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General Discussion / Re: Unexpected panel problem.
« Last post by carlb23 on February 15, 2019, 12:55:52 PM »
my 11.5kw array is ground mounted on a tiltable frame.  Its 10' tall and 103' wide sitting on 7 schedule 40 posts each 9' in the ground with 1.5 yards of concrete in each 30" diameter hole.  they have withstood 80 mph winds and the wind gets under them pretty good since they are 5' off the ground.  This array has been on line for 9 years with no movement or problems.
the tiltable mounting was designed by TT solar in the US.
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Lister Based Generators / ST2 Start-O-Matic
« Last post by mikenash on February 15, 2019, 06:43:08 AM »
Still in use in the remote parts of NZ, just working quietly away & earning its living

I didn't realise there were SOM units into the later models of engines - although it makes sense of course
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General Discussion / Re: Unexpected panel problem.
« Last post by glort on February 14, 2019, 09:16:58 PM »


When I put the panels up very early in my solar learning curve I was contemplating putting them on tilts.
 I was concerned about the wind even though it would have largely been from the side not behind which was the same angle  as these panels were positioned flat.

Seems my concerns about the wind were not unfounded.
We have had some bad winds here in the last 12 Months. I'm very glad I went with flat panels  and didn't worry about tilting them.
The small price I pay in lost winter generation is more than worth the removed worry specially now I have seen this.
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General Discussion / Re: Unexpected panel problem.
« Last post by dieselspanner on February 14, 2019, 08:27:45 PM »
Perhaps not as weird as it might seem, once the wind got under the panel there would have been a massive force upward from just a little pressure.

It looks like later in the year I'm off to the UK to commission a new hover barge, with a 150 tonne payload, The whole thing runs on less than 1 psi, or 0.07 bar, pretty standard for most hovercraft.  When one considers that it's planned to be 52.5 m long by 25 m wide that's a lot of square inches - 2,027,800 or so!

I'd guess, as you said, the position on the roof and the surrounding panels etc. had a lot to do with it, add in a low pressure area caused by the wind direction and the shape of the roof it's self you've got some mighty forces to contend with....

Cheers
Stef
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General Discussion / Unexpected panel problem.
« Last post by glort on February 14, 2019, 01:21:18 PM »

Was looking over my shed inverter today and thought the generation was down. it was overcast but the smaller array  less optimally positioned on the house was doing better than the much larger and better orientated arrays on the shed.

Tracked it down to one array was not producing any power.
Tested for volts, amps output to the inverter, changed the breakers and swapped trackers. All to no avail. Finally thought it must be something  on teh roof, maybe a bad connection but couldn't see how.
Got the ladder, got up there and spotted it straight off.  One panel on the top pitch of the American barn type shed had done a front flip and face planeted itself forward ontop on another panel on the lower array.

This panel is on the end where the wind normaly blows.  I had it lift before so I screwd the thing down well.  I saw the solar bracket I secured it at the top, the clamp on the side looked like it had slipped off and the L bracket on the end was now a U  bracket where the panel had done a front 180.
The panel was shattered which was annoying but I was more amazed with teh fact the wind had got under a 20 Kd panel sitting flat on a roof ( I don't use solar rails)  and torn the tek screw right out of the metal Purlin.  I though maybe I missed the purlin and only got the roof iron itself but when I got down to get what I needed for the replacement, I could indeed see it had pulled through the roof truss itself.

Amazing.

I knew the end panels got more wind and I set the thing back from the edge knowing that was where the wind came from and I secured it down in 3 places. I would have bet a lot of money that panels would never have moved.
And I'd have lost. Badly.

 I realised as well I missed some panels along that run and they are just laying there completely unsecured, or at least they were till today, but none of them had moves probably because of being flat, in a line and maybe the prevailing wind hits the end of the shed and rotates pressing them down.
Perhaps the end is worse than normal because there is a big water tank underneath and although there is a lot of hedging 25M away on the boundary fence, maybe the air  hits the tank and  creates a more powerful updraft?

In any case, I was pretty amazed to see that there was enough force to tear the thing out of the metal.

I decided to eliminate the problem and removed the old smashed panel from the end and put the replacement in the last spot I had which is tilted between the 2 roof sections.  I think I'll get back up and re arrange a few panels and there is one I noticed I'll also have to replace.

There is a junction on the panel that is quite clearly burnt and creating a hot spot.  From what I read fire potential. Longshot  I think but it will be screwing with the output of the rest of the array so I'll change it out as well.
Getting more broken panels that what I'd like but they are ok for running shed and ceiling fans and other low volt solar experiments.

I'm doing another array on the house and I think I'll take another look at the solar clamps and go back to my own DIY soloution that did hold and use the little L brackets from the hardware and screw them direct into the panels and remove and replace the roof screw with the bracket underneath. I think I had that on the flipped panel it would not have. At some time I think the clamp shifted and put the force on the top bracket which was 2 much. If 2 brackets were sharing the load and couldn't move, I don't thik they could have both pulled out.

Anyway, problem fixed.  Just one I thought I had addressed with over kill but there you go.
I know the winds are strong here and get pretty scary but the force to left a 20 KG panel and pull out a tek screw, that I didn't give credit for.



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Hi Bob

You are indeed young, and your idea is crystal clear of an entrepreneur.
The picture is already made. Go ahead we are with you.
Cheers
VP
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Didn't someone here buy one of those not so long ago?
Same sell going by the pic.
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Other Slow Speed Diesels / Re: Southern Cross ETB diesel engine
« Last post by BruceM on February 13, 2019, 04:08:47 PM »
I'm "centrally located" aka middle of nowhere, at 5600 ft and the night sky is very bright here too; the plane of the Milky Way is obvious. A big reminder of how very small we are, even within our own galaxy.
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 I agree, great price
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Other Slow Speed Diesels / Re: Southern Cross ETB diesel engine
« Last post by 38ac on February 13, 2019, 02:55:29 PM »
 You guys have all the best old engines over there :(
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