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.

 

[v lowery]

have checked company paperwork and it says savings of up to 25% and old inverter ok.

 

[Startinez]

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.

It is in fact the other way round. You are allowed an inverter underrating of 80% and not that you should allow 20% extra over Wp rating.

 

[v lowery]

It is in fact the other way round. You are allowed an inverter underrating of 80% and not that you should allow 20% extra over Wp rating.

 

[v lowery]

don't know what this means, but they say on site 25% increase in electric.

 

[Gavin A]

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.

unfortunately you've been ripped off, there was never any chance of a 20% increase in generation unless your previous system was heavily shaded and using a poorly performing inverter in the first place.

Please complain to trading standards about the company who mis-sold you that 'upgrade'.

 

[Bobster]

unfortunately you've been ripped off, there was never any chance of a 20% increase in generation unless your previous system was heavily shaded and using a poorly performing inverter in the first place.

Please complain to trading standards about the company who mis-sold you that 'upgrade'.

He wont get anywhere with complaining to trading standards, they stated 'up to' which is as good as saying, you're not going to get anything.

As for the performance issues, I've seen a 10% reduction in power production just with having a fine layer of dust on the panels. Fine this was on a site generating 80MW, but the principal is the same.

 

[v lowery]

unfortunately you've been ripped off, there was never any chance of a 20% increase in generation unless your previous system was heavily shaded and using a poorly performing inverter in the first place.

Please complain to trading standards about the company who mis-sold you that 'upgrade'.

thanks for info.

 

[v lowery]

He wont get anywhere with complaining to trading standards, they stated 'up to' which is as good as saying, you're not going to get anything.

As for the performance issues, I've seen a 10% reduction in power production just with having a fine layer of dust on the panels. Fine this was on a site generating 80MW, but the principal is the same.

thanks for message, yes it said up to 25% but 3 of the first 5 years are better than the last 2 years with solar edge, there,s only 120 kwhs between my best year and worst, also its strange I would have dust only the solar edge years?. I will just go to smalls claims court thanks for info about trading standards.

 

[Bobster]

thanks for message, yes it said up to 25% but 3 of the first 5 years are better than the last 2 years with solar edge, there,s only 120 kwhs between my best year and worst, also its strange I would have dust only the solar edge years?. I will just go to smalls claims court thanks for info about trading standards.

I wasn't suggesting that the panels being cleaned was your issue. Just pointing out that poor maintenance can reduce their output over time.

 

[v lowery]

I wasn't suggesting that the panels being cleaned was your issue. Just pointing out that poor maintenance can reduce their output over time.

i know thanks, but 2 years ago they cleaned panels when fitting system and panels are self cleaning" if you believe paperwork". cheers Rob.

 

[Bobster]

i know thanks, but 2 years ago they cleaned panels when fitting system and panels are self cleaning" if you believe paperwork". cheers Rob.

Self cleaning only stops mold and algi growing on the panels.

 

[v lowery]

Self cleaning only stops mold and algi growing on the panels.

thanks for that Rob I now know to, believe nothing a solar salesperson says or the claims they make on paper.

 

[tlsambo]

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.

Unless you have severe and i mean SEVERE shading you won't see a 20% increase from a Solar Edge system. More likely to be 2-5% depending on the degradation of your panels. Solar Edge helps to make up for the natural differences in each individual panel's output as they'll degrade at different rates. Unfortunately Solar Edge is often mis-sold with the classic broadband statement of 'up to' 20% increase in yeild. If your installer isn't using either PV Sol or PV Syst software to calculate the yeild then the figures won't be accurate.

 

[tlsambo]

thanks for that Rob I now know to, believe nothing a solar salesperson says or the claims they make on paper.

We've been carrying out a cleaning experiment on a Solar Edge monitored system so we can compare panels performance side by side. We clean one panel every 2 months, one every 6 months and one is left dirty. The difference in performance is around 0.3%.

 

[mrbroons]

As far I have read over supplying the inverter is done to assist with Winter generation. The inverter should clip the output to 3.68 kw see the following for the guidelines Western Power Distribution - G59 Connection procedure - https://www.westernpower.co.uk/Connections/Generation/Installation/G59-2.aspx. If a system was installed with 3.68kw of panels it would never see that value due to loses and non perfect generation conditions. So it is possible to over supply the inverter to effectively maximise the available generation throughout the year without tripping the G59 limitation. The inverter will simply cap or clip the generation to the value specified regardless of the panels attached (assuming they are within the inverter max spec) but this will mean that you will more often be generating a higher value rather than very rarely if ever getting near the rated capacity of the install.

 

[tlsambo]

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.

The common practice for these type of installers is to quote a figure of 'up to 20%'. If you've got severe shading, that means a pole, tree or chimney right in front of your array that will shade some part of your array throughout the day then yes, you may get close to a 20% increase in yield. This type of shading is very rare and most Solar Edge upgrades are likely to average between 2-5% increase in yield.

 

[tlsambo]

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.

The common practice for these type of installers is to quote a figure of 'up to 20%'. If you've got severe shading, that means a pole, tree or chimney right in front of your array that will shade some part of your array throughout the day then yes, you may get close to a 20% increase in yield. This type of shading is very rare and most Solar Edge upgrades are likely to average between 2-5% increase in yield.

 

[v lowery]

The common practice for these type of installers is to quote a figure of 'up to 20%'. If you've got severe shading, that means a pole, tree or chimney right in front of your array that will shade some part of your array throughout the day then yes, you may get close to a 20% increase in yield. This type of shading is very rare and most Solar Edge upgrades are likely to average between 2-5% increase in yield.

can it get any worse? I now have a optimizer failure , the installer has gone bust and solar edge will send out a free optimizer to another company which I have to pay £600./700 for scaffold and £300 to fit? have emailed solar edge as this is the 2nd failed optimizer and total system failure in 3 years that's 3 faults in 3 years they say they should last 25 years and are ultra reliable ? they never fail? so I got an email saying the 1st optimizer had "early stage failure" the other "random failure" so for something that never fails they have got names for them " still waiting for my reply to last email. 17 years left on tariff I could have no panels working by then.

 

[tlsambo]

Solar Edge will cover some scaffold costs, normally about £200 which would cover a tower and in most cases this will be enough as the installer will know which part of your array they need to access so won't need full scaffold. If it does cost a lot more then the installer can get permission from Solar Edge to claim a higher figure from them. I work for www.nakedsolar.co.uk and we don't charge for Solar Edge optimiser replacements as they now cover all our costs. Sorry we don't cover your area yet, we're getting there.