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  • Martyn1981
    Martyn1981 Posts: 14,781 Forumite
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    1961Nick wrote: »
    .....which is possibly less than the cost of a standard panel 5 years ago?

    Information is difficult to find & conflicting but the efficiency rates of mid-market panels seem to have improved from about 14% to 16% over the past 5 years, an increase of 15%. Some manufacturers claim 17% efficiency for a fairly small premium (not 70%), so that would be a 21% increase in efficiency over 5 years.

    Hiya Nick. I know exactly where you are coming from, but I'm not sure you are fairly comparing like for like. To compare panel efficiencies (or prices) you'd really need to compare the same make and model and how it has changed across the years.

    Otherwise, you may wrongly compare 14, 15, 16, 19 even 22% efficient panels to each other, but that's not really fair. The changes in same model production lines is small, without any big step changes, but, you are absolutely right, these small changes are important, and over time will give changes of perhaps 10% across this decade.

    I have to agree with Z and Ed, the R&R companies will have always tried to pick the best rooves and where possible maximise installs to the 4kWp point. To get from 2kWp to 4kWp would really involve changing from a poorly laid out, low poly efficiency to a perfectly fitted 22% hybrid panel, and I don't think that's a fair comparison.

    Back in 2011 when my ESE was installed I could only get 1.5kWp to 2kWp on my top roof in 1.6m by 1m panels. So we switched to 1.3m by 1m panels and filled it to the brim (around a large Velux). So choosing panels to max out roof dimensions isn't new. Those panels were 180Wp, below them on the small single story roof and rear canopy, we fitted 235Wp 'regular' panels, as they were a better fit than the 180's.

    You could compare 230Wp panels to todays 270Wp. But I suspect the model lines aren't the same, with the 230's moving to 250's and the 270's evolving from 250's.

    I think there is a common misconception that PV technology has improved dramatically in the last 10 years, and that it was this that held it back. But the reality is that the technology has been very good and sound for decades, but was held back by costs, since production scales were too low.

    Please don't think I'm nocking you, a 10% improvement this decade is important, that brings into play any houses that were within 10% of being viable, that could be roof size, orientation, shading.

    You may be interested in this article on efficiency levels as it was only posted yesterday:

    Future PV: Incremental innovations to drive change
    “It is astonishing the level of innovation we have seen in PV,” says Stassen, “only a few years ago we had cell lines being sold with 16% or 16.5% efficiencies and these same lines are now turning out 17.5% cells.”

    This chosen upper example shows an increase of 6 to 10%. I also read an article on YingLi a few years ago (2013ish) (can't find it now) suggesting their lines would improve by 8% by the end of the decade.
    In reflecting on the presentations and conversations held at the event and in its aftermath, Stassen notes that small changes, rather than step changes, are the likely technological pathway the PV manufacturing industry will take.

    “I don’t see any major breakthroughs impacting on the industry and creating sudden improvements,” says Stassen. “I see an overall improvement of the entire field with evolutionary steps.

    Mart.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW). Two A2A units for cleaner heating.

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • Martyn1981
    Martyn1981 Posts: 14,781 Forumite
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    Martyn1981 wrote: »
    This chosen upper example shows an increase of 6 to 10%. I also read an article on YingLi a few years ago (2013ish) (can't find it now) suggesting their lines would improve by 8% by the end of the decade.

    Ok hats off to Google, get the search criteria right and it does all the heavy lifting for you.

    Here's the YingLi article, suggesting a cell efficiency improvement from 17.6% to 19% this decade (2013 to 2010), which allows me and my memory a big 'PHEW!' as that's ~8%.

    SPI 2013: Yingli Green details long-term cell efficiency roadmap to 2020

    Mart.
    Mart. Cardiff. 5.58 kWp PV systems (3.58 ESE & 2.0 WNW). Two A2A units for cleaner heating.

    For general PV advice please see the PV FAQ thread on the Green & Ethical Board.
  • 1961Nick
    1961Nick Posts: 2,078 Forumite
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    Hi Martyn,

    I do get the point about comparing like with like but this debate did start with a comment I made regarding older installations & their effect on current house prices....
    House purchasers might not want to be saddled with an inefficient & not very aesthetically pleasing installation for the next 15 years.

    Perhaps if I'd used the phrase 'not optimised to benefit from the latest technology/efficiency' rather than 'inefficient' it might have caused less furore.

    My parents were looking at buying a bungalow which had a 2.6kW (12x220w) rentaroof array installed about 6 years ago. The panels were silver & on the front of the property & tbh are pretty ugly. Using the latest panels that area would accommodate 3.6kW (14x260w) of black panels. The original installation probably cost more than a 3.6kW one would today. That's really my reason for using the rather contentious 'I' word.
    4kWp (black/black) - Sofar Inverter - SSE(141°) - 30° pitch - North Lincs
    Installed June 2013 - PVGIS = 3400
    Sofar ME3000SP Inverter & 5 x Pylontech US2000B Plus & 3 x US2000C Batteries - 19.2kWh
  • zeupater
    zeupater Posts: 5,355 Forumite
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    edited 15 January 2015 at 4:32PM
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    1961Nick wrote: »
    .....which is possibly less than the cost of a standard panel 5 years ago?

    Information is difficult to find & conflicting but the efficiency rates of mid-market panels seem to have improved from about 14% to 16% over the past 5 years, an increase of 15%. Some manufacturers claim 17% efficiency for a fairly small premium (not 70%), so that would be a 21% increase in efficiency over 5 years.
    Hi

    It does really seem like :wall:... but we seem to be getting there ... however so slowly ... ;)

    We've now moved from a claimed panel efficiency improvement of 50% - 100% over the last 4/5 years in this post ....
    1961Nick wrote: »
    .... An old 2kW array may be great for the 'Rent a roof' company receiving over 40p FIT, but that same area would now accommodate a 3-4kw system.
    ... to 21%, however ....

    In terms of panel efficiency, well that's straightforward, but it'll need a little background information. Think of the Sun's surface as being a sphere and at the distance of the orbit of the earth another sphere exists ... it's pretty easy to calculate the relative surface areas of the sphere's (4*Pi*R2) to show how energy density has been diluted over distance. When the energy reaches the top of earth's atmosphere it averages 1366W/m2 , this is known as the solar constant. The earth's atmosphere absorbs reflects and refracts a proportion of this energy, therefore by the time that it reaches a surface which is perpendicular to the sun on a clear day the irradiance is approximately 1000W/m2 . To be able to rate/test/compare solar panels a standard test procedure was developed based on the clear sky irradiance and a nominal surface temperature of 25C. The rating procedure is known as a 'flash test' - panels are allowed to warm to 25C then placed under a light source which momentarily simulates the makeup of sunlight at 1000W/m2 and registers the panel generation - it is this figure which manufacturers use to rate their panels ... however it doesn't stop there ....

    The process of creating the silicon wafers used in pv panels is effectively the controlled growth of crystals, however, there are still natural variations in each crystal. large crystals are shaped, sliced into wafers and onward manufactured into useable individual cells. Now for something which is totally relevant .... when constructing a panel from individual cells, any underperforming cell will pull the entire performance of every other cell in series in the same circuit and differences between parallel strings of in-series-cells within a panel effect the entire panel performance. To compensate for this each cell is flash tested and sorted by performance ... only cells with similar test results should be used in a panel.

    Due to manufacturing process differences and tolerances, each panel is individually flash tested at the end of the production line ... it is at this stage that it is actually allocated a part-number. Manufacturers will normally sell their product under different model numbers, differentiated by output (say 240/250/260W) ... the only difference being sorting by the test result. What must be accepted is that the highest output is set by the manufactures at a level where they would be guaranteed a reasonable level of production - that doesn't mean that better performing panels aren't made even at the top band, just that not enough are manufactured to justify & supply a higher rated band. Now, let's take the effect of increased production volumes into consideration - it becomes obvious that if the proportion of higher performing panels remains constant, if there's a massive increase in production, enough will likely be available to create a new performance band (say 270W) which can be sold into the most lucrative market at a premium price ...

    There have been marginal improvements in the quality of the crystalline ingots and production processes, but much of what we see as efficiency improvements are more related to simple volume increases and added value available to the manufacturer ... As mentioned before all of our panels are +ve nominal performance rated by the manufacturers, however the range of individual panel test results is very interesting ...

    Anyway, back to 'efficiency' ... as stated in an earlier post, our panels are 1652x994mm (1.642m2) .. therefore a 230W variant would be 14% (230/(1000x1.642)) efficient, with 240W 14.6%, 245W 14.9%, 250 15.2% ... and so on. The rated efficiency for any panel, from any manufacturer can be calculated in the same way ...

    As mentioned before, increasing efficiency by paying a premium for the panels really means nothing as you could have done exactly the same 4/5 years ago, it's just that many/most don't see it as an efficient use of capital. Unless there's a specific need to do so, paying more for higher efficiency panels only becomes economical (efficient use of capital) if the percentage increase in generation is greater than the percentage increase in system cost .... The 70% panel cost difference used in the previous post wasn't plucked out of the air, it was for Benq panels (20.2%) at ~£0.83/Wp Vs Sharp (15.2%) at £0.49/Wp with 83/49 being a 70% increase .... if you want a 16.8% panel you could go for Yingli 275W panels at £0.57/Wp, an on-cost of 16.3% ...

    So, a 50%-100% efficiency increase in 5 years, no .... a step change in efficiency due to technology, not really .... small incremental improvements due to better control of manufacturing process and small technology changes, yes (but likely much closer to ~5% than 100%) .... premium cell availability allocated to premium panels due to volume related selection, most definitely ....

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • 1961Nick
    1961Nick Posts: 2,078 Forumite
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    Z,

    Wow, the conclusion you arrived at from the 2nd quote was a bit of a leap! Clarification - 50 - 100% from the roof (no mention of panel efficiency as far as I can see).

    A small reduction in the panel size may lead to additional panels fitting onto a given roof (enough room for 0.9 of a panel is useless). Couple this with improvements in efficiency over 5 years & 50% more generation is do-able. Frame dimensions appear to have got smaller as well, but that could just be my imagination. Anyway, I'm sure you'll know the answer.

    Likewise>>>>:wall:
    4kWp (black/black) - Sofar Inverter - SSE(141°) - 30° pitch - North Lincs
    Installed June 2013 - PVGIS = 3400
    Sofar ME3000SP Inverter & 5 x Pylontech US2000B Plus & 3 x US2000C Batteries - 19.2kWh
  • zeupater
    zeupater Posts: 5,355 Forumite
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    edited 15 January 2015 at 5:47PM
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    1961Nick wrote: »
    Z,

    Wow, the conclusion you arrived at from the 2nd quote was a bit of a leap! Clarification - 50 - 100% from the roof (no mention of panel efficiency as far as I can see).

    A small reduction in the panel size may lead to additional panels fitting onto a given roof (enough room for 0.9 of a panel is useless). Couple this with improvements in efficiency over 5 years & 50% more generation is do-able. Frame dimensions appear to have got smaller as well, but that could just be my imagination. Anyway, I'm sure you'll know the answer.

    Likewise>>>>:wall:
    Hi

    Excellent, an entire post containing a full description of the logic which would need to be employed, and why, simply waived aside with yet more unquantified and unqualified assumptions .. it really looks like you cannot accept the concept that you could actually be in error .

    Anyway, directly addressing the referenced post .... where is there a leap between reading this ...
    1961Nick wrote: »
    ... An old 2kW array may be great for the 'Rent a roof' company receiving over 40p FIT, but that same area would now accommodate a 3-4kw system.
    ... and concluding that placing a 4kWp system on the same roof area as a current 2kWp system would require a panel efficiency increase of 50%-100% ?? ....

    Yes, I accept that there's the possibility that a marginal increase in efficiency could result in more panels being installed on a greater area due to making more efficient use of the available roof space, but, and it's an important but ... this does not make the existing panels inefficient -and- it will always be the case if you decide to source more efficient, premium priced panels ...

    The example issue you described regarding the bungalow isn't really anything to do with panel efficiencies or changes over time, it's simply a combination of a sourcing decision by the RaR scheme operator at the time (they could have specified more efficient, more costly panels but chose not to) and the decision of the property owner, for whatever reason, to not purchase their own system and select the particular RaR scheme operator they did .... not panels, not efficiency, just people & decisions ...

    What is important in open forum discussions is the casual reader. Simply letting erroneous remarks relating to massive increases in panel efficiencies over a short period pass without challenge could possibly lead to others believing that it's actually the case and thus influence their own thought processes and viewpoint ...

    HTH
    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • 1961Nick
    1961Nick Posts: 2,078 Forumite
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    Z,

    You understood the original suggestion I made about property prices & solar panels. You were the one that decided to jump on one word & take the conversation in a whole new direction.

    I even withdrew the 'I' word & substituted it with a phrase that I hoped would be more acceptable to you. That clearly didn't work either.
    4kWp (black/black) - Sofar Inverter - SSE(141°) - 30° pitch - North Lincs
    Installed June 2013 - PVGIS = 3400
    Sofar ME3000SP Inverter & 5 x Pylontech US2000B Plus & 3 x US2000C Batteries - 19.2kWh
  • zeupater
    zeupater Posts: 5,355 Forumite
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    1961Nick wrote: »
    Z,

    You understood the original suggestion I made about property prices & solar panels. You were the one that decided to jump on one word & take the conversation in a whole new direction.

    I even withdrew the 'I' word & substituted it with a phrase that I hoped would be more acceptable to you. That clearly didn't work either.
    Hi

    All I'm attempting to do is explain the reasons why you can't expect to get 4kWp onto the same roof space as a 2kWp one due to panel efficiency improvements over 4/5 years ..

    regarding withdrawing the 'I' ... this is what was written in response to Martyn ...
    1961Nick wrote: »
    Hi Martyn,

    I do get the point about comparing like with like but this debate did start with a comment I made regarding older installations & their effect on current house prices....

    Perhaps if I'd used the phrase 'not optimised to benefit from the latest technology/efficiency' rather than 'inefficient' it might have caused less furore.

    My parents were looking at buying a bungalow which had a 2.6kW (12x220w) rentaroof array installed about 6 years ago. The panels were silver & on the front of the property & tbh are pretty ugly. Using the latest panels that area would accommodate 3.6kW (14x260w) of black panels. The original installation probably cost more than a 3.6kW one would today. That's really my reason for using the rather contentious 'I' word.

    I really do understand the reason for the post, I also understand that the above is more of a justification than a withdrawal, a conclusion reinforced by the inclusion of the following in a later post "... Couple this with improvements in efficiency over 5 years & 50% more generation is do-able. Frame dimensions appear to have got smaller as well ..." which suggests that there's a reluctance to accept that higher efficiency panels were available 5 years ago ...

    For now, for the sake of the sanity of all reading this thread, let's just park the discussion as a stalemate between face-saving and data supported logic ...

    Z
    "We are what we repeatedly do, excellence then is not an act, but a habit. " ...... Aristotle
    B)
  • tunnel
    tunnel Posts: 2,588 Forumite
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    1961Nick wrote: »
    Hi Martyn,
    My parents were looking at buying a bungalow which had a 2.6kW (12x220w) rentaroof array installed about 6 years ago. The panels were silver & on the front of the property & tbh are pretty ugly. Using the latest panels that area would accommodate 3.6kW (14x260w) of black panels. The original installation probably cost more than a 3.6kW one would today. That's really my reason for using the rather contentious 'I' word.
    Hi Nick,
    You sure about that....6 years, RaR's only appeared with the FiT which was just under 5 years ago
    Also, depending on which RaR company installed panels...some do allow a buyout
    Personally I wouldn't touch a RaR house with a bargepole....but...and only a but, I may consider it if the householder was able to buy out the contract, something I've not had the pleasure of yet with my collection of rental properties


    Ps, All the RaR around my area are a shade greener and none have less than 16 panels, with some having 18 panels(if they have a bigger roof(cheaper lower wattage panels))
    2 kWp SEbE , 2kWp SSW & 2.5kWp NWbW.....in sunny North Derbyshire17.7kWh Givenergy battery added(for the power hungry kids)
  • 1961Nick
    1961Nick Posts: 2,078 Forumite
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    edited 15 January 2015 at 8:53PM
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    tunnel wrote: »
    Hi Nick,
    You sure about that....6 years, RaR's only appeared with the FiT which was just under 5 years ago
    Also, depending on which RaR company installed panels...some do allow a buyout
    Personally I wouldn't touch a RaR house with a bargepole....but...and only a but, I may consider it if the householder was able to buy out the contract, something I've not had the pleasure of yet with my collection of rental properties


    Ps, All the RaR around my area are a shade greener and none have less than 16 panels, with some having 18 panels(if they have a bigger roof(cheaper lower wattage panels))
    Just going by what the seller told me regarding dates. He said about 5 years & it was about a year ago that I looked at the property for my parents. Apparently the installer/referrer was British Gas.
    tunnel wrote: »
    Personally I wouldn't touch a RaR house with a bargepole....but...and only a but, I may consider it if the householder was able to buy out the contract, something I've not had the pleasure of yet with my collection of rental properties

    That was my original point about property prices & 'rentaroof' systems.
    4kWp (black/black) - Sofar Inverter - SSE(141°) - 30° pitch - North Lincs
    Installed June 2013 - PVGIS = 3400
    Sofar ME3000SP Inverter & 5 x Pylontech US2000B Plus & 3 x US2000C Batteries - 19.2kWh
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