Lee Haefele wrote: > I have 2 pairs of 120W Evergreen brand panels. Each pair has individual 50' > round trip #10 wire. > I have Blue Sky 50A (output rating) MPPT controller. > The controller accepts 12V or 24V (nominal, actual voltave is ~ 17/34V) and > can be either 12V or 24Voutput. Change is done with dip switches. > Originally I had the panels in series which gives 32A in good sun with high > battery voltages and up to 38A with lower battery voltages, like when I run > the microwave. I noticed that at low light levels, (current below ~2A @ > 24V input) the unit goes to bypass, effectively losing half the power. I > think below this current level, the controller operations are not efficient, > so they are shut down. > Seeing this, I rewired for 12V input by placing the panels in parallel and > changing the dip switch. This helped with the low end current, but the max > output dropped to 24A. I decided I get more overall power from the series > config and assume the cause is less wire loss. > Any shading in series config effectively removes the 2 panels in that > circuit. I am planning a long passage, Grenada to Ithaca, NY and sails > shading the panels is a big issue. I will probably wire for 12V input for > the trip. > Shading is a big problem, set a baseball cap on a big solar panel and it > mostly stops. > Keep in mind: Maximum current is roughly 4 hours a day, possibly half > current for 4 more hours. > 480 Watts of panels supplies my ~150A/H per day needs and in the spring I > have excess that I use to heat hot water using the 120V inverter. I can get > behind if there is a long overcast period, but catch up while using the > engines for moving. > Lee Haefele > Leopard 38 Cat, Alesto 2 > > That's good info. I'll have to arrange it so I can quickly reconfigure from series to parallel and do some testing of my own. I may break down and buy two controllers, putting one on each battery bank. The panels are mounted on both sides of the boat, aft. The mizzen and main can block if they're up. Even the mizzen mast will block once in a while.
Thanks, Jim. _______________________________________________ Liveaboard mailing list [email protected] To adjust your membership settings over the web http://www.liveaboardnow.org/mailman/listinfo/liveaboard To subscribe send an email to [email protected] To unsubscribe send an email to [email protected] The archives are at http://www.liveaboardnow.org/pipermail/liveaboard/ To search the archives http://www.mail-archive.com/[email protected] The Mailman Users Guide can be found here http://www.gnu.org/software/mailman/mailman-member/index.html
