Quote Advice

[pat72]

Hi,


New to the forum and looking for some quote advice if possible.
Had 4 quotes for bungalow in North West with SE/SW roof at 30 degree tilt as follows:


1) 4KW: £7K inc vat
- 16 x Suntech 250-20Wd Poly Panels
- Power One PVI3,6-OUTD 3.6Kw Inverter
- K2 Roof Mounting System
- Yield Reduction due to shading (1%) - PVSOL
- Estimated annual output: 3690kWh(PVSOL)


2) 4KW: £6.2K inc vat
- 16 x JA Solar JAM60-250w Mono Panels
- Power One Aurora 3.6Kw Inverter
- Roof Mounting Kit
- Yield Reduction due to shading (<20%) - SAP2009
- Estimated annual output: 3286kWh(SAP2009)


3) 4WK: £5.6K inc vat
- 16 x Renesola 250W Virtus II Poly Panels
- Samil Solar river 3680TL Inverter
- Roof Mounting Kit
- Remote Monitor
- Yield Reduction due to shading (<20%) -SAP2009
- Estimated annual output: 3286kWh(SAP2009)


4) 3KW: 5.2 inc vat
- 12 x Suntellite 250W Mono Panels
- Samil Solar river 3300TL Inverter
- Schletter roof mounting system
- GEO Solo Remote Monitor
- Yield Reduction due to shading (8%)-PVSOL (<20%)-SAP2009
- Estimated annual output: 2430kWh(PVSOL) / 2464(SAP2009)




Quote 4 was interesting as surveyor/installer calculated that a 16 panel install would get 12% shading after taking account of tree and a neighbouring property.
Hence he recomended 12 panel 3KW system.


Any advice in which looks like the best system in terms of quality, performance and longevity?


Thanks in advance for any replies.

 

[jason121]

If shading go with the powerone and maybe the Renesola
There are other ways to improve output by using using Solaredge inverter or micro inverters cost will increase a little but will be a good system long term
Give this thread time i am sure others on here, that are in your area, will be glad to quote you.

 

[FB.]

I would be concerned to further evaluate the shading.

Shading during peak generation times can cause a lot of problems with solar panels by affecting power flow through the shaded parts of the string - when a panel drops out of the string while shaded, it can confuse the inverter software which tracks the optimum power point to maximise generation - it's quite possible that an unshaded 3kW will perform much better than a partially shaded 4kW, although the type of shading, the number of panels affected, the time of day the shading occurs and the string configuration will have an effect on how significant the shading is in the real world.

I can't say I'd be overly bothered which panels as they're all 250W. I'd be more concerned about the quality of workmanship.

 

[Earthstore]

Option 1 Suntech, the largest PV panel manufacturer went bust today, also prediction is too high for e/w split in your location.

option 2 looks OK, but mono panels good inverter though.

option 3 looks OK, but personally not keen on Chinese inverters although others will say different I am sure.

option 4 he is the only one to comment on the shading and as so has tried to work around it, shading can be the kiss of death to a PV system, this is where good system design will pay you dividends, there are other ways to negate shading issues, but they do come at a price, but may well pay dividends in the long term.
Remember though that trees do grow.
Again though, Chinese inverter, which would not be my choice.

This is just my opinion on the information provided, but I feel you could get a better designed system in that sort of price range.

Just noticed, inverter on option 4 is a 3300, for a 3kwp split system, which may be a little large, as a smaller inverter may be more efficient so could produce more power.

 

[SRE]

1st 3 look like sales people, last one like an installer. Whereabouts in the North West are you? My advice every time would be to worry slightly less about the panels & inverter and more about the quality of the installation and after sales. You may buy Panasonic panels and an SMA inverter but if they are installed badly you'll have wasted your money.

 

[Gavin A]

none of them.

if shading is an issue then I'd definitely be at least using the power-one for the shading function, but using the renesola panels or similar to get somewhere close to quote 3 prices - they'll perform at least as well as the suntech, probably better than the mono.

I don't understand quote 4, and suspect neither do they - if shading do not use the chinese inverter, it doesn't cope as well with shading, and are both roofs equally shaded, or are they planning to do 8 on one, 4 on the shaded roof? If the latter, then it won't work due to the low voltage of 4 panel strings.... also the inverter quoted for is not dual tracking, or is he fitting 12 panels on the single unshaded roof? (if it's all on one unshaded roof, then fair enough).

Where in the North West are you? We're just back from an installation in South Manchester, and cover the south east portion of the North West... if that makes any sense, or SRE is North West based, though I can't remember exactly where.

 

[MCS Renewables]

Put your postcode in here ...... Microgeneration Certification Scheme - Installer Search

And get some more quotes from local installers.

Look into Enphase inverters ( Enphase UK | By combining the power of solar energy and the proven advantages of communications technology, Enphase Energy products make solar power systems productive, reliable, smart and safe. ) if you have a shading issue . Will cost you about £1500 more than standard inverters but have 25 year guarantee and superb "real time" on line information.

Personally would not touch Chinese inverters or Poly modules.

Download this FREE information pack from the Energy Savings Trust
( A buyer's guide to solar electricity panels / Buyers' guides / Generating energy / Publications / Home (England) - Energy Saving Trust England )

 

[SRE]

We have poly modules on two of our rental houses and they are outperforming the mono's on our own house

 

[Gavin A]

Personally would not touch Chinese inverters or Poly modules.

why not?

Decent quality poly panels will usually outperform most mono panels in the UK for the same Wp rated output due to their better medium to low light performance.

About the only panels where this is in question would be the newer Mono panels like the Panda from Yingli which have better high temperature performance than most poly panels, and better medium and low light performance than most mono, but still not as good as most poly panels.

 

[pat72]

Thanks all for posts.
In answer to some of the questions:
I'm based in Preston.
All the panels would be installed on one roof as one set.
The roof is actually SE, nearly south but not quite.

 

[Worcester]

We've installed 100's and 100's of kW of poly modules - we have some poly sites outperforming neighbouring mono sites...

With these quotes, firstly take the advice above, though quality of workmanship should be the most signiifcant factor when selecting your installer.

 

[Spoon]

With these quotes, firstly take the advice above, though quality of workmanship should be the most signiifcant factor when selecting your installer.

I don't want this to sound sarcastic (but it will sound like it is) but can you judge Quality & Workmanship from a quote? Its not like they are going to quote that they are crap at these.

 

[Ian-LS]

I don't want this to sound sarcastic (but it will sound like it is) but can you judge Quality & Workmanship from a quote? Its not like they are going to quote that they are crap at these.

You can. If the quote is professional. accurate and informative with details over installer warranty it will bode well that the installation will be of a high standard. You can't guarantee it obv but imo if its a poorly designed system and porr quality quote then you'll wonder if the same lack of attention to details comes through in the installation. Choose a company who you feel comfotable with based on the site survey and quality of the quote, price is a factor but not the most important factor imo.

 

[Earthstore]

QUOTE=Spoon;739342]I don't want this to sound sarcastic (but it will sound like it is) but can you judge Quality & Workmanship from a quote? Its not like they are going to quote that they are crap at these.[/QUOTE]

You could be right, if you get a good salesperson, with experience and knowledge of this industry, he could well put together a good quotation, and tell the customer what he wants to hear, therefore "selling the system".
Some salesmen are trained to sell, and do it very well, sadly this industry has been blighted by poor salesmen.
On this forum it is mainly proffesional companies, whose knowledge is second to none, and they sell on their experience and knowledge and complete first class installs too.

 

[pat72]

Got some more info on shading issue (Quote 4).
A 16 panel install (landscape) would have 6.1% and 9.4% shading on panel row 1&2 receptively on column 1 at west cable and 3.9% and 5.4% on column 2. Shading at east gable would be 2.6% and 4.7% column 7 and 2.8% and 5.7% column 8.
Proposed 12 panel solution has 3.7% & 4.9% column 1 and 2.7% & 4.9% column 8 with rest on panels ranging from 2.7% to 3.7% on rest of panels.

Would it be better to go with 12 panel solution with reduced and better shading spread or 16 panel solution more compromised on shading but with better inverter that could handle shading issues?

 

[Somecamel]

Yer, I'd go with him

 

[FB.]

Got some more info on shading issue (Quote 4).
A 16 panel install (landscape) would have 6.1% and 9.4% shading on panel row 1&2 receptively on column 1 at west cable and 3.9% and 5.4% on column 2. Shading at east gable would be 2.6% and 4.7% column 7 and 2.8% and 5.7% column 8.
Proposed 12 panel solution has 3.7% & 4.9% column 1 and 2.7% & 4.9% column 8 with rest on panels ranging from 2.7% to 3.7% on rest of panels.

Would it be better to go with 12 panel solution with reduced and better shading spread or 16 panel solution more compromised on shading but with better inverter that could handle shading issues?

It sounds as if the shading issues are complex - affecting both ends of the array and at different times of the day as the shadow moves around.
If shading is not a problem from 9am-3pm in March-October then the shading might not be worth worrying about. If shading is between peak hours (9am-3pm) then you could have all sorts of gremlins to deal with.

Can you take a screenshot of your house roof from Google Maps and post it up, so it is easier to visualise?
Link to Google maps here:
Google Maps

-

 

[pat72]

It sounds as if the shading issues are complex - affecting both ends of the array and at different times of the day as the shadow moves around.
If shading is not a problem from 9am-3pm in March-October then the shading might not be worth worrying about. If shading is between peak hours (9am-3pm) then you could have all sorts of gremlins to deal with.

Can you take a screenshot of your house roof from Google Maps and post it up, so it is easier to visualise?
Link to Google maps here:
Google Maps

-

Thanks for the info' Overhead of bungalow roof attached
Cheers.

 

[FB.]

I'm struggling to see where any significant shading will come from, unless there is something tall off the bottom edge of the picture, or a TV aerial which isn't showing in the picture. The Google picture will have been taken in summer, and you can see the whole roof is in full sun.

From what I can see, your proposed panels should be free from shading at their peak generation times (9am-1pm for SE and 11am-3pm for SW) during spring, summer, autumn.
Generation early or late in the day is much less due to low-in-the-sky weak sun. The same is true of winter. Most arrays have minor shading early or late in the day - even if it's a terrace of houses across the street!

As for how attractive rectangular panels will look on a triangle/pyramid-shaped roof is a different matter.

 

[FB.]

You may be able to use the following sun chart to visualise which arc, and how high the sun will be at various times of day and various times of the year:

Sun Position Calculator | PVEducation

My position, in Cambridgeshire, is approx latitude 52 and longitude 0, GMT offset 0 until British Summer time kicks in.
Bolton (you mentioned living in the NorthWest) is approx latitude 54, longitude -2.