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Clean Power Solar-Panel-Technology-Advancements

Published on February 6th, 2014 | by Zachary Shahan

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Solar Panel Efficiency Has Come A Long Way (Infographic)

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Originally published on Cost Of Solar.

There are many reasons why solar panel prices are down so much. But technological advancements in solar panel technologies are certainly a big one. We wouldn’t be where we are today if it weren’t for the technological advancements made to solar cells and solar panels over the past couple centuries, and especially over the past few decades.

This infographic below, created by the folks at spheralsolar.com, certainly does a great job illustrating how much solar panel efficiency has improved since 1953 — 60 years ago. Solar efficiency records are actually set pretty much every month, so don’t expect that upward solar panel efficiency trend and downward solar panel price trend to change (well, actually part of this infographic is a projection to 2015).



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Solar-Panel-Technology-Advancements

Check out (and share!) the interesting infographic below, and be sure make note of the drop in solar panel prices, and note one thing — in the first quarter of 2013, the average price of a solar panel was already down to $0.64/watt, so this infographic was actually a bit pessimistic on the drop in solar panel prices! (By the way, I’ve got no idea why the men standing next to the solar panels are standing the way they are.)






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About the Author

is the director of CleanTechnica, the most popular cleantech-focused website in the world, and Planetsave, a world-leading green and science news site. He has been covering green news of various sorts since 2008, and he has been especially focused on solar energy, electric vehicles, and wind energy since 2009. Aside from his work on CleanTechnica and Planetsave, he's the founder and director of Solar Love, EV Obsession, and Bikocity. To connect with Zach on some of your favorite social networks, go to ZacharyShahan.com and click on the relevant buttons.



  • Al Taylor

    I live in Texas where the sun shines almost too bright most all the time yet I haven’t seen evidence of adoption of solar systems anywhere in my area (Plano, TX.) Being retired and on fixed income I see absolutely no advantage to being an early adopter. Clearly there is some break even cost/benefit coming but I fear it won’t be in my lifetime. Battery storage is still too expensive as evidenced by the slow adoption of electric vehicles. So while I applaud the direction of technology, I can only conclude it is for those that have lots of expendable cash which is not much of a justification for buy-in by the rest of the (real) world.

    • Bob_Wallace

      The average cost of electricity in Texas is 11.3 cents per kWh. If you live at least ten more years I think you’ll see roof-top solar cheaper than the cost of grid electricity.

      If you have TOU or tiered pricing you may already be there now.

      Other countries (Germany, Australia and the UK) are installing rooftop solar for $2/watt. We’ll get there soon.

      I ran an LCOE for you using $2/watt. Looks like you might get an average of 5 solar hours per day.

      The cost of roof-top at $2/watt would be 7.3 cents. A significant savings over the current average price of electricity in Texas.

      The break-even point seems to be about $2.75/watt. Figure in the 30% federal subsidy and anything under $3.90 installed should be cheaper than purchased power.

      Keep watching.

      As for storing your own power, the numbers probably don’t yet work. They might if you lived in a place with high electricity cost and TOU billing. Or somewhere like Hawaii, Germany or Australia which have expensive electricity.

      Battery prices are almost certainly on their way down.

      • Al Taylor

        I appreciate the reply Bob. More efficient and cheaper batteries will also help as you mentioned and should help with electric car and home solar adoption.

  • Vera Wera
    • JamesWimberley

      The “23.5%” is suspiciously and misleadingly precise. There are, as you point out, a range of technologies out there, with different current efficiency records and rates of improvement. The number looks as if it might be a lab record for a monocrystalline Pv cell, the type used in premium products from Sunpower and Sharp, on the market today at around 21%. The 15% in 2012 corresponds to standard grade polycrystalline panels from the likes of Trina. The chart really isn’t comparing like with like and overstates the true rate of improvement for end-users.

  • KenC

    The infographic is wrong, there is a basic math error.

    Going from 4.5% to 15% to 23.5% efficiency means you could produce the same power with a panel 0.3x and then 0.19x the area of the original. But the graphic shows *both* the length and width at 0.3x and 0.19x. That would cut the area to half what is shown.

    The correct dimensions for a 213″ x 130″ panel at 4.5% efficiency would be 117″ x 71″ at 15% eff (shown here as 64″ x 39″), and 93″ x 57″ @ 23.5% eff (shown here as 41″ x 25″).

    I guess no one questions anything that makes solar look better than it is? Where are the editors/proofreaders? Is basic math (area = L*W) not taught in schools anymore?

    • Bob_Wallace

      This isn’t an attempt at an excuse but it might be the explanation -

      Web sites run on a thin margin and need to pump out new content to hang on to eyeballs There may not be the resources needed to pay for an editor with adequate background and a sharp eye.

      • KenC

        @ Bob Wallace – you are probably right. But then, why should I read anything on this site if basic information is presented incorrectly?

        We always need to be skeptical when we read, no matter the source, but IMO, this is a pretty low bar. If I visit again, I will take everything with a larger than usual grain of salt!

        Environmental and ‘clean tech’ issues are typically complex issues. It’s disappointing to see basic math errors in a report. How will we solve these complex issues if we aren’t even paying attention to basic math? I don’t see a date on this or the original article, so I don’t know how long this error has gone w/o question.

        • Bob_Wallace

          I don’t know how to improve the quality of the original articles but I do see a willingness to make corrections to articles which I rarely/never see on other sites.

          Perhaps we need to appoint ourselves the proof readers and editors.

          Point out the problems to other readers and poke Zach so he’ll step in and improve the article.

          We’re all students, are we not?

          • KenC

            OK that’s fine, but I don’t see any easy way to ‘poke Zach’ about this article. Unless I missed it, everything is through a social media site, or his web site. I don’t do facebook, twitter, etc. Does cleantechnica have a ‘contact author’ link somewhere?

          • Kyle Field

            He will likely see your comment here as it’s his article. The key thing is that the efficiency numbers and savings (the important numbers) are right. Good catch on the dimensions though…simple math mistake by whoever created that infographic.

  • Jouni Valkonen

    ¢70 per watt was reached already in 2013. We should go below ¢50 per watt in 2015 and beyond.

    • KenC

      A couple points. Unless you live in an area where solar power is regularly producing more power than the grid can use, batteries aren’t really required – just feed the grid. So that will reduce the costs you posted, at least until there is a lot of solar in your area (I read Hawaii is at this point, but most places are not).

      But even w/o batteries, I have not been able to make solar ‘pencil out’ for me w/o subsidies. Subsidies just mean we are paying for them through taxes/debt – it doesn’t really change the true economic payback. You mention the ‘wealthiest quarter’ – well, they are the ones paying most of the taxes, so it is just a circle game with the money.

      So please show me the math on how a non-subsidized PV installation would be a good investment for me (location, Northern IL). And don’t forget to include ‘opportunity cost’ – the money I ‘invest’ in solar could be invested elsewhere, making me some money. A conservative approach would be a 30 year treasury, currently paying 3.6%. So the first $360 savings on a $10,000 solar investment would be nulled out.

      Of course, there is the environmental side of this, which is a different value calculation – but your comment was specific to the investment (I assume you meant financial investment).

      My view is, since prices are dropping faster than 1/30 per year (the expected life of a panel), I should wait for lower prices. Also, is the environmental footprint of panels coming down as well? Maybe that leans towards waiting?

      • Jouni Valkonen

        First, solar needs batteries if the peak output of solar exceeds the difference between off-peak and peak demand of electricity.

        Second. How much is your annual electricity bill? Multiply that with 30 years and if the result is larger than $15 000, then solar is good investment. Everything above $15k are interests.

        Third. Also note that 12 kW solar system is quite large. Even with 12 kWh battery, there is plenty of electricity left for feeding back to grid on peak hours.

        And Fourth. It is matter of saving the planet! There cannot possible be anything that gives more reward for money. Investing on solar is pretty much the same as not stealing the cars. It is a moral duty!

        • KenC

          @ Jouni Valkonen I’ll reply by your numbers:

          (First) True, but my solar install would not exceed what the local grid could absorb. This works in your (and my) favor – batteries are expensive and have an enviro-impact. Let’s not use them unless they are needed! Save the $ and the environment! Win-Win!

          (Second) My annual bill is ~ $1,200 and a calculator at findsolar dot com shows I would need a 7.4 kW system. They show a price of $44,300 unsubsidized, which seems high at ~ $6.00/watt, but the $1.30 watt shown above is panels only. Add in the inverters (~ $0.50/watt?), installation, hire an electrician, permits etc, and I think a $3.00 installed cost would be a reasonable low-end guess. That’s $22,200. If we make a ballpark assumption that electric rates increase at the same rate as my investment would, those wash. So $22,200/$1,200 is an 18.5 year payback (and inverters are only rated for about 10 years, so there may be maint costs along the way). So from an economic stance, this is not attractive to me. I won’t live in this house long enough to get payback, and home-seekers are not willing to pay a premium for solar. It’s just too risky for me.

          (Third) – That is factored in at the site I referenced.

          (Fourth) – I’m all for using alternate energy sources where they make sense. I’m not so sure they will ‘save the planet’, but I would like to see less of the environment destroyed by coal mining, burning coal, etc. And solar can play a positive roll in that, I think.

          But when it makes real economic sense, we won’t have to ‘sell’ it – it will sell itself. I’m hoping costs come down to the point it sells itself, then it will get wide-spread adoption and wide-spread benefits. But at that point, we need to start dealing with storage, which will add back some costs and have its own enviro-cost.

          As long as I’ve gone this far, I’ll add another point. I don’t think solar on home rooftops makes sense. There is too much overhead for each individual install, often imperfect positioning of the panels, shade from trees or nearby buildings, etc. I think it would be far better to install larger ‘farms’, say on a warehouse or retail big-box building roof. One site analysis, one large scale installation – a huge economy of scale over hundreds of little rooftop systems on homes. There are ‘solar farms’ which allow people to buy a share of the farm. I’d rather buy 1/1000 of a large ‘farm’ than have that same amount on my roof. Everything about it would be more cost effective.

          With all these small rooftop installs, injuries/death for solar is far higher than for nuclear per energy unit produced. There’s a dark side to solar as well (pun intended). But working on one big flat rof is far safer than a crew climbing up/down 1000 roofs on single family homes.

          • sault

            First of all, expecting solar (or any clean energy source for that matter) to compete without subsidies while dirty, established energy sources ARE subsidized out the wazoo is unfair. As long as fossil fuels and nuclear power are subsidized many times more than renewables, you cannot fairly exclude subsidies. If anything, clean energy LOWERS the long-term deficit by reducing the effects of climate change and healthcare costs due to pollution.
            Secondly, you should maximize your energy efficiency before installing a solar array anyway since efficiency is cheaper.
            Thirdly, as far as opportunity cost, you also need to incorporate the savings on your electric bill as an income stream that can be invested to generate its own returns instead of dissappearing down into the utility company’s coffers.
            Fourthly, studies have shown that when people sell their houses with solar arrays, 90% to over 100% of the money they spent on the solar array gets added to the sale price of their house. This shows that your claim ” home-seekers are not willing to pay a premium for solar.” is totally false:
            “the analysis finds strong evidence that California homes with PV systems have sold for a premium over comparable homes without PV systems.”
            The premium ranged from $3.90 to $6.40 per watt of capacity, but tended most often to be about $5.50 per watt. This, the study said, “corresponds to a home sales price premium of approximately $17,000 for a relatively new 3,100-watt PV system (the average size of PV systems in the study).”
            And the bottom line: “These average sales price premiums appear to be comparable to the investment that homeowners have made to install PV systems in California, which from 2001 through 2009 averaged approximately $5/watt.”

            http://green.blogs.nytimes.com/2011/04/21/study-finds-solar-panels-increase-home-values/?_php=true&_type=blogs&_r=0

            Please do more research before reaching premature conclusions.

          • KenC

            @sault – First, I do believe that the ‘subsidies’ to fossil fuels are way overstated. Many of these are normal business expenses that are written off against income, just as any business (including solar producers) does. It appears there are a few incentives to allow faster depreciation on some items, but this probably does not amount to a large % of what we pay for fossil fuel. But I agree with you in principle, any special subsidies to any specific industry should be eliminated. Maybe I’ll search later, and see if I can find a reasonable estimate for the % this would affect my electric bill.

            If we can truly assign a cost to pollution from any specific source, we probably should – but that is a very complex and contentious exercise.

            But most of my response is not about the environmental side. I do think we should focus on conservation first (I’ve got the heat down to 62.5F in my house right now!), and try to reduce our environmental impact. My response was addressing the comment that solar makes economic sense for me. And I do discount subsidies, because those just come back to us, as a group, on our tax bill – it’s a shell game, it is not a true savings.

            Thanks for the correction on home sales. I had researched it (but probably some years ago), and I guess this has changed from the earlier reports I had read. But if I have a 20 year payback, and PVs are rated for 30 year life, how much am I going to get back? And if solar comes down in price as predicted, nobody is going to want to pay 2014 prices in 2034. So I’ll get a fraction of original price, discounted by years of remaining life. It’s a factor, but probably won’t be much. I could envision that in 2034, it might be cheaper to install fewer, more efficient, new panels that might have a longer life than minty 2014 model originally had, than to bear the cost of removing the old ones in a few years?

            It’s just so hard to predict what the future may bring, so for myself, I’m looking for a much shorter payback for a big investment like this. I’ll accept longer payback for lower risk, more static options (like added insulation, etc.).

          • KenC

            mea culpa – I made a mistake in applying estimated electric rate increases against opportunity cost investment gains. I noted it above, here are the details:

            I said – >>>> If we make a ballpark assumption that electric rates increase at the same rate as my investment would, those wash. So $22,200/$1,200 is an 18.5 year payback…<<<<

            But they don't exactly wash. An assumed 3.6% return on the investment applies to the entire $22,200. A similar 3.6% increase in electric rates applies only to my initial $1,200. But then I put this in a spreadsheet, and realized that if you also apply that investment return to your cumulative savings, it comes very close to washing out again. But then again, you might not be able to get long term rates on all that money, but we're splitting hairs. So 18.5 year payback is still a reasonable ballpark figure.

          • Bob_Wallace

            First, rooftop solar pays for itself in under 10 years for many people. A ten year payback is a 7.2% return on investment. A 20 year payoaff is a 3.6% return which is better than CDs and Treasuries.

            Second, inverters last more like 20 to 25 years. 10 years is the typical warranty. And extended warranties are available if desired.

            Finally, there is absolutely no need for deaths from falls. We have very effective safety gear. Strap in.

          • KenC

            Well, a 10 year payback might tempt me – but I’m in an area of near average rates ( ~ $0.11 kWhr) and that findsolar.com site says that a 100% system would cost me ~ $24K after subsidies ($44K before), so I’m looking at ~ 20 years. And I really dislike including the subsidy in these calculations, as that is just other people paying for my system. Doesn’t seem fair to me – I’m well off enough to be able to invest the $24K (or $44K) if I decided, why should others foot the bill for $10K worth of my solar panels, so that I can save money on my electric bill?

            If you want to say that we all benefit from any environmental pluses, OK. But then why not install a solar farm, and split the cost and benefit evenly? It sure would be cheaper, which means we could do more of it.

            The inverters may last 20-25 years, but I’m seeing 5-10 year warranties, and the little info I found on average lifespans was all over the map, so I’ll stick with my statement that it *may* add to the costs.

            My searching also brought up another point I missed, the panel output does degrade over time ( maybe 5% in 10 years?), so that cut savings a bit.

            Sure, we can wish that installers would use all the safety equipment that would prevent injuries and death, but that isn’t likely to change when you have many small crews installing at a different location each week. I think my statement stands that a crew working on one big installation like the flat roof of a big-box retail or warehouse, is going to be safer and better managed than small crews on a different residential rooftop (multi-story, steep slopes, maybe obstacles, etc) every week. It wasn’t an argument against solar, it was an argument in favor of large scale installations over small scale residential installations. Nuclear was thrown is for reference, as that seems to scare so many people. OTOH, even with these small installs, solar is far safer than coal.

          • Bob_Wallace

            How do you feel about using that “~ $0.11 kWhr” grid electricity when other people are paying another $0.05 to $0.12 per kWh to cover the damage caused by the coal you’re using?

          • KenC

            You’re taking this in a different direction from what I was responding to. The posts I was responding to were telling me that solar made economic sense for me at current costs.

            The externalities are a separate (valid, but separate) issue.

            Did I ever try to argue that solar wasn’t cleaner than coal? No. If you want to argue that we should all install solar regardless of the cost, fine, have at it. But that has nothing to do with me responding to someone who tells me solar will be a great financial investment for me.

          • Bob_Wallace

            Perhaps you remember posting this?

            ” And I really dislike including the subsidy in these calculations, as that is just other people paying for my system. Doesn’t seem fair to me”

            What’s the difference between others paying to clean up your coal mess and paying to help you quit making your coal mess?

          • KenC

            @ Bob Wallace – Ahhh – OK, with that added context your comment makes more sense to me, and I can respond.

            First, I agree with you in concept – it would be beneficial if the external costs were added to the price of my (our) kWh. Then the free market would just work better, the hidden external costs distort that. Deciding/agreeing on what those costs should be and how to use the revenue would be a minefield, but even an imperfect stab at it would be better than nothing. Of course, this would also drive up the initial cost of solar panels, which take large amounts of energy to produce, and there are some concerns over the waste products.

            Second – I still say the current subsidy system stinks. I want to see the (not just ‘my’) coal mess cleaned up, and there are far better uses for that subsidy money than paying a well-to-do person to install solar on their roof, so they can now brag they get ‘free electricity’ on the backs of other taxpayers.

            As I’ve stated above – those same $ could go much further with a solar farm installation, which benefits from more optimal placement and economy of scale. If there is a true economic payback, then let everyone on that utility share in it, not just the well-to-do person who got the subsidy. My argument is not anti-solar at all, my argument is if we are going to subsidize it, lets do it efficiently so we get MORE of it for our $. Is that so controversial on a ‘green’ website?

            It also bothers me that the Fed subsidy applies no matter where you are. It should be scaled to reflect how dirty your grid is. Since it takes energy and resources to make a solar panel, we should be using them wisely, like any resource. A solar panel on a dirty grid is doing more to cut pollution than it is on a relatively clean grid. These one-size-fit-all subsidies are terribly inefficient.

            I’ve had discussions with people in Hawaii, and their power is mostly (>80%?) generated by oil shipped in with tankers. I think they pay ~ 30 something cents per kWh, and that is dirty power. So solar can make great economic and environmental sense there (and most areas get lots of solar exposure, though some areas have local cloud cover). Shouldn’t places like that be getting panels first?

          • Bob_Wallace

            Could the subsidy program be tweaked to make it better?

            Absolutely.

            Are we better off investing a few billion dollars in renewable subsidies in order to get enough of our grid supply from wind and solar, thus eliminating the billion dollars per day we have to pay for the external costs of burning coal?

            Absolutely.

          • KenC

            My point is, the subsidy system is so very bad, so out of whack with the goals, that every ‘green-mined’ person should be clamoring for change.

            I’m not looking for anything near perfection, but clearly these dollars could do so much more.

            I’d be interested in discussing your numbers further, but is there an actual forum you post to? This ‘Disqus’ format is painful for anything beyond a quick comment – threaded responses are a jumble, and my entry field is now about an inch wide and way down in the screen. If you can post a link, I’ll see about signing up there to discuss. Otherwise, I think I’ll probably end here, I just can’t follow the threads/responses – I’m lost! But I do wish to follow up the discussion.

          • Bob_Wallace

            If the column width gets too narrow then restart the subthread by using the Reply box under the article. Include a “restarted” comment if you feel its needed.

            And make sure you subscribe to the thread. That way you’ll get notified by email when a new comment is added.

            Truthfully I do not know of a better place to discuss renewable energy. This site minimizes spam and commentors whose motivation seems to be to disrupt.

            As for the current subsidy system being bad, agreed. But what’s that old saying about democracy – it’s the worst system ever invented except for all the others which are worse.

            I think we would have done far better, moved prices down much quicker, had we adopted a FiT (feed in tariff) system like Germany used. That made it possible for people who installed solar to make some profit off their panels. By getting the installed price down as much as possible they maximized profit and that, I think, drove prices down in Germany much faster than what we’ve seen in the US.

            I think we needed to subsidize in all states, regardless of how they generated power. The idea was to build an installation industry which would install at low prices. We’re doing that. We’re now seeing large installation companies emerge which will be able to install for less simply due to economies of scale. And they will be large enough to afford an attorney in a very nice suit who can talk to local governments about reducing the permitting overhead.

            We lag Germany two or three years in installed solar costs. My guess is that in a couple of years we’ll be down to about their $2/watt installed price and solar will be competitive in almost all the US.

            Whatever the flaws with our subsidy programs, they are likely short lived. They’re dropping from 30% to 10% in a couple more years and soon after may go away completely.

          • Bob_Wallace

            “Sure, we can wish that installers would use all the safety equipment that would prevent injuries and death, but that isn’t likely to change when you have many small crews installing at a different location each week.”

            In the US you do not keep your company insurance if you don’t keep your crew strapped. Insurance companies keep a close watch on customers who work on roofs. They do not like to pay for people who fall off roofs.
            You’re not going to get much business if the building owner finds out your aren’t insured. I would guess that you will not get a signed contract if there’s a lending agency in the mix. One of the blanks they will insist to be filled in is your policy number.

          • Richard

            Car bumpers have a 3 year warranty. How long do they last?
            Warranties are a poor guide. Seems like you are seeking reasons to be cool towards solar.

          • KenC

            @ Richard – I said that in my post – do you have reliable info on average lifespans in the field? As I said, the data I found was all over the map. Warranty was just a piece of information, not something I took as a ‘data’.

            I stand by my point – if the inverter life is less than the panel, it is an additional cost. That is a fact. Quoting myself from that post: “it *may* add to the costs”. As mentioned in the post I replied to, one can purchase extended warranties – and that is an added cost.

            “Reasons to be cool on solar”. Heck no, but I *am* trying to understand the numbers. Articles like this with FACTUALLY INCORRECT GRAPHICS do not help.

            Maybe I’m skeptical that they/you are ‘seeking reasons to be hot on solar’?

            -KenC

          • Bob_Wallace

            There’s one 30 year study of a large array which reported a 2% panel fail for the life of the study. A few panels had connection or lamination problems.

            When one considers that those panels were manufactured more like 40 years ago it wouldn’t be unreasonable to expect current panels to have lower failure rates. Manufacturers tend to learn from product failures.

            Lots of studies report roughly a 0.5% performance drop per year.

            Inverters seem to last at least 20 years. They used to be warrantied for 20. Now they are typically sold with a 10 year warranty but a 15 or 20 year warranty is sometimes offered for a bit higher price. I suspect dropping down to a 10 year warranty had to do with competitive pricing.

            We normally calculate LCOE prices on a 20 year basis. With solar one might expect to replace the inverter after the 20 year window has closed and then do a new LCOE based on new inverter cost and panels rated at 90% of new.

          • KenC

            @ Bob_Wallace Thanks, that sounds reasonable – do you have any actual studies on those inverter life-cycles? I’d just be interested to see actual data.

            Regarding the 40 year old panels versus current ones, that could work both ways. Yes, mfg improvements could bring longer life-cycles, but the cost-competition could lead to cut-corners that affect it negatively. Recall the electrolytic cap fiasco from ~ 2005? And how many times do we hear the phrase “They don’t make them like they used to!”? Though I think the phrase is over-used, but it applies in some cases.

            -KenC

          • Bob_Wallace

            No, I can’t find any lifespan studies for inverters. I did contact a couple of inverter dealers with whom I’ve done business and both volunteered the 20 year number. They said that they just aren’t seeing people replacing inverters.

            And I know a number of people who are off grid. It’s common around here. I’ve turned up no one who has experienced an inverter failure.

            There do seem to have been some problems with some micro inverters. I don’t know if that applies to all micros, one/some brands, or one model. I’m addressing large ‘central’ inverters on retail/home/small business systems.

            If you’re really interested you might do a search on Home Power and see if there is any discussion of inverter failure. (Just occurred to me.) –

            Panels – there definitely were some questionable quality ones that flowed out of China in the last days of the industry shakeout. Failing companies were trying to recoup any money they could is my guess.

            Now there are a couple of independent labs that test panel quality. Financing companies want to make sure they are likely to get paid back and will be requiring independent testing. If one sticks with brands that are being used on large utility scale projects I would think they would be quite safe.

          • Jouni Valkonen

            Grid electricity is expensive. Therefore it is better to have distributed electricity generation and battery storage. Today battery storage is almost cheaper than feeding electricity back to the grid and using grid as a battery (net metering).

            E.g. here is storage batteries available for sale. These batteries are best suited for storage as they have long lifetime — up to 20 years. http://www.ev-power.eu/Winston-300Ah-1000Ah/WB-LYP1000AHC-LiFeYPO4-3-2V-1000Ah.html

            Solar may cost in US $6 / watt, but it costs in Germany and Australia less than $2 / watt. This is factor of three cost difference. And like I said, Government should sponsor the soft costs of installing solar, because it generates local jobs.

            Shading is a problem if solar array is installed in a series. This is usually needed, if solar electricity is inverted into AC power and fed back to the grid. But if instead solar power is used for charging batteries and you have DC home-grid, solar panels can be installed in parallel and therefore irregular shadings do not pose a problem.

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