Hi!
Does anyone have any experience with the new flexible photovoltaic mats mounted directly on standing seam metal roofs? Are they reliable, durable, non-leaky, etc? As far as I know, the only company that makes them is Uni-Solar. Are they worth the considerable investment? I’d like to use this system, especially with the spectre of rolling blackouts becoming a southern California reality.
Thanks!
Barbara
Replies
Barbara,
I helped install just such a system on a Habitat for Humanity house here in Sacramento. Panels and inverter were donated by the manufacturers, who had a pro video crew here filming the company bigwigs during the install. My guess is that the event will be featured at the shareholders meeting...not that I'm ungrateful. But it definitely was a media circus.
Anyway, the system is a grid-tied, net metering set up. Very straightforward to install, though not a DIY project. No batteries for energy storage. And consequently, when the grid goes down, the system shuts off. If it didn't, the panels would be pumping lots of power into the inverter, and there'd be nowhere for it to go.
In a storage system, one with batteries, the batteries take the energy from the panels. When they are charged up and the energy usage is less than what the inverter is putting out, the excess energy is diverted to heating coils and turned into heat (usually waste heat; sophisticated systems can be set up to heat water).
So, with most grid-tied, net metering systems, when the grid goes down, so does your PV (photovoltaic) power.
Realizing the irony in this, some companies are designing package systems that have some storage batteries in a cabinet to be located outside, and a charge controller (the gizmo that moderates the flow of energy to the batteries). So you can run limited loads for a while off the PV power, without having to have a small room full of batteries like you would for completely self sufficient off-grid systems.
About the panels designed to fit 'tween the seams of a standing seam roof--like most PV panels, they come with a manufacturers warrantee of durability and a guarantee of output over time (something like 80-90 percent of new output at 10 or 20 years, depending on the quality of the panel).
As far as leaks (of rain through the roof), there are no penetrations of the roof. The panels are glued and screwed to the roof. The wires run under a ridge cap, and down to the cutoff box (a big, very expensive DC knife switch) in conduit. Properly installed, there's essentially zero chance of water intrusion.
This PV power stuff is really fun to work on; I've taken PV installation classes, worked on a couple of systems, and would love to do some off-grid system installs. Thing is, I live in an urban area, and the off-grid systems are really only practical in areas remote from the grid. I spend enough time in the truck already...
If you want a good source of info on PV, read Home Power magazine, and check out their website. Also there's a fantastic company north of the SF bay area called "Real Goods" (http://www.realgoods.com) and an associated non-profit institute (the Solar Living Institute) that has a good website and holds classes in solar (PV and hot water) and other alternative energy sources (low-head hydro, biodiesel, etc). It's a whole 'nother world, alternative energy is.
I took my solar installer training through the Solar Living Institute. It was real good :-)
BTW, the California Energy Commission (http://www.energy.ca.gov) has a program to subsidize PV systems, and the subsidy is ramping down and is set to expire at the end of June. Wouldn't it be great if , instead of spending obscene amounts of money to promote nuclear power plants (or conduct a major war), the federal govt would seriously subsidize alternative energy, and energy efficiency? The California Energy Commission has been doing both for many years, but on a small scale. As far as energy efficiency and conservation goes, we ought to act like we're at war over energy. When pigs fly, I suppose...
One neat thing, the IBEW (International Brotherhood of Electircal Workers) has an active, formal solar installer training program, and sees a future in PV.
A suggestion: if you want to make a difference energy-wise, your first step should be to become as energy-efficient as possible with your house, car/transportation, and work place. Then cut down consumption by modifying behavior as far as you would like (both energy comsumption and materials consumption, cuz it takes a hell of a lot of energy to extract, produce, manufacture, transport, and sell stuff. most of which we really don't need). Then if you want to make a real statement, go PV solar. But in my opinion, being wasteful of energy and putting a PV system on the roof is a hollow statement. If you're already there with respect to conservation, sorry to lecture you.
Best regards,
Cliff
Edited 4/28/2005 2:01 am ET by CAP
Edited 4/28/2005 2:05 am ET by CAP
Dear Cliff,Wow!Thank you so much for your thoughtful and detailed response.It does seem like not having power during a grid outage would kind of defeat the concept of putting PV on your house. Here in southern California, we've had a few rolling blackouts, and they are a pain in the neck, to put it mildly. It would be nice to be somewhat protected against them, at least for a few hours. So in the line-tied non-battery systems, is the power being generated by the PV just going straight to the utility? Or is it actually running the house? I don't understand why it doesn't run the house during an outage, as long as it's getting solar energy.I'll check the websites you mentioned.Don't worry about lecturing people--it's the truth. slapping a PV array on your house in order to run your air conditioner full blast all summer while driving your Hummer around town all day sends a definite mixed message. Though our re-model/addition project is not unconventional in form, I am making maximum use of natural cross-ventilation, convection, strategic shading, insulation, and a certain amount of being tough to handle summer cooling loads, and trying to re-use as much as possible from the original house to reduce manufacturing cost. And of course we re-cycle and re-use like crazy. Of course, this is southern California. and we can't walk to anything useful. But you can't have everything.Thanks again!Barbara
Barbara,You're welcome.Yes, with a grid-tied net metering system, the PV array feeds DC power to an inverter, which turns it into AC and gets the cycles in sync with the utility grid power. Then, what you don't use in your house is fed into the utility grid. I believe it's still a state law that utilities in California HAVE to buy the excess power generated by such a system. There are actually two meters in a net metering system, one for power you're buying from the utility company, and one for the power you're selling them. Another state law dictates that when the utility company buys your excess power, they have to pay a premium rate. So having a net metering system and a very energy-efficient house can really reduce your electricity bill. If your utility offers time-of-use metering, where they charge different rates depending on the time of day (lower at night when thay have excess power), and you sell them the PV power during the day and use most of your power hungry appliances in the middle of the night, you can really reduce your electricity bill. The payback period for the PV system looks much better.You could design and build a system that'd run your house right off the PV power (after it's converted to AC). There are several reasons why this isn't done. First, it'd be a complex system, 'cuz you'd need an automatic transfer switch so the house-generated power isn't sent onto the utility lines, maybe electrocuting a lineman. Second, you'd need a way to dump the excess energy (it's a weird thought, but you just can't generate electricity and not use it; it has to have somewhere to go. The heating coils in the charge controller of a battery-based storage system serve that purpose). Third, if a cloud passes by and shades the PV array, well, you could have your own little brownout or blackout. Not good for either electronics or motors. There are other issues as well, but you get the idea. Systems with limited storage capacity are available, it's just that they're a lot more complex than a net metering system, and so are more expensive. Some of the limited storage systems require regular maintenance of the batteries, and of course, with any of them, you have to have space for the batteries. One system I've seen has a battery box that looks like a 2' by 2' by 4' garden seat or storage box, and it's placed outside next to the inverter and other electricals. It's located outside because, when being charged, lead-acid batteries produce hydrogen; if you want to put them inside a building, you have to take steps to make sure the hydrogn doesn't build up (as in BOOM!)What part of So Cal are you in? I grew up in Glendale.Glad to hear that you're doing what you can for conservation. And I know exactly what you mean about many parts of L.A. being "pedestrian hostile". I loved that scene in the movie "L.A. Stories" here Steve Martin's character hops in his car to drive 30 feet. People just don't even think of walking anywhere. Cheers,Cliff
Edited 4/28/2005 1:15 pm ET by CAP
Dear Cliff,I'm in El Cajon, east of San Diego. We get plenty of sun all year on our long southwest-facing exposure, especially in the afternoons. It didn't take too many of those rolling blackouts during the time when Enron was jerking California around to make us start thinking about not being so dependent on the power grid. We're planning a major re-model and addition for our house, and it seemed the perfect time to incorporate a PV system that would give us some backup, reduce our bill, and put our money where our mouths are about alternative energy and sustainable building (I guess we must have big mouths!). I also got started thinking about metal roofs after the Cedar fire came within a couple of miles of us year before last. Finding out about the PV mats integrated with metal roofs seems like it's made for us, if we can afford it. Seems to me I just read in the paper about some legislation being introduced in Sacramento that would reduce the costs of such installations--the utilities are expected to fight vigorously, of course. That would be nice, but I think we would have to budget for no rebates or incentives, because they seem to be intermittent.So if you don't have batteries, and there is a power outage during the day when your system is working, you won't have power because your inverter is not sending it directly into your house? I'm still confused on that part. Thanks again for all your help. Your name jumped off the page at me last night when I was reading the latest FHB on line voltage vs. low voltage track lighting. Very timely for us--we'll probbly be using some track lighting in the re-do.Barbara
Barbara,Glad you like the track light piece.I know how you feel about wanting to do something to both reduce fossil-fuel dependence, AND have some backup power for when the grid goes down. With a grid-tied system, when the sun is shining and the grid power is on, your house uses what it needs from the PV array & inverter, and either gets additional power from the grid, or sells the excess power to the grid, depending on what the energy demand of the house is at that instant.But with a typical grid-tied system, when the grid goes down, the PV system shuts itself off. Yes, you'd think that it'd be possible to use the PV energy right from the inverter to run the house. It's not that simple...--what if your house needs more power than the PV system can provide? It'll shut down to protect itself.
--What happens when the sun sets or a cloud passes by? Again, not enough power, and you're in the dark.
--how do you keep your PV-produced power off of the utility wires when the grid is down? This is a big deal to the linemen who may be working on the utility lines, because it's not just during planned blackouts that your PV system will be backfeeding power into the local power lines; it'll happen when there's an unplanned outage and the linemen are up a pole repairing a broken line. Yes, there are safety practices that ought to be employed to prevent linemen from being electrocuted, but what about your neighbors? The house next door to you is going to have some voltage on their supply line because your PV system is backfeeding power into the neighborhood power lines. This low-power condition can damage some of their stuff, as well as drain the energy your PV system is producing!O.K., there's a way to prevent this, and it's called a transfer switch. It's a switch that allows your house to be powered by only one source, with the other disconnected. That means power to your house comes from EITHER an alternative energy source (PV inverter, or a generator, for that matter) OR from the grid. A transfer switch is expensive, and an automatic trancfer switch is really expensive.
--what if the grid is down, and your house is running off of the the PV array, but is pumping out more power than the house needs? Like I mentioned in an earlier post, there must be some way to dump the excess power. This can be done, all it takes is another gizmo in the PV system. And this costs more money.So, why would you want a PV backup system (one with no battery storage) that was really expensive and very limited in what it could do for you? That's why the PV systems that are grid-tied are either set up only to supplement the grid (not provide backup power), or have modest battery storage components, and so CAN provide a few hours to a day of backup power. These battery backup systems do have a transfer switch, and a way to dump excess power. As you can imagine, the PV grid-tied systms with battery backup cost a lot more than a pure grid-tied system.There are other issues for such systems, like having to rearrange your house electrical system so that when the backup system takes over, you can't run the airconditioning (which uses way too much energy for a modest storge system to support). This is called load management, and no, it's not practical to do it by just remembering not to run the AC or the electric range during an off-grid period. It has to be hard-wired into the system. This also costs money.I agree with the sentiment of using PV to reduce reliance on fossil fuels. A grid-tied system will do that. As far as blackouts because of inadequate utility grid capacity or reliability--well, isn't electric utility deregulation great? Rates go up, AND the most reliable power system in the world goes to hell in a handbasket. How about this?--instead of spending the additional money for limited battery storage for the grid-tied PV system, take the money, and use it to lobby your government representatives to require the utilities to provide us with reliable power again. And when the power is off because of rolling blackouts, live with it. I'm assuming that no one in your household is on a respirator or an oxygen generator...seriously. If it's not life and death, just make the best of camping out at home. And use the experience as a motivator to support demands for a more reliable power system.Best regards,Cliff
Dear Cliff, Once again, thank you for your detailed and considered response. I really appreciate the time you've put into this discussion.If I understand you correctly, you would recommend a grid-tied system without battery backup, on the theory that the occasional blackout, rolling or otherwise, will be not be a frequent enough or long enough disruption to make the extra expense and complexity worthwhile. Am I interpreting you correctly here? No, we have no one here whose life depends on an uninterrupted power source, so that's not an issue. I guess it's just the idea of being independent of the grid when it is acting up that is so appealing about batteries. Since I don't know what the actual relative prices are, it's hard to judge whether it would be really worth the extra money.Do you know any people in the San Diego area who have expertise in BIPV? We're hoping to integrate it with a standing seam metal roof.Thanks again for your time and sound advice.Barbara
Barbara,
Of course, it's up to you, but I think you get the benefit of reducing fossil fuel dependence by having a good sized grid-tied system, one without storage (batteries). You're pumping energy into the grid at the times when it's most needed (especially 3-7 P.M. in the summer).
So your understanding of my suggestion is correct. Get a net metering system, and enjoy selling power back to SDG&E! Put up with the outages (which I believe will be less frequent in the future, because the politicians and utility companies realize people won't put up with an unreliable power grid).
I'll check my solar contacts up here, and see if I can get a recommendation for someone in your area.
By the way, have you considered solar water heating? The technology is simple and mature, it also reduces fossil fuel use, and the payback period is excellent. Twenty years ago, I had a condo here in Sacto that had solar hot water. It was really great. That's about all I know about domestic solar hot water, but Home Power is a great resource for all things renewable energy, including solar water heating. They have back issues on CD-ROM, too.
Cheers,
Cliff
Dear Cliff,Thanks again! I've learned a lot. The only thing with domestic solar hot water is that you have to store it in a tank somewhere and then keep it hot till you need it. I don't have first hand experience with it, only that the systems installed in the '70's, like my parents', tended to run into problems because so many companies went out of business as soon as the rebate program ended (hope that doesn't happen with the BIPV!) I don't know what has developed since. My current plan is to keep the existing one we have and use a tankless one for the other end of the house where there is plumbing. This does reduce energy usage because there is no storage, and the supply runs are very short. Then when the existing tank dies, I'll replace it with a tankless also, assuming I like the first one.Besides, my roof will be full of PV panels!Did I ask your opinion on the crystalline vs. triple junction thin layer amorphous flexible mats? Sorry if I repeat myself, but what do you think? From what I have read, the mats sound like the better option.Thanks again! I hope others have learned as much as I have.Barbara
> By the way, have you considered solar water heating?
Yes, much more practical and cost effective than PV. Some neighbors of my parents put in solar pool heating about 30 years ago. It worked so well that the pool got too hot, so they re-plumbed to use some of the panels for domestic hot water. AFAIK, that installation is still working today. The cost per square foot for water heating panels is way far less than for electricity.
-- J.S.
"I agree with the sentiment of using PV to reduce reliance on fossil fuels. A grid-tied system will do that. As far as blackouts because of inadequate utility grid capacity or reliability--well, isn't electric utility deregulation great? Rates go up, AND the most reliable power system in the world goes to hell in a handbasket."I wonder what advantage PV really has in reducing reliance on fossil fuel.Right now they are such an singificant amount of energy that the utilites probably never now it.But if where a significant amount then most one area would be affected at the same time by clouds and all of them by night.The fossil fuel utilities need to have ready standby to replace that. And I down think that the more cost effective coal burners can respond fast enough. Would need to use more rapid responding gas turbine systems which would increase the average cost of power produced.
> there must be some way to dump the excess power.
This is the part I don't understand. I've had some PV panels for about 10 - 15 years now that I use for charging 12 volt batteries. It seems not to matter at all whether I have a battery attached or not. Pull the plug, plug it in, no problem. Leave it unplugged, no problem.
-- J.S.
John,
Ah, a big difference--you're feeding the DC output of the PV panel directly to the battery, right?
But with the household systems we are talking about, the DC power from the panels goes into an inverter to be converted to AC and to be transformed to 120 or 120/240 AC.
That's the difference--it's the inverter that can't take the excess energy put out by the PV panels. Now, if you has some way to switch off the DC output of the panels to the inverter when the load on the inverter was not matched to the PV output, things would be O.K. But it wouldn't be very practical.
The battery bank in a PV system with storage takes the excess DC output and when the batteries are topped off (fully charged), a charge controller dumps the excess power to a big heating coil. Before charge controllers got to be commonly used, a lot of people cooked their batteries (i.e., overcharged them).
Is that clear as mud?
Regards,
Cliff
"That's the difference--it's the inverter that can't take the excess energy put out by the PV panels. Now, if you has some way to switch off the DC output of the panels to the inverter when the load on the inverter was not matched to the PV output, things would be O.K. But it wouldn't be very practical.The battery bank in a PV system with storage takes the excess DC output and when the batteries are topped off (fully charged), a charge controller dumps the excess power to a big heating coil. Before charge controllers got to be commonly used, a lot of people cooked their batteries (i.e., overcharged them)."From an engineering point this just did not ring true.So I did some searching and had a google web site and the system locked and could not find it again. But I found some others. And I don't have time to get too deep into it.But here is what I have found.http://www.volker-quaschning.de/articles/fundamentals3/index_e.htmlFig 3 show the VI characteristics of the PV cells. the are basically constant current upto .4 volts and then drop off. Also they have a fairly narrow peak power point. And limited open circuit voltage.I did not really look for details of the inverters. But the PV cells can only pump out limited amount of power. There is no way force power into the inverter. A "reasonable" (not the equivalent of the 33 cent receptacles)has have feedback regulation anyway. It should keep the output voltage constant reguardless of charge of the battery, much less the change in PV voltage.And even more so if it tied to the power line. It needs to match the power line voltage even as it varies.Now batteries are clearly limited in the amount of power that absorb and some kind of regulator is needed.And shunt regulator is a cheap way of doing it. I guess it is based on the idea that the energy is free so we can just dump what is not neeeded.http://www.polarpowerinc.com/info/operation20/operation25.htm#2.5.2But there are much better designs. Series switching. Unfortunately this cuts off short.Here is a good technical description of the switching controllers.http://www.azsolarcenter.com/technology/batteries/pdfs/ch6.pdf&e=10141Here is one commercial unit.http://www.polarpowerinc.com/products/battery-charger/model9650.htm
> --it's the inverter that can't take the excess energy put out by the PV panels. Now, if you has some way to switch off the DC output of the panels to the inverter when the load on the inverter was not matched to the PV output, things would be O.K. But it wouldn't be very practical.
Hmmm.... I'd think that the inverter could just use pulse width/duty cycle modulation much like a switching power supply. Is it that the thyristors for that much power are too expensive? Compared with the huge cost of the PV's, I'd be surprised if that were it.
> The battery bank in a PV system with storage takes the excess DC output and when the batteries are topped off (fully charged), a charge controller dumps the excess power to a big heating coil. Before charge controllers got to be commonly used, a lot of people cooked their batteries (i.e., overcharged them).
Sounds to me like a proportion error. Too much PV, not enough battery. I know I spent like $200 on the two little panels I have, and that about 10 - 15 years ago at the TRW swap meet. Never cooked any battery with that thing, not even a little motorcycle battery. At the moment, it lives on the dashboard of a 1985 F-350, to keep the battery topped up. I use the truck so little that the last time I filled up was exactly nine months since the time before.
-- J.S.
Quite the response (and well appreciated). You've obviously educated yourself in these areas. Here in the northeast we don't have quite the drive for renewable energy you do out in CA (wish we did). Even with our more limited sunshine I think every house built today should be installed with Photovoltaic roof shingles. Unfortunately the government would rather subsidize the oil and nuclear industry than a clean energy source.I'm presently trying to gain as much insight into these things as possible. I wasn't aware the PV systems "had" to be connected to a grid. There has to be a way to set them up as a storage system with, charge controllers, inverters and some form of deep cell (I know there are other kinds as well) batteries. I'm sure these are more complicated but in the end seem a lot more realistic unless everyone in the country is taking part in generating Energy. Your second post seems to show just how complicated this is. Isn't their someway to make all this work better?I also work with an NGO that works in extremely remote and poor settings. If I can learn enough about this technology I hope to be able to apply it to some of our work in these remote locations (Haiti in particular)I do have a question for you (hope it doesn't upset you) but why does every professional installer automatically assume anyone that doesn't do this as a profession could ever undertake a project in their particular field "though not a DIY project" Not meant as a slam but I think professional installers have to look at an individual rather than automatically assume nobody can do it on their own (although after reading your descriptions above it does seem a daunting task). Again lack of gov't subsidies makes my installing photovoltaics completely cost prohibitive unless I can do it myself. I have a degree in Civil and Biomedical engineering and work as a Computer System Administrator, so why can't I learn enough about this to do it on my own. I do virtually every improvement to my house on my own (only way I can afford most of them). If a home owner is willing to properly educate themselves, why can't they do this type of project (Mind you it might take a few years to learn what I need to know) but I'm a lot more likely to do this on my own than ever have it done by someone else (I just don't have that kind of money). I'm already making conscious efforts to cut down on my energy consumption (bike to work, rain barrels, grey water recycling), never mind not living particularly extravagantly and am constantly looking for other ways. This is just one more way on along list.Tom
Edited 4/28/2005 2:01 pm ET by Ribs
Ribs,Easy there, pilgrim! Based on what you've said, you're an intelligent and detail-oriented person and I'm sure you could learn how to do a PV install on your own. I don't recommend, nay, I actually discourage, PV system installation as a DIY effort. Here are some of the key issues:--knowledge. The systems are virtually all custom-designed at this point, so a DIY would have to get deep into load calculations and other aspects of design. It's essential that the DIYer be willing to spend the time to develop the necessary knowledge. It's available, and it's not rocket science. But many don't want to spend the time to learn a new vocabulary, get smart on the principles, and become familiar with practical aspects (some of which come only from experience).--familiarity with installation techniques. How to actually manipulate the materials is not fully written down in any book I've seen. Also, there's no substitute for being shown something and practicing it while being coached. That's a big part of what an appreticeship is all about.I've seen what awful, dangerous electrical work some DIYers do, either wantonly through willful lack of knowledge or carelessness, or by omission because of incomplete information. Poor installation techniques translate to an inefficient, unreliable, or unsafe system. Will a system that's installed using sloppy techniques work? Probably. Will it fail sooner, creating an unsafe condition when it does? Probably. Do DIYers have the market cornered on poor installation techniques? No. There are incompetent paid installers out there, too.safety--More PV systems are being set up to generate high DC voltage (hundreds of volts). There are good reasons for this, mainly efficiency (in both energy transfer and materials). I'm talking 400v to 600v DC from the array to the inverter.You may not get a second chance if you are hit with 400v DC because of carelessness, sloppy technique, or an inadvertent slip of the hand. Is it possible for the DIY to work safely with electricity? Well, going to the NIOSH website and reading the electrical student safety manual will help. Then again, there is no substitute for hands-on training. And that goes double for working in the house breaker panel, which you're going to have to do to connect the PV system to the house wiring. Even with the panels main breaker off, in many panels, there are exposed energized surfaces in there. Woe unto the DIY who thinks the panel is dead 'cuz he turned off the main breaker. Beyond personal safety, grid-tied PV systems involve safety of utility company personnel and neighbors as well, so the consequences of error are great. Even if you think you know enough, and have great intentions, your systems installation will probably be the first one you do. Are you absolutely sure you're doing it right? That's why I have more faith in a professional, trained installer. He or she is qualified to do the work, meaning they've learned what they need to know, and have performed the work while being monitored/coached. Special, essential tooling. O.K., if you spend a couple of years of your spare time reading up on PV, and basic residential electrical systems, and electrical safety, and you think you really understand it all, you're still gonna need some tools not common to the DIY.For starters, a torque wrench and a torque screwdriver, a DC ammeter (not a digital multimeter, either; you need an amp-clamp that'll measure more than 20 amps DC w/o having to break a wire), conduit benders (probably), all of which are pricey and not usually available for rental.So I'll grant you that it's not impossible for a DIY to successfully install a PV system. Home Power magazine has a story in almost every issue about an advanced, dedicated DIY who successfully installed an alterntive energy system. Many of these DIY, though, have direct help from, or at least consult with, a qualified alternative energy installer/electrician.And lastly, I want to make clear that if you put in a PV system, the electric utility is not required to buy your excess power; they're only required to buy it if you want to sell it to them. And it's a federal law, not a state one.About your point that you can't afford to have the work done--like I said, there are a lot of things you can probably do to make your home more energy efficient, before you install PV solar. And if you want to do the PV install yourself, and pay the price in your time and money (wasted materials) to do it right, that's great. Otherwise, it's just another case where you have to decide what your priorities are, and where you want your money to go.Best of success,Cliff
Cliff,Thanks for your response and not ripping into me. I truly was looking for an explanation. I understand all your points and agree it looks like a pretty daunting task (one probably beyond my capabilities and one I probably will never undertake). Perhaps in time these systems will become more mainstream and the prices will come down to an affordable level.I do plan to continually work on increasing the energy efficiency of my house. Like many others I just wish I could find a cleaner more environmentally friendly way around our dependence on fossil fuel. In a perfect world I'd have the money to put a PV system in but unfortunately that won't happen any time soon (unless I win the lottery or something of course :) I think too many people look at PV systems incorrectly, they simply look at the payback over time yet leave out too many intangibles when they decide if these systems make sense.Thank for the input. Even if I never install one I'm still going to try to learn more about them and would welcome any references you could provideTom
Barbara,
When we looked at PV options we were steered away from the flexible panels 'cause (we were told) they are more expensive/less efficient. I'd check the sites CAP listed, especially the CEC (Cal. Energy Commission) site, which lists all the manufacturers and the CEC output and efficiency ratings (which will drive the rebate levels), to see how the flexible panel products rate. Also talk to some of your local installers.
We opted for standard PV panels instead - they get installed in July - can't wait!
Wayne