SolarEdge - is it worth retrofitting?


I have been contacted by phone by this company and they are trying to get me to take a free efficiency test on my system, and then started talking about Solar Edge (which I hadn’t heard of). So I put them off and started doing a bit of research. It seems that is costs quite a bit and it’s doubtful whether it’s worth the expense to fit on an existing system.

Does anyone have any experience they could share?




My installer now uses solaredge optimisers almost exclusively on new installations because the cost of around £20 a panel is almost certainly saved over the lifetime of a system as they minimize the effect of partial shading. He also suggested it might be worthwhile retrofitting on systems that are frequently subject to shading. But it means new inverters.

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Thanks Ian. I do have some partial shading, but replacing the inverter is going to make it much more expensive. I think this installers idea is to install them when my current inverter dies. It’s coming up to 5 years so I guess it could go at any time!

No, it’s certainly not worth replacing your standard inverter with micro inverters.

(Was this a cold call? Sounds like all the other eco scams to me.)

Saying it costs only £20 a panel is a bit of a distortion. At £25 a panel (a more realistic price difference) that’s £4-500 for a typical installation. A retrofit will involve the installers getting up on the roof, removing all the panels, adding the inverter to each panel and replacing the DC wiring with AC wiring. That’s going to amount to quite a big bill for labour.

If you have a serious shading issue it could have been worth installing micro-inverters at the outset, but retrofitting a satisfactorily working system is a waste of money and resources.

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Hi Bill

The cost of £20 was specific to a new installation. They are optimisers not inverters, they just plug in to the DC cables, no rewiring. They need a SolarEdge inverter. They communicate by some means (Maybe over the DC cables) You have to pair optimsers and the inverter after installation. Having said that I agree probably not worth retrofitting unless you have to access the panels any way.
We have had to have 2 panels replaced. One was damaged by something dropped by a seagull and the other by a brick we think thrown by Vandals.

Thanks for all your input. Yes it was a cold call, but the guy was not a slick salesman, he was quite nervous. He just called back again, at my agreement (after I had researched the SolarEdge). After some discussion I told him I wasn’t interested, but had his details if I needed them in the future.

I think the company who initially installed our panels was also a bit of a rogue outfit, as they should have used microconverters, as we have several panels at different angles. But the cost of putting up all the scaffolding again and getting the SolarEdge modules installed might not be worthwhile. I know our system is suboptimal, but I can heat a tank of hot water and save on electricity during the day, so I’m happy. Maybe better thing would be to reduce even more the amount I export, and use more of it instead.

On a side-topic. How are people getting on with smart meters and solar panels? I’m avoiding having one as long as possible, but it may be inevitable.

Correct. They are Maximum Power Point Trackers.
Essentially, DC to DC converters.

I think over the lifetime, it is probably cheaper to replace a string inverter with micro inverters, than to put in optimizers (plus you’ve added in one more component that can fail). You generally get 20% more energy output and they usually last 2+ times longer than a string inverter - as most companies will warranty them for 25 years now. A string inverter, depending on how it’s sized, has a lifespan of ~10years. Then there are newer micro grid-ties based on "resonant conversion” instead of PWM. They are expected to have a lifespan longer than the usable lifespan of the solar panels themselves, i.e. 50+ years and they are pretty cool. One inverter can handle 120-600 Volt AC output range. SPARQ Systems (Canadian), and some Asian companies as well, are starting to make them.

Hi Allen, we install PV for a living (along with other renewable energy solutions)
Solar Edge vs string Inverter
It depends upon 3 things

  1. The shading that the panels will be exposed to
  2. The panel layout / string configuration
  3. The inverter chosen.

We will only install SMA Inverters or Solaredge Inverters, with their optimisers (I have both configured on my own installations)

So why SMA vs other inverters? SMA offer
a) Multiple Strings, i.e multiple Multi Power Point Trackers (MPPT)
b) Good range of string sizing per MPPT
c) Global Optitrac that does frequent analysis of the string and is very good at maximising the string output. (search Google for the SMA Global Optitrac published papers if you want to see more for yourself)

As a design principle / golden rule is that a string should only have panels that are a) the same orientation (lansdcape / portrait) b) the same angle of elevation and c) the same direction d) the same panels.
Unfortunately not all installers followed these design rules and cut costs by joinning panels together that don’t fit those criteria and installed cheaper single string inverters.

In MOST cases the SMA inverter is more than adequate and SolarEdge will happily acknowledge that compared to a properly configured SMA inverter then the gains offered by their panel fixed optimisers is minimal or non-existant.

All inverters are not the same, single string, poor mppt perfornance, poor shading compensation, warranties noit worth the epaper they’re written on. So the benefits over other inverters could/might be worthwhile either by replacing the current inverter or by swapping over to SolarEdge

So when do we use SolarEdge

  1. Complicated Panel layouts
  2. Complicated Shading
  3. Smaller systems where SMA don’t offer a multi string inverter (e.g. 2kWp 1kWp East, 1kWp West)
    Then there is no discussion :slight_smile:
    One other advantage is the low output needed to start generating, some inverters require a much higher string voltage before they’ll start generating.

I’ve had the same cold call three times now and when I ask them to validate their claim against how my systems are installed, they have always admit that they can’t.

They guy who called you was almost certainly a telesales agent working from a script. (though usually pretty well trained)

So there are SOME instances, i.e. a poorly / badly designed, configured or installed system when it may be worthwhile to spend the money on converting to SolarEdge optimisers and inverter.

My system that runs on SolarEdge is actually made up of 16 panels of 5 different types of panels in 3 different orientations and 3 different elevations - ad ideal use of SolarEdge :slight_smile:

As for micro-inverters, being a cautious individual, the smaller the number of on-roof components that could fail, the better. Once again it is only on the very small output systems that we have to install for some developers just to meet building regs (2 - 4 panels) that we install them and once again, our preferred product comes from SMA.

Hope that helps, Rgds Gordon

but does not the optimiser installation make that argument moot? I do not know what they cost in your region, but here they are about $70 each for a p300 optimiser and say a Hoymiles mi-250 micro inverter is ~$98 for 250 watt or APsystem yc1000 (1000w) for $258. These ones do not have the horrible cost of cabling that Enphase does, the cable is included with the inverter and you simply string the inverters together to reach the 30 amp breaker limit. ( Enphase i believe is 15 amp - not a fan of Enphase, their pricing is terrible.)

So 28 panel system 7 kW 70X28 ($1960) plus $1569 for a SMA 7.7kW = $3529
or mi-250 98X 28 = $2744
or mi -500 165X14 = $2300
or yc1000 = 258X7 = $1806

I’ve had a SolarEdge system for almost 5 years now and have been extremely happy with it. My roof design means my 16 panels are spread over five different orientations, some north facing, some east. Upper and lower roofs have different rakes and lots of different shading issues … lower eastern panels get shaded by the upper storey at about 1pm, lower northern panels get shaded by some big gum trees during winter’s lower sun. Those per-panel optimisers just sort it out. Plus, you get per-panel reporting. Their monitoring portal is very classy with lots of display/graphing/reporting options.

As an example, this one shows my panel layout (North is the top of the pic) and my lifetime per-panel energy output:


Only to some degree, as there are signficantly fewer components in the optimiser, and therefore a significantly lower chance of unit failure.

if you take components with a I on 10,000 chance of failure in 5 years and have 100 components, you now have a 1 in 100 chance of failure, use 200 components and you have a in in 50 chance of failure.

Also in the UK< Solaredge’s warranty covers the replacement liability, so no obligation on the installer. - Why would they do that? - answer confidence in their own product.

Grid approved micro-inverters cost significantly more than your costs over here. (enphase 250W = £90+Tax, +n comms gateway (£250+tax) + lots of other components)
We have also seen a significant number of micro-inverter manufacturers come and go in the UK market.


An ideal use for SolarEdge :slight_smile:

not really- that much different component wise ( other then the missing transformer but that not what fails on micro -inverter it the same thing that fails on a optimizer a cap or a MOSFET ) . they have similar warranties such as the above mention mi-250 the default warranty is 12 years but if you want to pay $25 more they will extent it to 25 years same as some optimisers . or one can buy the SPARQ micro inverter and they have a starting warranty of +25 years.

as i said enphase micro inverter are not my choice for micro inverter- they sell the inverters “cheap” but get you terribly on cabling and other stuff not to mention a subscription for their gateway. the other ones do not do this

sure I get why installer recommend string-- as it a cash cow. that kind of locks the home owner in. because there generally no room for expansion ( as the inverter generally has to be size for your panels). string inverter are relatively short lived and need to be replaced and generally if something goes wrong the whole system goes down . and it can be a complete overhaul to sort out an issue, ( ie blown diode on the panel)

where as micro - inverters generally last longer- if something goes wrong, only that inverter is affected and the system stays running - easily debug though gateway or visually with LED on the inverter themselves .- in my experience – - in my ~7 years of using micro grid tie inverters personally - for wind and solar - I had 2 die on me both were killed by an UPS that began to seep modified sine wave during a power outage causing the inverters to hammer - if you ever seen modified sine on a grid- its not good-- things blow up really bad and very quickly. the 500w UPS was seeping 30 watt but it was enough to intialize a GTI .on one. it melted the board the other it blew up all the caps there was nothing left of either of them that could be repaired- moral of the story if using GTIs be weary of using UPS inside the building unless you isolated them for your GTIs

And, for US customers, Enphase no longer does either. They stopped charging for the monitoring service about two years ago. (and they may have stopped charging customers outside of the US, but I don’t have any info regarding that) True, they did charge an annual subscription fee, and it wasn’t cheap.
Many customers weren’t happy about that.

I’ve had an Enlighten account since Dec of '16, and haven’t given them a cent.

Good debate and I think we’ll agree to differ.

An inverter has components that require it to match grid conditions - voltage and phase, stop generating when there’s no grid, wait a period of time before reconnecting etc, additionally to be installed in the UK they have to be certified to defined standards - G83 or G59 depending upon total size connected to the single grid connection point (G83 < 3.68kW and G59> 3.68kW (16A @ 230V)

Also UK roofs are generally higher, steeper and made of more fragile, slippier coverings (think natural slate at 40° vs felt shingle at 20°), so replacing a failed unit will generally require scaffolding that would cost way more than a string inverter.

Don’t get me wrong, yes there are occasions where micro-inverters are the correct choice. I am not however convinced that is is ALWAYS the BEST choice compared to a good string inverter or SolarEdge optimisers.

oh okay thanks Bill for the update on enphase- I stopped enquiring about them a couple years ago. I had a solar project i was going to do with them. the inverter was about $130 then the short trunk cable was 60$ then the multiple 9 port main trunk was +$200 then the end trunk was $XX. the gateway was $400 i think and the subscription was $300 a year by the end of the day it averaged out to +$300 an inverter . a I went scr#w that and bought other micro gti for <1/2 the price that include all it cabling with the inverter

sure no problem Grordon. but like the UK not all houses are 40 or 20 degrees in NA mine is is 45. and i did not mount mine on the roof either. clearing snow would be a brutal . I have evacuated solar tubes on my roof and they are generally self clearing unless you get 3 feet of snow on your roof . also my PV panels are set in arc to broaden and flatten my production period currently it about 18hrs i produce +500w peaking at ~2.6 kw between 11am to 1pm… currently sun up at 4am down at 11pm