PVs on tower [RE-wrenches]

Thu Jan 8 09:22:09 PST 2004

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Hi Kelly,

I don't think any of us were saying it couldn't be done or that it 
was an inherently bad idea.  I used to live and work in Oly and Yelm, 
WA and shading due to 100' firs was always a hassle for siting PV so 
yes it's a great solution!

We were just being good colleagues and making sure you didn't just 
take a wind tower and throw some PVs up on it without doing the 
engineering.

Obviously you guy are way on top of that.  I think it's great you are 
getting dual function out of the tower and moving the industry 
forward in creative solutions!

Have a great time installing it!  It'll be a pretty sight!

Best,

Jeff C.
Village Power Design

>Hi Jeff,
>
>Kelly and I are working together on the same project. It will be the 
>wind and PV project for SEI's NW workshops in October of this year.
>
>I'm surprised that there's so much concern over this. It seems to me 
>that it's an engineering problem, and tower manufacturers have to 
>deal with this all the time. That's been proven in our contact with 
>these companies. They can engineer for whatever loads we specify, 
>and have no trouble supplying a tower for the wind generator and PV 
>array we are planning. This project is going through the local 
>permitting process (!), so it will be fully engineered for our local 
>winds.
>
>Kelly's recent question was about tilt angle and a compromise we 
>were considering to make mounting easier and keep the array compact. 
>Our original plan was to lay the modules out in a tall, narrow 
>arrangement on the tower, but if they were tilted, we'd have to 
>spread them much higher than we preferred to avoid them shading each 
>other. We've recently decided to go with a wider layout, and to tilt 
>the modules to the optimum angle, and space them to avoid shading. 
>This is still under discussion, but the rough plan is to have the 
>modules between 50 and 100 feet on the tower.
>
>In our part of the country where 100 to 150 foot trees are the norm, 
>siting PVs up high is a great solution. Many people put small arrays 
>in trees, and larger arrays on high poles or multiple-story home 
>roofs. Putting this large of an array on a tower is a new 
>experience, but I feel that it's a strategy that will be copied by 
>others because it makes lots of sense here. The cost of the tower 
>increases with the additional wind loading, but that cost is 
>recouped in the increased solar window. In wind generator 
>installations, the purpose of the tower is to get the collector up 
>into the fuel. It serves the same purpose in this case with the PVs.
>
>Best,
>
>Ian
>
>
>>Hi Kelly,
>>
>>Did you follow the thread that Ian started on this same subject 
>>last year?  A number of us chimed in with some serioius concerns 
>>about mounting PVs on a wind tower.
>>
>>I just wanted to make sure you hadn't missed that discussion.  You 
>>could check the archives (11/15-11/16 - "Tubular Towers & PV 
>>Mounting").
>>
>>Keep us up to date with how that project goes!  Sounds like a fun one!
>>
>>Best,
>>
>>Jeff C.
>>Village Power Design
>>
>>>Kurt & Wrenches,
>>>Thanks. The PV Watts calculator confirms my efficiency assumptions for the
>>>steep angle.
>>>
>>>Has anyone used the Sanyo modules, or have comments about 'em?
>>>
>>>-Kelly
>>>
>>>>
>>>>" I'm designing an interesting off-grid system where the PV array will be
>>>>  mounted on the same free-standing lattice tower (160-ft) used for the
>>>>  wind turbine."
>>>>
>>>>  I would be more than a little worried about wind loads on the tower.
>>>>  Regarding the angle of incidence, check out
>>>>  http://rredc.nrel.gov/solar/codes_algs/PVWATTS/
>>>>
>>>>  Just enter in a city near your site and type in the degrees from
>>>>  horizontal for a fixed array and you get monthly production numbers.
>>>>  Not going to look very good with near vertical array.
>>>>
>>>>  Kurt Nelson
>>
>
>--
>
>Ian Woofenden <ian.woofenden at homepower.com>, Senior Editor
>Home Power magazine; Subscriptions: $22.50 per year, PO Box 520, 
>Ashland, OR 97520 USA
>800-707-6585 (US), 541-512-0220, or download current issue at 
><http://www.homepower.com>
>
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