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/
