Hi wrenches, Have any of you all installed the smart mount system for panel racking? Smart mount is a penetrationless racking system that is sold by Sunpower. We are thinking of using it, though we wonder how it has proven itself in the real world. Thanks for your expertise and advice everyone......
Jeff Blick PV installer Sunlight Solar Inc. 4 NW Franklin Bend, OR 97701 direct: 541-306-4196 fax: 541-322-1911 [EMAIL PROTECTED] www.sunlightsolar.com -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] Sent: Friday, October 31, 2008 11:39 AM To: [email protected] Subject: RE-wrenches Digest, Vol 1, Issue 258 Send RE-wrenches mailing list submissions to [email protected] To subscribe or unsubscribe via the World Wide Web, visit http://lists.re-wrenches.org/listinfo.cgi/re-wrenches-re-wrenches.org or, via email, send a message with subject or body 'help' to [EMAIL PROTECTED] You can reach the person managing the list at [EMAIL PROTECTED] When replying, please edit your Subject line so it is more specific than "Re: Contents of RE-wrenches digest..." When responding to posts within the Digest, be sure to restore the Subject: line to the original, and please edit out any extraneous lines from the quoted message. Today's Topics: 1. Request for signage, disconnect, other safety photos (Dan Fink) 2. Re: Trouble Shooting Bad Diode (Bill Brooks) 3. Re: mix-n-match Unisolar (Bill Brooks) ---------------------------------------------------------------------- Message: 1 Date: Fri, 31 Oct 2008 12:22:20 -0600 From: Dan Fink <[EMAIL PROTECTED]> Subject: [RE-wrenches] Request for signage, disconnect, other safety photos To: RE-wrenches <[email protected]> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Hi all. In addition to being a solar and wind system consultant and author, I'm an officer on a volunteer fire department in a remote area of the Northern Colorado mountains. About 5 percent of the residences in our response area are off-grid, though the gridless area comprises over 75% of the district. We are a classic "urban interface" department, both wildland and structural. I'm working on a short powerpoint presentation about renewable energy systems to give at meetings of other local urban-interface fire departments, and likely make available free on the internet. I'm the only responder on our department who lives off-grid, and most firefighters don't realize the special issues with off-grid systems. They expect that when you swing your axe and chop the mains off from the powerline (or, preferably, throw the switch, but that's not always possible), all circuits in the home, outbuildings and property are dead. This is not the case with islanding systems, nor with solar arrays and wind turbines using non-islanding grid-tie. And now that we commonly wire PV and wind at voltages over 100v, it could be hazardous to the firefighter that was not informed. Other aspects of the presentation include wind turbine tower guy wires and their anchors that are vulnerable to weakening from vegetation burning under them, the hazards of battery banks, various ways well pumps might be connected (nice to have water at the scene), and more. Please contact me off list if you have any photos you would be willing to share, with credit and copyright notice to you. Images of signage, interesting system disconnects (not everyone has a factory-built power panel) and their labeling, anything that might relate to firefighter safety, would be much appreciated. DAN FINK Technical Director http://www.otherpower.com/ Rist Canyon Volunteer Fire Department http://rcvfd.org/ KC0VRD WQGS890 ------------------------------ Message: 2 Date: Fri, 31 Oct 2008 11:33:51 -0700 From: "Bill Brooks" <[EMAIL PROTECTED]> Subject: Re: [RE-wrenches] Trouble Shooting Bad Diode To: "'RE-wrenches'" <[email protected]> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset="us-ascii" Kirpal, When you parallel, your voltages have to be the same, so you are correct in that assumption. Your assumption about the diodes is not correct. Diodes don't work like that. You could have a shorted module (all three diodes shorted) which would lower the Voc by one module. It looks like you have nearly two modules worth of problems. It could be a total of 5 bad diodes, but that would be weird. It could be you have a ground fault, and haven't tripped the GFP yet because of lower sunlight levels-(it has to be very low sun to stay under 1 amp). You also could have a wiring mistake, either because the factory reversed wired a module (rare, but it happens)-that would be 2 modules low; or, you could have skipped two modules somehow. It does seem like a quarter of the bad string is out. Your assumption about bad diodes could be correct, but it only affects the groups of cells its connected to. Each diode protects 24 cells-it looks like you have 5 diodes worth of loss. It could be in 2 modules, or up to 5 modules. The shading test is the best way to find bad diodes. Disconnect the bad string from the good one and take a piece of cardboard the dimension of the module. With your meter testing Voc on the back string, completely cover each module, one at a time. When the Voc is not affected by complete shading of a module, that module is completely bad. If the shaded module only loses a portion of one module's Voc, then you have one or two, of the three diodes, bad. This is a great opportunity to learn how to troubleshoot a PV array. Take the time, and the effort, to run through it carefully, learn the problems, and report back with your findings. It's a beautiful thing to learn something new. Bill. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Kirpal Khalsa Sent: Friday, October 31, 2008 10:43 AM To: RE-wrenches Subject: [RE-wrenches] Trouble Shooting Bad Diode Greetings all......I was hoping i could have someone help me confirm a troubled series string on a system we have installed..... System consists of 16 BP 170 W 24V nominal modules......2 strings of 8 modules.....Vmp of each module is roughly 34V and Voc of each module is roughly 41V. One string is under-producing......String 1 Voc is 346V and String 2 Voc is 272V. String 1 Vmp under load is 270V and String 2 Vmp underload is 270V. I am hypothesizing that String 2 has a bad diode on the 3rd panel in and is reducing the Voc of that string by th 2 panels ahead of it in the string. I am hoping to figure this out without removing the entire string and checking each panel if possible..... I think the Vmp is equal due to the fact that both strings are paralleled in the inverter and the 1st string is being pulled to the same level V as the 2nd string under load......Is my logic good? Thanks for the help and advice..... Cheers, Kirpal Khalsa Renewable Energy Sytems -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org/attachme nts/20081031/ded40350/attachment-0001.htm> ------------------------------ Message: 3 Date: Fri, 31 Oct 2008 11:38:55 -0700 From: "Bill Brooks" <[EMAIL PROTECTED]> Subject: Re: [RE-wrenches] mix-n-match Unisolar To: "'RE-wrenches'" <[email protected]> Message-ID: <[EMAIL PROTECTED]> Content-Type: text/plain; charset="us-ascii" Geoff, The ultimate issue is how many cells are in each series string and is the voltage of the cells nearly the same. As long as the number and the voltage of the cells match up for each string, it makes no difference what arrangement the modules are in. You could have 5 + 6 + 7 = 18 cells in one group and 3+10+5 =18 cells in another group, and its all good as long as they are similar cells. Unisolar, due to the low fill factor, is actually pretty forgiving of difference modules and cells. If you need help, let me know. Bill. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Jason Lombard Sent: Friday, October 31, 2008 8:55 AM To: RE-wrenches Subject: Re: [RE-wrenches] mix-n-match Unisolar You are correct and they are not. The entire string or array will drop the lowest performing panel and seriously detain performance. On Thu, Oct 30, 2008 at 2:29 PM, Geoff Greenfield <[EMAIL PROTECTED]> wrote: I thought I knew the answer to this one, but wanted to run it by the list. We are responding to a bid where the electrical engineer has designed a system with different sized Uni-solar laminates in some series strings paralelled with consistant full size strings. (this was done to work around skylights etc). We suggested that this was a poor design and will lead to "least common denomenator" performance, exacerbated by MPPT confusion. The EE responded that "the bypass diodes allow for this". Any experience with this in practice? For a brighter energy future, Geoff Greenfield Founder and CEO Third Sun Solar & Wind Power Ltd. 340 West State Street, Unit 25 Athens, OH 45701 740.597.3111 Fax 740.597.1548 www.Third-Sun.com Clean Energy - Expertly Installed _______________________________________________ List sponsored by Home Power magazine List Address: [email protected] Options & settings: http://lists.re-wrenches.org/options.cgi/re-wrenches-re-wrenches.org List-Archive: http://lists.re-wrenches.org/pipermail/re-wrenches-re-wrenches.org List rules & etiquette: www.re-wrenches.org/etiquette.htm Check out participant bios: www.members.re-wrenches.org -- Jason Lombard Open Hand Solar LLC. HC74 Box13 Pecos, NM. 87552 505 795 8646 -------------- next part -------------- An HTML attachment was scrubbed... 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