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tracker verses roof mount

PostPosted: Fri Apr 18, 2014 9:51 pm
by treechange
with the new house I only have a north facing roof space to install pabels on. 18m x 6.3m on this side of the roof, so we could get a few panels on it. the roof pitch is 35 degrees.

Now I was wondering if I would be better putting in a couple of trackers in, a total of about 3.2

Now I know I could put a lot more than 3.2k on the roof, but would I get the same from 3.2 of tracked panels as maybe 5 or 6 of panels fixed on the roof.

Tell me what you think, or what you would recommend.

Regards Nig

Re: tracker verses roof mount

PostPosted: Sat Apr 19, 2014 12:09 am
by davidg
treechange wrote:Now I know I could put a lot more than 3.2k on the roof, but would I get the same from 3.2 of tracked panels as maybe 5 or 6 of panels fixed on the roof.


3.2k ............. ?

It's not clear what your basing anything on...............price, production or ??
More detail would be somewhat helpful.

Tracking systems are not cheap, often a few extra panels are a lower cost option than a bunch of moving parts that will eventually breakdown.

Re: tracker verses roof mount

PostPosted: Sat Apr 19, 2014 7:24 am
by Whitespeed
I am assuming your 3.2k and 5-6k are kw and not cost of panels in thousands.

A tracker will always loose in value and practicality. There was a time where a case might have been made for them for grid feed. But this is where there was a 66c FIT and you where not allowed to add any more panels or you loose your FIT. Or of course back in the 70's-80's when 80w was huge and worth a fortune :)

A tracker adds complexity to he install, it gives you more moving parts to breakdown, can be a real worry in unusually high winds and depending on where you live, can take up valuable ground space for no benefit and depending on surroundings, can be harder to get clear sky for than the much higher roof mount.

If you live in the suburbs with only a quarter acre you won't have a big back yard. A good bit of homework would be to find out the dimensions of 3.2kw of panels and set this out on your lawn where you plan them to go. A lot of newcomers to solar will look at numbers without realising just how big an array looks on the ground in their backyard.

As far as I understand a tracker will only increase production by around 30% on average (people will have varying opinions on this) this means less than 2 kw extra on the roof of reliable, out of the way panels are all that is required to break even with the tracker.

You won't get a tracker built to reliably swing 3.2kw of panels in unusually strong winds installed and wired for anywhere near as little as an extra 2kw of panels on the roof.

Re: tracker verses roof mount

PostPosted: Sat Apr 19, 2014 7:30 am
by Gordon-Loomberah
Unless you can build the trackers yourself, Id suggest it is not worth your while, since the price of panels has come down so much. A much better plan would be to use an arrangement of fixed panels that gives you even output throughout the day, or a variation on that to match your energy use. Have a read of this Virtual Tracker thread: solar-wind-gear/topic5064.html

Re: tracker verses roof mount

PostPosted: Sat Apr 19, 2014 8:51 am
by treechange
sorry David I meant kw,.

I was meaning 2 trackers, with a total of 3.2kw, sorry I didn't explain that very well. Now I am not meaning that 3.2kw is the total I would have , not sure at this stage what my requirements will be, but I like the idea of being able to change the angle of the the panels for each season. this would make these panels very efficient........yes?
I am not looking at cost so much but more at efficiency.

I have no roof space facing east or west, unless I move the garage further back to not be shaded by the house.

But I have plenty of land to put some ground mount panels. maybe ground mount would be better, with the ability to adjust the angle for summer/winter sun,.............or am I just dreaming.

Maybe I should just fill the north facing roof with panels??????? :?:

Nig

Re: tracker verses roof mount

PostPosted: Sat Apr 19, 2014 8:56 am
by Gordon-Loomberah
You don't need E and W facing roof- you can use tilt mounts, but if you have the space, I'd go for a ground mount Virtual Tracker, which makes them much easier to access for cleaning etc.

Re: tracker verses roof mount

PostPosted: Sat Apr 19, 2014 9:07 am
by treechange
Thanks Gordon, I am not sure I know what you mean. is it something like the end panels of the array are tilted to face N/W

Nig

Re: tracker verses roof mount

PostPosted: Sat Apr 19, 2014 9:21 am
by Gordon-Loomberah
None of the panels need to face north in the Virtual Tracker. WNW and ENE, about 30 deg above the horizon is close to ideal for year round even output throughout the day. Easy to do with a ground mount. Check out the VT thread to see the output curves for E and W facing, vs N facing.

Re: tracker verses roof mount

PostPosted: Sat Apr 19, 2014 9:54 am
by Bthree
Treechange you have not indicated if you are on grid or off grid but regardless that is a large north face and would accommodate 50-60 panels giving you a possible 10Kw of generation.

Why bother with trackers unless you want a technical challenge

Re: tracker verses roof mount

PostPosted: Sat Apr 19, 2014 10:50 am
by treechange
Hi Bthree, we are not anything yet, but probably planning some sort of hybrid system, or maybe off grid. I am not sure yet, the main issue will be a ducted air con 22kw system.
Still in the planning stages of solar, but we have to install a min of 4.5kw to comply with our certification.

Nig