# Measuring Solar Capabilites



## blooba (Feb 9, 2010)

What would be the best way to measure my solar capabilities on my property in TN? I would like to stay offgrid even though there is power on the road but not sure how much power I would be able to produce. The problem is I am in a small wooded valley so that cuts down my solar hours. I don't want to clearcut the entire property just for solar but how would I go about figuring out how efficient solar panels would be on my property?

I am south facing (valley runs N to S and the "open" side is S) so that will help me and its not like there are mountains on each side of me. Its less than 100' elevation difference.(Probably less than 50') I am outside of Puryear,TN if that would help. I get a decent amount of wind at treetop level so that maybe another option or a combination of them. 

I was thinking about buying one of those cheap Harbor Freight solar setups and testing the output I receive for like a week and go from there. I just would hate to spend thousands of dollars on solar just to find out I don't receive enough light. 

Any ideas?


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## SolarGary (Sep 8, 2005)

Hi,
Do this solar survey:
Solar Site Survey

It will tell you exactly how many hours your collectors will be in the sun and how much shading they will get every day of the year.

Takes about an hour to do, but well worth it if you are in doubt about shading.

Gary


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## Jim-mi (May 15, 2002)

Or you can find a dealer / installer in your area and ask him/her to use a "Solar Pathfinder" at your location.

Well worth it............


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## bonesbigrig (Nov 25, 2012)

blooba said:


> What would be the best way to measure my solar capabilities on my property in TN? I would like to stay offgrid even though there is power on the road but not sure how much power I would be able to produce. The problem is I am in a small wooded valley so that cuts down my solar hours. I don't want to clearcut the entire property just for solar but how would I go about figuring out how efficient solar panels would be on my property?
> 
> I am south facing (valley runs N to S and the "open" side is S) so that will help me and its not like there are mountains on each side of me. Its less than 100' elevation difference.(Probably less than 50') I am outside of Puryear,TN if that would help. I get a decent amount of wind at treetop level so that maybe another option or a combination of them.
> 
> ...


try going to the usgeo site and see if ya cant get the anual wind average by day and the average sunlight for your area then ya can make a wiser decision of what ya need then get local solar guy give estimate for panels and wind mill and inverter package that will tell ya what ya need then go to well drilling site and call them for used parts cheep they just leave them in the field when they move on


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## TnAndy (Sep 15, 2005)

blooba said:


> I get a decent amount of wind at treetop level so that maybe another option or a combination of them.


What seems like decent wind to many people is merely a breeze. Even IF ( that that's a mighty BIG if ) you have wind, you'd need to be 30-50' ABOVE those trees to take advantage of it.....how tall are the trees ? 60-75' ? See what kind of tower you're looking at ?

Better get a recording wind speed device and measure before you put a dime in wind equipment, or be in for big disappointment. Buddy of mine thought he had a decent site.....high on a cleared off ridge, wind blows fiercely sometimes. We put a recorder up there Feb/Mar of last year.....8mph average over the windiest two months of the year. You need 12. Yeah, sometimes it gusted to 50-60mph !......but the AVERAGE is what you have to look at.








blooba said:


> I was thinking about buying one of those cheap Harbor Freight solar setups and testing the output I receive for like a week and go from there. I just would hate to spend thousands of dollars on solar just to find out I don't receive enough light.


How would a small panel set up show you much ? How would you record it, unless you sit there 9am to 4pm or so, and write it down every few minutes.
And even then, does that represent an average period ?

No, if you're in doubt about your site, use a Pathfinder.....most accurate solar measuring tool out there.


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## SolarGary (Sep 8, 2005)

TnAndy said:


> No, if you're in doubt about your site, use a Pathfinder.....most accurate solar measuring tool out there.



Or, if you want to save yourself $300, use the Solar Survey method above, which is just as accurate as a pathfinder. Aside from the dollar saving, the main advantage of the hand method is that you learn quite a bit about the path of the sun through the seasons -- some schools have taken it up as a school project just because of this.

There are also now some smart phone apps for phones that have the compass and angle finder --some listed here: Solar analysis tools
Lawrence like the $16 Android one, and he makes his living doing this kind of work.

But, the main thing is to be sure to do some kind of real solar shading analysis before you commit to a system.

Gary


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## WisJim (Jan 14, 2004)

I have been doing site assessments for both solar electric and wind electric systems for years, and I find that people regularly overestimate the wind resource at their location and also underestimate the amount of shade on potential solar sites. A small amount of shade can have a surprisingly large affect on the energy output of a solar electric array and the actual percentage of shading can be difficult to estimate without using a device such as a Solar Pathfinder or similar unit. As for wind, if your trees have branches growing to one side due to strong winds, and it is too windy to put out tomato plants without some kind of protection from the wind, it probably isn't windy enough to consider spending the money on a wind turbine and the necessary TALL tower.


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