Inverter Choice: SolarEdge, SMA SB3600TL or SMA SB4000TL?

[JH69]

Hi All,

Apologies for the consumer-oriented questions, but this seems to be one of the best forums on the web for discussing PV.

I’m looking at getting a 4Kwp Solar PV system installed (15 x 265W Yingli Panda Panels), but I have a choice of inverters.

Our house is south facing, approx 45% roof angle, with minimal shading (the neighbour’s roof to the east of our house will shade one or two panels but only in the early morning).

The installer I’m most likely to go with has said he’ll get permission from the DNO to go for the full 4Kw output, and has offered the following inverters:

- SMA SB3600TL
- SMA SB4000TL (£100 premium over SB3600TL)
- SolarEdge system with SE4000 and 15 Power Optimizers (£640 premium over SB3600TL)

I’m aware that the SolarEdge system will probably yield the most Kwh, but given we have minimal shading issues, is it worth spending an extra £640 on? (This is approx 9% more than the SMA system).

If I go with an SMA inverter, which would be the better choice out of the SB3600 or SB4000? I really like the idea of being able output the full 4Kw, but I’ve tinkered with SMA’s Sunny Design software and the projected difference in annual Kwh is only about 30Kwh, so it probably wouldn’t pay to spend the extra £100.

Is Sunny Design a good way to judge potential yield on these systems, or am I likely to see better real-world performance from the SB4000 than Sunny Design suggests?

Is there anything else I should be considering when choosing an inverter?

Many Thanks!

JH69

 

[Vegelen]

Fronius 3.6TL shouldn't be discounted as one of your inverter options.
If you use a transformer less inverter, make sure the inverter manufacturers earthing requirements are met.

 

[jason121]

dont forget STECA, very good inverter like Fronius no bluetooth but only weights 9kg,
If you go with the 4000 must rated to 16amps for G83 or else will require permission from DNO for the 4kw inverters

 

[infinity]

Depends how much shade the neighbours house gives. Its it 2-3 good hrs of sunshine then thats 2-3 hrs of decent output you lose every day! could soon add up, say its 1-2 KWh less a day, X 250 days a year (allowing for dark winter days) soon adds up!

 

[Vegelen]

Depends how much shade the neighbours house gives. If its 2-3 good hrs of sunshine then that is 2-3 hrs of decent output you lose every day!

Time of shading is also important.
Shading in the early morning or later in the evening is less important than around midday, when the suns output is approaching its peak.

 

[infinity]

Time of shading is also important.
Shading in the early morning or later in the evening is less important than around midday, when the suns output is approaching its peak.

Yes true

 

[sedgy34]

We're in the uk are you you could get a few quotes too from here

Also you dont require permission on 1x4kw solar installation
Its only on multi installs in the same street you need permission from DNO
hope your not taking in any spiel!

 

[pww]

Using a 4000TL would require pre approval and really offer nothing over the 3600TL (which is basically a 16A capped 4000TL). Do you want to know what your system is doing on a per panel basis? Do you want to reduce your potential downtime if there is a fault? Do you want an additional 5/10% production? Do you want to minimise what shading issues you have on the system? Answer yes = go with Solaredge! Answer no and to be honest I would use a Fronius IG 3.6TL.

 

[moggy1968]

unless you want blue tooth monitoring, in which case SMA knocks spots off Fronius.
Have used a lot of fronius and very happy with the outputs, noisier than the SMA though I think so depends a bit where it is to be mounted.

 

[Earthstore]

This is for the OP, I fully understand your queries, however your chosen supplier should be specifying the inverter for you and explaining the reasons why.
There are many you could use, and also some can be set with different options to minimise the shading issues that you have.
So my advise would be to choose a supplier that understands how inverters really work, just one example would be how optitrack works on an SMA, and would you benefit from using this facility on your installation.

Without surveying your house it really is impossible to suggest which inverter would perform the best, although for different reasons many have their favourites.

I hope this helps.

Ps Most, not all but most DNO's require a maximum output of 16A, which is 3.68 KW without having prior permission to connect to the grid, some inverters are supplied this way(G83 approved), and some can be set to this.

 

[wstevew]

+1 to Earthstore's comment above.

You need to get the shading modeled to know the impact on yield.

In my opinion the potential downtime reduction of solaredge could be negated by the fact you have more devices (more to go wrong).

 

[Worcester]

We're in the uk are you you could get a few quotes too from here

Also you dont require permission on 1x4kw solar installation
Its only on multi installs in the same street you need permission from DNO
hope your not taking in any spiel!

@sedgy34 if he's going to install an unrestricted 4000TL he will almost certainly need DNO approval to exceed 16A (3.68kWp) and it may even have to be a G59 application now since the gudileines expired in March.

 

[JH69]

Time of shading is also important.
Shading in the early morning or later in the evening is less important than around midday, when the suns output is approaching its peak.

Shading will be minimal, and only early on during the day when the sun is weak. The installer has said he will connect the strings to take this into consideration, so while I expect a SolarEdge system to slightly outperform SMA, in this case, I don’t imagine it would that significant. I suspect around 90% of the time there will be no hard shading, and certainly none when the sun is shining directly on it.

 

[JH69]

Using a 4000TL would require pre approval and really offer nothing over the 3600TL (which is basically a 16A capped 4000TL). Do you want to know what your system is doing on a per panel basis? Do you want to reduce your potential downtime if there is a fault? Do you want an additional 5/10% production? Do you want to minimise what shading issues you have on the system? Answer yes = go with Solaredge! Answer no and to be honest I would use a Fronius IG 3.6TL.

Thanks for the reply.

There are a few things that put me off the SolarEdge system:

1. Extra expense
2. Lack of “Sunny Beam” type portable monitor
3. Need to have the inverter connected to the internet
4. More components to go wrong.
5. If the inverter fails, it needs to be replaced with another SolarEdge inverter.

The thing that I am curious about though is what the extra yield might be on a relatively unshaded roof. I’ve read some suggestions that it can be around 5% or more, but an article in Photon magazine indicates that when there are no shading issues the advantage is probably only 1 – 2% (i.e. not enough to warrant the 9% price premium).

As for approval to use the SB4000TL, the installer has said he has a good relationship with the local DNO and is happy to get approval for the install. For me, it’s really a question of whether it’s worth paying the extra £100 for what will potentially only marginal extra Kwh, but I do like the idea that the system’s output won’t be capped in the way it would be with the SB3600TL

I haven’t looked at the Fronuis inverters, simply because none of the installers have yet offered it to me. How is the Fronius IG 3.6TL when it comes to remote monitoring?

I really like the look of the SMA Bluetooth and the ability to monitor the inverter using either Sunny Beam or a Laptop.

 

[provr6]

If you go SMA, save your money and don't go for the sunnybeam. Laptop does all and more for free (bar the cost of a wireless dongle if you don't have wifi built in to the laptop).