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Musings of an Energy Nerd

A New Ground-Mounted Solar Array

My newly installed PV modules are delivering a lot of amps to my batteries — a fact that re-ignites my sense of wonder and excitement

My new array has ten PV modules, with room on the rack for a couple more.
Image Credit: All photos: Martin Holladay

I’ve lived in an off-grid house for the past 39 years. Since I make my own electricity, my electricity costs are much higher than those of most Americans. Because of my off-grid lifestyle, I often lack perspective when I try to help people who ask questions about ordinary energy choices. (I’ve had to compensate for my lack of relevant experience by undertaking anthropological studies of my grid-connected neighbors.)

Back in the old days, I used to haul water in a bucket from the spring, and I made whole-wheat flour with a hand-cranked mill. (Don’t ask.) So when I’m in a retrospective mood, I can be amazed by simple things.

“Look: all I have to to is turn this little knob and water flows out of the faucet!”

“If I flip this switch, the mill will make flour by itself!”

Karyn and I try to keep our batteries charged, of course. In sunny weather, we get most of our electricity from our rooftop photovoltaic (PV) array. When the weather turns cloudy, or days get short, we have to charge the batteries with a gasoline-powered Honda generator.

Since I still have vivid memories of the old days, when I did everything by hand, I’m grateful for the conveniences made possible by our Honda generator. But generators are a pain. Anyone who lives off-grid has a visceral understanding of how complicated it is to burn fossil fuels to create the rotary motion needed to power a generator or alternator. Gasoline-powered generators are noisy, require frequent maintenance, and use expensive fuel. Every kilowatt-hour we generate this way is hard-won and expensive.

One solar panel at a time

I bought my first PV module (a 33-watt Arco panel that cost $275, or $8.33/watt) in 1980. My PV array (like those of most off-grid hippies) is a collection of mismatched panels collected over several years.

When the Carizzo utility-scale solar facility in California closed down in the early 1990s, I bought three used Arco modules from the dismantled plant. Over the years, I continued to buy PV panels, usually one at a time, as I could afford them.

I didn’t keep perfect records, but I have receipts for some of my purchases. In 2002, I bought a 120-watt Kyocera module for $525. That’s only $4.37/watt — about half the price of my first module.

In 2004, I bought another 120-watt Kyocera module, this time for $477 — down to $3.98/watt.

Eventually, I accumulated 16 miscellaneous PV modules that produced about 700 watts. A few years ago, I realized that my roof was getting crowded, so I stopped buying PV modules.

Meanwhile, the cost of PV modules just kept dropping. This summer, I saw an ad for ten used 120-watt Kyocera modules for $1,000 — in other words, 83 cents a watt. So I sprang for another 1,200 watts of PV.

This latest batch of modules was an order of magnitude cheaper than the first module I purchased.

Time for a second array

Over the last few weekends, I’ve been installing a ground-mounted rack to hold my ten new PV modules. I recently flipped the breaker that sends power from the new array to my charge controller.

The array is wired for 70 volts DC. It delivers PV power to my electrical room through #6 cables in a buried conduit.

It’s hard to describe the feeling I have when the sun is shining on the new array and I read the display on my new charge controller. The system is making gobs of electricity, and I didn’t have to haul in any gasoline to make it happen. Of course, the PV array has no moving parts, and it isn’t making any noise. The 10 new panels are sitting out there in the sun, silently pumping just as many amps into my battery bank as I get when my Honda generator is running.

Isn’t that amazing? These simple slabs of glass, aluminum, and silicon are inexpensive, foolproof, durable — and fun. I fully expect my new PV array to produce power for the next 30 years, without any maintenance.

Waking up in the future

Over the last 34 years, I’ve seen the cost per watt for PV modules drop to 1/10 of the price in 1980 — or, more accurately, to 1/29 the price, if inflation is taken into account. So my $1,000 buys 29 times as many watts now as it used to.

Lots of things have gotten worse since 1980, including biodiversity and suburban sprawl. But some technical developments (including the development of inexpensive PV modules) have been so surprising that I sometimes feel that I took a short nap and woke up in the future.

Just watch: in the next two or three decades, inexpensive PV modules will change the world.

Martin Holladay’s previous blog: “Dense-Packed Cellulose and a Wrong-Side Vapor Barrier.”

Click here to follow Martin Holladay on Twitter.

44 Comments

  1. John Roy | | #1

    Installation costs
    Has anyone quantified the cost savings self installing a (ground mounted) 5kw system vs having a contractor perform the work?

  2. Allan Edwards | | #2

    Cost of Solar
    I have been paying attention to the cost of solar for a long time and now and for the past few years it has made real economic sense to consider solar. I had a custom client who wanted solar, the cost for a 10KW system, installed and after tax credit, added $105 to their mortgage payment. The $105 added payment was mostly deductible interest, so their after tax cost was about $85/month. The projected savings in monthly electric was $140, and of course that cost will increase 3%-4% a year while the cost of solar panels is fixed. Also, as an incentive, we offer to install solar panels on our new custom homes at our cost, we do not add out 16%-18% markup. Solar is going to increase exponentially in years to come, in my opinion. I'm not sure costs can go down at the rate they have, but I believe panels will continue to become more efficient.

  3. User avater GBA Editor
    Martin Holladay | | #3

    Response to John Roy
    John,
    In most areas of the country, PV installations have to be performed (or at least supervised) by a licensed electrician. That makes do-it-yourself installations rare.

    I think that it's probable that about 50% of the cost of a typical PV installation is for materials, and 50% for labor -- about the same ratio for most remodeling work.

    If you hire a solar contractor to install a PV system at your home, you will pay anywhere from $3.50 to $5.00 a watt, depending on where you live.

  4. User avater
    Greg Labbe | | #4

    Life isn't such a grind afterall!
    What a feel good story [sorely needed] and I don't feel like such a nutter hand-grinding coffee, or using a hand-powered crank whisk now!

  5. User avater GBA Editor
    Martin Holladay | | #5

    About roof acne
    John,
    Because I started out hauling water in a bucket from the spring, my attitude toward "roof acne" is probably more akin the the feelings of rural people in Africa and the poorer countries in Asia.

    When you live off-grid, PV panels are semi-miraculous. Any off-grid rural resident -- a category that includes the vast majority of the residents of sub-Saharan Africa -- who can afford a PV module will eagerly and proudly attach it to the sunniest part of his roof.

    So I consider "roof acne" concerns a First World problem. It is a concern, of course -- but it doesn't undermine my prediction that, in the next two or three decades, inexpensive PV modules will change the world.

  6. Allan Edwards | | #6

    Cost of Solar
    I had a job quoted with Kyocera panels that nets out costing $2.30 per watt, installed by contractor. This is company I am using:

    http://www.texassolaroutfitters.com/

  7. Terry Lee | | #7

    Tracking
    It will be interesting to see if this solar boom gets past the sub-division US Architectural Control Committees (ACC) which puts their fate in the hands of average homeowners. Whether they increase or decease curb appeal and home values, compared to areas with low grid cost. You'll find lots of opinions on the aesthetics of roof top mounts. I think in some areas of the country it makes no sense to design a roof for PV, or have them drive design criteria. I personally find environmental loads more appealing ;) ....and many existing roofs, landscaping, are not designed for them. That train left the station when the home was built. I drive all around the US and midwest and I rarely see one. In five years I just don't see the vision of them on even 10% of rooftops. Price drops are only a small part of hurdles. There is also insurance, legal, structural, roof replacements, etc....to consider.

    If there is room, not likely in most US homes, ground pods make better sense at the sub-division level or designated area, or at the power plant. CA has done this don't ask me how. At these locations tracking devices can be incorporated into the design. It would be interesting to see a GBA article on designs, cost, of them. They say 75% is lost in morning-evening hours from being fixed.

    Here is one I found on a quick search: http://www.altestore.com/store/multimedia/Images/Wattsun_Tracker_Prices_2010.pdf

    Less is more when it comes to PV space, roof or ground, I wonder if one did a cost analysis on the latest pricing if more ft2 of fixed makes more economical sense compared to single tracking with less panels.

    Perhaps by the time we figure that out they'll be in our windows: http://www.newenergytechnologiesinc.com/new-energy/new-energy-unveils-companys-largest-and-highest-performance-see-through-solarwindow-capable-of-generating-electricity-on-glass

  8. Antonio Oliver | | #8

    battery costs?
    Martin,

    I wonder if you might be able to say a few words about costs and performance trends of other equipment necessary for your power generation, batteries and inverters for example. Also, do you have experience with DC powered appliances?

  9. User avater GBA Editor
    Martin Holladay | | #9

    Response to Antonio Oliver
    Antonio,
    Like all off-grid homeowners who put together their PV systems in the 1980s, I have plenty of experience with DC appliances. All of us started out with 12-volt DC equipment developed for recreational vehicles (RVs).

    There is lots to say on the issue, but here is the short version: improvements in inverter technology mean that most off-grid homeowners now use 120-volt AC appliances, which tend to be better made and more durable than 12-volt DC appliances.

    In our house, we still have a few DC lights and DC battery chargers (for example, a DeWalt battery charger sold to contractors for use in a pickup truck). My kitchen radio is 12-volts DC. When I bought my wireless router, I noticed that it was 12 volts DC, so I threw away the wall cube and wired it to my DC circuit. I have a few 12-volt DC LED lamps.

    Everything else is 120 volts AC.

    Are batteries expensive? Absolutely. I have moved up the chain from 6-volt DC golf cart batteries to 6-volt Trojans to our latest battery bank, purchased from GB Industrial Battery in October 2011. The specs:
    1,576 amp-hours (20 hr. rate) at 24 volts, 38" x 13" x 30.5" high (twelve 2-volt cells) -- $4,621 delivered.

    I wired the batteries for 12 volts DC, with an option to upgrade to 24 volts DC when I decide that it's time for a new inverter.

  10. John Brooks | | #10

    PV Carport
    I think PV on almost any House is "Ugly".
    I consider PV to be "Roof Acne".....
    Even when the PV is integrated with the design of the house.
    And the ground mounted array is not-so-nice to look at.
    My dream house would be a One Story House with a PV Carport.

  11. User avater
    Robert Swinburne | | #11

    Roof Acne
    As an architect with an often modernist bent I actually like seeing PV on a roof. It seems more holistic.
    Une maison est une machine-à-habiter.
    "A house is a machine for living in." - Le Corbusier

  12. Lucas Durand - 7A | | #12

    Hmm...
    Martin,
    Did you consider a tracking setup?
    Is the "backyard tape test" still going on the other side of your shed?

  13. User avater GBA Editor
    Martin Holladay | | #13

    Response to Lucas Durand
    Lucas,
    Trackers don't make a lot of sense. If you take the money you were going to use to buy a tracker, and use the money to buy a few more PV modules instead, you'll make more electricity on an annual basis.

    Trackers improve the summer performance of a PV array, because they follow the sun from sunrise in the northeast, across the southern sky, to sunset in the northwest.

    Trackers don't do much in the winter, when the sun moves (barely) from southeast to southwest. Point the array south, and you're lucky to get a few hours of sun in December. There is no need at that time of year to aim the array east or west.

    Off-grid homeowners don't need any extra electricity in the summer. We need extra electricity in the winter.

    The small structure in the background of the photo is my garden shed. The backyard tape test was on my woodshed (not shown in this photo). The backyard tape test has been dismantled. I'm passing the baton on to other researchers.

  14. John Roy | | #14

    suppliers
    Martin
    Thanks for answering my question from earlier today. I'm fortunate that I have an electrician who has worked for a solar installer available to handle the hookup. So at this point I'm looking for a supplier of equipment and wonder with whom do you go to for your supplies? Ive been looking at online suppliers, and the alt-e store is based in my home state of Massachusetts.

  15. User avater GBA Editor
    Martin Holladay | | #15

    Response to John Roy
    John,
    Off-grid homeowners who started their PV systems in the 1980s were loyal to Backwoods Solar Electric Systems, a company founded by Steve and Elizabeth Willey in Sandpoint, Idaho. In New England, a few years later, we had the option of buying equipment from New England Solar Electric in Worthington, Mass.

    These days, the PV equipment business has become a commodity business. Retailers suffer, because end users just chase the lowest prices on the internet.

    I'm like everybody else. When I know what I want to buy (a specific piece of equipment), I look for the best price online.

    Anyone who needs a little hand-holding or wants good service should pay a little extra and support their local contractors and suppliers. Buying locally makes sense in the long run.

  16. User avater
    Dana Dorsett | | #16

    Ugly is in the eye of the beholder.
    Hanegy may be (finally) producing CIGS technology roofing products using Miasole's process that are as efficient as commodity silicon PV panel products (~15% conversion efficiency), for those who can't stand the sight of blue silicon or brown Cd-Te panels on a roof.

    http://www.greentechmedia.com/articles/read/Hanergy-Aims-MiaSoles-Flexible-PV-at-Rooftops-and-Altas-Cells-at-Drones

    Tracking adds more cost per watt than simply going for more panels using simpler racking, if you have the space, at current hardware costs. Even paying the premium for 20% efficiency panels is usually better bang/buck. But it's a constantly moving target. Until/unless small scale PV is compensated more for peak-hours than mid-day production, the loss of evening performance from south facing fixed-mount isn't an issue worth worrying about. Net metered at block-retail rates, the number to optimize the annual kwh/$, and that almost never means springing for tracking mounting systems.

    $2.30/watt system prices in TX demonstrates that when you pare back on the "soft-cost", the US can build small scale PV at the same price point as Australia, but Germans where the competition is even hotter they are still beating that by more than 10%. A big chunk of the soft costs in the US in most markets is the customer-acquisition cost- the advertizing, bidding, hand-holding that goes along with the sale. Once PV becomes mainstream (as it has in some TX neighborhoods, and as it did in Australia & Germany) those costs shrink rapidly.

    Another chunk is regulatory and utility red-tape, such complexity & delay in the permitting process, multiple system design reviews & inspections, etc., (which in some markets is put up as road blocks by utilities antagonistic to that competition.) In locations where the process is streamlined that too melts away at the total system cost. Germany has reduced the red tape aspect to an astounding level, due to the fact that the regulations and the deal is uniform nation wide, and PV installers have certification credentials that allow them to self-permit and self-inspect. The customer can call up a PV contractor, get a price, have the thing installed, and only AFTER the system is installed and switched on is the paperwork filed with the local regulatory authorities, and utility.

    NREL just in the past week released the 2014 update on PV pricing trends in the US. It's a fairly straightforward set of slides with pretty graphs, not a tome full of math. For those looking for insight into where the US market for grid tied PV (at both small-scale and utility scale) is going it's worth a peek.

    http://www.nrel.gov/docs/fy14osti/62558.pdf

  17. John Roy | | #17

    reflection
    Just wondering would solar production be enhanced if system is positioned near a body of water (pool) that would reflect light (towards the panel)?

  18. Lucas Durand - 7A | | #18

    Reply to Martin.
    Martin,
    That makes sense.
    A neighbour of mine (not off-grid) has a "rack" of PV panels with tracker.
    I was never too sure if that really made any sense, but it was neat the way it was set up to "park" the panels in a vertical easterly facing position at the end of the day...
    I don't think he's ever had to worry about cleaning snow off of them.

  19. User avater GBA Editor
    Martin Holladay | | #19

    Response to John Roy
    Q. "Would solar production be enhanced if system is positioned near a body of water (pool) that would reflect light (towards the panel)?"

    A. Yes. Reflection from snow also increases electricity output.

    Researchers have experimented with various concentrator arrangements (parabolic troughs or heliostats) to increase PV output. In general, concentrators raise the temperature of a PV module, thereby shortening its life.

    PV output is also a function of temperature: the colder the module, the higher the output. So while you can get increased output with a mirror, the higher temperature also works against you.

  20. User avater
    Dana Dorsett | | #20

    Trackers made sense...
    ... when the panel costs alone were well north of $5/watt.

    The wholesale cost of panels now is in the 75 cents/watt range and falling.

    Retail (not installed) commodity panels from first-tier manufacturers is about a buck and a quarter per watt, even in onesie-twosie type quantities at internet stores. (Presumably it would be something like a buck a watt or less in 50 panel quantities, for a small commercial rooftop type application.)

    To do concentrating solar right you need to have a cooling system. That is sometimes financially rational for utility scale operations, not so much at residential scale.

    There is a clear path to getting silicon PV down to the 30-35cent/watt range at the wholesale price level, a combination of better manufacturing processes (=lower scrap rates), higher efficiency (=more panel-watts for the same material cost), and higher automation in the manufacturing & test.

    Vertically integrated PV companies are even looking at transportation & management costs. Solar City is building a high-efficiency silicon PV manufacturing facility in NY (near Buffalo) in part because that's where they expect the next hot market to be. They can control their process better than trying to manage a plant in Asia, and they don't have to ship by sea & rail to get it to the market they intend to serve. Less handling, less delay, fewer trans-shipment points to drop & bash the container , etc. To get to buck-a-watt grid tied PV (installed cost, if not price) takes some streamlining of every aspect. The production-prototype runs for their process (located in California) are yielding 20-21% efficiency panels, but they expect to have standard product in the 24-25% range once the NY factory is fully up and running.

    On a somewhat longer time scale hybrid perovskite / silicon panels look promising, since the perovskites themselves are dirt cheap, utilizes a different part of the solar spectrum than the silicon cell, and can be fabricated on top of the silicon cell (or so it seems.) It's likely that somebody will have a standard process for panel efficiencies north of 30% efficiency (2x that of current commodity panels) within 10 years. But don't hold your breath on that- the promise isn't in writing just yet, they're not field tested & proven.

  21. Andrew Michler | | #21

    PV History
    My first PV array was four very brown Arco's hooked up to the cabin I bought in 1994. I gave them away when I found cases of abandoned 10 watt panels at a HVAC wholesale company I worked for in 1996. When PV was written into the NEC my inspector balked at the labeling so I got four 75 watt panels for $4.25 watt and ground mounted them in 2002. It was never quite enough to top the batteries off so when solar hit $1.25 I had to pull the trigger on 1800 watts from Schott made in Albuquerque. Now batteries without fail are full by noon unless we have a few cloudy days.

    (pic is of the High Park fire in back 2012)

  22. Dick Russell | | #22

    Tracking vs sectional aiming
    I'm wondering if there may be some users of PV, with predictable power use patterns, who could benefit from evening out the power generation or from matching peak generation to higher periods of use, by selectively aiming some groups of panels in different directions (easterly for early hour use, southerly for mid-day, westerly for late-day), as opposed to installing a tracking system. I suppose there at least is the cost of perhaps more panels vs cost of tracking. Thoughts?

  23. User avater
    Brian Knight | | #23

    PV and wind turbines are beautiful
    Congrats on the new addition and I think they are looking good.

    Just wanted to post a pic of what I think is ugly. This is also what I think of when I see those stupid, trendy edison bulbs. Those things are really ugly.

  24. Terry Lee | | #24

    Tracking Cost...
    It appears tracking devices have a long history. Whether they "make sense" of course is not as simple of an answer as some make it appear. Does this make sense?

    http://solarprofessional.com/articles/products-equipment/racking/pv-trackers/page/0/9

    "Ron Corio and Michael Reed of Array Technologies and Lewis Fraas of JX Crystals—consider historical, current and future PV module and system cost scenarios and conclude that single-axis trackers typically improve PV plant performance by 24% over fixed-tilt mounting while incurring a cost increase in the 3%–5% range. For dual-axis trackers, the authors assume yield improvements of 38% but estimate a double-digit cost increase of 12% to 14%. These conclusions are fairly representative of the conventional wisdom among financiers, developers, and engineering, procurement and construction (EPC) contractors working in the US today. "

    Seems as if it does, read the article more and you'll see there is more to it,

    While it may reflect commonly held opinions in the industry, the Corio, Fraas and Reed analysis is of limited value. For example, it unrealistically assumes a uniform total system cost for all three mounting options. In reality, a shift from fixed tilt to single- or double-axis tracking has complex and cascading cost implications. To undertake an accurate cost benefit analysis is equally complex. Many financial variables need to be quantified and compared, including increased costs for land, labor, materials and O&M, as well as the increased value of the energy revenue projections. These revenue projections are in turn impacted by PV technology, inverter selection, mounting system, location, climate and the rate structure of the offtaker, the utility purchasing the power.

    Now lets look at the conclusion,

    The good news for manufacturers of PV trackers is that the general trend toward larger and more efficient PV modules definitely helps their cause. Since the price per watt for trackers is based on tracker area, as PV technologies become more efficient, the price per watt for trackers goes down. However, the price of PV has also fallen so much that trackers have become a larger percentage of total system costs. This underscores the importance of a concerted effort to optimize total system cost and performance by streamlining planning, construction and installation.

    It is worth noting that this effort is clearly well under way. For example, Suntech Power has launched its Reliathon platform, which was designed using a whole-system approach. The system features 270 W modules that self-align when mounted on the tracker. In addition to providing integrated wire management, Reliathon eliminates module frame grounding with a special frame-to-frame connection. With a similar end in mind, SunPower has developed the Oasis power plant, which is optimized around 1.5 MW power blocks. The Oasis system includes every part needed to deploy and operate these power blocks and is scalable to 500 MW.

    Though every part of a PV power plant invariably has to stand before the cost-cutting guillotine and justify its value, few components have the potential to increase plant production like PV trackers. If the race to grid parity is a sprint and not a marathon, solar will clearly need its fastest horse to win.

    Cost of trackers are coming down along with panels. OEMS are bundling "total systems" that make perfect sense....I don't think the market would be so strong and getting better if they did not make "sense", the market would have folded by now if they did not make sense. The OEM will be in the best position to integrate the tracker(s) with the panels, electrical,etc, at a reduced cost as the case withm with so many "kit" installation designed products. Good design, manufacturing Engineers and a good supply chain or buyer can make this happen better than a home owner trying to piece meal it together. A tracker is not the space shuttle, it should not be that difficult nor costly to integrate them to the panel structure, and electrical systems.

    Newer utility "grease free"...makes sense, getting more robust taking down the cost of maintenance (O&M)...it's just a matter of time before trackers are an integrated part of the pv solar system boom.

    http://www.pv-magazine.com/news/details/beitrag/the-utility-solar-tracker_100011377/#axzz3HBE0JqhU

    Here is tornado alley structurally, I take a steel tracker on a pod over a fixed roof wood rafter install any day of the week, especially if there are no grease zurks ;)

  25. Malcolm Taylor | | #25

    Martin
    "It's hard to describe the feeling I have when the sun is shining on the new array and I read the display on my new charge controller."

    Martin, there are certain experiences like that which are pure alchemy. Finding your bread dough has risen, eating things that you planted, walking through a house you have built. Those experiences evoke feelings that are beyond all the calculations in the world.

  26. User avater
    Paul Kuenn | | #26

    Living the life
    Nice improvement Martin!

    I do stay in touch with those living in my CO first home with 1984 modules and they still perform over their original rating. My 2005 modules are Evergreen (tears come to my eyes with the loss of that MA company) and were 190W at $985. Second array were Evergreen 215 at $525 each. If I had more rooftop I'd add more but a car port would steal sun from my garden so I still have to watch my batteries. I'm fortunate to have the grid down my block to take from when there's 40 days of clouds in a row come November & December. The rest of the year we are 20% over our use and utility owes us.

    I HATE asphalt shingles. Ugly as H_LL and PV looks so cool when the modules are all dark and powerful. Zen like. People know you're "cool" and envious when they pass by.

    Cheers,
    PK

  27. Jin Kazama | | #27

    Panel prices ...
    I've been monitoring panel prices for personal info from sites such as solarblvd. com
    ( no add here, but they do have great panel prices in pallet quantities )

    Lot's of choice from 0.65$ to 0.9$/w.
    With the price of inverters going down also,
    DIY installtion costs are very low now . ( been sub 1$/W there for almost 2 years now )

    That said,
    if you take in account size of panels relative to its pricing :

    the average size of panels being approx 18sq ft
    and costing from 150-200$
    this equates to approx 9-10$/sq ft.

    PV panels now make a relatively cheap and solid finish for most surfaces, even some vertical ones that would point south side.

    Let's say you are making a car port, using solely PV panels as top surface , using a basic structure underneath it ...the PV panels may cost a little bit more than standard finishes, though not that much more, and make even more economical senses since replacing the cost of the other finish.

    Imagine within a few years, when the prices will be going down even more,
    and if thin film technology moves fast ...we could have ( i dream of this ) architectural finishes that could be used on sunny sides of buildings , and generate electricity .

    Been looking around for cheap thin films, even with low efficiency, found nothing worth of using
    as finish as of yet, but we will get there soon !!

    Currently, there is no question as to what material to use for sunshades on south orientation of buidlgins... PV panels should be used without hesitation.

    for the count, i do also like the look of PV panels, the black mono ones coming on top of it !!

  28. Jin Kazama | | #28

    woa ..
    first time i notice this is available at that kind of pricing :

    http://www.solarblvd.com/Solar-Panels-&-Systems-24-Volt-Solar-Panels/c1_270/p2962/Unisolar-136-Watt-24-Volt-Flexible-Solar-Panel-PV-Laminate/product_info.html

    roughly ~ 22sq ft for 99$
    that makes up to a neat ~ 4.5$/sq ft.

    This can be applied on many different cheap surfaces.

    No reason not to use solar anymore :)

    ( note that this is still ~ 100W real performance thus ~ 1$/w .. but the area price is interesting )

  29. Kevin Dickson, MSME | | #29

    Thin Film not in Production
    Jin,

    That company is out of business, so they've marked down the price to reflect that no one wants orphaned panels. I had heard that they just didn't remain "stuck" to any substrate very long.

  30. John Brooks | | #30

    "Roof Acne"
    I apologize for my "Roof Acne" comment.
    When I first opened up this blog and saw Martin's new Ground Mounted Array...
    My first thought was ...what a vast improvement over his Roof Mounted Array.
    I also imagined what a challenge it must have been to install the roof top panels in the first place...
    Not to mention maintenance ... and aesthetics.
    I considered asking Martin what he would do if he could start over......
    ..........................
    Martin, if you were starting from scratch ... would you mount ALL of the panels near the ground?
    or perhaps on top of a carport or tractor shed?

  31. User avater GBA Editor
    Martin Holladay | | #31

    Response to John Brooks
    John,
    The reasons governing the location of my PV panels are entirely technical, not aesthetic.

    When my house was first built, MPPT (maximum power point tracking) charge controllers had not yet been invented. MPPT controllers include DC to DC converters that accept a wide range of DC input voltages and automatically adjust the voltage to match the needs of the battery to which they are connected.

    My batteries are 12 volts DC. Low voltage DC wiring needs to have a higher gauge than 120 AC voltage wiring, because (for the same watt load) the low-voltage wiring has to carry higher amperage. That means that 16-volt DC modules need to be fairly close to a 12-volt battery, unless you want to invest in expensive copper cables.

    During the dark days of December, when the sun skims the treetops, the only part of my roof that gets any sun is near the peak. That's where the PV modules went.

    The invention of MPPT controllers allowed me to wire my new array for a higher voltage (about 70 volts DC). That allows me to use lighter cables than would be necessary for 12 to 16 volts DC, so my new array can be farther from the house. I found a patch of land near my vegetable garden that is far away enough from the maple trees (that is, sunny enough) to allow the installation of my new array. There are many limitations on where the array could go; this is about the only spot that works.

  32. John Brooks | | #32

    Starting over "Today"
    Martin, By "starting over" ... I was thinking of "today".
    Given today's technology ... would you install...
    Some roof mount and some ground mount?
    Or ALL Ground Mount?

  33. User avater GBA Editor
    Martin Holladay | | #33

    Response to John Brooks
    John,
    There are advantages and disadvantages to each approach. For off-grid homeowners, wiring costs and charge controller costs will usually be lower with roof-mounted panels (close to the batteries) than ground-mounted arrays (farther from the batteries). All other factors being equal, MPPT controllers cost more than simpler charge controllers, and every extra foot of copper cable adds to the cost.

    As a roofer, however, my preference is for ground-mounted arrays. The main problem for a ground-mounted array (other than the cost issues I just mentioned) is that it is sometimes hard to find a patch of ground that gets good solar exposure. Not every house has the luxury of a ground-mounted array.

  34. Terry Lee | | #34

    Peal and stick PV
    Jin: "Ethylene propylene copolymer adhesive-sealant with microbial inhibitor.
    “Peel & stick” adhesive backing capable of withstanding 160 mph wind loads"

    It won't last, laminates, that depends on several factors, not just wind load cycles, more combined wind, temp, moisture cycles, add hail or impact resistance in some areas. The property of "lap shear and tensile" is usually low 60-100 psi. with room temp cures approx 70F or non-structural adhesives, high structural are pressure and temp fused in a clean vacuum pressure. That value gets knocked down 40-60% if there is dirt, debris, which is in the hands of the installer. That property can increase or decrease based on the material being bonded to. There are too many knock down factors. Mechanical attachments are best IF they are designed correctly, more than likely not by a DIY that is not well versed in structures.

    When you find one that has third party hot box testing to include common bonding materials, wind and hail, temp, moisture, fatigue life, let me know.

  35. Fred Greenhalgh | | #35

    Beautiful story
    Great story, Martin. I have been in the solar world a much shorter period of time (my parents were homesteader in the 80s but grid-connected, I got my start in mid-2000s). I really didn't know much about solar but my girlfriend (now wife) and I were sick of living in an apartment which was always expensive to heat and never warm. Through a combination of dumb luck, determination, and some nice advice from people like you, we built our own 550sq. ft. yurt-inspired SIPs house in rural Maine. I went from being an agency web designer on a pretty much suburban track to the two of us being pretty heavily deep into this homesteader business. All because it sucked to have cold winter air blow on my feet while I washed dishes at our old apartment.

    In 2007, an HVAC friend got some Shuco panels for $4.5/watt. By 2010, I was working for ReVision Energy (great solar contractor in ME, NH, and MA) and we got some Isofoton solar panels from the scratch & dent bin for about $1/watt. We're (ReVision) now fully designing and installing systems for significantly less than that 2007 wholesale price of the panel off the shelf! Pretty impressive. We (wife and I) live pretty deep in the woods, so, it's ironically easier to add more PV panels than it is to deforest the place. Though having an affinity for both solar and cord wood is a nice way to go.

    Here's to hope for the future.

    - Fred
    Digital Marketing Manager, ReVision Energy
    (yes, off-grid digital marketing/SEO guy)

  36. Brian Carter | | #36

    PV pleasure
    Martin, I have been feeling exactly the same way. I installed a 980 watt ,24 volt system on my 300 sq ft house this summer, and I can't get enough of just watching the monitor as the batteries soak up the juice.I have a 10 watt panel wired directly to a salvaged computer fan that ventilates the battery box, so it's speed fluctuates all the time in synch with the light it gets. Step in front of the little 10 watt and hear the fan start to lag.-it's almost like a magic trick.
    It was $8000 bucks and a lot of reading to put this in place. I opted for more off-the shelf power-handling gear and less wiring to make it easier on myself. My modules are Solarworld (US made) and purchased new for 1 buck per watt. With the abundance of .info and suppliers on the web now I think this is all in reach for anyone interested. Here in Vermont, as I'm sure you've noticed, solar is just exploding.Like you, I'm off-grid so this is just the best way to go, but net-metering and helping to build a resilient, decentralized power supply is something we should all be talking about

  37. Chris Stratton | | #37

    The wonders of gratitude
    Martin, thanks for this story. I especially appreciated the line "when I'm in a retrospective mood, I can be amazed by simple things." More of us (myself included) would do well to spend more of our time being amazed by simple things.

  38. Jonathan Beers | | #38

    California west-facing PV rebates higher

    Thought this was worth adding to the discussion - obviously only applies to grid-tied systems:

    http://www.renewableenergyworld.com/rea/blog/post/2014/09/california-encouraging-west-facing-solar-panels

  39. User avater GBA Editor
    Martin Holladay | | #39

    Response to Jonathan Beers
    Jonathan,
    Thanks for your comments. GBA reported that news on Sept. 17, 2014.

    In his report, Scott Gibson wrote, "The California Energy Commission has issued new guidelines calling for 15% higher rebates for solar arrays that face west instead of south. South-facing panels generate more energy overall, but panels that face west produce more power in the late afternoon when demand for electricity goes up."

  40. Terry Lee | | #40

    CA
    When everyone else is heading South, CA is going west, got to love it! Next up, East Coaster's say east beats west, in between stays out of it :)

  41. Derek Roff | | #41

    Trackers sometimes help
    I don't think the comments have mentioned the advantage of trackers under some regulations. Where I live, the maximum size for a residential grid-tied PV installation is 10kW rated power. There is no limit on energy produced, just on rated maximum power. Conversely, and perhaps perversely, regulations pay us based on energy produced, not on power. Adding two-axis trackers doesn't change the rated power at all, but can raise energy production by 40%. The other possible advantage is that more energy can be produced in a smaller space. Downsides include greater cost and vastly greater maintenance/reliability concerns. Our experience includes lots of repair calls for the trackers. So far, all under warranty.

    As for aesthetics, I love the look of my tracker PV system. I like watching it move against the sky and surrounding trees. I wish it was bigger, and more visible. I may not be a normal person.

  42. Andy Friedland | | #42

    Trackers have merit for other reasons too
    Martin,
    There are reasons why solar trackers are a better choice for certain people, especially if you are doing ground mount and you are connected to the grid:

    -The payback for the embodied energy of pv production is quicker if you track the sun.

    -Following your line of reasoning, if you choose to purchase more pv panels, you are contributing to the manufacture of more pv panels, which causes greater environmental harm. Spend the money on a tracker, and you get the same output as buying more pv panels, but you are contributing to the manufacturing of things that cause less environmental harm (producing steel, copper and plastic causes less harm than producing pv panels, which generate large quantities of toxic waste during production).

    -If you are doing ground mount and are going to build a structure anyway, a tracker gives you greater ability to withstand high winds (by stowing to a horizontal position) and shed snow (by stowing to a vertical position).

    -Even if you don't get paid a premium for producing electricity later in the day during summer, that's when demand is greatest, so your tracker pv array connected to the grid provides a greater good. And as other posts have indicated, some grid-tied systems do receive time-of-generation premiums.

  43. User avater GBA Editor
    Martin Holladay | | #43

    Response to Andy Friedland
    Andy,
    Thanks for sharing your succinct list of reasons why someone might consider using a PV tracker.

  44. C. B. | | #44

    Response to Derek Roff
    Derek, what state/town is your tracker located in?

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