[RE-wrenches] PENTAMETRIC
Input appreciated. How well does the Pentametric work as a generator control. The spec sheet states a control relay based on % charged is available. Any experience using the Pentamatic as a gen start control. Does this yield better battery control than voltage based approach? Thanks for any field experience on this control. Don Loweburg Offline Solar ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
Re: [RE-wrenches] Power Factor and Grid Tied PV
We worked on dozens of commercial PV systems in Southern California Edison (SCE), Los Angeles Department of Water Power (LADWP), and San Diego Gas Electric (SDGE) territories. We installed Xantrex, SMA, and SatCon inverters and measured power factor on both the grid and the inverters. In every case, inverter power factor was 1. In almost every case LADWP's power factor was less than 1 and in older parts of Los Angeles power factor was often 0.75. SCE and SDGE generally has pretty good power factors. In general, PV inverters do not worsen grid power factor. In general, newer sections of the grid are better designed and better managed than older grid sections. When utility companies or anyone says PV causes grid problems, ask for proof. Joel Davidson - Original Message - From: Darryl Thayer daryl_so...@yahoo.com To: RE-wrenches re-wrenches@lists.re-wrenches.org Sent: Wednesday, January 06, 2010 9:39 PM Subject: Re: [RE-wrenches] Power Factor and Grid Tied PV I recently spoke with an inverter manufacture and I left with the following opinion. Normally the inverter takes the unity power factor load and leaves the reactive load. making the power factor worse. However the power factor could be corrected by the inverter, However this would add cost to the inverter and would not appear to have value to the solar industry. There are variable reactance devices existing that can correct power factor, is there need for another device? Darryl Hello Wrenches, Commercial power customers often are penalized for low power factors. Looking for other info I came across this article, which seems to cover the subject from an academic standpoint. http://tinyurl.com/ye5pzrw Does anyone have real world data which might shed light on the impact of a DGT PV system on power factor. With Regards Carl Adams SunRock Solar, LLC. ___ ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
Re: [RE-wrenches] Best angle - direct grid tie
Great format for an integrator and its staff. Thanks for sharing, Mike. David Brearley, Senior Technical Editor SolarPro magazine NABCEP Certified PV Installer david.brear...@solarprofessional.com On 1/7/10 1:26 PM, Michael Kelly m...@solarflair.com wrote: Drake, I did an analysis for optimum conditions based on tilt and azimuth a while ago for our area around Boston. I did it in such a way as any combination of tilt and azimuth gives you % of optimum conditions. See attached. All of the data was from PVWatts simulations. Maybe you can make one for your area when you have some free time. - Mike -- Michael Kelly Project Manager / Project Engineer NABCEP Certified Solar PV Installer SolarFlair Energy, Inc. 11 Mayhew Street Framingham, MA 01702 Direct Mobile: 617-899-9840 Main Phone: 508-293-4293 Main Fax: 508-293-4003 m...@solarflair.com On Wed, Jan 6, 2010 at 9:48 AM, Drake Chamberlin drake.chamber...@redwoodalliance.org wrote: Thanks for all of the excellent advice regarding the best tilt angle. It is a real privilege to be a part of, and have access to the incredible resource of the knowledge and experience represented by this list. It looks like a 30 degree angle will work fine for 39 degrees N. This corresponds well with the Unirac U-LA, pre engineered designs. Drake Drake Chamberlin Athens Electric OH License 44810 CO License 3773 NABCEP TM Certified PV Installer Office - 740-448-7328 Mobile - 740-856-9648 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
Re: [RE-wrenches] To Megger or not to Megger
Hi Bill, I wanted to follow up on your results finding a ground fault with a lower resolution megger. Do you think the .1MOhm meters will work in field applications? Do you know of any .001MOhm meters like the old 1520? I have taken a position with a cadtel mfgr as their field application engineer. I hope to be using your consulting services if I get over my head. Thanks and Happy New Year! -Wes Kennedy 303-653-3073 --- On Tue, 4/28/09, Bill Brooks billbroo...@yahoo.com wrote: From: Bill Brooks billbroo...@yahoo.com Subject: Re: [RE-wrenches] To Megger or not to Megger To: 'RE-wrenches' re-wrenches@lists.re-wrenches.org Date: Tuesday, April 28, 2009, 11:39 AM Dave, The issue is definitely resolution. The cool thing about the Fluke 1520 is that it goes down to 0.001MOhms (1000 Ohms). That is the resolution you are looking for. Neither of the current Flukes go low enough. That is why I’m going into the field later this week to see how a 0.1MOhm meter stacks up to finding faults—I have an array with a pesky fault that should make it fun. Many arrays will ring out as a faulted array when, in fact, everything is fine. This is especially true of a-Si arrays with low quality glass. They are very leaky. I’ll keep looking and report back on a recommendation for Christmas shopping. Just to add punctuation to this thread, I always recommend that contractors megger their arrays, because it has saved my butt several times. Also, with exterior wiring systems it is even more important. The problem in the early days is that people would whine about the $600-$1000 price tag. In my opinion, that argument is gone. With contractors routinely putting down $1400 for a SunEye, the value of a good megger is similar and costs less. Bill. From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of David Palumbo Sent: Tuesday, April 28, 2009 7:59 AM To: gilliga...@gmail.com; 'RE-wrenches' Subject: Re: [RE-wrenches] To Megger or not to Megger Matt, “Muggering”, I think that will catch on. The last post, I think, ol’ Uncle Bill Brooks (4/13/09 8:17 PM) had on this topic raised a concern about “not having enough resolution in the low impedance area. PV arrays can have an impedance to ground of a slow as 2kOhms. A resolution of 0.1MOhms will likely not cut it.” Bill went on to say that he had bought a cheaper meter to test out “for fun”. Some of us do enjoy “muggering around”. So my question is. Do the Fluke 1503’s and 1507’s have enough resolution in the low range? Dave From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Matt Lafferty Sent: Tuesday, April 28, 2009 9:56 AM To: 'RE-wrenches' Subject: Re: [RE-wrenches] To Megger or not to Megger RE: Suggested replacements for Fluke 1520 and pricey meters... Good News below! Another Wrench sent me a note off-list last night, asking how much a muggering would cost. Here's what I sent him: When I got that 1520 it was just over $600. I just checked online and find that it's a discontinued item... Bummer! Fluke recommends the 1587 or the 1507 or the 1503. They also mention the 1577, but it's an ugly stepsister, or maybe a retarded adopted relative, to the 1587. The 1587 is basically a multimeter that also has a TEST button to discharge a high voltage shock into the sample under test... It runs about $620 from standard distributors. http://us.fluke.com/usen/products/Fluke+1587+1577.htm?catalog_name=FlukeUnitedStates You can get it for $522 here: http://www.testequipmentdepot.com/fluke/megohmmeters/1577_87.htm NOTE: It does not test at 10A in DMM mode which means it wouldn't be able to test short-circuit current in strings. Don't bother with the 1577! The 1507 1503 are more robust equipment. You can check them out here: http://us.fluke.com/usen/products/features.htm?cs_id=35391(FlukeProducts)category=HMA(FlukeProducts) While they do measure AC DC Voltages to 600V as well as some lower ohm continuity work, they are really more tailored to being a megger. The 1503 will suffice for most of what I expect you will get into, but there are some features on the 1507 that might make it worth considering. Mind you, I haven't looked at at price on either yet, so that last comment may just be noises coming out my ass. The 1507 has a Compare function which basically sets up a Pass/Fail value so you can quickly run through repeated tests. This would be useful for doing larger systems where you are testing dozens or hundreds of circuits at a time. For my purposes, I want my guys to think a little more than Buzz = OK and I want them to write an actual tested value down on a piece of paper so this is not a big plus to me. The 1507 also does Polarization Index and Absorption Ratios. These are more advanced
Re: [RE-wrenches] Power Factor and Grid Tied PV
Marco, Three components of power delivered by the utility company: Watts, volt-amps-reactive (VAR), and apparent power or volt-amps (VA). Power factor is the ratio of the watts to the volt-amps. PF = Watts/VA. To see how this works: draw a right triangle with 8 kW as the horizontal leg, 6 kVAR as the vertical leg, and 10 kVA as the hypotenuse. The power factor is 8 kW/10 kVA = 0.8. Now put in a 4-kW solar system. The 6 kVAR reactive load doesn't change So the solar system reduces the real power delivered by the utility by 50%, the reactive power by 0%, and the apparent power by 28%. The power factor afterwards is PF = 4 kW/7.21 kVA = 0.55. The power factor did get worse! To see how that all works just draw a new hypotenuse starting from the midpoint of the 8-kW horizontal leg. Hardly seems worthy of a paper. But the utility doesn't like to supply power for a load with a power factor less than 0.8 because the out of phase current still causes I-squared x R losses or line losses. Joel, The utility company isn't responsible for the power factor. The customers' loads determine the power used and the power factor. The utility company is responsible for the power quality, which is really poor in lots of locations. Kent Osterberg Blue Mountain Solar, Inc. Marco Mangelsdorf wrote: According to an article, written by a utility engineer on O'ahu, PF can be worsened at the site where a substantial PV system is located. If there is a poor or wavering PF due to an abundance of inductive loads at a particular site, having a large inverter, in relation to the overall power consumption of the facility, can actually make the PF worse. I can track down that piece for anyone interested. Marco ProVision Solar -Original Message- From: re-wrenches-boun...@lists.re-wrenches.org [mailto:re-wrenches-boun...@lists.re-wrenches.org] On Behalf Of Joel Davidson Sent: Thursday, January 07, 2010 5:42 AM To: RE-wrenches Subject: Re: [RE-wrenches] Power Factor and Grid Tied PV We worked on dozens of commercial PV systems in Southern California Edison (SCE), Los Angeles Department of Water Power (LADWP), and San Diego Gas Electric (SDGE) territories. We installed Xantrex, SMA, and SatCon inverters and measured power factor on both the grid and the inverters. In every case, inverter power factor was 1. In almost every case LADWP's power factor was less than 1 and in older parts of Los Angeles power factor was often 0.75. SCE and SDGE generally has pretty good power factors. In general, PV inverters do not worsen grid power factor. In general, newer sections of the grid are better designed and better managed than older grid sections. When utility companies or anyone says PV causes grid problems, ask for proof. Joel Davidson - Original Message - From: "Darryl Thayer" daryl_so...@yahoo.com To: "RE-wrenches" re-wrenches@lists.re-wrenches.org Sent: Wednesday, January 06, 2010 9:39 PM Subject: Re: [RE-wrenches] Power Factor and Grid Tied PV I recently spoke with an inverter manufacture and I left with the following opinion. Normally the inverter takes the unity power factor load and leaves the reactive load. making the power factor worse. However the power factor could be corrected by the inverter, However this would add cost to the inverter and would not appear to have value to the solar industry. There are variable reactance devices existing that can correct power factor, is there need for another device? Darryl Hello Wrenches, Commercial power customers often are penalized for low power factors. Looking for other info I came across this article, which seems to cover the subject from an academic standpoint. http://tinyurl.com/ye5pzrw Does anyone have real world data which might shed light on the impact of a DGT PV system on power factor. With Regards Carl Adams SunRock Solar, LLC. ___ ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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 No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.725 / Virus Database: 270.14.129/2606 - Release Date: 01/07/10 21:35:00
[RE-wrenches] Xantrex XW4548 noise problem
I have a customer that we installed a Xantrex XW4548 on a Midnite Epanel. He has 3kw of pv and 400ah of lead acid battery's. The issue is he feels the inverter is to noisy. The inverter is hung in a garage on a plywood wall that is 2 by 6 constructed with fiberglass and then drywall on the house side. The XW is fairly noisy a lot louder then the SW or SW+ series and a call to Xantrex got me a response that the transformer needs about 30 days of cycling to seat the windings and it will quite right down. So has any one else noticed the XW being extra loud? Has anyone noticed the XW quite down after 30 days? And if this noise is normal what would everyone recommend for a cushion to help keep the noise out of the house? I had thought of a sheet of 1 inch foam and then another layer of plywood but unsure if that would be worth the effort? ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
Re: [RE-wrenches] Power Factor and Grid Tied PV
Thanks to all who responded, The article Marco references, is the one referenced in the tinyurl in my original post. I did not find anything of significance in the previous Solar Pro issues. Based on the responses it seems there is no good data out there to answer the question posted. This may be due to 1) the fact that PV systems are not being installed in commercial facilities with large reactive loads 2) those facilities are not penalized for PF therefor the question is irrelevant to those system owners 3) the PV systems installed in such facilities are small with respect to the overall facilities load and any negative impact on PF is insignificant Cheers Carl ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
Re: [RE-wrenches] Power Factor and Grid Tied PV
swingjun...@gmail.com wrote: Thanks to all who responded, The article Marco references, is the one referenced in the tinyurl in my original post. I did not find anything of significance in the previous Solar Pro issues. Based on the responses it seems there is no good data out there to answer the question posted. This may be due to 1) the fact that PV systems are not being installed in commercial facilities with large reactive loads 2) those facilities are not penalized for PF therefor the question is irrelevant to those system owners 3) the PV systems installed in such facilities are small with respect to the overall facilities load and any negative impact on PF is insignificant Cheers Carl I don't think there is anything to be concerned about if the PF goes down because a grid tie inverter is helping to support the real power loads. The I-squared-R losses won't get any larger for the utility. I think it's just because the Numerator of Watts / VAR goes down, and the denominator staying the same that is making the measure Power Factor measurement go down. Also, I believe that this is only for current source inverters, which accounts for most GT inverters today... An older SW inverter, say, (voltage source) would actually supply VARs to the system and probably wouldn't change the measured PF to the utility very much, if at all. My 2 cents for today. boB ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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 ___ List sponsored by Home Power magazine List Address: RE-wrenches@lists.re-wrenches.org 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
