Tuesday, December 3, 2013

A year and a bit on Solar Panels - Last post perhaps??

During these long winter days, with little to do  (err, ok - there is a LOT to do, but at times I find little motivation) I at times over-nerd, and just become all giddy over data.   Well, today I am posting yet another graph documenting our Solar panel output.  And this time we have a complete year in it, plus much of the core cruising months of another year:




Our two 245w panels delivered an average of 135Ah/day over the period of April 1st to September 30th.  And as you can see, from May through August we mostly pulled in over 150Ah/day.

The TriStar also reports out Wh/day results, and here is the same time period - showing Wh vs. Ah as above:


Same as above, but plotting reported Wh/day output

So there you go.  Data.

Note I also plotted the 'modeled' or predicted line on the Ah chart.  I am very happy with how close the actual performance tracked to what was predicted, as before laying out the $$ for our solar panels, I really wanted to get an idea what I could expect.  Unfortunately, asking fellow boaters did not really give useful information.  "All I need", "Charged my batteries by 10:30am", and other non-specific responses really do not help.   But for me, I can now answer "Around 135Ah/day average from May through September.  Over 150Ah/day during the peak of the summer".  And with the good modeling tools out there, you can rather accurately predict output for your situation.

This might be one of my last Solar postings, as I am not sure there really is much more that can be said.  I will continue to include Solar output in our monthly 'Costs' posts, but other than that - am about done in terms of being able to give additional value with further posts.  If you have stumbled across this and want to see more about our experience and system, here are a few links:

See All posts tagged with Solar:  http://mvvikingstar.blogspot.com/search/label/Solar
Some details about our installation:  mvVikingStar.blogspot.com/..../we-have-solar
Model / predict YOUR solar output: mvVikingStar.blogspot.com/..../solar-panels-on-boat-modeling


Solar on a boat?  As mentioned in some prior postings, our usage greatly influences our outcome; mainly that we are away from the dock 8+ months out of a year and hence produce 100% of our own electricity - which is very expensive.  For us, we continue to be very happy with our investments.  They are well on track to cross the ROI point some time next year, and until then we enjoy the oh-so-quiet hours of reduced generator run time they provide. 

In closing, a few quick thoughts on purchasing Solar panels for a boat:
The Twins on Viking Star
  • Best value in terms of $/watt will be the LARGE panels used on houses - hopefully you can fit them.
  • Shipping of panels can be very expensive, try looking at a local installer and see if they will add you on to a larger shipment they are making.
  • Use an MPPT controller, they are well worth the extra $
  • There is some value in installing a separate MPPT controller on each panel, esp with regards to shading.  Depending on controller costs you might look into this.
  • Look into Solar credits or tax savings, both at the Fed level and the local state level.  Many times Boats will qualify for these.

OK, I do hope this series of posts are helpful to someone considering Solar on their boat.  Feel free to contact me if  have any specific questions, and I will try to answer best as I can.








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