What is the real cost of Solar Panels?

Question

How much per sq inch do they cost? Will i have to worry about them blowing off during hurricane season? If the sun isnt out for a week will my power go out? Will I have to check them every week and check which ones arent working and replace them? Is there anyway for them to be damaged by acid rain or any type of erosion like hail? When do I have to replace them? How do I dispose of old ones (like recycling)? What is smarter and more economical having few big panels or many small ones? I know I have alot of questions but I want a good detailed answer.

Answer 1

Omigoodness, you're just full of curiosity, aren't you? Since these answers are readily available to anyone who knows how to use Yahoo (or the Big G), you may already have educated yourself by the time you read this; so bear with me!

First, let's define terms. When you say "solar panels" I'm going to assume you're referring to photovoltaic modules, also known as PV modules, which produce electricity from sunlight. There are other devices that could easily be described as solar panels, such as solar thermal collectors for water or air heating. In common usage, the term solar panels has come to mean PV modules, though we in the industry still tend to flinch a bit when we hear it!

1. How much per square inch do they cost?

Are you planning to buy tiny ones? The question is odd, since they are not sold by surface area, and the industry typically measures price in dollars per Watt of rated output. But a little arithmetic will yield your answer. There is a very wide range of prices and module sizes on the market because there is a very wide range of applications for PV. Prices at the Alternative Energy Store (where I work) range from $45.71 per rated Watt to as low as $4.39 per rated Watt (W). Why the huge range? Well, that higher price is for a hand-held small electronic device charger (think cell phones and iPods) that produces only 2 Watts of power in sunlight. Technically, that price is unfairly derived from the total cost of the product ($91.42) which includes the casing and adapters for charging various devices. In order to compare apples to apples, we need to stick to the same kinds of PV modules. So among modules only, without any additional parts, prices range up to about $26/Watt. The expensive ones are typically quite small (perhaps a square foot or so), and include such specialized modules as foldable units that use exotic elements in their manufacture. Most were designed for light weight and portability--- and you pay for advanced technology and convenience. I suspect you're more interested in the classic framed, glass-topped, stiff modules that can be seen here and there on commercial or public buildings and house rooftops. For such applications, the price range narrows further, from about $12-15/W (for small, low-Wattage modules, about 2-10W) down to the $4.40 price point. The large modules measure up to five feet or more in length and perhaps three feet in width (though shapes and sizes vary considerably among manufacturers). Most large-Wattage modules intended for significant energy production (homes and businesses) have prices per Watt in the $5.50-4.40 range, give or take a few cents.

So we're finally ready for price per square inch! The low end (large modules) is around $0.36/square inch, the high end (small or specialized modules) can be as high as $1.72/sq. in. Even in this simple analysis, there is room for equivocation--- I'm using the outer frame dimensions in my calculations but in most cases the entire measured surface area is not covered with electricity-producing PV cells or film, so the prices will tend to be higher, especially for the smaller modules. For our purposes, it's fair to say the range of price per square inch, for the modules you're likely interested in, is $0.36 - 0.60.

2. Will I have to worry about them blowing off during hurricane season?

Only if you live where there are hurricanes! Ha ha! Just kidding. We get calls all the time from Floridians (and others in hurricane-prone areas) who are naturally concerned about high wind survivability of proposed solar power installations. The answer lies not in the manufacture of the PV modules themselves, but in the methods and practices used in their installation. Most household modules are attached to rooftops using well-designed racking systems made by a number of different manufacturers. These systems have been designed to be installed according to specific instructions in order to meet wind load requirements. The issue of wind loading is a science in itself and the end result is that a PV array (a group of panels producing power for a home or business) is only as good as the roof it is attached to. Most household roof racks are designed to be lag-bolted to the roof's rafters, through the roof sheeting material (usually plywood or OSB). There are also roof racks, typically used on flat roofs, that do not use penetrations, but rely on ballast--- weight, such as concrete blocks or tiles--- to stay in place on the roof, and will perform well under certain wind load limits. In hurricane country, ballasted mounts probably aren't the best idea. Lag-bolted rack types, if properly installed, will provide security in all but the highest winds--- and then it's a question of which will fail first, the racks or the whole roof? It is possible that the roof itself could come off the house before well-installed PV array racks would come off the roof. The short answer is, of course you should be concerned about PV array mounting in relation to your location, but the racking systems are arguably only as good as your roof.

3. If the sun isn't out for a week, will my power go out?

No sun, no power. Solar PV modules only produce electricity when there is sunlight, and most modules only produce electricity (or any reasonable amount of it) when there is full sunlight. Clouds, tree shadows, bird droppings, chimney shadows--- all these can reduce your modules' output to near zero. In many cases, even shading a small corner of a PV module can essentially shut down your system.

The good news is that your household electrical circuits are not powered directly by the solar panels. Imagine what watching TV would be like if a few fair-weather clouds passed before the sun on a given day! On and off, on and off--- it would be madness. No, typical PV systems are designed either to feed the local utility grid through the wires that come to your home, or they feed batteries that your main circuit panels draw from to feed the household loads. You can also have a system that does both: feeds your batteries (usually for backup purposes), then sends any excess energy produced back to the utility grid. But in most grid-tied systems, your PV modules will be feeding the utility grid when they make power, and you will be using power from the grid whenever you turn on a load in the house. There are specific reasons for this arrangement that we needn't get into here, but the main question is: are you connected to an electric utility grid (the power company) or is your house out in the boonies without utilities? If you'reon the grid, the National Electric Code (NEC) mandates that your system MUST shut down when the grid goes down. And if you don't have battery backup (expensive!), you'll be out of power.

4. Will I have to check them every week and check which ones aren't working and replace them?

Generally, no. Most PV modules sold for house-scale energy production carry 20 year (or longer) warranties, so you know the manufacturers are planning for them to be in use for a very long time. While it is possible that a given module could fail, it is extremely unlikely to occur; and damage from weather is also relatively unlikely, as framed modules use tempered glass rated to survive typical hailstone impacts and to carry reasonable loads of snow. The only maintenance you should do is to check for anything that might shade the modules and thereby affect their performance. I'm serious about the bird droppings! Even a silver dollar-sized splotch could severely reduce your array output.

5. Is there anyway for them to be damaged by acid rain or any type of erosion like hail?

Very unlikely. Does acid rain damage your window glass? Glass is very stable, chemically, which is why it's used in chemistry labs! Most modules are framed in aluminum (sometimes anondized) which also is very stable under ambient weather conditions. I've mentioned hailstones above; only very large hailstones may present a problem by shattering the glass modules. Any shattered modules must be replaced, as water will eventually seep into them through the cracks, damaging or shorting them.

6. When do I have to replace them?

The very first modern PV module, made by Bell Labs in (I think) 1954, is still functional. That ought to give you an idea of longevity of this simple, solid-state technology. Cracking or shattering is the only significant concern facing outdoor use of modules. It is likely that the modules will continue to function (and possibly even within typical warranty specifications of 80% of rated power output) throughout your lifetime.

7. How do I dispose of old ones (like recycling)?

Good question. I don't know. Since even if there were some reason to replace a module (shattered glass, or perhaps you changed module types as you upgraded your system), it will likely still be capable of producing power, you might just resell it or give it to a school for classroom demonstrations. If you're serious about this, contact the module manufacturers and ask them.

8. What is smarter and more economical having few big panels or many small ones?

It depends on your application. When we at the Alternative Energy Store size a system for a customer, we do so on a custom basis. There is no one-size-fits-all approach, though some manufacturers offer package systems. There will always be issues with installation details (selecting rack sizes to avoid rooftop vents, for example) that will necessitate some customization. And the PV modules that are available on the market today for home-scale electricity production do not vary so widely that the issue will be of major import in pricing the system. There are some modules that I would recommend to certain customers that would not be appropriate for others; the determination is based on site conditions and must be addressed on a case-by-case basis.

I hope this has been helpful for you. Please visit us online.

Cheers,

Ben Gorman

Answer 2

The cost of solar is measured in dollars per watt. That means the cost of a cell that can make one watt continuously in full sunlight. A friend of mine is starting a new job to set up a new solar cell factory and he said the present cost is $3 per watt, but that they expect to get that down to $1 per watt in a few years.

They can be damaged by weather, just like any regular roof. My insurance agent asked if I had solar panels, so it is a factor in insurance cost.

I never heard of recycling or disposing of old panels, maybe because they are so new and last so long that not many are ready to be disposed of yet.

Answer 3

They don't sell them by the square inch. It costs about $10 per watt of generating capacity. Unless you are connected to the grid you will need a battery bank to storage power "for rainy days".

As for the effects of weather ... you can probably make a cover out of plywood... but if your house blows away the solar panel goes with it. Before you buy one make sure your insurance covers it.

Answer 4

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Answer 5

What's your Source (Optional)

Answer 6

Depends on where you stay and how they are installed. They usually have a battery backup.