Optimisers or micro inverter?

[izzypops]

Hi. I'm looking to get a full 4kw system installed and have had 3 quotes. 1 I dismissed as the company didn't check out too well. The other two quotes appear to both be reputable companies with all similar credentials and warranties. The main difference is one is favouring solaredge and the other enphase. I have had long discussions with both but appear to be no further forward. Again I've tried to research the two options online but again to no real benefit. It seems both systems are pushing the same benefits in their own way. The enphase is very slightly more expensive, but has longer warrantee. Is this worth it?

 

[Worcester]

What are the shading issues - a well designed string system using Power-one or SMA inverveters can both outperform enphase or solarredge.

We have installed all three technologies, and it is very dependant upon the configuration - how many roofs, how amny panels per roof, what orientation and elevations and what shading affects the roofs.

 

[izzypops]

Have east pitch for 11 panels and south 5. The main issue is one pitch shading another. All 3 companies quoting suggested one or another.

 

[MCS Renewables]

Enphase has no single point of failure whereas the Solaredge system will completely stop if the inverter fails. So with Enphase you lose 1/16th of your 4kW system compared to all of it with Solaredge inverter failure.

Enphase outperforms Solareddge according to the ONLY independent test results available from PV evolution labs at :- dated Sept 2013 so very current.
http://www.metgen.co.uk/assets/download/index/assets/122/

There are three U tube videos available here about why Enphase is better
Enphase Inverters | Solar PV & Renewable Energy Trade Supplier | Metgen, UK

There is side by side testing regarding Enphase v SMA but it is a little dated and I need to find the link for it.

Solaredge seem to shout the loudest about being the best and keep on about Enphase capacitors failing despite the fact they and SMA use the exactly the same capacitors. We have over 100 Enphase systems and have had one unit fail as a squirrel decided to eat the cable which is hardly the manufacturers fault.

There is some evidence that systems over 14 modules are less efficient with Solaredge.

We have used all three systems but now only fit Enphase and SMA as both of these have superb customer support whereas Solaredge back up is patchy at best.

The Solaredge optimiser unit is about £30 on eBay and the Enphase micro over £90
which is also a guide. The Solaredge optimiser clearly marked as made in China on unit whereas the Enphase is USA or German.

i have an SMA inverter on my own roof and when it fails I will be upgrading my system to Enphase for the warranty and better performance.

 

[MCS Renewables]

Enphase swopped the squirrel eaten inverter cable with a complete new inverter within one day and paid us £125 to fit it.

With SMA and Solaredge you need to find a suitable cool space for the inverter which in my opinion should not be a loft space.

 

[MCS Renewables]

With Enphase you have no high or dangerous DC voltages anywhere in the system.


Shading report here :

http://enphase.com/global/files/Enphase-Study-Shade-Impact.pdf

 

[Worcester]

We are open minded and will design the best system case by case, some installers are particularly pro one technology or another. - Still need answers to the questions I posed of the OP before I'll comment.

Micro-inverters have issues with start up voltages, string Inverters usually have a maximum of two MPP trackers.

Optimisers and Micro-inverters are 'at panel' technology meaning that in a domestic on-roof installation, there will be significant costs in fixing faults. £125 doesn't get a scaffold / tower plus a person on site, it will cost more than that to replace a faulty one. In ground mount or flat roof / elevated installations, the access costs are no different between the technology types.

We do not install string inverters in lofts except as last resort

 

[MCS Renewables]

I understand that Solaredge and standard string systems may have a start up issue with having to achieve a higher DC voltage from multiple modules but an Enphase inverter is stand alone once there is 5 watts of light.
Enphase systems start earlier and finish later than combined module systems which we can prove as we have a 4000TL East West split system at home with Sanyo HIT modules. Our Enphase systems that we can access on line are up and running a long long time before mine.

The £125 was a good will gesture, the normal swop out fee is a lot more however I agree that if you need scaffold it's probably not enough. The same applies to replacement DC optimiser units from Solaredge as well.

The Solaredge main inverter only comes with a 12 year warranty and needs additional payment to get to 20/25 years.

 

[Worcester]

5 watts is low light, not necessarily shading.

What's the minimum start up voltage for the enphase unit?

That is the significant factor with micro-inverters and shading, as string inverters are not so affected by one bypass diode kicking in on a panel. Most micro-inverters start up voltage is greater than that output by a panel when it's lost 1/3 of it's Voc when the bypass diode has kicked in.

 

[MCS Renewables]

Sorry it's a cut and paste :

Enphase Energy sets itself apart from any other inverter on the market with the M215’s exceptional low voltage performance. The unit maintains its high level of efficiency even as panel input voltage drops below 20 percent, greatly improving low light performance. Its direct current input peak power ranges from 22 to 36 volts, yet the unit has been tested to perform well at input voltages as low as 16 volts and up to a maximum of 45 volts.

 

[Earthstore]

Just curious, what is the KWP of your east/west split system?

 

[MCS Renewables]

8 Sanyo HIT 240 East and West to an SMA 4000TL inverter.
Installed June 2011, at 43p rate, done over 12,700 kW hours so far.

Before that we had a 3.6 kW system which I think was 10 Moser Baer 180 modules East and West with a SMA 1700 for each side. This was fitted in late 2008/early 2009 and was my original MCS test case project. Decommissioned it when we saw the better performance our customers were getting with Sanyo.

So currently waiting for Enphase to release the next generation of micros which we can pair HIT modules and with 72 cell modules, been told they are on test and will be available by Spring 2015.

 

[Earthstore]

This is just an opinion and I respect your expertise, but I would have used a smaller inverter on an east/west split...

 

[MCS Renewables]

There were not that many inverter choices available that were twin tracker in the early days of solar.
The SMA3600 came along later.

As an East West split this system averages over 3600 kW hours of generation a year with the top modules and inverter available at that time.
With respect I do not expect many E/W splits in the UK have generated a lot more !

 

[SolarCity]

For a bit of balance to the Solar Edge vs. Enphase argument:

http://www.solaredge.com/files/pdfs/microinverters_vs_optimisers_the_true_story.pdf

 

[Earthstore]

There were not that manyinstalled one if inverter choices available that were twin tracker in the early days of solar.
The SMA3600 came along later.

As an East West split this system averages over 3600 kW hours of generation a year with the top modules and inverter available at that time.
With respect I do not expect many E/W splits in the UK have generated a lot more !

All fair comments, out of curiosity what does your system "peak" at, and how often?
The 3600tl was a long time coming but you would have installed one if it was available at the time and even though your system has performed excellently do you believe it could be better still with the 3600tl?

 

[wersolaruk]

Does MCS renewables work for enphase, bloody get a grip man

 

[Berneray]

Few months back I wrote to all the folks we had sent out quotes to over the last year that had not bought. I was more interested in the reasons they did not buy. This is what I got back.

10% did not buy because they might be moving house
11% did not buy because one party did not want to. Mainly because of the look.
40% did not buy because they just did not want to spend the money
39% did not buy because they said their brains were fried and were suffering information overload. Some said they were turned against solar because of all the conflicting advice they received from all the companies they got in.

Reading threads like this I know what they mean. Its so difficult for consumers to find advice on one product that another company will dispute.

 

[Worcester]

Debate is good

 

[Gavin A]

There were not that many inverter choices available that were twin tracker in the early days of solar.
The SMA3600 came along later.

As an East West split this system averages over 3600 kW hours of generation a year with the top modules and inverter available at that time.
With respect I do not expect many E/W splits in the UK have generated a lot more !

fair play, but then you are in dorset, so have a wee bit of an advantage

we've got a few similar 4000TL installs out there from 2011 when we were a bit more SMA biased, I think power-one actually had some smaller twin trackers even then.