Solar power literature will indicate that you can expect to get the equivalent of 6 hours per day of rated output on a clear summer's day, but that assumes that you have a fixed mount with the panels mounted facing south and at an angle approximating the latitude. My experience with 2 panels mounted flat on top of a bimini on a sailboat is half of that. Also, unless you are using an MPP (maximum power point) controller, the current rating of the panels is the only specification that matters in sizing. An MPP controller can deliver a few more amps by converting the power produced by the panels into power at the voltage required for charging the batteries at an improved efficiency as compared to a conventional controller which acts as a voltage limiter. MPP controllers can be thought of as DC transformers.
Steve Thomas ---- Dave S via CnC-List <cnc-list@cnc-list.com> wrote: Hello all, Need to replace my batteries and am contemplating an upgrade to Windstar's off-the-dock power system. Specifically evauating a battery upgrade and potential top-up-charging. Based on what I've read, a 100w panel would conservatively contribute 400-500w daily (average) in summer and be enough to help extend my "off the grid" time. I am on the North shore of Lake Ontario, Toronto area. Does anyone have any real-world data or experience with the actual charging capacity of a sailboat mounted solar panel? Would like to factor this into my decisions. Many thanks! Dave Windstar 33-2 https://cncwindstar.blogspot.com/2019/09/going-off-grid-charging-and-battery.html _______________________________________________ Thanks everyone for supporting this list with your contributions. Each and every one is greatly appreciated. If you want to support the list - use PayPal to send contribution -- https://www.paypal.me/stumurray
