When do Micro inverters or Solaredge make sense

reloaded25

This Solar game is a lot to take in. I am currently gathering quotes for 4KW system of 16 panels and I have a wide variety of specs and prices. One particular company is pushing quite hard to supply Enphase micro inverters. I have a roof that faces due south and I am told that I have a shading factor of 1 (no shading issues). Can a roof like this benefit from micro inverters or DC power optimisers or should I save my cash and get a good quality single inverter. I like the monitoring that comes with the enphase and solar edge and the longer service life of the units but is the ROI really viable if I have no shading?

HELP please.

Ageing_Stick_Insect

In my limited experience I would say you don't need micro-inverters. Those are only required in two circumstances:-

1) Panels on multiple roofs.
2) Shading problems.

As you intend to have all panels on a single roof with no shading a standard inverter should be fine. Ask the company to justify why you need micro-inverters.

tunnel

On the other thread you posted on you've mentioned shading in winter.....do you have shading issues(that YOU can see on your roof at any time of the day)? No point discussing micro inverters or solaredge until you clear that up. As the saying goes, no smoke without fire!

reloaded25

In the very depths of winter I have shading on as much as 10% of the roof but only until 0900 - 1000am. Other companies not selling micro inverters or solar edge have said this is not a shading issue because the panels will not be producing much at this point.

Thanks

Martyn1981

reloaded25 wrote: »

In the very depths of winter I have shading on as much as 10% of the roof but only until 0900 - 1000am. Other companies not selling micro inverters or solar edge have said this is not a shading issue because the panels will not be producing much at this point.

Thanks

Hiya - don't bother.

Worst case(ish) that 10% shading may knock total generation down by about 50%. But from 9 to 10am in the winter, it's not really worth worrying about. The sun is low (poor angle to panels), the sun is less strong having travelled through more atmosphere, there will be more bad days, when nothing will save your generation anyway.

Best case, and ignoring the morning/winter generation, is that micro's of PO's will maximise the performance of each panel, but the small gain will be outweighed by the extra expense, and more bits that could go wrong.

Tunnel, Ray (Ageing Stick Insect) and myself, all have SolarEdge systems on some or all panels. It's a great system, does a great job, but I don't think you really have a job for it to do.

Lastly, a good quality 3.6 to 4kW inverter will probably be set up with two strings (equal number of panels on each string). Placing the shaded panels on one string will mean they only affect that string, so perhaps a loss of 50% on 50% of the panels, so not so bad.

Lastly (again!) never underestimate shading, definitely worth pondering and asking, so I'm certainly not belittling you. However, if your terms are correct 'very depths of winter' and '9am to 10am' then don't worry about it.

Mart.

Martyn1981

reloaded25 wrote: »

In the very depths of winter I have shading on as much as 10% of the roof but only until 0900 - 1000am.

Hello again, just a thought, but might be able to put some numbers to this.

Assume depths of winter, generation is from 9am to 3pm, so 1 hour is 1/6, but that will be one of the poorest hours (lower sun further from south), so let's guess at 1/10 (10%) of the days generation.

Also assuming that it knocks all gen down by 50% (split strings, more like 25%).

Also taking a guess at December generation of 100kWh (have a play on PVGIS, see FAQ thread).

So impact is 50% losses, for 10% of day, against 100kWh = 5kWh, worth about £1 pa in December. Possibly similar in Nov & Jan if shading affects them too.

Mart.

jimmyboy420

I also have SolarEdge - don't forget me Martyn!

I would agree - a small amount of shading will impact on generation - but when you're not making much anyway, it's not worth worryng about too much.

My chimney starts shading one panel considerably from 2pm, then more panels from 3 until it stops around 5 or 6pm. That's quite a decent part of the day, even for South East facing panels, so I'm satisfied with my SolarEdge, but just for an hour in the depths of winter... I wouldn't.

nigelpm

The other disadvantage to note with individual inverters is you'll have 16 points of failure rather than 1!

I have a very tiny shading issue and the company who quoted me assessed the difference individual inverters would make and it was minimal. They provided both options to me but made no recommendations.

I'd question why they are pursuing the individual route. Is it to their benefit or yours?

I'd seriously consider using them at all if they can't provide you with the additional benefits and quantify them.

Fruit_and_Nut_Case

Another SolarEdge owner chiming in. My shading issue is with the neighbour's chimney and the inverter deals with it very well. The slightly longer guarantee was also something that appealed to me.

I suspect if I only had minor shading issues in deepest winter and was installing now I probably wouldn't have bothered. As I was an "early adopter" and am on a higher FiT rate it certainly made sense at the time to maximise my output.

Good luck with making the right decision.

nigelpm

Fruit_and_Nut_Case wrote: »

As I was an "early adopter" and am on a higher FiT rate it certainly made sense at the time to maximise my output.
)

That's probably the nail on head.

The £500 additional extra on £6,000 is proportionally a lot more than £600-£700 (?) on £15,000

reloaded25

Thanks for the advice guys, I have settled on a string inverter (Aurora power one) due to my very minimal shading. As suggested by some one we'll put the panels that do have minimal shading on one string and the rest on another. Opted for the 833 Eternity because of their reduced degradation and a top quality mounting system. Ended up at £5700 for a 4kw system and monitoring a device, could have gone cheaper but I am happy with the company I have selected. Once installed and up and running I'll post a review but for now I'd like to say a genuine thank you to all those that have commented.