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#1 cj!

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Posted 18 June 2017 - 01:02 PM

I've been giving some thought to systems for a boat with electric propulsion and recharging it. Obviously using solar panels is a pretty common solution for charging the battery bank but as most panels seem to mounted in a fixed position they are very rarely at the optimum position for maximum output. One option would be to mount the panels that would normally be fixed to an arch on tiltable and rotatable poles instead. It may mean less total panel area but would the efficiency gains of adjusting throughout the day be worth it? Here's a couple of examples and some anecdotal evidence from the panel on Kapowai that indicates the potential.

 

 

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#2 cj!

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Posted 18 June 2017 - 01:05 PM

I also came across this adjustable solar panel that has a heat exchanger behind to provide hot water while also cooling the panel thereby increasing its efficiency which is useful as a replacement for the hot water generated by IC engines.

 

 

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#3 cj!

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Posted 18 June 2017 - 01:20 PM

They seem to think that by using the heat exchanger to take some heat out of the panel increases the panel output by 10%.

 

 

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#4 eruptn

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Posted 19 June 2017 - 01:16 PM

I'm involved in numerous remote data collection sites (seismic, GPS etc) and we design for a min 7:1 ratio. That is if the site draws 1A, we have solar that is rated for at least 7A of output. If its a poor site (hill that is often in cloud etc we up it to 10:1).

 

Our panels are fixed and we are looking at the system going all year (we Tx continuously).

 

Only a boat in a marina with the panels orientated similar would meet the same efficiency we achieve; anything under way, at anchor etc would be less efficient. More efficiency would be gained if the boat in a marina tracked the sun.

 

Another way to look at this is a well set up system (fixed orientated set of panels) will deliver over/about 15% of its rated out put over a year (often in winter the battery voltages can get low; lots of amber lights show on the monitoring software after 7-10 days of rain).

 

Solar is a great aid, just so long as you understand its capability. I've spoken to many panel owners and they often perceive its producing the 'rated output' (or close to) while the sun shines.


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Ross 650 Farr 940


#5 Knot Me... maybe

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Posted 19 June 2017 - 02:56 PM

I've set mine up so the panels can follow the sun even when sailing. As noted above that can make a huge difference to their output each day, very huge.

 

That will have to happen manually though, we couldn't work out a decent auto tracking system for when at sea in a small boat, they wobble too much for the trackers to handle.


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