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Which solar panels are best?

Posted by Chris Jardine on 25 April 2013 at 12:10 pm

Choosing the best solar panel is a bit like choosing the best sandwich for your lunch. What’s better for you – a BLT or a cheese and pickle sandwich? Well, the cheese sandwich wins in terms of lower calories and lower fat, but the BLT contains more protein and more vitamins and nutrients from the vegetables. So it’s a difficult multi-faceted decision, and one that could be argued either way. And that’s even before you’ve looked at salt content, sugar content, sustainability of packaging, carbon footprint, ethics and welfare standards in the supply chain, etc, etc.

It’s much the same for solar panels, with many different criteria that can be used to judge products, and it can be difficult to get good information from installers. This is because the installers themselves are subject to intense marketing pressure from manufacturers of solar panels, with the manufacturers trying to tie down installers to using their particular product. They will do a sales job on the installer by promoting the key benefits of their product. And often, the installer will just then repeat these same benefits to sell to you the customer.

Unfortunately this doesn’t mean that these benefits used to sell panels are either particularly important in the grand scheme of things, or particularly unique among all the products out there.  Most common is choosing a cheap product that is perceived as easier to sell (PV customers tend to be price sensitive), and then talking up its warranties, or other attribute.  It’s quite easy to mislead here – something I call the “Men’s Health” effect; going back to our food analogy, nutritional information in men’s lifestyle magazines will often say something like “This doner kebab contains more vitamin B2 than a grapefruit”.  Whilst this may be technically true, it can certainly mislead the overall benefits by focussing solely on one minor attribute.  When choosing a solar panel you need to be able to read between the lines in a similar way.

Some of you, I’m sure, will be reading this blog hoping for a definitive list of the ‘best’ modules.  It’s not possible I’m afraid, as it depends on how you value the different judgement criteria.  In the same way, I couldn’t give you a list of the healthiest sandwiches without knowing if you value calorie intake more highly than salt content.

So how do you make a judgement? Well a ‘bad’ installer will choose a product, perhaps on the basis of price alone, or because they like what the manufacturers told them, or because they get good supply chain terms.  They will then try and sell you the positive attributes of the panel chosen. A ‘good’ installer, however, will have used their expertise to undertake a full technical assessment of the different products, warranties and prices and provide you with a balanced argument in favour of their chosen product. For example, in my company we rated 30 manufacturers against cell efficiency, measured outdoor performance, long-term degradation, brand value, warranties, speed of supply chain and company ethics and only sell product that scores highly in most, if not all of these aspects. This is a much more nuanced assessment, and I’ll be using future blogs to talk through the details of these different panel attributes more explicitly.

From the customer point of view, it’s still difficult to find the best product for you, because at face value all you will hear is different installers claiming the product they use is the best.  So you need to do a little digging. Here are my top tips for you to at least see who’s done their homework and who hasn’t.

• Ask why they recommend the panels they do. If they only give 1 reason why, be sceptical – one positive attribute does not make a good panel, but several is much more reassuring.

• Ask how they chose what panels they offer?  How comprehensive has their decision-making process been?

• Cost isn’t everything.  If you are being sold a particular product just because it is cheap then that may not be best value in the longer term.

So go careful when choosing what make of solar panel you want for your house.  And make sure your potential installer has looked at product choice as carefully as you.

Also in this series:

2. How important is solar panel efficiency?

3. What's in a brand?

More information on solar PV from YouGen

Introduction to solar PV

10 tips for choosing a solar installer

Find a solar PV installer and read what their customers say about them

About the author: Chris Jardine is technical director of Joju Solar and teaches on the MSc course in Environmental Change and Management at Oxford University.

If you have a question about anything in the above blog, please ask it in the comments section below.

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Comments

9 comments - read them below or add one

arm987

arm987Comment left on: 29 October 2016 at 2:12 am

Was there ever a comment or suggestion re Viking request for info. The question seems very good commonsense and worth following any possible answers or comments.

arm987

 

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Susan Smythe

Susan SmytheComment left on: 28 October 2016 at 4:02 pm

I phoned my energy provider SSE today to ask about a smart meter and was told that it would'nt be compatable with my FIT meter as I have solar panels but that they were working on how to solve this problem. I don't think this is fair and wondered if anyone else has had this problem. Also is this the case with all energy suppliers. Would appreciate any input on this

 

Sue S

 

 

 

 

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CRMTI

CRMTIComment left on: 27 October 2016 at 10:15 am

i recently read about a mixture of different solar pannels on methods on http://crmti.org/ i must say i am worried about crack cells leading to hotspots.

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Cathy Debenham

Cathy DebenhamComment left on: 3 April 2014 at 4:20 pm

Hi Jack

We don't recommend installers, but you can search for installers in Liverpool here, and see what their customers say about them.

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Jack Frost

Jack FrostComment left on: 3 April 2014 at 1:59 pm

Thanks for sharing such an informative article with us. I really appreciate your research and work done for the collection of information. I am influenced by the working efficiency of solar panels, but can you please suggest me a better solar panel installation provider in Liverpool. Someone suggested me a professional firm Total Energy Installation and it has a great past too.

Can you suggest me, what should I do?

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Chris Jardine

Chris Jardine from Joju SolarComment left on: 3 May 2013 at 1:35 pm

Hi Julie,

The first thing to note is that the Sanyo and Panasonic products are the same - Sanyo have rebranded their modules as Panasonic last year.

The Panasonic product is one of the highest efficiency modules on the market as the hybrid technology it uses is unique and it gives you a high yield per m2.  In terms of market niche, it competes with Sunpower which offers about 20% efficient modules.  Both the Panasonic and Sunpower are at the pricier end of the market as you would expect for the more advanced technology you are purchasing.  I have personally shied away from Panasonic as they do not enter their modules into Photon Magazine's outdoor module test, so there isn't the scientific evidence to prove they perform well (although I suspect they do).

Your comments really reinforce what I was trying to get across in my blog piece; how do you make an informed decision when everyone you speak to claims their offering is "best you can buy".  It's worth asking them again why the panels are the "best you can buy".  They will cite it's high efficiency compared to conventional modules (true), but I'd look for some other reasons as well, perhaps your potential installers have some evidence of actual yields from systems they have installed in your area?

Hope this helps,

Chris

 

 

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julessanger

julessangerComment left on: 3 May 2013 at 1:17 pm

I have had two potential installers round to do a preliminary survey for PV panels. Both were engineers rather than salesmen; both claimed the panels their company uses are the "best you can buy".  Are you able to reassure me that both makes are reputable, and if there is anything to chose between them?  I have been unable to find an independent site which compares relative merits.  Is there such a site?  The recommended panels are Sanyo and Panasonic.  I live in the South of England, and would be using a south-facing and an east facing roof (50/50).  Thank you for your help.

Julie Sanger

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Chris Jardine

Chris Jardine from Joju SolarComment left on: 30 April 2013 at 10:44 am

I'm not aware of a definitive list, but off the top of my head common failure modes might include:

Cracked cells leading to hotspots

Water ingress if lamination is faulty

Loose connections in junction box from thermal cycling

Faster than expected cell degradation

It's difficult to tell what future failure modes are likely to be, and improvements are being made all the time to eliminate historic failure modes.  I think the only way you can really mitigate this is by looking at warranties and brand value.  The risk of any failure mode is higher with an 'unknown' manufacturer than a proven company with a long record, but very difficult to say how much more!  

I'll be blogging about warranties and brands over the next couple of months.

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viking

vikingComment left on: 30 April 2013 at 12:41 am

Thanks Chris - However, I'm one of those people who have already bought their system. I was wondering if their was a record of common failure modes with PV systems and if there was anything that I could do to mitigate against these failures please?

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