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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 (SDG&E) 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 SDG&E 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? DarrylHello 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. 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