4.57Kw PV with a 4Kw inverter. Inverter too small?

[topo77]

Hi,

I bought a 4.57Kw PV system (14x SunPower 327W panels) for my house last year.

I now noticed that the installer fitted a SE4000 Solaredge which is limited to 4Kw.

I can see from my stats that the system goes up to 3.98Kw but never above. It just goes flat and stays at 3.98Kw (especially in July/August when the PV generate most energy).

Did the installer fit the wrong inverter?

regards,

tp

 

[Scuba]

Unless you had specific permission from your DNO you're limited to 16 amps.

 

[topo77]

I appreciate that specific permission from the DNO would be required above 4kw.

I expected my installer to ask the DNO for special permission and my system to be able to export 4.57Kw back into the grid (sold as advertised).

In addition it also means that I can generate more than 4kw AC power from my PV - even if I would not get permission from my DNO I would still like to consume the missing 0.57 kw myself.

Is it normal to have a smaller inverter than the max PV output that is possible?


regards,

tp

 

[snowhead]

The best person to ask about the system is the original installer.
They'll be able to explain the logic of what they did.

 

[Gavin A]

yes it's a normal set up.

Panels are rated under standard test conditions at 25degreesC and 1000W/m2 light, in full sunlight they usually reduce efficiency by around 0.45% per degree above this, so in full sun would be expected to peak at least 10% below their nominal rating due to temperature, other than a few short periods before the panels warm up - and that's if the sun was giving 1000W/m2 and perpendicular to the panel.

Your panels have lower impact from heat, so the case is a bit more arguable for a higher rated inverter.

I was also going to make the point that inverters efficiency drops off at lower outputs, usually roughly proportional to the inverter capacity, which means that small losses due to capping at the top end can be made up by improved efficiency in cloudy weather... but apparently on solar edge this doesn't apply as they seem to all have the same efficiency curve at the bottom end from 3kW to 5kW, which is very odd, pretty much as if they're all actually the same unit just capped at different levels.

 

[The Solar King]

I hope it is not a SE4000 as this is a 22amp inverter and would need a G59 permission to connect. Trust this is in fact the SE3680 16amp unit. You need to get your original installer to verify exactly what they have fitted.

 

[LeeH]

Crikey, glad I used one of the forum members for my array.

Seems to be a right dodgy industry.

 

[whinmoor]

I hope it is not a SE4000 as this is a 22amp inverter and would need a G59 permission to connect. Trust this is in fact the SE3680 16amp unit. You need to get your original installer to verify exactly what they have fitted.

You could also look at the data on the ID plate which is usually on the side of the inverter. It's likely to be more accurate than the installer's memory!

 

[v lowery]

yes it's a normal set up.

Panels are rated under standard test conditions at 25degreesC and 1000W/m2 light, in full sunlight they usually reduce efficiency by around 0.45% per degree above this, so in full sun would be expected to peak at least 10% below their nominal rating due to temperature, other than a few short periods before the panels warm up - and that's if the sun was giving 1000W/m2 and perpendicular to the panel.

Your panels have lower impact from heat, so the case is a bit more arguable for a higher rated inverter.

I was also going to make the point that inverters efficiency drops off at lower outputs, usually roughly proportional to the inverter capacity, which means that small losses due to capping at the top end can be made up by improved efficiency in cloudy weather... but apparently on solar edge this doesn't apply as they seem to all have the same efficiency curve at the bottom end from 3kW to 5kW, which is very odd, pretty much as if they're all actually the same unit just capped at different levels.

You could also look at the data on the ID plate which is usually on the side of the inverter. It's likely to be more accurate than the installer's memory!

 

[v lowery]

hi, I have solar panels 7 years, for the last 2 years I have solaredge upgrade and I have my yearly data the last 2 years are worse than my original set up. I am not seeing the 20% raise in electric as promised. checked weather patterns and we do seem to have had 2 years with 20% less light. any thoughts. solaredge cannot see I problem, I can as I have lost £2600 plus yearly interest for something that is losing me money.

 

[Startinez]

Hi,

I bought a 4.57Kw PV system (14x SunPower 327W panels) for my house last year.

I now noticed that the installer fitted a SE4000 Solaredge which is limited to 4Kw.

I can see from my stats that the system goes up to 3.98Kw but never above. It just goes flat and stays at 3.98Kw (especially in July/August when the PV generate most energy).

Did the installer fit the wrong inverter?

regards,

tp

From my recollection, the inverter should be down-rated from the maximum generation. If the system actually hits 3.98kW, I believe that's too close. I'll double check my notes on it tomorrow and let you know.

 

[The Solar King]

Why did you upgrade to Solaredge? Unless you have an inverter failure, it is unlikely to be a cost effective thing to to do. Who promised you 20% more output? It won't have been Solaredge. There are only a few very specific circumstances where you will get this kind of improvement. If you have it in writing from the installer of the equipment, I would raise the matter with them. You will however probably find the claim of improved performance is 'up to' with no actual promise of a gain.

As to why your system should be performing worse than before the upgrade, it sounds as if the new configuration needs to be checked. Best to get your installer back to do this.

There are many benefits to the Solaredge system other than just enhanced performance.

 

[v lowery]

Why did you upgrade to Solaredge? Unless you have an inverter failure, it is unlikely to be a cost effective thing to to do. Who promised you 20% more output? It won't have been Solaredge. There are only a few very specific circumstances where you will get this kind of improvement. If you have it in writing from the installer of the equipment, I would raise the matter with them. You will however probably find the claim of improved performance is 'up to' with no actual promise of a gain.

As to why your system should be performing worse than before the upgrade, it sounds as if the new configuration needs to be checked. Best to get your installer back to do this.

There are many benefits to the Solaredge system other than just enhanced performance.

 

[v lowery]

thanks, I have 16 sharp 245 panels . 10 panels east facing and 6 west facing. yearly est. "2893 company figures" which I was getting with sunny boy inverter. solaredge is worse than est. and I was told I would get 20% more.

 

[v lowery]

Why did you upgrade to Solaredge? Unless you have an inverter failure, it is unlikely to be a cost effective thing to to do. Who promised you 20% more output? It won't have been Solaredge. There are only a few very specific circumstances where you will get this kind of improvement. If you have it in writing from the installer of the equipment, I would raise the matter with them. You will however probably find the claim of improved performance is 'up to' with no actual promise of a gain.

As to why your system should be performing worse than before the upgrade, it sounds as if the new configuration needs to be checked. Best to get your installer back to do this.

There are many benefits to the Solaredge system other than just enhanced performance.