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SolarCity Pushing Industry To 40% Increase In Useful Lifetime of Solar Power Installations (electrek.co) 109

An anonymous reader writes: SolarCity released a new report that says solar power systems have a usable lifetime of at least 35 years, which is 40% longer than what the market expects. Electrek reports: "The key finding of the report is that power degradation (annual efficiency loss) of solar panels supplied to SolarCity is as much as 35% lower than for a comparable industry-wide selection of non-SolarCity panels, which are typically expected to last for 25 years. In the study here, SolarCity looked at greater than 11,000 panels to determine their data points and come to their conclusion that their solar panels are performing well beyond expected industry standards. Today, standard efficiency solar panels put out by Tier 1 suppliers are generally warranted to lose no more than 0.7% efficiency per year for the first 25 years -- this is the Power Production Warranty. The key finding in this study is that the annual 0.7% efficiency loss is too high an estimation -- and that the number ought be closer to 0.5%. While it might seem a small number -- a difference of 0.2% -- when applied over a multiple decades timeframe, it means that instead of the standard twenty five year assumed productive life, we can expect at least another ten years of production above 80% of the original system output. Large installers like SolarCity, able to do this type of wide-scale research -- and to also demand higher quality, are showing their ability to pull the manufacturers of the world upward. With SolarCity building their own solar panel Gigafactory we ought expect the quality levels to be even greater in the near future.
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SolarCity Pushing Industry To 40% Increase In Useful Lifetime of Solar Power Installations

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  • makes just as much sense. https://www.youtube.com/watch?... [youtube.com]
  • by Anonymous Coward
    That's what I saw on the boxes as Solarcity was unpacking them for my neighbors house. If they're anything like the rest of BenQ electronics... no thanks.
  • How about 40 years [pureenergies.com]?

    • by Anonymous Coward

      How about 40 years [pureenergies.com]?

      Warranties are only as good as the terms in them. They decrease in value over time since they are based on the value of the used panel, not a new one. Many people may not even exercise a warranty after about 15 years, as it is often just a small credit applied to a full cost new replacement, and the installation costs can be more than the warranty amount itself.

      • by Anonymous Coward

        SolarCity does not charge for installation and has a full 20 year bumper to number warranty!

    • by hattig ( 47930 )

      I thought it was commonly understood that solar panels were likely to be useful for way longer than 25 years. All this does is increase that useful lifetime - and given that it's 25 years (now apparently 35 years) for 80% of the power generation, I think it's likely that houses may not need to replace their panels for many decades after installation. Especially if the power used by a household drops due to efficiency gains in that same period.

      I doubt the panels are that different really in terms of lifespan

  • when did self promoting 'reports' with unverified claims become newsworthy?
    especially considering rather dodgy nature of company concerned, with all sort of litigations going on, rising borrowing costs( that necessitated a takeover from musk's other company), subsidy driven(=politician dependent crony capitalist) industry, etc , etc.

    • Re: (Score:1, Insightful)

      by Anonymous Coward

      It's even simpler than that. How can any company, that has only existed for 9 years, have any proof their product lasts 35 years let alone even 10?

      • Math (Score:5, Informative)

        by Okian Warrior ( 537106 ) on Monday July 04, 2016 @09:50PM (#52445837) Homepage Journal

        It's even simpler than that. How can any company, that has only existed for 9 years, have any proof their product lasts 35 years let alone even 10?

        By using math.

  • "Unless something corrodes the electrical contacts, it will still keep working." [greenbuildingadvisor.com]

    Probably not a bad idea for the factory to be a little modest with the specs to begin with.

    The article does read more like a SolarCity ad than anything else. They certainly don't bring anything new to the table.

  • Actual repor link: (Score:5, Informative)

    by Ecuador ( 740021 ) on Monday July 04, 2016 @08:58PM (#52445713) Homepage

    I get a 404 error on the first link. The actual report link is at : http://www.solarcity.com/sites/default/files/reports/SolarCity%20Photovoltaic%20Modules%20with%2035%20year%20Useful%20Life.pdf [solarcity.com]
    As for the degradation of panels, I have a 10kW system made of relatively inexpensive Chinese Renesola Virtus II hybrid panels for over 3 years now and I have seen no measurable degradation in performance so far. And I even look at the peak days of month to avoid the issue of daily weather and still it seems the peak has not reduced (rather increased by 1% which should be within the margin of error) in these three years. So there goes two myths my installer told me "you need to pay me to service and wash them every year to maintain peak output" and "output will measurably drop yearly anyway though". No I haven't washed them. So, I don't know if they will continue this trend or will suddenly drop in efficiency, but at least for the first few years they seem stable.

    • If you don't get hit by a hail storm. The panels should last until you see your first grandchild at least. But you may have to hose them down occasionally if you are downwind from an active volcano. Aside from that, they will probably never have to be touched by human hands ever again. They'll probably last longer than the house.

      • We get a lot of pine pollen coating the panels in the spring. Need to hose them every week. Other than that,they maintain peak production.

      • Anecdotal, but what I've seen is that the panels survive better than a typical asphalt roof. Those get beat up pretty bad in hail storms, but it takes a lucky strike at just the right angle to crack a solar panel; otherwise the hail just bounces off.

        Now a tin roof of course would last longer than either, but most people don't invest in those.

        • by Martin Blank ( 154261 ) on Tuesday July 05, 2016 @12:16AM (#52446203) Homepage Journal

          Panels do better than asphalt roofs because they're tested to higher levels. Asphalt shingles get various ratings based on tests using various size balls of ice to see how they take it. Solar panels are generally tested using one-inch steel balls impacting perpendicular to the panel, usually at or near terminal velocity. The ice used in asphalt testing can break, absorbing some of the energy, but the steel ball gets no such benefit.

          Extreme hail can still damage a solar installation, and hail might be able to damage non-panel components, but if your panels are suffering damage from hail, you stand a good chance of finding holes punched in the asphalt and wood the rest of the roof is made of.

        • I'm curious how you replace your roof once you have panels on them. I'm guessing the short answer is "take them off" -- but does this including the mounting hardware, too, and how much of a hassle is this -- is a lot of the wiring modular and disconnectable, or is it hardwired for minimal losses?

          If the panels last anything like the estimates, it seems likely that a roof replacement would be likely at least once during the PV system lifetime, perhaps more if the roof wasn't brand new. I'm guessing basic be

          • If the panels last anything like the estimates, it seems likely that a roof replacement would be likely at least once during the PV system lifetime, perhaps more if the roof wasn't brand new.

            Depends on the type of roof [mcgarryandmadsen.com]. Metal roofs can last 30-50 years. It also depends on the particulars of the roof. Color, pitch, orientation, installation, material quality, local climate, etc. If I was having solar panels put on I would have the roof done at the same time if possible. You can get a roof that should outlast the panels but it won't be the cheapest option. Of course if you can afford solar panels today, chances are that the cost of a new roof probably isn't a huge deal to you. Plus the pan

            • A roof is a lot more complex than "flat thing at the top of the house." It's got multiple support layers, insulation, water infiltration protection, frost protection, and so forth. A high-efficiency asphalt roof would start with rafters (roof joists) with stone wool insulation between them, an OSB roofing board, felt, tie battens, possibly a radiant barrier and counter-batten, and integrated frost barriers to prevent the roof from weakening from water vapor (humidity) infiltrating and freezing. The exac

              • A roof is a lot more complex than "flat thing at the top of the house....

                Well said. I think we're mostly talking about the outermost bit of the roof (shingles, etc) but you are quite right that a roof is a complicated structure which is much deeper than just the bit you can see from the outside. Far more complicated than many people realize.

                I hope one day we figure out how to make it economically practical to turn the outer layer of the roof into solar panels or other useful things. Right now so many roofs are really just wasted space that could be put to better use much of t

                • Grid tie-in makes generation location semi-moot. Transmission loss is a factor, although HVDC from generation centers to distribution centers makes remote transmission feasible. It's actually optimal to just rooftop generate in the middle of any population center, and have a substation servicing that population center convert HVDC from remote power plant to local grid AC: the power-in will supplement the rooftop solar; that solar will have very little distance to travel from source to point-of-use, redu

                  • I intersected these various ideas and concluded we could preserve natural habitats by engineering the no-car type cities to maximize walkability and bicyclability, while providing a maximization of modern conveniences such as subway transit to a city edge garage, and minimizing the additional costs of maintaining such an urban center.

                    Excellent ideas but the real obstacle is supplanting existing infrastructure and finding some way to force it to happen on a wide scale as you seem to indicate. I'm not sure how you turn a city with a car based infrastructure like LA or Detroit into a pedestrian paradise as a practical matter no matter how sensible the plans.

                    It will at least make for good scifi; although eliminating both yard work

                    I'm a huge fan of anything that does away with grass yards. They aren't super attractive and maintaining them wastes VAST amounts of power and water and generates a huge amount of noi

                    • It's not as serious as all that. Some people really are content with walkable cities and public transit; there's an intersection of demands that would supply a population genuinely interested in such things, which enables a reduction of habitat destruction without the economic cost of locking up said habitat as federally-protected land. Basically, it's an opportunistic extension: instead of 1,000,000 acres of federally-protected land and 50,000,000,000 acres of pavement, you have 1,000,000 acres of fede

              • by cusco ( 717999 )

                tie battens, possibly a radiant barrier and counter-batten, and integrated frost barriers

                None of that is necessary if you vent your attic space adequately, they're only needed if you attic is occupied living space. Vents aren't pretty so most architects leave them out as much as possible, but anyone who has worked on very old houses can tell you the dramatic difference between the state of a roof when the attic has 2'x3' gable vents in each gable end with soffit vents and ridge vents in likely dead-air sp

                • Rock wool is the new technology that's replacing fiberglass. It's easier to handle and has better insulation value. It's slightly more expensive, but that's about it.

                  • by cusco ( 717999 )

                    Looked it up, as rock wool batts were always cheaper and inferior to fiberglass, besides sometimes being contaminated with asbestos. What you're referring to is a different product that I've never dealt with. Looks interesting, although wiring and plumbing would be a pain to deal with. Odd that they reused the name of a product that most installers hated.

                    • Rock wool batts are advertised as 5% asbestos today. They cost about $45 for 8 batts; fiberglass is somewhat cheaper. Rock wool has a 9.5% increase in insulation value over Asbestos, R-23 at 5.5 inches versus R-21 for Fiberglass (mind you, the comparison is not huge; the extra R2 might eliminate like 60%-70% of the remaining heat transfer R21 doesn't, but it's only like a .01% difference in total heat transfer). Rock wool is a *lot* easier to handle.

                      It's also cut into cubes and used as a planter for m

    • 10kW? Wow, you must use a lot of electricity.

      I have recently had a system installed. The peak output is less than the inverter is rated at, and significantly less than the total DC rating of the panels. I suspect that the installers have limited the max AC output, since the peak output I see varies by less than 1%. I suspect that the panels could degrade significantly and my system's peak output would be unaffected.

      On the other hand. the output at less than peak may be affected by degradation, but that is m

      • Depending on where he is, it's not hard to draw 10kW. My electric company lets me see my power usage on as fine a grain as every 15 minutes. During the summer in north Texas with a home that's only 10 years old and with the AC set to 78F throughout the house, I can easily use 4.5kWh over the course of an hour (so an average draw of 4.5kW). When it's very warm, I have drawn an average of over 8kW over an hour. This isn't factoring in additional people soon to live in the house. On that basis, a 10kW sys

      • No, I don't actually use it. It is in my summer house in Greece and produces about 14MWh per year, which is sold to the electric company.
        It is not optimally oriented, since it lies flat on a dual-pitched roof, with half the panels facing east and half facing west, but on some summer days I peak at 8.4kWh hourly, which is not bad at all.
        And I'll throw in a graph I like, a partial (30%) solar eclipse [ecuadors.net] as "seen" by my panels ;) (from my eclipse report [ecuadors.net])

  • by Streetlight ( 1102081 ) on Monday July 04, 2016 @10:15PM (#52445915) Journal
    What's the expected lifetime and warranty of the inverter? The cost of inverters seem to be about $0.40 per watt so for a 3,000 watt system it would cost ~$1,200. There surely are It looks like they are warranted for 5 years but one would hope they would last longer than that. And I'm sure there are service contracts with guaranteed replacement. How many would be needed over 35 years? Hopefully not too many.
    • by Anonymous Coward

      $0.40 per watt for American/German made inverters. $0.27 per watt for cheaper Chinese inverters (4,000-6,000W inverters for both). Average lifespan is 11 to 14 years, although that is steadily improving.

    • by necro81 ( 917438 )

      What's the expected lifetime and warranty of the inverter?....There surely are It looks like they are warranted for 5 years but one would hope they would last longer than that.

      One of the major limiting factors for inverter lifetime is operating temperature. Bulk electrolytic capacitors have a finite lifetime, and operating at elevated temperatures decreases that pretty rapidly. (The same is true in AC/DC power supplies.) This means that the lifetime is heavily influenced by how and where the inverter i

  • by blockhouse ( 42351 ) on Monday July 04, 2016 @10:26PM (#52445937)

    Good for Solar City.

    They're still not putting their panels on my roof and charging me money for the electricity they generate. They can lease the space from me, but if they retain full ownership interest in the panels, I'm not giving them anything for free, much less paying them for the privilege.

    • Re:Good for them (Score:4, Insightful)

      by Okian Warrior ( 537106 ) on Monday July 04, 2016 @11:23PM (#52446113) Homepage Journal

      Good for Solar City.

      They're still not putting their panels on my roof and charging me money for the electricity they generate. They can lease the space from me, but if they retain full ownership interest in the panels, I'm not giving them anything for free, much less paying them for the privilege.

      Solar city came around and handed out brochures, and I got an estimate from them.

      Of their 3 plans in the estimate, none "charge me" for the electricity they produce. The three plans are three tiers representing the amount I pay up front, and the amount my electricity bill is reduced going forward.

      So in other words, I could buy the panels outright ('sorta) and get a big reduction on my electricity consumption, or I could pay nothing and get a small reduction.

      All of which was surveyed to my house, which accounted for the latitude, number of sunny days, estimated cost of electricity, and my average usage.

      Putting up solar cells is a project that a lot of people don't have the skills or ambition for (especially older folks) - this is basically a turn-key solution. "Pay nothing, get a (small) decrease in electricity costs, and we'll maintain the system for 20 years".

      For a lot of people, it's a good deal.

    • They're still not putting their panels on my roof and charging me money for the electricity they generate. They can lease the space from me, but if they retain full ownership interest in the panels, I'm not giving them anything for free, much less paying them for the privilege.

      You seem to completely misunderstand the deal SolarCity (and others like them) offer. It's basically a lease on a solar array. They install a solar array on your roof and sell the power generated to the power company. In return they sell you power at a discounted rate (fixed by contract) for the service life of the array. In essence they split the savings from the array with you. So you get all the benefits of a solar array without having to front the (substantial) cost of purchasing one and maintainin

      • by NotAPK ( 4529127 )

        "You're not giving them anything for free."

        You are giving them free rent on your rooftop space.

        Not saying it's worth it either way, but it's a cost that has to be factored into the assessment.

        • It's not "free rent". You are renting them your rooftop space in exchange for a discount on your electric rate. There is no opportunity cost here, I doubt you can rent your roof to someone else (other than a solar producer).
  • by Jim Sadler ( 3430529 ) on Monday July 04, 2016 @11:01PM (#52446063)
    How severe a hail storm can the panels survive? If the panels are well installed how much wind can they tolerate. In my part of Florida we will tend to have a hurricane every four years. 150 mph winds are common with gusts going even higher. Replacing a system every few years might make solar a really bad choice here. Also how much storm wind can windmills take without damage? It is hard to imagine one of the huge, tall windmills being smacked by the type of tornado so common in Oklahoma.
    • by dwywit ( 1109409 )

      IIRC, here in Oz they have to be rated for rooftop fixtures according to the zone they're in. Where I live, we have from zero to four cyclones a year, so the panels and mounts have to meet that standard. In practice, brand-name panels are all rated to the highest (wait for it) danger zone - hail, cyclones, etc.

    • by thegarbz ( 1787294 ) on Tuesday July 05, 2016 @04:31AM (#52446737)

      Just an anecdote, I lived in Brisbane Australia. We got some horrendous hail storms, my most memorable being one where the golfball - tennisball sized hail wasn't even round but rather had sharp edges.

      I was wondering the same thing as you were one crazy storm we had so I went to watch my neighbours panels (my house was slightly taller than theirs). I was not so happily watching these huge hailstones deflect off their panels ... shatting the windows in my study. Zero damage to their panels. I had to replace windows on the side of my house deflected by their roof, and everyone in the street had the insurance company replace their cars as we didn't have car ports.

      Sidenote: I've never seen so much damage to a 4-wheel drive. All windows completely missing except for the windscreen which shattered but didn't actually fall out due to being laminated.

      But this is just an anecdote. These panels are super tough, and glass (well it's not actually glass) does incredibly well under compression loads with a lot of the force of impact absorbed by the various layers underneath like the substrate and metal backing.

    • by cusco ( 717999 )

      In the case of windmills, under high wind conditions the blades are feathered so the windmill isn't rotating at all. In large installations this is done automatically, including in response to the automated National Weather Service tornado alerts. In the case of a tornado a windmill tower is about as likely to survive as an antenna tower, at any sort of distance they're fine but a direct hit will destroy them.

    • Modern panels are developed to endure ordinary hail. Panels designed around international standard can withstand hail stones travelling at 50 mph. If you live in such place and want to use solar energy – think about its protection. It’s possible to construct some protecting frames. And be sure to talk with insurance company.
  • 40% longer than what the market expects.

    Lose the "what". It's redundant and makes you sound like a music-hall cockney.

  • I always think of the 80's anti-apartheid song where nobody cool wants to play there. I-I-I-I don't want to play SolarCity-ay-ay,
  • Did you hear? Pilip Morris has completed a decade long study that proves that cigarettes are good for your health. And, they verified that!

    Can you believe that?!

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