Do the math on the worst case scenario. What kind of values do you need for the bad days - assuming you get a minimal charge during cloudy days, how long does the few hours of that charge last?
Josh Luthman Office: 937-552-2340 Direct: 937-552-2343 1100 Wayne St Suite 1337 Troy, OH 45373 "When you have eliminated the impossible, that which remains, however improbable, must be the truth." --- Sir Arthur Conan Doyle On Thu, Aug 27, 2009 at 1:45 PM, jp <j...@saucer.midcoast.com> wrote: > All this fuzzy math about hours of sun in 33.3 days is useless and not > the way the calculators work. > > If you are consuming 12w and generating 60w (4 toy panels), here's some > math. 288w/day (12x24) load. According to the sun maps, we are in the 4 > hour of sun (average!) area according to the sun calculation charts. > (Maine). This means 240w/day (60x4) generated. In such as case, if it's > working, you are either running partly on existing battery charge, > getting lucky with sunny weather, or not actually drawing 12w load. > > Provide some overhead for charging, charging inneficiencies, cable > loss, charge controller loss, bad weather. What percent overhead is > based on how conservative the calculator is. If it's expensive to visit > the site, go extra conservative. > > I really like to see the batteries fully charged as much as possible. If > you have batteries that stay fully charged most of the time, they won't > freeze when it's -20f. My extra recommended 40w will help the batteries > to stay fully charged and provide the overhead your calculations are > missing. In cold weather, the AH capacity of the battery shrinks as > well. > > On Wed, Aug 26, 2009 at 11:05:33PM -0500, Mike wrote: > > I'm not sure I buy into your math. If I have a repeater site that is > > pulling 1A @ 12V, then it is consuming something like 12W, right? If > > I have 60W of solar panel (2 toys) then when conditions are optimal, > > I have 48W left over to charge the battery. > > > > Lets say I am REALLY north, and the panels are only producing 45W. I > > still am consuming 12W with the radios, and have 33W left over to > > charge the battery. If I have an 800AH battery 24 Hours of sun will > > run the radios AND fully charge the battery. If the sun shines 24 > > hours out of 33.3 days, I will stay ahead of the curve and the > > battery will stay charged. > > > > No sun for 33.3 days and my 800AH battery will finally die. I NEVER > > see those conditions here in the midwest. I'll still maintain you > > can do a repeater site for $500 in solar power costs and if you > > monitor battery condition it will work just fine. > > > > At 09:54 PM 8/26/2009, you wrote: > > >Here in the north, I wouldn't bother with anything less than 100w of > > >panel. > > > > > > > > > > > -------------------------------------------------------------------------------- > > WISPA Wants You! Join today! > > http://signup.wispa.org/ > > > -------------------------------------------------------------------------------- > > > > WISPA Wireless List: wireless@wispa.org > > > > Subscribe/Unsubscribe: > > http://lists.wispa.org/mailman/listinfo/wireless > > > > Archives: http://lists.wispa.org/pipermail/wireless/ > > -- > /* > Jason Philbrook | Midcoast Internet Solutions - Wireless and DSL > KB1IOJ | Broadband Internet Access, Dialup, and Hosting > http://f64.nu/ | for Midcoast Maine http://www.midcoast.com/ > */ > > > > -------------------------------------------------------------------------------- > WISPA Wants You! Join today! > http://signup.wispa.org/ > > -------------------------------------------------------------------------------- > > WISPA Wireless List: wireless@wispa.org > > 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: wireless@wispa.org Subscribe/Unsubscribe: http://lists.wispa.org/mailman/listinfo/wireless Archives: http://lists.wispa.org/pipermail/wireless/
