1st off - you can parallel them into one controller with only the very tiniest loss of efficiency despite shadows. 2nd - many controllers out there are crap at best. Morningstar makes excellent PWM and MPPT controllers. I have had great luck with mine. I would not even consider cheap FleaBay contollers. YMMV. PWM controllers are less efficient, but they are a lot cheaper. See http://support.morningstarcorp.com/wp-content/uploads/2014/07/Trad-PWM-vs-TrakStar-MPPT-April-2014.pdf Morningstar MPPT : http://www.amazon.com/Morningstar-Sunsaver-TrackStar-Charge-Controller/dp/B006H9VPL6/ref=sr_1_1?ie=UTF8&qid=1413293847&sr=8-1&keywords=morningstar+solar+controller+mppt+15+amp about $220.
http://www.amazon.com/MorningStar-ProStar-PS-30-Charge-Controller/dp/B003YIB7QQ/ref=sr_1_7?ie=UTF8&qid=1413293962&sr=8-7&keywords=morningstar+solar+controller+PWM About half that price and includes an anchor light output. Just get one QUALITY controller. Good PWM beats some random MPPT scavenged off of Fleabay. Don't forget to look at panel amp output, don't do the math for 12 volts. Most panels are 16-18 volts, so 200 watts at 16 volts is 12.5 amps and within the range of a 15 amp controller. Joe Della Barba Coquina C&C 35 MK I From: CnC-List [mailto:cnc-list-boun...@cnc-list.com] On Behalf Of Josh Muckley via CnC-List Sent: Tuesday, October 14, 2014 5:43 AM To: C&C List Subject: Stus-List Solar panels and charge controllers Hey folks, I'm looking to add solar panels to my boat. I have a new hard top dodger that will be a great place to mount some flexible panels. I realize that attention will have to be given to the boom so that it's shadow it minimized. I've given consideration to the fact that some shadow is likely inevitable. My understanding is that one large solar panel can have a substantial drop in it's output or be completely disabled if only a relatively small shadow is cast. As such I am planning for 4 smaller 50w panels instead of 2 100w panels. The idea being that a small shadow will only disable 1 or 2 of the panels at a time. This design also adds reliability such that a mechanical or electrical failure of a single panel doesn't disable the entire system. Additionally, a smaller panel is easier to replace and cost less. To ensure reliability I was also planning to NOT creat an array of series and parallel panels going to one controller but rather each panel to its own controller. I believe the current recommendation is to use MPPT over PWM? There is a wide range of prices for panels and controllers but I'm having a hard time determining which ones are a good value. I know you get what you pay for but over paying is silly. At the boat show, 50w, semi-flexible, >20% efficient, monocrystalline panels were going for as much as $500! I've seen charge controllers as high as $250. I know there are a few ebay haters here but the comparable panels I found were $125 and 20A MPPT controllers for $11 with free shipping. Is there something I'm missing? Besides disparaging comments about ebay or about me being cheap, does anyone have any insights about the design or component selection. I was originally pursuing a multi-channel controller but it seems no one makes them. When using multiple (4) controllers do they need to be diode separated from the battery? What about the dump load? I plan to use a single 200w resistive heater. Would it need to be diode separated from each controller? Thanks, Josh Muckley S/V Sea Hawk 1989 C&C 37+ Solomons, MD
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