FTR, the electrical output of wind and solar are very different in voltage, frequency, and amplitude and they both require other components to render then “useable” power.
PV panels are set at an angle to optimize of the path of the sun throughout the day. Another reason is cooling. Air flowing below the panels helps cool them as they lose efficiency as they heat up.
OK, lots of good answers, but obviously I didn’t make something clear. In the OP, I imagined the solar panels would be very close to the tower, not extending outward significantly in any direction. So there shouldn’t be much more wind resistance than the tower already produces. If they’re made flush with the tower surface, there wouldn’t be any more.
The questions about whether or not to put solar panels on a roof are the same questions in general about whether or not to put them anywhere else - is it worth the money? Are there enough days when it isn’t raining/snowing/overcast, is it close enough to where the power is going to be used to make sense, what is the prevailing local cost of energy, etc.?
Maybe. If Wal-Mart is getting subsidies or tax breaks, it might make economic sense from their point of view. If the subsidies are being funded by other utility customers or the taxpayer, then it’s cost-shifting and that’s much closer to feel-good than serious.
Regards,
Shodan
Not following you here… unless you’re suggesting the tower be clad in solar panels? Otherwise, the air resistance of flat solar panel(s) projecting from a tower at a height of 10-20 meters at any angle would tear it apart fairly quickly.
Yes. Although the north side can be skipped, since that probably wouldn’t generate enough power to make it worthwhile.
There’s no real data on whether putting panels on the south side would be worthwhile. Crunching the actual numbers is required and I suspect the windmill people may have already looked at it.
The big trend around these parts is high schools putting up solar panels over their parking lots. Double benefit: defrays/eliminates the overhead costs of electricity for the school and shields cars from the heat of the sun, which can be brutal 6 months of the year.
What is the life expectancy of a wind turbine. I know they are tending to get bigger and the older ones retired. It makes little sense to install a 25 plus year panel on something that won’t last a decade if there are alternative places to put them that last longer.
Around here commercial electric rates are about double if you go over a certain usage. Installing solar panels can zero out the bill and avoid that extra charge (called a demand charge).
double post - deleted
Sure, that could happen. If on the days when you need the extra electricity it isn’t raining/snowing/overcast. And it isn’t at night. And if you have enough surface areas to cover with enough solar panels to make up the difference. And if the amortized cost of the panels and wiring over the life of the system, including maintenance, is less than the cost of paying the higher electric rates.
Regards,
Shodan
The way it works is you can bank excess power so one doesn’t have to produce it at the time you are using the power. For one place the payback for paying outright for the solar was 5 years, there was no subsidy, most of that was because of the removal of demand billing which again that charge basically doubled the cost of power.
All you have to do is produce enough to zero out your bill over time, you can even use a bit more then you put back. Excess power produced can be banked up to a year.
“Nearby” in this case doesn’t have to be directly adjacent to, although I’m questioning the logic of why putting solar panels 30 feet up in the air, leaving the agricultural land beneath in a permanent state of shadow is somehow a better use of landspace. “Nearby” could be 5 miles away, on land that isn’t otherwise suitable for agricultural use. Or on rooftops. Or create a covered parking lot. There are probably hundreds of potential solar installation locations that are easier to install/maintain before one would even consider the sides of a windmill.
More important is the life expectancy of the tower. That probably exceeds the life of a turbine, but a new, improved turbine can be installed on top of the same tower (connecting to the same electrical connections, etc.).
In fact, that may even happen before the turbine reaches its life expectancy, if new turbines are enough more efficient – it might be worthwhile to replace a still-functioning turbine with a newer, more efficient one.
This has not been the trend, but to replace the tower with a higher one and a turbine with longer blades. This also requires a stronger tower. Perhaps that will change but it appears that as long as the materials have the strength, the higher and larger, the more power one gets. And making it bigger may be a better power gain then increasing the efficiency of the existing size.
The land is already in shadow because of the tower. I’m not advocating having the panels extend away from the tower. I clearly said that upthread.
There is one group that doesn’t like solar panels on roofs, & actively discourage them or even get them banned in some communities - the fire dept.
Standard practice is a building fire is to vent the roof by cutting a hole in it to let the gas/heat escape. Having solar on the roof makes that both harder (need to get thru the solar panel first & more dangerous (solar panels are electrified); probably not the best place to be putting a metal saw to; especially in an emergency situation where the power may not yet have been cutoff.
They also make it much more expensive when roof repairs &/or replacement need to be made.
That maybe true for offshore applications, but inland there are usually noise emissions regulations. Making the blade longer makes the tips go faster for the same RPM.
The noise emissions are a power function of the tip speed and hence often limit speed or length of blades. It is not uncommon to run turbines at lower output to avoid noise emissions issues.
So the panels will be curved?