# Solar panels on wind turbine towers **URL:** \ **Category:** Factual Questions\ **Created:** [March 25, 2019, 6:36pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522 "2019-03-25T18:36:50Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![Sparky812](https://avatars.discourse-cdn.com/v4/letter/s/eb9ed0/32.png) [@Sparky812](https://boards.straightdope.com/u/Sparky812)\ **Post date:** [March 26, 2019, 2:17pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/21 "2019-03-26T14:17:12Z")
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. ---
**Author:** ![lingyi](https://avatars.discourse-cdn.com/v4/letter/l/d2c977/32.png) [@lingyi](https://boards.straightdope.com/u/lingyi)\ **Post date:** [March 26, 2019, 4:47pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/22 "2019-03-26T16:47:35Z")
> [@Melbourne](#): > > There are several reasons for angling solar panels, but there are no absolutes, only costs. Solar panels used to be dynamically mounted so that they could fallow the sun. That’s not done any more because it’s cheaper to buy more panels than it is to provide dynamic mounting. Roof tiles are angled at the angle of the roof. An important reason for angling is to allow self-cleaning: a benefit of putting panels in separated rows is to allow walking access. > > You can just put panels flat: if you cover the surface, you catch all the sun, just as you would with perfectly angled panels. Now that panels are so cheap, “solar incidence” is less significant than it once was. 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. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [March 26, 2019, 4:57pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/23 "2019-03-26T16:57:11Z")
> [@Sparky812](#): > > The most obvious reason is wind resistance. 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. ---
**Author:** ![Shodan](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shodan](https://boards.straightdope.com/u/Shodan)\ **Post date:** [March 26, 2019, 5:03pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/24 "2019-03-26T17:03:59Z")
> [@dtilque](#): > > OK, that’s retail stores, but what about all the suburban lowrises out there? They have vast amounts of horizontal rooftop real estate. 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.? > [@ftg](#): > > This is one key thing to remember about solar power: If Walmart has crunched the numbers and decided they will make money on this, then it isn’t some sort of environmental feel-good thing. Solar Power: It’s Serious Business! 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 ---
**Author:** ![Sparky812](https://avatars.discourse-cdn.com/v4/letter/s/eb9ed0/32.png) [@Sparky812](https://boards.straightdope.com/u/Sparky812)\ **Post date:** [March 26, 2019, 6:02pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/25 "2019-03-26T18:02:43Z")
> [@dtilque](#): > > 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. 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. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [March 26, 2019, 6:11pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/26 "2019-03-26T18:11:26Z")
> [@Sparky812](#): > > Not following you here… unless you’re suggesting the tower be clad in solar panels? Yes. Although the north side can be skipped, since that probably wouldn’t generate enough power to make it worthwhile. ---
**Author:** ![Telemark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/telemark/32/372_2.png) [@Telemark](https://boards.straightdope.com/u/Telemark)\ **Post date:** [March 26, 2019, 6:22pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/27 "2019-03-26T18:22:50Z")
> [@dtilque](#): > > 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. ---
**Author:** ![silenus](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/silenus/32/166_2.png) [@silenus](https://boards.straightdope.com/u/silenus)\ **Post date:** [March 26, 2019, 6:26pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/28 "2019-03-26T18:26:06Z")
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. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [March 26, 2019, 7:13pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/29 "2019-03-26T19:13:52Z")
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. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [March 26, 2019, 7:16pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/30 "2019-03-26T19:16:17Z")
> [@Shodan](#): > > … 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 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). ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [March 26, 2019, 7:33pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/31 "2019-03-26T19:33:01Z")
double post - deleted ---
**Author:** ![Shodan](https://avatars.discourse-cdn.com/v4/letter/s/9f8e36/32.png) [@Shodan](https://boards.straightdope.com/u/Shodan)\ **Post date:** [March 26, 2019, 8:01pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/32 "2019-03-26T20:01:05Z")
> [@kanicbird](#): > > 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). 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 ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [March 26, 2019, 8:09pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/33 "2019-03-26T20:09:44Z")
> [@Shodan](#): > > 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. ---
**Author:** ![YamatoTwinkie](https://avatars.discourse-cdn.com/v4/letter/y/cc9497/32.png) [@YamatoTwinkie](https://boards.straightdope.com/u/YamatoTwinkie)\ **Post date:** [March 26, 2019, 8:31pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/34 "2019-03-26T20:31:41Z")
> [@dtilque](#): > > Not really. There’s open space nearby, but I’ve already ruled it out. Most land near wind turbines is agricultural. Putting a solar panel farm there means you can’t farm it anymore. “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. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [March 26, 2019, 8:40pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/35 "2019-03-26T20:40:48Z")
> [@kanicbird](#): > > 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. 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. ---
**Author:** ![kanicbird](https://avatars.discourse-cdn.com/v4/letter/k/5f8ce5/32.png) [@kanicbird](https://boards.straightdope.com/u/kanicbird)\ **Post date:** [March 26, 2019, 9:35pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/36 "2019-03-26T21:35:17Z")
> [@Tim\_T-Bonham.net](#): > > 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. ---
**Author:** ![dtilque](https://avatars.discourse-cdn.com/v4/letter/d/d6d6ee/32.png) [@dtilque](https://boards.straightdope.com/u/dtilque)\ **Post date:** [March 26, 2019, 10:54pm UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/37 "2019-03-26T22:54:18Z")
> [@YamatoTwinkie](#): > > “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. 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. ---
**Author:** ![Spiderman](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spiderman/32/230_2.png) [@Spiderman](https://boards.straightdope.com/u/Spiderman)\ **Post date:** [March 27, 2019, 1:54am UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/38 "2019-03-27T01:54:51Z")
> [@Tim\_T-Bonham.net](#): > > There are acres of empty roof space available on buildings all over the country. > They are horizontal, so better exposed to sunlight. They already have access built in. They are often unobstructed by trees, so exposed to sunlight. They are located near people, where the electricity is needed. The solar panels would absorb sunlight on the roof, reducing the need for air conditioning in the summer. The roof space is largely unused, so won’t reduce agricultural or recreational space. > > One drawback would be the increased weight, which some buildings are not strong enough to hold. But buildings can be strengthened, and solar panels are getting lighter all the time. 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. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [March 27, 2019, 3:30am UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/39 "2019-03-27T03:30:01Z")
> [@kanicbird](#): > > This has not been the trend, but to replace the tower with a higher one and a turbine with longer blades. 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. ---
**Author:** ![Ruken](https://avatars.discourse-cdn.com/v4/letter/r/f475e1/32.png) [@Ruken](https://boards.straightdope.com/u/Ruken)\ **Post date:** [March 27, 2019, 3:36am UTC](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522/40 "2019-03-27T03:36:28Z")
> [@dtilque](#): > > 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. So the panels will be curved? [Previous page](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522.md?page=1) [Next page](https://boards.straightdope.com/t/solar-panels-on-wind-turbine-towers/831522.md?page=3)