Have I got the wrong Inverter?

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lydart

I ordered 16 x Sanyo HIT-240SE10 with a SMA 4000TL back in October last year, but due to all the FIT problems my supplier could only source HIT-235SE10 panels. No big deal and the installation went ahead on 241111. During the installation I noticed that they had installed a 3000TL so I called their sales office and they apologized for not telling me about the switch but assured me that the3000TL was a better choice for the system. I wasn’t happy, but with 12[SUP]th[/SUP]Dec looming I accepted the 3000TL and the final bill was reduced to reflect the change in equipment. I have been very happy with the installation and have been pleased to see the generation increase almost on a daily basis as the days lengthen. All was fine until today when the inverter maxed out at 3kW from12:00 to 15:00 and this is only February.

Am I looking at this happening every sunny day until November?

Is this OK or should the inverter be changed?

Regards Mike

Location:Edinburgh Facing 210[SUP]0[/SUP], Pitch 45[SUP]0[/SUP]
 
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The inverter is undersized, the max input for the inverter is 3200W DC. To be fair to the installer pre 12th December was a crazy time and inverters were hard to get hold of but they should give you a more suitable inverter.

You will find that often the highest output occurs in March when there is good sun and low tempretures.
 
Lots of people undersize, to much of sma software imo.
Most of your energy is produced in the bright long sunny days not in dark short days.
A company I know ..16 sharp 245w spec SB 3000 HF...16 sharp 250w spec SB 4000TL...?????
Cant work this one out myself.
 
I think people look at the Sunny Design software see the green ticks and assume that the inverter is correct and don't take any notice of the max dc input.
 
Undersizing is quite common but that seems a bit small.. would probably have been worth getting the larger one, but times were hard. Difficult to get stock. Even now its becoming a full time job sourcing inverters... Right now i'd happily swap one of the 4000TL in stock for a 3000TL i can't find....
 
bearing in mind your geographic location and orientation of your roof I would say a 4000TL is too much wheras a 3.6 inverter of some description would be ideal.
 
I agree with moggy - your current 3kW inverter is a bit too small. A 4kW is a little oversized. A 3.6kW inverter would be ideal (of which there are several; I have an Aurora 3.6).

My SouthEast-facing, 40-degree roof, 3.75kWp with 3.6kW Aurora inverter peaks out around 2.5kW at the moment, so there's still plenty more power to come as summer approaches and if you're maxed-out at the moment, you'll be losing about 25% of your potential in summer.
 
the efficiency of the 3800 is poor compared to other more modern inverters. IT's basically an older model and there are better ones out there
 
It was an emergency measure while the were waiting for the 3600TL to be released.
They were very slow filling the essential 3.6 market, it was a real gap in their range
 
Somecamel said:
Never used a lot of the Fronius Inverters- More of an Aesthetic thing :p They're bloody ugly :)
Click to expand...

Each to their own I guess :)
I'm happy with mine, guess looks take a back seat though I don't think it's particularly ugly. It's very efficient and came with a 20yr warranty so it kind of does it for me!
 
The fronius is handy in that you can run a single string of 16panels. I've used them a lot where single string is ok as power ones were impossible to get hold of during the autumn so I only used them where I had to have 2 strings.
SMA HFs are quite nice, and no need for bonding.

Fronius aint so ugly!! kirkup indoors 2.jpg
 
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The fronius inverters perform well in pvsol, not a whole lot more output but more than Sma and power one with lots of panels.
 
As far as I can see this is not a bad choice. If you check the data sheet the max ac output is 16A which is ideal for a G83/1 install. One important thing to note and something that confused me for a long time is that on the data sheet, where is states max dc input 3200W is not actually the max dc this inverter can handle. Its something to do with a nominal value they have to state for the European market. To find the max amount of dc you can wire to this inverter simply multiply the the max input voltage by the the max input current. In this case its 9,350W (obviously you'd never want to do this). You might think I'm mad but I've spoken to Fronius and SMA about this. Anyway, as I say I'm sure this inverter will be fine and as long as the rest of the installation has been carried out correctly, and on a clear day will give you your 16A output. I'm willing to bet the installers didn't have clearance from the DNO to go above 3.68kW of output anyway????
 
lewyames said:
. In this case its 9,350W (obviously you'd never want to do this). You might think I'm mad but I've spoken to Fronius and SMA about this.
Click to expand...

Are you sure you spoke to Fronius about this? There is no way that the 3000TL can output 9,350W. It may well cope with the higher power but it certainly won't process it. I believe the only way to truly damage an inverter is to use a voltage which is too high.

The 3000TL AC output is not 16A.
 
Thanks for all the replies. You have confirmed what I already thought and I will contact the installer to discuss swopping the 3000TL for something more appropriate. My preference would be the 3600TL as all the cables etc are in the correct positions and should make for a easier/quicker job.
 
GaryM said:
So in the real world why does the IG TL 3.6 yield more with 16 panels when I put them through PV SOL?
Click to expand...

PV SOL is not the real world imo...350 v 120..or even 200v if you dont lower power one kick in voltage.
The power one or sma will wake up earlier and go to bed later. The TL sma are second choice.
We had a case of over voltage with a sma 4000 tl, we took it out, put in a power one 3.6OUTD and no problems with the over voltage.
 
Start up voltage? If you have 4kWp of panels on a roof I don't think you'll be getting much issue getting up to 350v, especially on the Fronius IG TL 36 as its characteristics tend to mean that the system is wired up on one string.

Generally speaking, it doesn't take much light to get a decent voltage and enough to fire the inverter and I think that the benefit of a low start up voltage is often overstated. Unless I have missed something?
 
SolarCity said:
Are you sure you spoke to Fronius about this? There is no way that the 3000TL can output 9,350W. It may well cope with the higher power but it certainly won't process it. I believe the only way to truly damage an inverter is to use a voltage which is too high.

The 3000TL AC output is not 16A.
Click to expand...


I think you may misunderstand me, you can input 9,350W of DC, not output it. If you check the SMA data sheet the max AC output for a 3000TL is 16A, have a look.....
 
lewyames said:
I think you may misunderstand me, you can input 9,350W of DC, not output it. .....
Click to expand...

I definitely did misunderstand you. While it probably won't damage the inverter by connecting too much power to it, I don't think the OP is concerned about this. I think it is the OP concern that he may have an undersized inverter as it will mean that he isn't getting the maximum benefit from his system.

If you check the SMA data sheet the max AC output for a 3000TL is 16A, have a look.....[/QUOTE]

I don't see how this can be. If the maximum power output of the inverter is 3000w then you would need a grid voltage of around 180v to get 16A.

The maximum current you would expect from the inverter at 230v is 13A - in reality, I'd imagine that the output current is dependant on two things - the DC power and the grid voltage. The output power will never be above 3000w.

Again, I'm always ready to be proven incorrect.
 
I posted a similar question following the installation of my panels in November.

I have 16 x Hyundai HIS-250MG panels connected in 2 x 8 strings to a Sunny Boy SB 3000TL-20.

This inverter and configuration is as recommended by Sunny Design. I was expecting a 4000TL to be recommended but this was not the case according to the company installing. I ran the Sunny design software for myself and sure enough the 3000TL-20 is the only one the software recommends. All the ones above 3000 and below 4000 were coming up as incompatible. Although not recommended, the software allowed the 4000TL to be selected as it was compatible (it was only recommended for 17 panels). The 4000TL gave an estimated annual yield marginally above the 3000TL-20 by about a half-dozen kWh so I'll be losing less than £5 per year by keeping the 3000.
 
I've checked the figures and the 4000TL looks fine to me for 16 Hyundai 250w panels, unless I'm looking at the wrong data sheet. What does Sunny Design flag up as being an issue for the panels? Oversized?

I'd say a 3kW inverter on a 4kW array is undersized.
 
SolarCity said:
Start up voltage? If you have 4kWp of panels on a roof I don't think you'll be getting much issue getting up to 350v, especially on the Fronius IG TL 36 as its characteristics tend to mean that the system is wired up on one string.

Generally speaking, it doesn't take much light to get a decent voltage and enough to fire the inverter and I think that the benefit of a low start up voltage is often overstated. Unless I have missed something?
Click to expand...

£ FOR £ Power one is the best, lower kick in and will peak over 3.68. Sorry to be so closed minded but I think power one have it all. I would prefer a warehouse full of P1 as not all have perfect 4 kw roof.
 
My reading of the data sheets also made me think that the 4000 would be recommended but the Sunny Design software doesn't agree.

If the 4000 is manually entered in then there are no incompatibility issues and the annual estimated output is calculated. I don't know why Sunny Design does not offer the 4000 as a recommendation... but it doesn't.
 
I'd agree that Power One takes some beating for the price. I think Fronius IG TL range is the best for pure, unshaded yield. SMA are best for features and range. Power One are a good all rounder. The 3.0 model especially. Kostal Piko are a very good alternative.
 
clivep said:
My reading of the data sheets also made me think that the 4000 would be recommended but the Sunny Design software doesn't agree.

If the 4000 is manually entered in then there are no incompatibility issues and the annual estimated output is calculated. I don't know why Sunny Design does not offer the 4000 as a recommendation... but it doesn't.
Click to expand...

Very odd. I'm going to download the software and try to work out what I'm missing.
 
SolarCity said:
I'd agree that Power One takes some beating for the price. I think Fronius IG TL range is the best for pure, unshaded yield. SMA are best for features and range. Power One are a good all rounder. The 3.0 model especially. Kostal Piko are a very good alternative.
Click to expand...

Ye there are lots out there but some how I just keep comming back to P1. I think they lead, where others follow. They have not revised their inverters in a long while unlike sma, looking forward to the next generation of P1.
 
clivep said:
My reading of the data sheets also made me think that the 4000 would be recommended but the Sunny Design software doesn't agree.

If the 4000 is manually entered in then there are no incompatibility issues and the annual estimated output is calculated. I don't know why Sunny Design does not offer the 4000 as a recommendation... but it doesn't.
Click to expand...

You cant believe that rubbish...The computer says no...
 
SolarCity said:
I definitely did misunderstand you. While it probably won't damage the inverter by connecting too much power to it, I don't think the OP is concerned about this. I think it is the OP concern that he may have an undersized inverter as it will mean that he isn't getting the maximum benefit from his system.

If you check the SMA data sheet the max AC output for a 3000TL is 16A, have a look.....
Click to expand...

I don't see how this can be. If the maximum power output of the inverter is 3000w then you would need a grid voltage of around 180v to get 16A.

The maximum current you would expect from the inverter at 230v is 13A - in reality, I'd imagine that the output current is dependant on two things - the DC power and the grid voltage. The output power will never be above 3000w.

Again, I'm always ready to be proven incorrect.[/QUOTE]

Yeah I see where you're coming from! Product specifications can be very misleading, the most common inverter I've fitted is the Fronius IG TL 3.6 which for instance has on its data sheet a max power output of 3680W but they will regularly generate up to 4000W - my assumption is that as you allude to this is down to high grid voltages, but it also leads me to believe that when it comes to product specifications, the most important value is the max output current as this is the real limiting factor, especially for a G83/1 certificated inverter (as per DNO requirements). This is what leads me to believe that the max ac output in Watts can be misleading. SMA are probably the only ones who can really answer this (I've never fitted an SMA 3000TL) if I had an hour to spare to spend on hold I'd give them a call! If you're right and it won't go over 3000W then this guy has definitely had the wrong inverter fitted!
 
I've just downloaded the latest Sunny Design software and there are a couple of changes. The SB 3000TL-20 is still the recommeded inverter (in dark green) but the SB 3600TL-20 and SB 4000TL-20 are now shown as options (in light green).

No other single inverter is shown as compatible and I believe this to be because of yield loss (Min PV voltage for a string of 8 is 198V but inverters need 209V... 1 string of 16 is too high voltage).

Using my data of 16 x Hyundai HIS-S250MG panels, located in Leeds with azimuth of -30 degrees and inclination of 30 degrees gives the following comparison of design suggestions:

SB 3000TL-20 - Annual yield 3348.30 Usability factor 99.5% Performance ratio 83.7%
SB 3800TL-20 - 3327.70 100.0% 83.1%
SB 4000TL-20 - 3356.80 100.0% 83.9%

So the 3800 actually produces less than the 3000 and the 4000 only produces 8.30 kWh more per year than the 3000. Presumably the 3000 is recommended over the 4000 as the extra cost of the 4000 wouldn't be recovered over it's lifespan.

I still can't fathom why the yield of the 3000 and 4000 is so similar. The spec on the 3000 definitely states max AC power of 3kW so I would of thought that in summer there would be a lot more power being wasted.
 
clivep said:
I still can't fathom why the yield of the 3000 and 4000 is so similar. The spec on the 3000 definitely states max AC power of 3kW so I would of thought that in summer there would be a lot more power being wasted.
Click to expand...


It's probably because inverters work best when they're working at a medium to high capacity, relative to whath they were built to handle. When there's only a trickle of electricity coming in from the panels (on cloudy days, or when the sun was not in the panels arc, or in winter) the big inverter is well off its "sweet spot" and might only be 80% efficient at converting the DC to AC, while a smaller inverter might be only just off its "sweet spot" and be 90% efficient.
In recent cloudy days my SE-facing 3.75kWp system has only been generating about 3kW total per day, or about 0.6kW per hour at peak late-morning output. My P1 Aurora has a maximum input of 3.75kWp, but with only 0.6kW coming into the inverter (even at the peak in recent days), it was only running at 16% of the maximum that it can handle. Once the sun was out of its arc in the afternoon, it's probably only generating 0.3kW; about 8% of maximum potential.

I extracted this from an ealier posting of mine:

If we had a hypothetical 4kW inverter, it would most likely have efficiency something like this:

0.25kW DC -> 0.2kW AC (80% conversion efficiciency)
0.5kW DC -> 0.45kW AC (90%)
1kW DC -> 0.95kW AC (95%)
2.5kW DC -> 2.4kW AC (96%)
4kW DC -> 3.8kW AC (95%)
Click to expand...

In short: the smaller inverter is optimised to deal with smaller DC input, whereas the bigger inverter is optimised to handle higher DC input. To some extent it depends on the exact make/model of inverter as to how well they convert on dull days.
 
why SMA produce a 2 string 3.6 or 4kw inverter that can't cope with the voltages of a standard 2 string array is beyond me!!!
Sunny design obviously only recommends SMA inveters and my beleief that the best for a 4kW array is a 3.6 kW inverter from Fronius or Power one. I only use SMA for smaller systems or where I need remote monitoring via bluetooth.
 
moggy1968 said:
why SMA produce a 2 string 3.6 or 4kw inverter that can't cope with the voltages of a standard 2 string array is beyond me!!!.
Click to expand...
how do you mean?

They cope fine with every 2 string array we've installed on them, although we would drop the start up voltage down to it's lowest level (125V IIRC).

It's true that they're operating below their optimum voltage point when using 30V panels in 2 strings, but then so would the Aurora (not sure about the Fronius).

I'm looking forward to the TL-21 inverters coming our way though as the higher voltage range would give more options.
 
re the OP

According to sunny design, there's little to choose between the 3000TL and 4000TL, because the 3000TL will be performing closer to it's optimum efficiency point more of the time than the 4000TL and this largely offsets any limiting of output from a standard 4kWp system.

There is a problem with Sunny Design and sanyo's though as for some reason it doesn't (or at least it didn't) take account of the 1/3 lower reduction in high temperature output of the Sanyo's vs standard panels. In it's calculations it's still working on the basis of 0.45% reduction in output per degree of increased panel operating temperature over the STC temp of 25 degrees that the panels are rated at.

The Sanyo's only have 0.3% reduction in output per degree, so in full sunlight when the panels are something like 50-60 degrees, the output from the Sanyos will be around 4.5% higher than standard panels or in 1000W/m2 of sunlight would be 3494W DC input vs 3321W DC input for standard crystaline panels. The additional 170 odd watts of input power from the sanyo's in full sunlight would essentially be lost via the inverter limiting, which effectively negates the advantage the Sanyo's would usually offer in high temperature performance.

I raised this as an issue with SMA last year, but don't think they've resolved it, which is really annoying given that Sunny Design already has all the data incorporated within it that would be needed to make these calculations for the temperature performance.
 
To be fair to SMA, they have pointed out to me in the past that their software shouldn't be relied on for yield calculations and that PV Sol should be used for that instead.

Obviously this mean that, as Gary mentions above, they may not necessarily choose the right inverter for the job.
 
Has anyone used the Eversolar range of inverters, they are ip65 as standard, and perform very well from what I can see.

They also have inverter selection software called ever plan which is simple to use.
 
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