4kW system

[solgen]

Can someone tell me how it is possible to install :-

3.99kWp panels with a sunny boy 4000TL under G83 please? Surely this is a G59 install isn't it? Is there a simplified route for installing such a system?

Thanks

 

[TJLinks]

Try a SB3800V, limited to 16A

 

[BruceB]

It is normally a G83/1-1 Stage 2 install. Try google and the ENA site.

In other words, greater than 16A per phase, but not by much, so with prior DNO agreement you can install using G83/1 equipment. At least one DNO (WPD) will require the over frequency setting to be set to the G59 value.

Regards
Bruce

 

[solgen]

How do you limit to 16A?

 

[LightGEN]

3.99kWp of panels falls within the 'up to 4.0kWp' FIT tariff - the DNO is not interested in this figure. What the DNO is interested in is the net output from the inverter, which should not exceed 16A for a 'install and inform' type of installation. That 16A figure may equate to a maximum inverter output of 3.68kW or 3.84kW depending on the DNO in question - many DNO work to the 'nominal' network voltage of 230v, permitting a maximum inverter output of 3.68kW, a few DNO work to the 'actual' network design voltage of 240v, so they will permit a maximum of 3.84kW output from the inverter.

The SB 4000TL can be configured to limit its output to either of the maximum amounts above, via use of a 'GridGuard' code, which can be requested from SMA.

Stepping beyond this simplest approach, you can also submit a 'G83 stage 2' request to the DNO, for permission to connect a system exceeding 16A, but operated under G83 rules. If the local network infrastructure is capable of supporting this without remedial work, the DNO may permit you to just go ahead and connect, sometimes they require that minor adjustments are made to the inverter configuration.

Don't think I missed anything.

 

[solgen]

When I spoke to SMA the other day about limiting the output to 16A the person I spoke to said this wasn't possible, hence the reason for my post! I shall call them again and see if I get a different response. I assume its quite rare that over 16A is generated and so the overall higher output on the not so sunny days makes a system like this return high kWh'S?

 

[BruceB]

I am sure we have been through this before here recently.

The SMA person was correct (in a pedantic German way) that it is not possible to directly limit the output current to 16A.

But there is a setting to limit the output power. Hence by assuming nominal voltage or using an actual voltage you can limit indirectly the output current.

Regards
Bruce

 

[solgen]

I am sure we have been through this before here recently.

The SMA person was correct (in a pedantic German way) that it is not possible to directly limit the output current to 16A.

But there is a setting to limit the output power. Hence by assuming nominal voltage or using an actual voltage you can limit indirectly the output current.

Regards
Bruce

Hi Bruce, I spoke to SMA today and were very helpful it seems like building their UK arm is working!

What I would like to know is the cost effectiveness of a system like this. On days when it isn't so sunny I can see the benefit, however, on those days where potentially 22A could be generated there's quite a lot of energy wasted.

Some historical data here would be good and a comparison against a slightly smaller system which doesn't clip any output.

Also, how can you model clipping of power in something like PVsol or other packages to provide a customer with their estimated kWh per year?

Bruce, my questions aren't all re-directed at you I'm merely replying to this thread with questions entering so I could broadcast to all you knowledgeable people out there!

Cheers

 

[BruceB]

Not as much energy wasted as you might think. It would only hit 22A at very low voltages. My experience so far is that when pumping 4kW into the grid in a lot of places, the voltage can rise to approaching 250V. 4000W divided by 250V is 16A.

 

[solgen]

For a system submitted under G83/1 stage 2, I can see that it may be possible that energy from an inverter could get pumped back at or around 16A because of higher voltage developed. However, if a system is submitted under G83/1 stage 1 where the power output of a 4kW inverter is limited, it would be possible that power is still clipped even though less than 16A is developed because of rising voltage.


All of my questions around this subject are related to what I should quote for. I don't want to promise a customer a 4kW system and then it be subject to a DNO approval for it to then be rejected. As I see it there are two other options:

1. Design a system which keeps within the G83/1 stage 1 boundries avoiding all potential DNO problems.

2. Spec a 4kW array and configure the inverter to limit it's output.

 

[pcollins]

You could always spec a fronius IG TL 3.6 - for a 3.95kWp system this comes out as slightly better performance than the SMA 4000TL according to PVSol, only downside is you only get one MPP tracker but if you can run al in one string you're ok