I thought the Suns Solar Intensity was 1kW per square meter above the Earths atmosphere and what hit the ground was reduced by 90%. But it has been a few years since my college days :-)
Andrew Carson - Senior Compliance Engineer, Xyratex, UK Phone: +44 (0)23 9249 6855 Fax: +44 (0)23 9249 6014 -----Original Message----- From: don_borow...@selinc.com [mailto:don_borow...@selinc.com] Sent: 07 June 2002 15:09 To: emc-p...@majordomo.ieee.org Subject: RE: IEC 60950 & Solar Cells For the power limit part of the problem, a good rule of thumb to use for solar intensity is 1 kW per square meter. A garden variety solar cell (single crystal) is easily 10% efficiency these days, and the best ones are past 20%, so this yields 100 watts to beyond 200 watts per square meter for the expected power. Don Borowski Schweitzer Engineering Labs Pullman, WA "Andrew Carson" <andrew_car...@uk.xyratex.com> on 06/07/2002 02:19:03 AM Please respond to "Andrew Carson" <andrew_car...@uk.xyratex.com> To: "Ron Pickard" <rpick...@hypercom.com>, emc-p...@majordomo.ieee.org cc: (bcc: Don Borowski/SEL) Subject: RE: IEC 60950 & Solar Cells Ron Some help, I hope, to your questions. "Would this small LCD display device even be required to be evaluated to IEC 60950 3rd Edition or to IEC 60950-1?" This depends on what you are trying to achieve, good company practices, or a countries regulatory requirements. For Europe, the product does not need safety testing under the scope of the LVD, but would do under the RTTE. For the US market, there is no legislation that says the equipment vendor must safety test. So this will be driven by your customer and market place requirement. Depending on the equipments intended function, you might find more guidance in the UL Audio and Video equipment standards. "Would a solar cell energy source be treated similarly to a battery?" No. You do not have the risk of explosion associated with a battery, but then again the Solar Cell is not a limited Energy device like a battery. Treat the Solar Cell like an external SELV power source. As long as the sun still shines, it will continue to deliver power. However, for maximum energy available form the Cell, even in the most extreme fault conditions, there is a physical upper limit to how much solar energy can be converted into electricity. Off the top of my head it is around 10W per square meter with today's technology. Should you be concerned over the safety of a Solar Cell powered LCD screen. Yes. If the LCD screen has a back light inverter, then some very high voltages could be present within the equipment. So single fault protection. You also need to address the chemical nature of the LCD screen and any risk to the operator in a fault condition. Hope this helps. Andrew Carson - Senior Compliance Engineer, Xyratex, UK Phone: +44 (0)23 9249 6855 Fax: +44 (0)23 9249 6014 -----Original Message----- From: Ron Pickard [mailto:rpick...@hypercom.com] Sent: 06 June 2002 23:26 To: emc-p...@majordomo.ieee.org Subject: IEC 60950 & Solar Cells To all, First, a little background. I have been asked a question that I did not know the answer to, which relates to a potential new product. As I understand it, this device will be relatively small, consume very little power and will only display particular information depending on the application. What I have been told, this device will be powered by a solar cell with a potential 3V coin battery for back up (the battery part is iffy). I can't give anymore information about it because I don't know any more. Now, to the questions. As the scope of IEC 60950 3rd Edition or IEC 60950-1 applies to equipment that is powered "up to" 600V", it would seem that the standard would apply to this product. However, I cannot find a single reference to a solar cell energy source. Would a solar cell energy source be treated similarly to a battery? Would this small LCD display device even be required to be evaluated to IEC 60950 3rd Edition or to IEC 60950-1? As always, I look forward to your insightful replies. Best regards, Ron Pickard rpick...@hypercom.com This e-mail may contain SEL confidential information. The opinions expressed are not necessarily those of SEL. Any unauthorized disclosure, distribution or other use is prohibited. If you received this e-mail in error, please notify the sender, permanently delete it, and destroy any printout. Thank you. ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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