big a system I could run 

 but it will be limited really by your invertor  size and I see 11kW at most as my invertor is 11.5kW-- But seen it a few times this summer

It just sounded like he was limited to the amount of kW he could send back per day 

 

 good days here i,ve been sending back 50-60 kW

Edited 10 hours ago by scottishjohn

[-rick-]

1 hour ago, scottishjohn said:

 16 kW per phase

 

It's 16A per phase, ie, 3.8kW

[SteamyTea]

16 (amp) x 230 (nominal voltage) = 3.68 kW (power per phase)

 

 

[-rick-]

5 minutes ago, SteamyTea said:

16 (amp) x 230 (nominal voltage) = 3.68 kW (power per phase)

 

Yes, but mostly no. Technically the nominal voltage is 230V but for the vast amount of consumers the voltage at their socket is closer to 240 (likely higher).

 

The limit is set by amps to avoid any confusion here. You can export 16A whatever your local voltage.

[SteamyTea]

1 minute ago, -rick- said:

 

The limit is set by amps to avoid any confusion here

Correct.

 

[Dillsue]

2 minutes ago, -rick- said:

 

Yes, but mostly no. Technically the nominal voltage is 230V but for the vast amount of consumers the voltage at their socket is closer to 240 (likely higher).

 

The limit is set by amps to avoid any confusion here. You can export 16A whatever your local voltage.

16A is without consent via G98. We have 32A via a G99 but I think others have posted higher limits.

[Beelbeebub]

7 hours ago, Alan Ambrose said:

 

 

@Beelbeebub  Yeah, that's pretty much what I want to do for similar reasons. Presumably you had to limit the export in software but had a much larger inverter?

Yes. 8kw inverter 3.6kw export 

[Beelbeebub]

7 hours ago, scottishjohn said:

why are you limited to export volume?

I should have said export power - 16A export limit. 

[Beelbeebub]

1 hour ago, SteamyTea said:

Correct.

 

What is slightly annoying is my inverter limits by power - which varies the amps as the voltage goes up and down.

 

My voltage is regularly high 240's so i could export about 4kw but occasionally it dips to 230 or so which is only 3.6kw

 

It would be nice if the inverter had a current limit export 

[SteamyTea]

3 minutes ago, Beelbeebub said:

It would be nice if the inverter had a current limit export

I am not sure how current gets limited.  

[-rick-]

1 hour ago, Beelbeebub said:

It would be nice if the inverter had a current limit export 

 

Weird I would have thought limiting by current would be easier to implement.

[-rick-]

1 hour ago, SteamyTea said:

I am not sure how current gets limited.  

 

By controlling the inverter. To export more current the inverter has to boost the voltage target voltage higher and vice versa.

[Beelbeebub]

6 minutes ago, -rick- said:

 

Weird I would have thought limiting by current would be easier to implement.

Yeah, i'd have thought so too.

[SteamyTea]

18 minutes ago, -rick- said:

By controlling the inverter

I was thinking more at the electronic/component level.

Just putting a huge, variable resistor in parallel to the load would limit the current available for export, or you could quickly switch the inverter output, or even the DC input at varying rates.  I am just not sure which is the most effective.

 

 

 

 

 

[-rick-]

Just now, SteamyTea said:

I was thinking more at the electronic/component level.

Just putting a huge, variable resistor in parallel to the load would limit the current available for export, or you could quickly switch the inverter output, or even the DC input at varying rates.  I am just not sure which is the most effective.

 

You won't find a variable resistor anywhere near modern power electronics.

 

The electronics switch the power on and off very fast (kHz, not Hz) and the amount of output power can be controlled by varying how long the power is switched on each cycle. Any feasible circuit will monitor both the voltage and current and both are used for feedback.

 

You can go down a big rabbit hole if you want to know how it works. A quick google gave me this, not saying it's the best place to start but this will take you as deep as you like. It's a reference design for a 99% efficient hybrid inverter. https://www.ti.com/lit/ug/tiduf64c/tiduf64c.pdf?ts=1786346438488

[Dillsue]

One advantage for the DNOs if inverters are regulated by power rather than current is that if they wind the voltage up everyone's inverters throttle the current so easier on the grid.

 

Our original solaredge SE4000-16, limited the current rather than power and with our base voltage being 25x vac I've seen up to 4.2kw going to export. When that died the warranty replacement was a newer HD Wave version that limits by power so sadly always capped at 3.68kw

[G and J]

9 hours ago, scottishjohn said:

I did look at that but was assured by builder that by the time they GRP that area there would be no savings  and possible problems over time  if not GRP below the panels 

Dunno but the amount the cost of slate was reduced by was equivalent to quite a happy proportion of the cost of the solar system.