solar laminates

[Rover]

At that rate Wolv.. and others have said it. If the goal is to save money near term (I can't forecast power expenses in the future)... you will not save $ .

I do it as a hobby.. and pride etc....

Rover

[ghurd]

Oztules, The videos show diodes but I will check for them anyway. Good point.

Ghurd, that looks like a plastic junction box available at major US DYI retailers. I wondered if that would work. J-boxes on flee-bay are about $10 per box. The non-acid silicon should not have the acetic acid (vinegar) smell. Correct me if I'm wrong. 

I did NOT watch any of the videos.

There is no gain to be had with bypass diodes in a non-MPPT 12 or 24V system.  If I install PVs that the factory put bypass diodes in, I cut the diodes out to save returning later to do it after they failed.

Blocking diodes, maybe, but it depends on the situation, system, and controller, so I'd say use blocking diodes.
Not much potential for causing a problem, and they won't hurt anything in a decent system.

J-box.
If this was my project...
I would use a plastic box that is UV-resistant ("outdoor rated"), with a flat back.
I'd get a plan in place depending on how and where the PV conductors were, what terminal strip was available, and attack the back of the box with a Dremmel tool.
After a trail fitting, then I'd start by making the permanent electrical connections, more trial fitting, more planing, etc...
THEN I'd actually cut open the silicone.
It takes a LOT of silicone, so don't expect a tube will make 5 PVs.

Remember, there WILL be air moving between inside & outside of the J-box. Nothing you can do about that.
Keep the PV side of the J-box completely sealed to keep water out, natuarally.
But the moving air will cause condensation inside the box, and it would be best if that water could drain out.
I seal the high side, both side sides (?), and in about 25% of the way from the sides on the bottom side.
It leaves a place for the water to get out, but nowhere for the water to get in.
If the J-box has an O-ring gasket, cut out 1" in the center of the bottom side.
If it does not have an O-ring, silicone 3 and a half sides of the lid (you know what I mean).
Works for me.


"The non-acid silicon should not have the acetic acid (vinegar) smell. Correct me if I'm wrong."
You are correct.
The non-acid stuff is not at all offensive to me.
Smelling the acid stuff makes every sphincter in my being contract violently and uncontrollably.
The non-acid stuff takes a few hours before it can be exposed to water, and it costs more, so start looking at the expensive end of the caulking compound.

I would not use wood for the frame, ever.  Wood warps.
Aluminum angle stock is cheap enough.  Cheaper than wood here (by the foot, in context).

Mono vs Poly?
3 main arguements.
"Mono is more efficient" yet I have bought poly of the same size with 20% greater output ratings than monos of the same or smaller size.
"Mono is less fragile" yet I have seen more than a couple polys with shattered or broken to the point of 'gone' front glass still producing rated power (I do not expect they maintained it for long, but they did it when I was there).
"Poly is less expensive per rated watt" yet I have (many times) purchased larger monos of the same brand and model for less $/W than the mono counter parts.

To me, it all comes down to cost per amp into the battery under the conditions when the customer needs it the most...
And the reliability. So no amorphous PVs.
G-

[rossw]

Remember, there WILL be air moving between inside & outside of the J-box. Nothing you can do about that.

Actually, there is

I've done this in the past and it works. Using better materials will work far longer. If I need to take a picture, I will...

Your junction box (control box, remote radio node, whatever it is you want to keep the air (and thus moisture) out of needs to be a little oversize. Drill one additional hole towards the bottom of the box. Put in a standard (small) electrical gland. The type that seals. Do it up. Nice and tight.

Shove a cigarette filter or other "open pore foam rubber" material up the gland to stop critter access. (ants, mostly). And here's the kicker... a decent kiddies balloon goes over the inside and seals on to the thread protruding into the box. A tiewrap or twist tie or even adhesive tape just to keep it there.

The reason your air moves in and out of the box is changes in pressure. The balloon allows pressure to be equalised, but prevents nasty "outside" air getting into the box.

When I've done this, I usually fill the junction box with something dry. Nitrogen if you can get it. Just about any compressed gas (even refrigeration gas) will generally do, just to "flush out" the air. If you want to really do it properly, you have an extra hole you can seal. Suck out what you can of the air easily and re-introduce dry inert gas. Repeat a couple of times. When you're finished, leave the internal pressure SLIGHTLY below atmospheric pressure at the time, so the balloon is partly inflated. This will allow the pressure to drop without trying to suck the balloon back out the gland. (prolapse?)

Treated this way, I've kept slot antennas, resonant cavities and control equipment completely dry inside for many years without a single failure.

I've seen some of the nice rubber bulbs used on squeeze type horns, and on hydrometers, that I think would likely be an even better long-term solution than a cheap balloon, but I've never tried one.

[philb]

Thanks Ghurd. That's a wealth of information.
 
I'm planning a incoming solar voltage around 120 volts open circuit.
MPPT charge controller voltage 150 max.  Three brands to choose from. I haven't made a choice yet.

I'm leaning towards the new Outback Radian for its grid tie/non-grid and generator capabilities. I cannot see much difference in price between buying the Radian and two true sine inverters tied together for 240 V split phase. If I go with the Radian, I will loose redundancy. Chris discussed this in a thread not long ago.

Batteries...Rolls or Crown are the best choice IMHO. We will see.


Rover...I've been through the hobby phase. It's time to get serious for me. I won't get on my soap box about power companies here. 

RossW - I didn't put propane into the equation. I'm glad you mentioned that. For me, that's $100 per month averaged on an annual basis.

[Wolvenar]

@ Rover,
I plan to do this for a learning and fun project first, and a long term investment as the power costs are doing nothing but go up.  Thinking its best to get the big investments into this now while its semi affordable.

[birdhouse]

ghurd-
i'd have to disagree on "never using wood for a panel frame". 

provided certain species/steps are used, wood can be a perfect panel frame material. 

i used clear straight grained douglas fir.  it came out of a 80 year old building.  i resawed the beam into panel frame sized pieces, primed all six sides, painted all six sides, twice, with oil based aluminum paint.

if these pieces were going to warp, they would have done so in their previous 80 years of service in the building the beam was initially installed. 

old growth clear fir is hands down the straightest wood species i've ever encountered.  it's almost like it's engineered via nature for perfection. 

adam

[philb]

Birdhouse, you are lucky to find old growth wood like that. There's none around here. Most of the wood I can get would be from a major DYI store. Most of that will warp before I can get it home.
I've had a few sticks of 50 year old pine in years past. It was so hard I had to pre-drilled nail holes. 
I do like the way you are handling/treating the wood though.

RossW, that is  serious weatherproofing! Thanks!

If I can fill the J-box nearly full of non-acid silicon, that should work as well?

[rossw]

RossW, that is  serious weatherproofing! Thanks!

If I can fill the J-box nearly full of non-acid silicon, that should work as well?

If there is ANY airspace in there, it will expand and contract and try to suck in outside air (and moisture)
If you completely fill the space, it'll be a real PITA if you ever have to get back into it.

[ghurd]

Remember, there WILL be air moving between inside & outside of the J-box. Nothing you can do about that.

Actually, there is

Uhhh... OK?
I have seen factory made versions, I think, on panels.
J-box knock-outs were just 4 holes, so had to install the 4 fittings to seal the holes, even if the fittings did not hold wire.
The J-box fittings were made for single conductor wire.
The O-ring / gasket was sort of like an O-ring with a membrane covering the O.
Had to cut through the membrane to get a wire in, then tighten the fitting to the wire.
Pretty sure it would do what you said, and it was factory made.

Might have in been some of the earliest SolarWorld PVs I ever saw.
Made in Europe, circa '08?

Anything with a European J-box is a serious PITA in the states.
Our hardware does not fit the box, and our (common AND suitable) wire does not fit the fittings.
G-

[rossw]

The J-box fittings were made for single conductor wire.
The O-ring / gasket was sort of like an O-ring with a membrane covering the O.
Had to cut through the membrane to get a wire in, then tighten the fitting to the wire.
Pretty sure it would do what you said, and it was factory made.

The balloon or other bladder is a critical part of my cure.
A sealed box *WILL* get a pressure differential. Partly from normal diurnal variation, partly because high and low pressure systems will move through the area, and largely because of temperature changes.

The balloon, with the inside vented to the outside, allows the outside air pressure and the inside air pressure to equalize - the balloon itself just inflates or deflates, and thus there is no pressure difference elsewhere in the box, and air doesn't even try to squeeze past the o-rings and other cable entries.

The larger the container, and/or the larger the pressure variations, the better this system works.

[philb]

My laminates arrived. They are LG 235LP-24V, 235 watt poly.

There are 4 tabs that the J box should cover. I checked the voltage on a few panels for reference while they were inside a building, pointed to a bright cloud outside.  From right to left, first tab to second, I get ~+10volts. First tab to the third, I get ~+20 volts. First to the forth, 29.9 volts.


Now for the solar newby questions...


I'm thinking I connect the first(+) and fourth tab(-)  in series to the next panels and forget about connecting the middle two tabs to anything. 

The panels will have no obstructions except snow. From what I understand, I do not need blocking nor by-pass diodes. Is that correct?

I plan to use a Mid Nite Classic 150 volt controller with five panels in series with 3 sets of these in parallel.  Clear as mud?
Maybe someone can come up with a better connection strategy while keeping the wire runs between the panels to a minimum.

Here's the panel specs:
Peak power    235 watts
Peak Vmp      29.6 V
Imp                 7.94 A
Voc                36.8V
Isc                   8.58A

Wolv and TomW...
I plan on a story you asked for after I get it things all lined out. WIFI on my computer is on the blink and can't download pictures until I find out why it's is locking up Ubuntu. I'm definitely a solar newby but not afraid to risk letting the blue smoke out!

[Dave]

 Hi philb,

Exciting times! Glad to hear the modules came in, I've had both good and bad luck with 'sun' but you can't beat the price. 

May have been a typo? 3 of 5..or 5 of 3?

With 15 of those modules, best to go with 5 parallel strings of 3 panels in series* to a fused pv combiner box (each string with it's own fuse/breaker) into the mppt 150 and a 48v nominal system.

Not a big fan of adding in any bypass diodes..should do OK without them if we keep the array out of any shading?

Lots of work ahead of you now  ..more fun than work really....

Any ideas on your mounting strategy?

cheers, dave

* 3 series panels lets us keep within the controllers operating range.

[Wolvenar]

I should be following right behind you, really close (I hope) to getting some panels also.

Looking forward to your posts

[Dave]

Hey again philb,

Was just reading up a bit on that controller and wanted to share this link.

http://www.midnitesolar.com/classic/classicCP.php

Some real clever buggers over there at midnite..looks like that controller comes with an on board system set up menu that spits out everything you need right down to the wire size and breakers!

cool beans,

edit:(sic) changed midnight to midnite

[philb]

Hi Dave, I've been reading about the Classic for a while. It looks like an excellent piece of equipment. Excellent service after the sale too.
I got thing a bit backwards, it should have been 5 parallel strings of 3 panels in series.

Wolv - I'm not going to be in a big hurry. I'll hook up two for now. That will give me the electricity without running the generator for now.
I've already learned the laminates have a learning curve. Some came with silicon strips wrapped around the edges like they were ready to put the frame on. Others looked fresh out of the press with 1/2" edges to trim.