This has the potential to be a great panel for the toolbox of those who design PV systems. DIY's or marketing sensitive public with sloped residential roofs be warned I suppose.
For the rest who are interested in the fact that bifacials can provide aesthetic benefits (semi-translucent for some illumination, more interesting backside that camouflages leads more than a white backsheet) or can see enhanced production when properly installed on a flat white commercial roof or any ground mount or canopy where it snows, it is great to see a product from high volume manufacturer's like LG. If the price premium is as minimal as seen overseas (beyond the inherent LG price premium), these things will probably be in line to be used in many ground mount arrays in regions with moderate to heavy snow cover.
And I have seen energy boost of the old Sanyo bifacials in the range of 20% on a low-slope white roof. There were added racking costs associated with installing ballasted at 30 degrees for what it is worth. If these install in the same way any panel would on a ground mount - no added cost. And if one was already pricing semi-translucent options like those out or coming out from other manufacturer's, this has potential to be a cost saving. But not for a residential, DIY customer, with no professional advice, and a sloped roof, who has scoured LG's UK website, or Australian RE forums, and been fooled by their panel spec sheet, that does not include the backside contribution in the panel wattage rating.
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To reiterate, I have no issue with the cost, or for that matter, from what I've seen LG's quality.
It's the B.S. innuendo and the poor information that is, IMO, misleading and deceptive. To say, write or imply that bifacial schemes can improve output by 20-30% or possibly more under some unidentified time frames - from periods of hourly to yearly or anything in between, and also without some serious discussion of what type and how severely off common sensibilities and construction the surrounding reflective environment and its possible and likely necessary modification costs to achieve what are, as far as I can know from both some knowledge of the science involved as well as a lot of work on radiation enhancement techniques and schemes, with some of that in an academic environment, very unlikely to happen without some pretty serious changes from what people have come to expect in terms of extra $$ construction cost and appearance. (Sorry for the run on sentence.)
Such successes in enhancement as implied by the LG advertising paint a rosy but incomplete portrait, with only the LG panels in it. The rest of the family that costs $$ is missing. The purported enhancements in possible output come at a price, both in common aesthetics and time/$$. The raw product - the panel may cost the same or less. However, any output enhancement that utilizes changes in panel design are probably more costly in terms of both construction costs and aesthetic sensibilities which are usually not easy to monetize. Those costs are quite likely enough to make such designs cost ineffective. Since most folks have less than a sound footing on calculating cost effectiveness, I'm not real positive about a better outcome in calculating the modified cost effectiveness or the added total cost for using bifacial panels.
As a SWAG, I'd also (and charitably) guess that any enhancement achieved is somewhat positively proportional to the cost of off the standard modifications necessary to achieve such modifications, but perhaps not linear with say 10 % enhancement adding more than 10 % to the total cost.
In any reasonable configuration that looks like what most folks have come to recognize, a 20% or more enhancement in annual output is, IMO, unrealistic. 10% is kind of a stretch as well and would probably, even if possible, look pretty funky.
Since the P.O.A. irradiance on the back side of a panel that's, say, 6" from a roof and parallel to it will be close to zero, I'm quite sure any possible enhancements from a bifacial design will be the same, and = = zero. How many people do you think understand that statement ? My guess is few. And so, as a result of their ignorance, the great unwashed masses will see 30% enhancement for no more $$ per the adverts., and get reeled in based on their ignorance and usual slick but B.S. marketing. Caveat Emptor.
As for tilting a panel or array - an almost essential feature to utilize the attributes of bifacial panels - aside from the aesthetics and practical design considerations such a design would entail, the incident radiation will be a bear to calculate, even for the most simple configurations of the surrounding reflective surfaces.
The incident radiation will be a mix of diffuse and beam, with the beam coming from perhaps many sources, some accidental, some natural or coincidental, and some planned. The diffuse portion of the backside irradiance will be either scatter from diffuse reflecting surfaces, terrain, masonry, etc., or sky diffuse which will be mostly backscattered - that portion being the smaller portion of the mostly forward scattered sky diffuse irradiance. See any decent text on radiation heat transfer - and mostly the part about "view factors" or "exchange factors" for some idea of the scope of the problem and why the irradiance on the backside of an equator facing panel or array is usually quite small and in any case quite difficult to even estimate.
Bottom line, all my opinion only:
1.) Based on experience, education and some common sense, IMO, it is probably not cost effective to utilize the output enhancement bifacial panels may make possible.
2.) Such utilization may require modifications to the surroundings that may well be aesthetically unpleasant for a disproportionate number of people, with the degree of enhancement positively but in a hard to quantify way, correlated with the cost of the modifications to the environment needed to achieve any such possible enhancement.
3.) The first two considerations are mostly ignored by LG in their attempts to paint an overly rosy and overly optimistic picture for their bifacial panel.
As usual, take what you want. Scrap the rest.Leave a comment:
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I called my suppliers this morning to see about price and availability here in CA. They said look for them by 3red quarter this year and no pricing yet.Leave a comment:
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In the spirit that one snarky comment deserves another: Unwarranted is a matter of opinion, as is, IMO only, the practical worth of most of your opinions and cherry picked attachments with respect to R.E. that seem to substitute other's opinions for the one's you won't, don't or can't get on your own, and then, seem to imply they have the cloak of absolute truth to them simply because they are written and they reinforce what you seem to hold as the immutable truth.
In any case, thank you for the vote of confidence. I'll give it all the consideration it's due. I'm sure you reciprocate the courtesy.
As you have noted in the past - don't like what I or anyone writes - use the ignore button. I mostly use my informal ignore button with your stuff. That has the advantage of allowing me to call B.S. on some of your more egregious brain spoor, which, I'd do more of if I wasn't so lazy.Last edited by J.P.M.; 05-15-2016, 11:34 PM.Leave a comment:
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J.P.M. I was around and active when this all happened in the past, so I understand where it could go. But, enough is enough. We are all in business to make money yes but not every company is as unscrupulous as you are touting. You are lumping all of us in one bag and I personally take offense to that reference and pre judgement. You are just wasting valuable forum space with a negative view of what could be, how stupid people are, and pissin me off in the process. -
DanKegel, Awesome details, thanks. And did they get the cleaners to be more gentle? (Come to think of it, do you have data showing that cleaning is more helpful than harmful?)
As far as I know they stopped the cleaners from spraying within a foot from the J Boxes when using power washers. The problem there was constant Pidgeon poop everywhere and in mass quantities. We wore masks, gloves and the white painters suits when on that roof. It was pretty nasty. I have not collected data but I plan to. I did read a study from MIT? I think but not sure, it stated for residential systems, that it was only cost effective in most scenarios for a once a year cleaning vs more than once or not at all on average, due to the costs involved. I tend to agree with that and adopted that model as an average. I previously coupled cleanings with a complete system checkup / maintenance agreement. I piloted this maintenance program with random customers in random scenarios with great success. I stopped the pilot to adopt an even more standard approach for pricing and easy data collection. I have yet to start it again. The original customers call me frequently wanting to resume the service. I would love to have some of you guys check out what I have come up with in private, as long as you are not an installer in my area and agree to a NDA. I think it needs refining still. The biggest problem is every customer has a completely different system, roofs can be absolutely crammed and most do not have monitoring. We do not use power washers, we scrub the modules with an extendable car wash brush using biodegradable environmentally safe cleaner and rinse clean with the customers water. not the fastest way but this process gets the modules spotless.
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