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sirweste

Solar Panels - 110 / 120 / 130 Watt + 20% efficiency

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I know I know, another panel thread, sorry.

I've searched here and dug through ebay and google and not really come to a decent conclusion yet.

What I'm looking for is four of the "slim" (non-house sized) panels for my solar upgrade. I presently have two old 100 W ones which will be removed and replaced. Ideally I'd like 120 W panels and I'll most likely be buying mono rather than poly.

My question: Does anyone know if you can buy panels in this approximate size that use modules with over 20% efficiency? Or am I looking for something that doesn't exist / isn't readily available? I assume they would have to be back contact to achieve this level of efficiency?

 

Cheers

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On 10/05/2017 at 13:16, sirweste said:

I know I know, another panel thread, sorry.

I've searched here and dug through ebay and google and not really come to a decent conclusion yet.

What I'm looking for is four of the "slim" (non-house sized) panels for my solar upgrade. I presently have two old 100 W ones which will be removed and replaced. Ideally I'd like 120 W panels and I'll most likely be buying mono rather than poly.

My question: Does anyone know if you can buy panels in this approximate size that use modules with over 20% efficiency? Or am I looking for something that doesn't exist / isn't readily available? I assume they would have to be back contact to achieve this level of efficiency?

 

Cheers

 

Your question puzzles me. How are you measuring "efficiency"? 

My understanding is about  1kW per square metre is radiated from the sun so a typical panel of 0.5m2 with a peak output of 100W is already 20% efficient.

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10 hours ago, Mike the Boilerman said:

 

Your question puzzles me. How are you measuring "efficiency"? 

My understanding is about  1kW per square metre is radiated from the sun so a typical panel of 0.5m2 with a peak output of 100W is already 20% efficient.

It's the declared module performance. The panel manufacturers, sometimes, declare the efficiency of the individual modules they use. I can't remember the numbers, but I believe sunpower have the "best" modules which achieve something like a 23% efficiency. I'm wanting to buy a panel made of modules that are at least 20%, rather than most I seem to be able to find that are ~17%.

I can find panels made up of "good" efficiency modules in the "normal" house sized flavour. But really struggling in the narrow type, which are typically marketed at boats and vans.

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Ah I see. 

I think the 'efficiency' claims are highly suspect. Unless there is a defined method of calculating it you still have no idea if all the different manufacturers use the same basis so the figures are probably little more than techno-babble from the marketing dept designed to make you choose their panels over someone else's. And with you it seems to be working! ;)

In addition, even defined methods can be frigged, as VW et al ably demonstrated.

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When I researched into making my own solar panel a few years ago I found out that top of the range mono  solar cells were max 19% efficient and poly were around 16-17%. It may well be that cost effective panels may nowadays of crept up over the 20% mark. 

This link gives further info on panels that may be of interest to us mere mortals who may be looking at cost effective panels

http://www.theecoexperts.co.uk/which-solar-panels-are-most-efficient

I did bump into a professor on the towpath once  who had an experimental space station solar panel which was about 33% efficient however the price for these was slightly over my budget. 

Found this link for further details. 

http://www.solarpowerworldonline.com/2016/03/kind-solar-panels-nasa-use/

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16 minutes ago, Mike the Boilerman said:

Ah I see. 

I think the 'efficiency' claims are highly suspect. Unless there is a defined method of calculating it you still have no idea if all the different manufacturers use the same basis so the figures are probably little more than techno-babble from the marketing dept designed to make you choose their panels over someone else's. And with you it seems to be working! ;)

In addition, even defined methods can be frigged, as VW et al ably demonstrated.

Potentially, but some of the testing is independent, a solar module race if you will. The VW scandal isn't quite a fitting here I don't think, but I understand your point. 

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24 minutes ago, sirweste said:

Potentially, but some of the testing is independent, a solar module race if you will. The VW scandal isn't quite a fitting here I don't think, but I understand your point. 

and we all know how independence can be flawed, fooled, or biased :(

The VW analogy is entirely relevant as they were able to build something into the product which was able to fool the independent testing.

Which independent labs are testing the panels you are referring to? presumably there is a link or a reference on their web sites?

 

Cynical? Moi?? :)

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Yes it can, however, in lieu of conducting trials myself this is what I will be working from.

VW didn't fool independent testing at all from what I remember. And the practice that they employed is more widely used in automotive circles than most people think. Also, I don't think VW actually broke the testing rules either...

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Oh and for the module efficiencies have a google around, there's a few sources.

In summary then, it seems that until now nobody has the info that I'm looking for, so I will put in the leg work myself and post up what I find for people searching in the future

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On 11/05/2017 at 15:48, sirweste said:

Oh and for the module efficiencies have a google around, there's a few sources.

In summary then, it seems that until now nobody has the info that I'm looking for, so I will put in the leg work myself and post up what I find for people searching in the future

 

You still haven't answered my question "what do you mean by 'efficiency'?" Do you mean price efficiency, area efficiency, or something else?

Consider a solar panel that gives 1 Watt per £1 price, and is say 100mm square. Is this more or less efficient than a panel that gives 2 Watts per £1 price, but is 200mm square?

 

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The only difference is that a 19% efficient panel that outputs 100W will be slightly bigger than a 22% panel that outputs 100W.   Or to put it another way, for a given size a more efficient panel will have a slightly higher rated output but will be more expensive.  So I am not sure why efficiency bothers you.  For most of us the £ per W is what is important.

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21 hours ago, Richard10002 said:

Given that DIY is fairly straightforward, onboardsolar seem quite expensive. I'm probably going to fit a 2 panel 500w MPPT system for about £500 or so. Onboard solar want £1200.

The reason I posted the link is that I believe they say they are now doing a 120w panel for the same size as the 100w panels that they was/are fitting.

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that'll shut them up for a while.  B)

 

 

P.S.  this is in response to George Kennedy's post (that appears below :banghead: ).

Edited by Murflynn

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23 hours ago, George Kennedy said:

You asked for it, so here we go!

 
The global formula to estimate the electricity generated in output of a photovoltaic system is :

          E = A * r * H * PR 
 
E = Energy (kWh) 
A = Total solar panel Area (m²) 
r = solar panel yield or efficiency(%) 
H = Annual average solar radiation on tilted panels (shadings not included)
PR = Performance ratio, coefficient for losses (range between 0.5 and 0.9, default value = 0.75) 


r is the yield of the solar panel given by the ratio : electrical power (in kWp) of one solar panel divided by the area of one panel.
Example : the solar panel yield of a PV module of 250 Wp with an area of 1.6 m² is 15.6%. 
Be aware that this nominal ratio is given for standard test conditions (STC) : radiation=1000 W/m², cell temperature=25 °C, Wind speed=1 m/s, AM=1.5.
The unit of the nominal power of the photovoltaic panel in these conditions is called "Watt-peak" (Wp or kWp=1000 Wp or MWp=1000000 Wp). 


H  is the annual average solar radiation on tilted panels. Between 200 kWh/m².y (Norway) and 2600 kWh/m².y (Saudi Arabia). You can find this global radiation value here : Solar radiation data 
You have to find the global annual irradiation incident on your PV panels with your specific inclination (slope, tilt) and orientation (azimut). 

PR : PR (Performance Ratio) is a very important value to evaluate the quality of a photovoltaic installation because it gives the performance of the installation independently of the orientation, inclination of the panel. It includes all losses.

Example of detailed losses that gives the PR value (depend on the site, the technology, and sizing of the system): 
- Inverter losses (4% to 10 %) 
- Temperature losses (5% to 20%) 
- DC cables losses (1 to 3 %) 
- AC cables losses (1 to 3 %) 
- Shadings 0 % to 80% !!! (specific to each site) 
- Losses at weak radiation 3% to 7% 
- Losses due to dust, snow... (2%) 

 

I wasn't asking because I wanted to know, I was asking to try to get the OP who is obsessing about panel efficiency to think about what it actually means!

It doesn't appear to have worked though :-/

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5 hours ago, Mike the Boilerman said:

 

You still haven't answered my question "what do you mean by 'efficiency'?" Do you mean price efficiency, area efficiency, or something else?

Consider a solar panel that gives 1 Watt per £1 price, and is say 100mm square. Is this more or less efficient than a panel that gives 2 Watts per £1 price, but is 200mm square?

 

You asked for it, so here we go!

 
The global formula to estimate the electricity generated in output of a photovoltaic system is :

          E = A * r * H * PR 
 
E = Energy (kWh) 
A = Total solar panel Area (m²) 
r = solar panel yield or efficiency(%) 
H = Annual average solar radiation on tilted panels (shadings not included)
PR = Performance ratio, coefficient for losses (range between 0.5 and 0.9, default value = 0.75) 


r is the yield of the solar panel given by the ratio : electrical power (in kWp) of one solar panel divided by the area of one panel.
Example : the solar panel yield of a PV module of 250 Wp with an area of 1.6 m² is 15.6%. 
Be aware that this nominal ratio is given for standard test conditions (STC) : radiation=1000 W/m², cell temperature=25 °C, Wind speed=1 m/s, AM=1.5.
The unit of the nominal power of the photovoltaic panel in these conditions is called "Watt-peak" (Wp or kWp=1000 Wp or MWp=1000000 Wp). 


H  is the annual average solar radiation on tilted panels. Between 200 kWh/m².y (Norway) and 2600 kWh/m².y (Saudi Arabia). You can find this global radiation value here : Solar radiation data 
You have to find the global annual irradiation incident on your PV panels with your specific inclination (slope, tilt) and orientation (azimut). 

PR : PR (Performance Ratio) is a very important value to evaluate the quality of a photovoltaic installation because it gives the performance of the installation independently of the orientation, inclination of the panel. It includes all losses.

Example of detailed losses that gives the PR value (depend on the site, the technology, and sizing of the system): 
- Inverter losses (4% to 10 %) 
- Temperature losses (5% to 20%) 
- DC cables losses (1 to 3 %) 
- AC cables losses (1 to 3 %) 
- Shadings 0 % to 80% !!! (specific to each site) 
- Losses at weak radiation 3% to 7% 
- Losses due to dust, snow... (2%) 

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how come my response to George Kennedy's explanation is displayed before his?  ...............  and not for the first time.  :banghead:

CWDF time machine?  Please can the nerds and geeks sort this out.

 

P.S....... it makes MtB and myself look a bit stoopid .................. which maybe we are.  :unsure:

Edited by Murflynn

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7 hours ago, smileypete said:

Panasonic do a 800mm wide panel that's 20% efficient and not outragously expensive:

https://eu-solar.panasonic.net/en/solar-panel-vbhn240sj25-vbhn245sj25.htm

 

Have you had any luck in finding a supply-only source for one of those? I tried quite hard a while back and haven't been able to find one.

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10 hours ago, smileypete said:

Panasonic do a 800mm wide panel that's 20% efficient and not outragously expensive:

https://eu-solar.panasonic.net/en/solar-panel-vbhn240sj25-vbhn245sj25.htm

There are similarly efficient panels in smaller sizes, but they are very niche and directed at the offshore marine market, so almost certainly eyewateringly expensive! :o

http://www.buypvdirect.co.uk/index.php?route=product/product&product_id=273

£199 + VAT

  • Greenie 1

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3 hours ago, Sea Dog said:

Have you had any luck in finding a supply-only source for one of those? I tried quite hard a while back and haven't been able to find one.

They seem fairly widely available, maybe have another google/phone around, Richard has found one above.

If there's good roof space (big barge) then these come closer to the panasonics than most:

https://zerohomebills.com/product/solar-pv-panel-ja-solar-285w-mono-percium-bf/

For one or two panels delivery may be a killer, and so worth finding a nearby supplier for local collection.

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2 hours ago, Richard10002 said:

 

2 hours ago, smileypete said:

They seem fairly widely available, maybe have another google/phone around, Richard has found one above.

If there's good roof space (big barge) then these come closer to the panasonics than most:

https://zerohomebills.com/product/solar-pv-panel-ja-solar-285w-mono-percium-bf/

For one or two panels delivery may be a killer, and so worth finding a nearby supplier for local collection.

Thanks guys.  Actually, i had another search this morning after reading Pete's post above and found 'buypvdirect' too - located in Wisbech, it seems. 

I have an issue I should probably learn to get over - when I find something I'm interested in on the web but I can't find out about their delivery charges until I've provided them with all of my details, I move on.  Post Code I understand, but full name and address, telephone number and other details I baulk at.  I can't even guess how many companies have lost my custom because of that - or how much more I've paid to buy from another company who doesn't do it!  Anyway, I bit the bullet and entered false details.

In case anyone else can use the information, Shipping is £98.00 +VAT.  Total for one panel, including shipping and VAT - £356.40.

 

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