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Old 21-03-2013, 05:45   #31
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Re: Tilting solar panels

WOW you guys are mounting some big panels. I was getting by with 80w total giving me about 5 amps max.

With that much capacity in the tropics probably just bolt them down and be done with it. You can always add a tilting mechanism later if you need it.

If you were to hinge it make the hinges on the outside as diagram 1 to maximize the unshaded panels power. The down-sun side will get shaded by boom, mast and backstay at various times.

Saying that I don't have any experience with that sized bank or solar in the tropics.
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Old 21-03-2013, 05:49   #32
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Re: Tilting solar panels

Hi Gord, that is an interesting guideline.
Since I am between 5 and 10 degrees from the equator not sure how to apply the summer and winter adjustment

Used this tool to try and figure out if there is a major seasonal shift given the dynamics of a boat installation
Sustainable By Design :: sunangle
(I used North 8 and Long W 116 as my guideline)… just confused me even more

So my question remains whether it is worth adding the complexity of a tilting mechanism to squeeze out a bit more in the early and late daylight hours
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Old 21-03-2013, 06:19   #33
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Re: Tilting solar panels

I played with the Position part of the tool Sustainable By Design :: sunposition to identify if any significant seasonal changes… did not find one at my latitude

But it does show altitude angles in the fringe daylight periods, so is it worth tilting for those periods?
Azimuth is not important on a boat

SunPosition output complete
Latitude is 8 degrees north
Longitude is 116 degrees west
Time zone offset from GMT is -8 hours
Zero azimuth is south
Output angle units are degrees

date time altitude azimuth
March 30
3/30 06:00 3.41 -93.52
3/30 07:00 18.26 -91.57
3/30 08:00 33.12 -89.56
3/30 09:00 47.97 -87.11
3/30 10:00 62.78 -83.21
3/30 11:00 77.35 -72.47
3/30 12:00 85.11 36.51
3/30 13:00 71.76 78.63
3/30 14:00 57.04 85.16
3/30 15:00 42.21 88.29
3/30 16:00 27.35 90.52
3/30 17:00 12.51 92.49
3/30 18:00 -2.32 94.53

September 29
9/29 06:00 6.01 -86.51
9/29 07:00 20.81 -84.10
9/29 08:00 35.54 -80.94
9/29 09:00 50.10 -76.06
9/29 10:00 64.21 -66.50
9/29 11:00 76.33 -38.90
9/29 12:00 77.51 31.32
9/29 13:00 66.06 64.25
9/29 14:00 52.07 75.01
9/29 15:00 37.55 80.26
9/29 16:00 22.83 83.57
9/29 17:00 8.04 86.02
9/29 18:00 -6.80 88.12
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Old 21-03-2013, 06:26   #34
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Re: Tilting solar panels

Quote:
Originally Posted by Snowpetrel View Post
....
If you were to hinge it make the hinges on the outside as diagram 1 to maximize the unshaded panels power. The down-sun side will get shaded by boom, mast and backstay at various times.

Saying that I don't have any experience with that sized bank or solar in the tropics.
Those were my same thoughts. On my schooner, the aft boom is just a reaching sail, so my boom travel is very limited.

It will be easier if I make it hinged now if majority advice is that it is worth the trouble for early morning efficiency
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Old 25-03-2013, 02:36   #35
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Re: Tilting solar panels

Sun seeker is useful little, free program for the iPad (and probably android)

It will overlay your position, with the suns path on a google earth map. It also lists the suns current elevation etc.
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Old 29-03-2013, 06:15   #36
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Re: Tilting solar panels

Try this site: Solar Angle Calculator | Solar Panel Angle Calculator
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Old 29-03-2013, 22:01   #37
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Re: Tilting solar panels

We've had four 125 watt panels on a fixed mount over the cockpit since 1999. Four years in Western Mexico ( North 27 to 17 degrees ) at anchor almost the entire time. Never once needed to generate any electricity other that what the panels provided. We were electrical usage hogs: watermaker, lots of HAM radio usage, big computer, cold refrigerator, movies on the TV every night.

We could make 17 gph water, run the reefer, and still trickle charge the batteries with our fixed mount panels in mid-winter at 24 N.

My brother had full adjustable panels on his Tartan 42 in Mexico - after six months he quit adjusting them. He did notice a significant drop in power generated but still produced way more than he ever needed.

Same result for another friend who has been to Western Mexico three times on his Norseman 447 and on to Florida one time. He built fully adjustable panels in 2000 and quit adjusting them in 2002. He is still cruising and never bothers adjusting them.

Adjustments help a lot but 500 watts of nominal panel power is plenty for a fix mount in the tropics for most any application.

And, realistically - when cruising we were seldom on the boat during the time we would be adjusting the panels - mid-morning or mid-afternoon. We were usually out for a run, hike, snorkeling, fishing, visiting friends so who would do the adjustments?

NO shadows is far more important than adjustments on a practical day to day usage.

Just my opinion based on 14 years of usage.
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Old 31-03-2013, 15:21   #38
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Re: Tilting solar panels

For us having a tilting panel is fantastic & a definite must have.

We have one Sunpower E20 327W panel on a tilting mount over the davits. It works well here in North Queensland as most times when we need to tilt (morning & afternoon) the stern is facing the sun due to the predominantly easterly day breezes and westerly land breeze that kicks in most nights/mornings.

To illustrate, this morning I tilted the panel at 6.30am as the sun rose over the island behind me & I was getting 9.4amps into the batteries according to both the Tristar MPPT & Enerdrive battery monitor. Now at 7.15am I am already getting 14.0amps.

So when you are keeping it simple, tilting the panels makes a world of difference! Besides in our case it wasn't much extra to make the panel tilting as opposed to fixed over the davits .... the only difference being the telescoping front struts. For the cost of a little time in tilting against the cost of an an extra panel etc etc etc ... the little time taken to tend the panel a few times a day pays for itself many fold.

Dave
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