Good point :) It's not too severe down here in So Utah. Randy
Chuck McCown wrote: > They must not be subject to ice storms. > > ----- Original Message ----- > From: "Randy Cosby" <[EMAIL PROTECTED]> > To: "WISPA General List" <[email protected]> > Sent: Thursday, November 20, 2008 10:22 AM > Subject: Re: [WISPA] Remote Powered Access Pont > > > >> We recently visited a solar-powered site that had a supplementary >> wind-generation system. Seemed to work well for them to have wind power >> when the weather is bad, solar when it is good. Pretty windy place as >> well. >> >> Chuck McCown - 3 wrote: >> >>> Here is a note I posted several days ago on the Motorola list about solar >>> powering. >>> >>> From: Chuck McCown [mailto:[EMAIL PROTECTED] >>> Sent: Friday, November 14, 2008 9:17 AM >>> To: Dave Crim >>> Subject: Re: solar >>> >>> >>> >>> Continuing on a bit, lets say you have 5 lousy days and one good sunny >>> day >>> followed by 5 more lousy days. That one sunny day needs to store enough >>> to >>> charge the batts totally. 75 watts * 5 days * 24hours * 1.25 (batter >>> efficiency loss) + (75watts * 24 hours) current day = 13050 watt hours. >>> >>> To make 13050 watt hours in one 10 hour day you go: >>> >>> 13050/.707*10=1845 watts. You need 1845 watts of panel to do this. That >>> is >>> 24 times the load. >>> >>> So, my rule of thumb of 20 times the load is still a little shy of being >>> conservative. >>> >>> >>> >>> The thing that saves you in a situation like this is a massive battery. >>> A >>> one month battery with 20 X panels will never fail due to a lack of sun >>> energy. >>> >>> A 2 week battery and 10X panels will fail now and then every single >>> winter. >>> Sometimes for several days at a time. >>> >>> ----- Original Message ----- >>> >>> From: Chuck McCown >>> >>> To: [EMAIL PROTECTED] >>> >>> Sent: Friday, November 14, 2008 9:09 AM >>> >>> Subject: solar >>> >>> >>> >>> Several thing you may not be including. >>> >>> Assuming this panel is somewhere in this neck of the woods, December 21 >>> has 10 hours of time between runrise and sunset. >>> >>> But if you don't have tracking mounts (most don't) the amount of energy >>> you get out of a panel follows the first half of a sine wave. >>> >>> To estimate that energy, you integrate the area under the curve. That >>> will equal .707 of what you thought you were going to get. >>> >>> >>> >>> So, let's say you put up a 500 watt panel, your daily sunny output will >>> be >>> an average of 353 watts. The sun shines for 10 hours solid and you store >>> 3530 watt hours in your battery. Now your load is on during the daytime, >>> so >>> if you have a 75 watt load, you are now able to make 278 watts. You are >>> down to 2780 watt hours. You put in 2780 watt hours into a battery and >>> you >>> get maybe 80% back out. So you have 2224 watt hour available (if you >>> drain >>> the batts which is not good for them). >>> >>> >>> >>> You have 14 hours of darkness and actually more like 16 hours before >>> the >>> panel starts making any useful amount of energy. 16*75=1200 watt hours. >>> >>> But that next day is not sunny, there is frost and a light coating of >>> snow. The whole works dies 16 hours later. About 9 pm. >>> >>> >>> >>> One other note, you only want to draw your batteries down no more than >>> 10% >>> each night or they won't last long. That means a minimum of 12000 watt >>> hours. If that is a 12 volt system, 1000 amp hours. If it is a 24 volt >>> system, 500 amp hours. And that is a minimum because here we get a week >>> with snow and ice and no sun easy, sometimes two weeks. >>> >>> >>> >>> You really need a generator, less load, or a whole bunch more batts and >>> panels. >>> >>> >>> >>> -------------------------------------------------------------------------------- >>> WISPA Wants You! Join today! >>> http://signup.wispa.org/ >>> -------------------------------------------------------------------------------- >>> >>> WISPA Wireless List: [email protected] >>> >>> Subscribe/Unsubscribe: >>> http://lists.wispa.org/mailman/listinfo/wireless >>> >>> Archives: http://lists.wispa.org/pipermail/wireless/ >>> >>> >> -- >> Randy Cosby >> Vice President >> InfoWest, Inc >> >> office: 435-773-6071 >> >> >> >> >> -------------------------------------------------------------------------------- >> WISPA Wants You! Join today! >> http://signup.wispa.org/ >> -------------------------------------------------------------------------------- >> >> WISPA Wireless List: [email protected] >> >> Subscribe/Unsubscribe: >> http://lists.wispa.org/mailman/listinfo/wireless >> >> Archives: http://lists.wispa.org/pipermail/wireless/ >> >> > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > -------------------------------------------------------------------------------- > > WISPA Wireless List: [email protected] > > Subscribe/Unsubscribe: > http://lists.wispa.org/mailman/listinfo/wireless > > Archives: http://lists.wispa.org/pipermail/wireless/ > -- Randy Cosby Vice President InfoWest, Inc office: 435-773-6071 -------------------------------------------------------------------------------- WISPA Wants You! Join today! http://signup.wispa.org/ -------------------------------------------------------------------------------- WISPA Wireless List: [email protected] Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
