Woodstove flue adjacent to solar array?

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Woodstove flue adjacent to solar array?

Postby Bundaburra » Wed Sep 08, 2010 3:56 pm

We are installing a wood stove with a flue through the ceiling and roof ending in a gas cowl above the roof. If we go straight up from the wood stove, the flue will come out almost at the ridge line adjacent to our solar panels, about 500mm away, and higher up the sloping North face of the roof. The alternative is to take the flue out through the rear internal wall on a 45 degree angle bend and through the ceiling and roof, so it comes out on the south side of the roof, which would be maybe three metres away from the PV panels. In either case, the flue must be a minimum of 300mm above the ridge line, though we propose to at least double that height. Either location of the flue will create no overshadowing issues.

Our builder wants to do the easy straight up flue option and says it will make no difference to install the flue on the north side so close to the solar panels, but we are concerned that there will be ash fallout from the flue, which will degrade the efficiency of the panels, so the further away the better. Our prevailing winds are also from the north, so a flue on the south side would blow them away. We are quite protected from south winds by the rising terrain. and a shelter belt of large trees.

We would appreciate some opinions on what to do.
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Re: Woodstove flue adjacent to solar array?

Postby Tracker » Wed Sep 08, 2010 6:11 pm

Bundaburra wrote:but we are concerned that there will be ash fallout from the flue, which will degrade the efficiency of the panels, so the further away the better. Our prevailing winds are also from the north, so a flue on the south side would blow them away.


I would doubt that anyone could give you a definitive answer, without seeing images of the installation situation. In some ways, it could be better for the Flue to be closer to the panels, as there could be more chance that ash-fallout will be lower.
On the "Other-Side" of the ridge, I could imagine a wind from that side will vortex ash onto the panels..
I just think that anywhere near the panels , will create the same effects.

Hopefully, someone might have really practical experience of any detrimental effects ..
..
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Re: Woodstove flue adjacent to solar array?

Postby Gordon-Loomberah » Wed Sep 08, 2010 7:17 pm

If you do get ash on the panel frames, keep in mind that wood ash is quite caustic, just add water and you have Sodium Hydroxide, which does react with Aluminium, so long term, you may have corrosion problems.
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Re: Woodstove flue adjacent to solar array?

Postby Tracker » Wed Sep 08, 2010 7:34 pm

.
Gordon - could you imagine that 1Mtr or 5Mtr would make much difference.
I'm thinking in terms of "Fall-Out" distances, and that there could be more actual "Fall-Out' from a slightly more distant flue..

Any means of obtaining a serious separation, should be considered the most beneficial..
..
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Re: Woodstove flue adjacent to solar array?

Postby bpratt » Wed Sep 08, 2010 7:37 pm

I'd be more concerned about the shading that the flue might cause to your panels, than ash than might happen to fall on the panels.
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Re: Woodstove flue adjacent to solar array?

Postby Gordon-Loomberah » Wed Sep 08, 2010 8:23 pm

bpratt wrote:I'd be more concerned about the shading that the flue might cause to your panels, than ash than might happen to fall on the panels.


Given that we have heard that the flue is to the South of the PV array, that shouldn't be a problem, depending of course on the unknown slope of the roof. If it is nearly flat the chimney may shade the panels in summer in early morning and late afternoon. If it is steep, the panels will be in shade then anyway.

I'd be inclined to move it as far away as possible, even if that involves a couple of kinks in the flue, and perhaps make it at least 1 - 2 metres above the ridge. Without seeing the arrangement, really all I can suggest is that you install it and monitor the panels for ash deposits and work out any panel cleaning schedule that might be needed then.
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Re: Woodstove flue adjacent to solar array?

Postby Smurf1976 » Wed Sep 08, 2010 8:49 pm

Having been on several roofs with woodstoves, I've never noticed any ash at all. No doubt some does come out the flue, but I expect that even a moderate breeze simply blows it away.

I wouldn't want actual smoke contacting the panels however since that could cause formation of creosote which you certainly don't want. Shouldn't be a problem as long as the flue is high enough above the roof.
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Re: Woodstove flue adjacent to solar array?

Postby bpratt » Wed Sep 08, 2010 9:34 pm

Gordon-Loomberah wrote:
bpratt wrote:I'd be more concerned about the shading that the flue might cause to your panels, than ash than might happen to fall on the panels.


Given that we have heard that the flue is to the South of the PV array, that shouldn't be a problem, depending of course on the unknown slope of the roof. If it is nearly flat the chimney may shade the panels in summer in early morning and late afternoon. If it is steep, the panels will be in shade then anyway.


You're right, I read it as the flue being on the north roof, so therefore a shade consideration.... re-reading it says higher up the roof, which as you said is SOUTH of the panels.
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Re: Woodstove flue adjacent to solar array?

Postby Bundaburra » Thu Sep 09, 2010 9:09 am

Thanks for all the advice so far. Keep it coming, so I can have something to argue with the builder about!
As far as the flue shading the panels goes, that is not an issue at all, in either of the proposed locations, so my main concern is with emissions from the flue getting on the panels. The metal roof has a 30 degree pitch, with the ridge aligned slightly to the east of north-south.
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Re: Woodstove flue adjacent to solar array?

Postby Bundaburra » Thu Sep 09, 2010 9:13 am

I just reread that last post and it's not right. The roof ridge is actually east/west, so one side of the roof faces almost due north and the other side almost due south.
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