Solar Panel Layout for Sectional Roof (Sydney)

ihbh on 18/12/2020 - 23:12
Last edited 21/12/2020 - 20:29

My house has a sectional roof - originally a Federation house that was extended, and then had a second storey added, which makes it a non-standard solar installation. Given the challenges I've accepted a 6.6kw system with 18 panels is probably price optimal for my roof at the moment. I obtained a few quotes to understand the price/value offering from the various suppliers and also my situation. See attached layout diagrams; North is vertical up.

C1 - $3.9k - put panels on SE and didn't discuss it with me - didn't bother calling back to ask why he chose it.
C2 - $4.6k - same company (I clicked twice because the website didn't confirm receipt of my submission), chatted with his technical guy to come up with layout - says I need 4 optimisers for the 4 panels on the front second storey.
X - $3k standard install tried to flog a battery solar package; looked on map and said standard install too hard for my roof and ended it there.
A - $3.3k - Indian call centre - were prepared to discount and said no optimisers needed and wanted me to pay deposit pronto as the discount was for today only.
S - $4.8k - said I needed 18 optimisers. 1 for each panel. Seems like I was talking to an engineer, and just prepared to answer any questions technically, referred me to analysis on Solar Quotes, no pressure to sell.

Questions:

Optimisers: Do I really need 18 optimisers like S said? Can I get away with say 4 in the third direction of C2? Is A for real?
What is the optimal placement of the panels in your opinion, if price was not an issue, noting, for example, that in S, the top right 3 and bottom right 5 panels are on the bottom storey?
Who would you recommend given the price and panel layout, assuming panels and inverters and warranties similar?

S v2 - based on feedback we've moved 1 panel from the SE first storey to NW second storey.

E - Enphase quote by a high end installer - cheapest option is $8k with Trina panels; $9.4k with LG Mono X Plus panels; $11k with LG NeON2 panels

The panel placement is mostly similar to Sv2 except for the SW panels and one less on the North top storey (4 vs 5 panels; one issue raised by SBOB is if the fifth panel will fit).

Finn Peacock's discussion on optimizers vs microinverters have them neck and neck in terms of overall benefit for sectional roofs and partial shading. However, when you take the $3+k difference into account, S v2 seems the clear best choice. Both S and E have very good reviews everywhere.

Is there anything else I haven't considered?

Home & Garden Solar Energy System

Comments

lgacb08 on 19/12/2020 - 00:07

If you go with 18 optimiser, better just pay more and get and enphase system and don't have to worry about all these mess, all the panels will work independently against each other. From the look S seems to be reasonable, but ask him to confirm why only 3 panels facing north west, that'd be quite short of the string. If you don't have shading from tree or double storey nearby I'd say bugger all and no need for optimiser because the shade only hit once the sun is low in the sky and output is not that great by that time.
- lgacb08 on 19/12/2020 - 00:11
  
  Hmm, look more closely it seems you have double storey so the 5 panel on the lower right side of the house gonna be in the lower roof section, if that's the case you'll need optimiser for them because once the sun go over the west side those panels will be impacted and will pull voltage the string involved down. All other panel if on the upper roof section will not need optimiser. But seriously if an enphase system is about 1k higher I'd go for that option rather than scratching my head around
Hiroko on 19/12/2020 - 04:27

+1

Quote S is as close to best you’ll get.
From what is pictured, it looks like you do not need 18 optimisers.
IMO i’d move the 5 panels on the lower eastern side over to the western section just next to the 3 panels on NW.
Mid-day to afternoon sun on the upper western side will always yield more power than the lower eastern side, even with optimisers.
What brands are they offering for that price?
- ihbh on 19/12/2020 - 14:03
  
  18x Seraphim 370 panels
  Growatt MIN5000TL-X inverter
  18x Tigo optimizers
SBOB on 19/12/2020 - 08:29

+2

Some of those layouts won't actually fit in reality.
Too close to ridge lines or gutters.

For a roof like that you'd be insane not to find a decent local installer who actually does a site visit as part of their quote, and a focus on a decent install that fits.

That's not a simple install roof so the cheap end of the market that just quotes based on nearmaps pics might not be the best end result.
- ihbh on 19/12/2020 - 09:28
  
  I discounted the cheap quotes from the start when they were based on standard sales and letting me bear the cost of underperformance down the track.
  - SBOB on 19/12/2020 - 11:26
    
    you have a 3.9 and 3.3k quote in your list… thats my definition of a cheap quote
    
    an installer cant do a decent job with the panels positioned like that for that $. Its not like a simple single run of panels
    Theres multiple roof penetrations to do/seal, unless you want a bunch of ugly (and future failing) coro across your roof between panel segments
    - ihbh on 19/12/2020 - 12:07
      
      I left them in these options for the proposed panel layout and comments on real cost if they were ideal or some combination.
deeevan on 19/12/2020 - 08:38

I've also got a sectional roof with tree shade, ended up with an Enphase system - 5 arrays oriented NE, NW and SE (2 panels). The SE aren't that bad, they're rarely the worst performing panels for the day.
I agree with a mash of quote S and the NW panels of C2.
- ihbh on 19/12/2020 - 16:06
  
  What would be the cost your Enphase system today for approx 6.6kW today?
  
  We can only fit 1 more panel on the NW roof - see S v2 in OP for mash.
  - SBOB on 19/12/2020 - 16:45
    
    are you doing these layouts or the proposed solar company?
    I don't see those panels fitting on the roof layout as they are shown
    
    for that Sv2
    the northern panels are overlapping ridge lines and the middle 2 aren't even lined up so could struggle with clamping zones on a single rail (plus look ugly)
    the 3 panels on the left/upper eastern side are overlapping ridge lines
    the lower 3 panels on the north eastern side are overlapping gutters (hello waterfalls)
    - ihbh on 19/12/2020 - 17:00
      
      Proposed solar company. I asked if we could move 2.
      
      The company drew it up initially, but I will ask them to verify again; very useful comments - thanks. Is there any way I can get more certainty other than the installers going out?
      - SBOB on 19/12/2020 - 17:59
        
        +1
        
        @ihbh: nope,
        that roof with its multiple small spaces should be (imo) a 100% site visit before accepting any quote and a focus on finding a quality installer rather than just cheapest bulk 'base level gear' seller.
      - deeevan on 19/12/2020 - 22:56
        
        @ihbh: It was installed 18 months ago, 19 x 310W for $8000. Not the cheapest, priority was trust they knew how to install properly. Like SBOB, they pointed out the feasibility issues of other proposals.
        
        Seeing Sv2 I realised I meant SW not NW, but I have no idea how they'd perform given its the one orientation I don't have. Knowing that it was the company who drew it up makes me wary, the new layout at the front of the house looks a nightmare to install.
    - ihbh on 21/12/2020 - 20:24
      
      the northern panels are overlapping ridge lines and the middle 2 aren't even lined up so could struggle with clamping zones on a single rail (plus look ugly)
      
      The E quote also has placed it like this to get 4 panels up there. Federation house has high lower storey ceilings and upper storey ceiling is also high so only birds will notice the lack of looks.
      
      the 3 panels on the left/upper eastern side are overlapping ridge lines
      
      Yep, S has run it by his inhouse installers. Worse comes to worse they have space on the NE first storey with panel moved to second storey N.
      
      the lower 3 panels on the north eastern side are overlapping gutters (hello waterfalls)
      
      The first storey has wide eaves so they can move up the roof a bit (maybe at the cost of some shading), but I'll see what the installers say - I might have to accept some waterfall although there is a small drain nearby.
avoidfullprice on 19/12/2020 - 09:24

I obtained a few quotes to understand the price/value offering from the various suppliers and also my situation.

With the the panels all over the place - some on first storey (so will be blocked by second storey wall parts of the daytime) and some in different orientations - what was the estimate month by month energy production in the quote? And from that, based on your current consumption pattern, what will be your ROI timeframe?
- ihbh on 21/12/2020 - 20:53
  
  The quotes have the system generating over 8000 kWh / year; we use around 3000 kWh / year at the moment with two adults and two young children, but is increasing. With the current low usage ROI will be well over 5 years based on electricity bill savings; I'm not sure including feed-in, but gut feel is around 5 years.
  
  Do you have any rules of thumb to do better assessment?
  - avoidfullprice on 23/12/2020 - 09:33
    
    ROI is my go to decision. Two ROIs actually - one without feedin, and one with feedin.
    
    Estimate provided by reputable solar installer would factor in usage by day and usage by night in calculating self consumption, and so the ROI based on nominal feedin would be realistic.
    
    5 years to me is okay, provided the workmanship and material won't fail in the first 10 years.
Euphemistic on 19/12/2020 - 11:30

Steer clear of A. High pressure tactics indicate no care for customer.

They given you a bunch of options but obviously some are silly because they are putting panels on all 4 sides of the roof between them. One of those sides has got to be the least optimal and shouldn’t have any panels. Surely that would be obvious from a site visit.
- SBOB on 19/12/2020 - 11:41
  
  and at the price quoted, its string inverters
  So generally only 2 mppt, and therefore reduced output as they will need to pair east/west strings together for one of the inputs, resulting in a reduction in total generation over the day
  - Euphemistic on 19/12/2020 - 13:09
    
    Micro inverters would probably be required.
    - SBOB on 19/12/2020 - 13:24
      
      yep… though unlikely at the prices shown in the quote examples.
      
      For a roof like that I'd expect half decent gear with install to be 6k at least for something like SolarEdge, panels that aren't bottom of the barrel, and an install thats done right and wouldn't' later look at and wonder why i've got roof leaks or a bunch of ugly cabling across my roof
      - Slippery Fish on 23/12/2020 - 09:37
        
        @SBOB: I have a disability client who was quoted 8k in person but then they emailed her 12k, accepted over the phone next day never having checked emails until 3 months after install when ergon told her the system has never worked. Now she is fighting them over the fact the guy said 8 in person then they emailed 12k.
        
        Gota be careful.
- ihbh on 19/12/2020 - 13:53
  
  I had mentally discarded them at the start when I saw a former Aus cricket captain front their campaign, but persisted to see if there was anything worthwhile hearing.

Solar Panel Layout for Sectional Roof (Sydney)

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