Optimisers or micro inverter?

[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.

 

[Gavin A]

truth of the matter with enphase vs solar edge is that there are pros and cons to both options, they will both probably be within a whisker of each other on generation in most cases, so it's probably more important to sus out the quality of each installer - ask to be put in touch with a previous customer locally to see what they thought of them.

 

[SolarCity]

truth of the matter with enphase vs solar edge is that there are pros and cons to both options, they will both probably be within a whisker of each other on generation in most cases, so it's probably more important to sus out the quality of each installer - ask to be put in touch with a previous customer locally to see what they thought of them.

Precisely my expectation. Installer quality is far more important.

 

[wersolaruk]

i would agree with solar city hands down the quality of installation is key, I personally dont like enphase and i can see faults occurring through there rubbish trunk cable which to me is low qaulity and will not stand the test, plus with a lot more components behind each panel there is more to go wrong on the roof. gOING TO A SOLAR EDGE meeting to mo in durham should be interesting

 

[jason121]

Enphase predict a 10% share in the inverter market by the end of this year. There latest inverter is 4th generation, so has been around a long while. They also state that the first problem will occur within the first 5 years, after 5 years the inverters will work for another 15 year.
I have fitted a few Enphase systems and its surprising to see how the panels are mismatched due to the positive tolerance.

 

[Worcester]

There latest inverter is 4th generation, so has been around a long while.

4th Gen - already !!!! How long have enphase been in the market place? 3 years?

They also state that the first problem will occur within the first 5 years, after 5 years the inverters will work for another 15 year.

So whose going to pay to fix all those systems???

its surprising to see how the panels are mismatched due to the positive tolerance.

Which is nicely sorted by a well designed string inverter.

Don't get me wrong, I have a lot of time for the opinions of the regular contributors to this forum.

It does seem though that some are being swayed by the marketing guys.

Simple:
String inverters work - we all know that and some are more efficient than others. If they go wrong they are quick, simple and inexpensive to swap with regular 10 year warranties.

Micro-inverters (enphase, power-one, sma, enecsys) work, so do optimsers. If they go wrong though when installed on domestic roofs, the replacement costs are horrendous, even allowing for a £125 kick back from enphase. - Are you going to ask all your customers to pay up in say only 6 months / 18 months / 60 months time when one goes wrong (It's not workmanship on your part so not covered by your warranty...) - What are your customers going to say / think?


We all acknowledge that a well designed string array system can perform well, and that micro-inverters / optimisers allow you to install in less than ideal situations.

In which case should you not install? .... whose interests are you serving by installing a system in less than ideal circumstances that has a greater likely hood of costly repairs / maintenance.

What are the real lifetime costs then of a string inverter system vs an 'on-panel' system including replacement and maintenance costs?

Unless there is a significant difference then the argument for on-panel technology doesn't stack up.

 

[SibertSolar]

Fair comments, can't help but agree to be honest. Both solutions have their place but rarely are they a better option where a decent string inverter solution can already be effective

 

[jason121]

Enphase been around a while. They are American company. You can argue the case all day regarding warranties. A few months back I had a problem with a CL48 inverter. Called there technical dept telling me to do this and that to find fault. Eventually I found fault on my own, by pulling out all the power racks. One had burnt connection. Not being a registered Fronius partner I ask for free training because I had saved them a engineers time. The reply was don't do freebies. Sent me a cheque for £60 for my trouble after 2 days fault finding.

 

[jason121]

https://enlighten.enphaseenergy.com/public_systems


Approx 2500 units installed in the UK and yes I do like the system.

 

[Gavin A]

a bit more detail on the Enphase design reliability as I drilled down into this with them a while back.

IIRC they work on around a 0.2% failure rate per unit, which works out at around a 3.2% failure rate for one unit on a 16 panel array inside the first five years guarantee period when they'll pay towards the actual costs of replacement.

They work on the basis that the vast majority of faults should show up inside the first 5 years, so don't expect many failures inside the longer guarantee period.

They also reckon the actual design life of the units should be in the region of 50 years once any faults have worked their way out in the first few years due to the solid state nature of the units or something. Personally I suspect there could well be a weak link in the chain there such as the communications devices that might cause an earlier failure than for just the inverter side of things itself, but that's just my sods law suspicion rather than based on any data.

They undoubtedly are excellent bits of kit, we just struggle to justify them against the high end string inverters, and I find some of their performance claims vs string inverters to be highly dubious.

Oddly, I suspect that they will have the most impact when used in conjunction with cheaper panels, as they tend to have wider panel tolerances, so one panel could be 10Wp difference from the best to worst performing panels in a set, where s string inverter would operate at the lowest panel output, the microinverters would optimise each panel. Less of an issue where the panel tolerances around more like 2-4Wp from highest to lowest panel.

 

[MCS Renewables]

We offer customers both options ( SMA or Enphase ) where applicable and the price difference is only about £1000.

A lot of customers are choosing the Enphase despite the extra cost as they like the information accessibility and the warranty and do not have to give up space in the home for the inverter. They like the ability to log on with their phones and tablets worldwide and are not limited to the 100m sunny beam range!

We have hundreds of SMA systems which do very well but if one of those customers has a problem we are only made aware of it if or when the customer notices.

With our Enphase systems we can log in every day and instantly see the status of each module and inverter on every project in real time and historically.

When the SMA's with five year warranties start failing these customers will have to pay for replacement inverters and the £1000 will soon be eaten up especially if it happens twice. A lot of our customers are on the 25 year FIT contracts so a five year warranty could result in four inverters, although this seems unlikely.

So the replacement "cost" issue is not actually so different.
With the SMA you would have a cheaper labour cost but much higher inverter cost.
With the Enphase you would have a free replacement inverter but may need to use a tower and the swop out would take longer. Only in very extreme cases can I see that you would ever need an expensive fixed scaffolding.

With the Enphase you do have the advantage of knowing exactly which inverter and it's roof position you are replacing in advance and the PV system is still working until the day you undertake the works, which minimises generation losses. With the string inverter you may have a grumpy customer chasing you as they lost a week or so's worth of entire generation until you sourced a replacement and booked some swop out time.

Another consideration is module failure. With the Enphase system you can see immediately which module is underperforming or has failed but with the string inverter you have no chance it wil be a case of testing each individual module in that string, which could be very time consuming.

With regard to performance the Enphase system outperforms the string inverter by 15% according to the side by side test performed by Enphase up North.

I DO NOT consider that this was an ideal test and it is flawed in some respects however if we ONLY use 5% as a fairer figure, over the twenty years that represents an extra ONE year of generation and import kW hour savings for each system. That alone on a four kW system could be worth the £1000 with index linking and future import price rises avoided.

If the Enphase better performance is actually 10% or indeed 15% better over 20 years that is a considerable amount of additional FIT monies and import saving.

SMA obviously think micro inverters are the future and a viable option that's why they are releasing their own version later this year.

Then there is the safety issue of no DC cables or high voltages in the home, if an inverter catches fire it's better outside on your roof than under it, if you have a non PV fire the fireman only have <50v to deal with on the roof when the 240v is isolated.

You can add to the Enphase system at any point by extending the trunk cable without having to resize the original string inverter so that gives some flexibility.

So even on perfectly South roofs with absolutely no shading a lot of customers are choosing to fit Enphase systems because the initial £1000 extra is only a very small part of the overall picture.

There seems to be a lot of miss information about the Enphase system, the communication device has no bearing on the system and cannot interrupt generation, you do not actually need the envoy unit so it can be taken away from site although this does impact on the internet accessibility ! We have done this on several new build sites, four modules with Enphase on each property set them up and take the envoy. This is much much cheaper and easier than any string inverter for this size system. Plus we can always sell the home buyers an envoy and easy system upgrade later!!

If the envoy communication unit fails the Enphase PV systems keeps working which may not be the case with the Solaredge system ?