Hi Bob, While I'm at my summer place in the Upper Peninsula of Michigan (EN56), I run my satellite station purely by solar power. It is not by any means a high tech setup, but it works for me. I bought my 15watt solar panel from a RV (recreational vehicle) center, and charge up two 26 amp hour gel cell batteries. I also use one of those " $10 Dayton specials" power units with a 17ah battery and 400 watt inverter. This runs the laptop and rotator. But not for long. I think I've got less than $250 into the whole system. This is not by any means the most effective or efficient system to have, but it is portable and works for Field Day. So if I make contact with you from EN56, it's done from solar power. 73 de Doug KA8QCU
----- Original Message ----- From: "Robert Bruninga" <[email protected]> To: "'Greg D.'" <[email protected]>; <[email protected]>; <[email protected]>; <[email protected]> Sent: Friday, October 02, 2009 14:27 Subject: [amsat-bb] Re: Solar Power (I was wrong) > > ... I have... a roof angle exposure that is > > not solar-friendly... > > That was another error I had made in my situation. > > Again, there is a BIG difference between solar design for > stand-alone battery systems (must point south, optimum angle, > etc) and grid-tie systems that can be anything from SE to SW and > even FLAT and still be only a few percent off peak!. > > The economics are entirely different. > > The remote/battery system, MUST provide a minimum power on the > worst winter days and weather of the year. It MUST be optimized > for winter. > > On the other hand, the grid tie system only has to have a good > AVERAGE power averaged over a year. And you can make more money > in a month of summer sun making money at HIGH payback rates than > you can get all winter (3 months). > > Even a FLAT array makes more power in the 3 summer months than > the optimum tilt angle array does. > > And lastly, anything pointed SE to S to SW is about the same for > a grid-tie system. You lose at most about 5% SE or SW compared > to South. Again, the reason is not obvious. But any tilted > array is only going to see the sun for 180 degrees of path > across the sky. Even the ideal South facing tilted array does > not see the morning sun nor the evening sun in the summer when > you are getting your most payback.. It only sees the midle 6 > hours. Since the sun is up much longer than that most seasons, > then getting those 6 hours averaged before noon (SE) or getting > them in the afternoonn (SW) makes little difference for a > grid-tie array, though, I'd favor SW, since peak electric rates > apply longer in the afternoon than in the morning. So you want > to maximize your power when electricity rates are highest. > > Again, I am sharing this off topic with everyone, because I too > learned that my thinking was all wrong based on my previous > experiences with stand-alone power systems and that a > grid-tie-system has completely diffeerent economics to my normal > thinking... > > You can play with all the angles and directions for grid-tie > systems on-line with the solar energy calculator here: > > Yes, SOUTH with a latitude tilt is best... But based on annual > AVERAGEs: > Southeast only lost 5% > Southwest only lost 5% > Droping the tilt to the angle of my roof 25 deg only lost 1%! > Droping the tilt to FLAT on the ground only lost 14% > (but if I tilt them up to 45deg Sept to April) I GAIN 20%! And > that is a +5% over optimum south. > > http://www.nrel.gov/rredc/pvwatts/version1.html > > On the other hand, ANY shade will significantlly cut into your > power budget. > > Bob, Wb4APR > > _______________________________________________ > Sent via [email protected]. Opinions expressed are those of the author. > Not an AMSAT-NA member? Join now to support the amateur satellite program! > Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb _______________________________________________ Sent via [email protected]. Opinions expressed are those of the author. Not an AMSAT-NA member? Join now to support the amateur satellite program! Subscription settings: http://amsat.org/mailman/listinfo/amsat-bb
