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Hi,

 

I'm just getting a few quotes back on the installation of an in-roof system of 3.84 - 4.2kWp array of 12 PV panels, facing SE with no tree shading whatsoever but potentially a small chimney flue.

I am tempted by the SolarEdge addon but not by the price to be honest so my question is if SolarEdge is worth the investment addon or not?

Or is there an alternative optimiser that is almost as good? All I hear is SolarEdge are the best but there must other options perhaps that would not cost as much but do the same thing.

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Get a 2 string inverter and wire it so that the shaded modules are on the smallest string.

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Hi. I've gone for a full solar edge setup - 5.2pkW. Reason being that my panels are spread over three different roof elevations. I got a good price for everything from ITS - yet to be installed so yet to see how it works!

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Couple thoughts

- if you get the SolarEdge add on, make sure you get quotes with the newest HD-Wave  SolarEdge inverter as these are designed to work with the optimizers (only) and have cost savings based on that. (No MPPT tracking in the inverter, relies on the optimizers for that)

- the other 2 benefits of SolarEdge optimizers are (i) provide lifetime per-panel performance monitoring and graphing, (ii) auto safety cut out if the string is disconnected from the inverter.

 

I like these extra benefits, but really they are mostly interested for tinkerers and enthusiasts. If you just want to fit and forget PV then they really don't add a lot. (But IMHO grid scale Solar PV is getting so good I think domestic installs are increasingly the domain of enthusiasts only; the ROI is borderline and might actually make less sense over time)

 

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Our enphase microinverters are 5.5 years old and have never skipped a beat. 

 

Microinverters take a different approach to optimisers, but they both allow per-panel optimisation.

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Posted (edited)

Yes I have had Enphase micro-inverters and Tigo optimisers offered as well but have been told there isn't much price difference.

 

I must admit I am swaying towards not having it. For the extra £800-1400 I am being quoted it's probably not worth the extra benefit. Especially as I'm not going to have any shading issues really. The Growatt inverter has 2 string so in theory I could that like @SteamyTea suggested to be honest.

 

I am by no means a tinkerer or enthusiast but just want it to work as efficiently as possible for a sensible budget.

I may be better investing in an iBooster or Eddi by MyEnergi to divert any excess generation to my hot water cylinder.

 

Silly question but to make it more cost effective could I have just 4 SolarEdge optimisers and split the 12 panels into 4 groups of 3?

Is that sometimes done or does it not work like that? Would save me having to add 12 optimisers.

Edited by ashthekid

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Another vote here for enphase micro inverters. Makes installation very simple and you get the full power out of each panel. It’s also a single wire from the roof into a single isolator, only thing you need to find a home for is the bridge unit which is about the size of a cable router. 

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20 hours ago, ashthekid said:

getting a few quotes back on the installation of an in-roof system of 3.84 - 4.2kWp array of 12 PV panels


Out of interest - what prices are you getting ..?? Does it include installation ..?

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9 hours ago, ashthekid said:

Silly question but to make it more cost effective could I have just 4 SolarEdge optimisers and split the 12 panels into 4 groups of 3?

 

Not likely, I think it will overrun the max voltage on the optimizer.

 

9 hours ago, ashthekid said:

I may be better investing in an iBooster or Eddi by MyEnergi to divert any excess generation to my hot water cylinder.

 

Obviously "both" would be most efficient, but in a run off between these the HW tank redirect is almost certainly going to give the best £ ROI.  The larger and better insulated tank, and the more HW you you expect to use from it, the better the payback.

 

59 minutes ago, PeterW said:

Another vote here for enphase micro inverters. Makes installation very simple and you get the full power out of each panel. It’s also a single wire from the roof into a single isolator, only thing you need to find a home for is the bridge unit which is about the size of a cable router. 

 

Sounds much better than other micro-optimizers. Our contractor had horror stories of installing a system where each micro-optimizer had a separate AC cable that had to be brought inside the building before connecting together. Resulted in dozens of penetrations of the airtightness envelope and a lot of taping and remedial work to pass the air test.

 

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9 hours ago, ashthekid said:

I must admit I am swaying towards not having it. For the extra £800-1400 I am being quoted it's probably not worth the extra benefit. Especially as I'm not going to have any shading issues really.

 

It depends what sort of shading is involved with the chimney flue you mentioned. It's counter intuitive, but even a relatively small amount of shading on a single panel can massively lower the output of the entire string within which the panel sits. If the flue is south of and close to the array, it could result in almost permanent downgrading of the panels output for most of the day in sunny weather.

 

You shouldn't have to speculate on what impact optimisers or micro-inverters will have. All of these factors can be modelled, and an estimate given as to what sort of generation you can expect for each combo. I think these more expensive solutions probably made more sense when FiTs payment were higher, but it really depends on the individual circumstance.

 

As well as dealing better with shading, optimisers and micro-inverters can also have a lower turn-on voltage. With a standard string and inverter, the inverter won't produce power until the voltage of the string as a whole exceeds a certain value. Micro-inverters (and maybe optimisers - not sure) start generating as soon as each panel gets to operating voltage. The individual operating voltages enable power to start being produced at relatively lower light levels. I think the net effect is a bit more energy at the start and end of the day.

 

10 minutes ago, joth said:

Obviously "both" would be most efficient, but in a run off between these the HW tank redirect is almost certainly going to give the best £ ROI.  The larger and better insulated tank, and the more HW you you expect to use from it, the better the payback.

 

Are you perhaps thinking of the Zappi rather than the Eddi? The Eddi is an immersion diverter like the iBoost.

 

 

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53 minutes ago, jack said:

Are you perhaps thinking of the Zappi rather than the Eddi? The Eddi is an immersion diverter like the iBoost.

 

No - I see now I worded it ambiguously, but I was replying to this:

 

Quote

 

I am by no means a tinkerer or enthusiast but just want it to work as efficiently as possible for a sensible budget.

I may be better investing in an iBooster or Eddi by MyEnergi to divert any excess generation to my hot water cylinder.

 

I meant if the goal is the most efficient system possible, getting both the micro-optimizers (this topic) AND an Eddi/iBoost will be best.

 

It really depends on your definition of efficiency though: electrical energy captured per year per £ of capital investment, full lifetime financial ROI, or CO2 saved, will lead to different optimization choices.

 

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23 minutes ago, joth said:

No - I see now I worded it ambiguously, but I was replying to this:

 

Ah yes, got it!

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I went with Hoymiles microinverters- duals because of our configuration. They're very efficient,  daisy-chain together for easy cabling, and have per-panel MPPT. This works very well, you can see shading passing across individual panels in the monitoring software.

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@PeterW I am getting a range of prices from £5000-6000 for 3.9 - 4.3kWp in roof systems.

 

I've asked for quotes from about 6 companies which the best setup probably being these options:

  • 3.9kWp - 12 x Perlight panels with Growatt inverter via GSE - £4,997 inc VAT & installation
    • Solar iBoost included - £5,167 inc VAT
    • Eddi included - £5,327 inc VAT
    • NO SOLAREDGE
  • 4.3kWp - 12 x LG panels with Growatt inverter via GSE - £5,796 inc VAT & installation
    • Solar iBoost included - £5,986 inc VAT
    • Eddi included - £6,146 inc VAT
    • NO SOLAREDGE
  • 4.32kWp - 12 x 360w Longi Tier 1 with SolarEdge inverter via GSE - £5,865 inc VAT & installation
    • SolarEdge Optimiser on each panel included
    • Eddi included

I have scaffolding all up ready for it so they have taken that cost out of their quotes.

I think the last quote is possibly the best I am going to get with everything included.

 

Assuming SolarEdge inverter is probably best to go with the SolarEdge optimisers for obvious compatibility reasons?

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Sorry are these GSE in roof install or standard on roof install ..?? 
 

Those panels are £105 each, optimiser is £43, inverter is change of £550

 

What’s the remaining £3k..?
 


 

 

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In roof GSE.

 

@PeterW Which panels are you referring to for £105?

Where are you getting your component pricing from?

LG vs Perlight vs Tongi? Much difference?

 

I'm guessing the remaining £3k is installation and MCS Certification.

 

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£3k for install is eye watering. If you check midsummer for prices. 

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3 hours ago, ashthekid said:

I'm guessing the remaining £3k is installation and MCS Certification.

 

WHY do you want MCS certification?  The only tangible need for that in the past has been a requirement to claim the FIT.  But with no FIT any more, why would you want to pay the "MCS Premium" for a bit of paper that is worth virtually nothing to you?

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1 hour ago, ProDave said:

WHY do you want MCS certification?  The only tangible need for that in the past has been a requirement to claim the FIT.  But with no FIT any more, why would you want to pay the "MCS Premium" for a bit of paper that is worth virtually nothing to you?

 

MCS certificate is required to register for SEG payments (with Octopus at least). Also (not sure why) our building inspector is requesting it.

 

You can argue it may take a long time to recover additional "MCS appoved" install costs, and you may be right, but it is a bit more than just a peice of paper.  The SEG tariffs are low, but they do add up over time..

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14 hours ago, jack said:

You shouldn't have to speculate on what impact optimisers or micro-inverters will have. All of these factors can be modelled, and an estimate given as to what sort of generation you can expect for each combo.

 

Most supplier won't do full modelling that includes things like chimmneys, and from our expeirence we didn't even have anyone model the optimzers (or not) options.  Rather, quotes just used marketing statements about optimizers giving x% more yield etc.  Agree with @jack though, suppliers should really give you both options backed up with data.

 

If you have time on your hands you and want to model both options yourself (including your chimmeny!) then you can do this with a trial of Pvsol.  Take some time to get a hang of it, but if your roof design is quite simple, it's not that hard.  You plug in the exact location, panels, inverter, string configuration etc. as well as shading objects and it simulates everything for you.

 

 

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9 hours ago, Dan F said:

 

MCS certificate is required to register for SEG payments (with Octopus at least). Also (not sure why) our building inspector is requesting it.

 

You can argue it may take a long time to recover additional "MCS appoved" install costs, and you may be right, but it is a bit more than just a peice of paper.  The SEG tariffs are low, but they do add up over time..

In the 2 1/2 years I have had my solar PV, i have exported 283kWh.  The rest I have self used.

 

Assuming 5.5p export payment, I would have received £15.56 so far.

 

I will let you do the maths and work out the payback time on the "MCS premium"

 

Just get a competent electrician to install it for a lot less money, then ask your BC inspector to show you where in the building regs it states they must be installed by an MCS company.

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9 hours ago, Dan F said:

Also (not sure why) our building inspector is requesting it


It isn’t a requirement yet some LABC inspectors insist on it as they confuse it with the requirements under B and P to check the structural integrity of the roof and the electrical installation. If it’s a new build and the engineer has sized accordingly (or the panels weigh less than the tiles they replace) and the installation isn’t a retrofit then there is no requirement for MCS. 
 

Some go down the MCS required route purely to cover their ar$e as they don’t need to check anything as an MCS install does this for them ... 

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I agree with Dave, get a competent , even incompetent electrician to do it, it’s a doddle.

 

spend the money on a structural engineer if you must.

 

MCS no longer worth the premium now.

self installing 10 panels myself later this year.

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9 hours ago, ProDave said:

In the 2 1/2 years I have had my solar PV, i have exported 283kWh.  The rest I have self used.

 

Whereas I exported 611kWh in April alone.

 

YMMV, it's really up to the buyer to do their own maths and make their own decision

 

 

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