My senior year of college, I did a group project for our senior design class that involved a 100 GW solar facility. We were to figure out the size, start up capital and running cost, location and general feasibility to build a giant solar facility about 50 years in the future. It was really difficult for us to extrapolate what solar cells would cost 50 years down the road. Instead, extrapolated modestly the efficiency and figured out how much the solar cells would have to cost in order for our imaginary investor to break even in one year.
What we didn’t account for very well was how much we would spend maintaining this admittedly massive facility. Since it is hard to really say where we would be in 50 years, how durable is a typical solar panel today? How much weight can you set on it before it breaks? If it breaks, can it be repaired or do all breaks on the panel require it to be completely replaced?
(I graduated in 2011. A recent discussion on Facebook with other smart people got me curious again.)
You can read up on actual installations people have built with panels installed in the around 1980. The panels themselves last for over 30 years with little degradation in output over that time-span. (sure, they accumulate dirt on the outer surface, but this can be scrubbed off)
Granted, 1980 era panels would be thicker and heavier.
Contemporary manufacturers usually guarantee the panels will produce a certain % of rated output after 20 years.
But efficiency degradation is different from physical damage, isn’t it?
The OP asked: “How much weight can you set on it before it breaks? If it breaks, can it be repaired or do all breaks on the panel require it to be completely replaced?”
Panel will last, with gradual degradation, until the frame rusts out or decays.
A panel that is cracked must be replaced: when it cracks, you probably tore one of the conductors. If you tore a small conductor, the effect is similar to shading, and degrades the efficiency of the whole string. If you tore a large conductor, the whole string stopped working. And if you didn’t tear a conductor, you breached the enviromental seal, and the conductors will corrode out.
Not that I ever hear of anyone cracking a panel around here: they aren’t even at a convinent angle for putting stuff down on, and at higher lattitude they mount at even steaper angles.
Let’s simplify the problem. There’s 3 main things that could happen to kill panels :
a. UV exposure, or moisture corrosion damages the photo-voltaic elements themselves. The panel doesn’t produce as much voltage or current as rated, usually this is a slow decline.
b. Windblown dust and other particulates scours away the glass layer at the surface of the panel. Eventually, too much damage or cracks will kill the panel.
c. A natural disaster dumps something the panel can’t handle. This might be a mountain of snow, windblown debris, etc.
Obviously, for the panels to be worth it, they need to pay for themselves compared to other methods of power generation before the above kill them.
I, personally, perceive the problem as now being one of storage. The panels have plummeted in price, to the point that they cost on the order of $0.50 a watt in bulk quantities. However, batteries able to store large quantities of power have barely budged in price and reliability.
I have never seen a price near this cheap, though you did say “in bulk.” Out of curiosity, I assume this is just the price of the panel - by the time you’ve added in installation (for something like an industrial scale solar array), you’re probably looking at quite a bit more?
The website “sunelec.com” is sort of the newegg of solar panels. Note that this is the price for just the panels : to be fair, you have to include the cost of the inverters and the wiring. Inverters are priced something like $2800/4000 watt or similar, so at this point the inverters are costing more than the panels.
Professional installers of course charge lots more, but I’ve had a keen interest in the DIY approach. It can’t be that complicated to install them, just a bit of sweat equity.
There’s also the matter that a huge power plant like a 100 GW facility probably wouldn’t use photovoltaic panels. At that kind of scale, it’s much more cost-effective to install mirrors to heat up a focus point and use a conventional heat engine to harness the energy. This can also let you smooth out production somewhat, by putting some material with high specific heat in the hot spot (molten salt is often proposed for this purpose).
Solar panels do degrade over time just from normal use, but fairly slowly. I’ve seen degradation for consumer solar panels generally assumed to be in the 0.5%-1% per year range.
Other than that, though, there’s not a lot of maintenance. Cleaning the glass once in a while probably isn’t a bad idea (though they’re usually at an angle such that you won’t have much large stuff accumulating). But the wiring, supports, etc. will generally last until some accident breaks it or everything is replaced.
We are now seeing a problem in the UK, where power companies have to keep expensive plant idle in reserve for when the sun don’t shine and the wind don’t blow.
The solar panel itself is barely able to hold itself up and is fragile…
But should be able to be repaired. In fact they want to sell flexible panel that is basically glued to your surface… but for home use you want the glass layer to protect it from tree branches and hail stones.
That’s conventional wisdom, and it fails to take into account the incredibly large price-drops on the photovoltaics. They are selling for about 1/5 what they sold for a few years ago.
Right, which is I brought up the industrial scale part. No one is installing those out of keen interest. Do you know what the “all-in” cost per watt for industrial-scale solar is now?
Thanks for your help, guys. If I am understanding correctly, the durability of the solar panel would be a function of the glass used to protect it. This leads me to another set of questions. Don’t they use a special glass to make sure the optimal wavelengths of light can travel through the glass to the cell? Could they use an ultra durable glass like Gorilla Glass for the best protection?