effectiveness of solar & wind

[camaraderie]

Tomaz...yes...same here...just trying to get at the truth with relevant research since everything else is just claims at this point. Your points are well taken.
Actually, I would not assume that panels on a boat are flat. Mine were hinged and could be set flat or otherwise...though at caribe lattitudes flat is about best I think. I am assuming that a fixed panel simply means fixed in one position and that on a boat one would fix at at the angle of one's cruising lattitude.
I would think that water reflection would have an impact on photons received vs. land based but on the other hand, being at anchor and drifting around doesn't happen on land so I would think there is much more downside on the water to collection. No data on that though. What would really be neat would be an on water test at anchor with a fixed and adjustable system side by side hooked up with identical controllers to identically discharged (to 50%...not the 11.5V fully discharged level) batteries. That is my Easter dream! Thanks and have a great holiday.

[sailingdog]

Tomaz-

Mine are also not mounted flat. They're on a set of rails and could be tilted fairly easily.

[hellosailor]

Okay, if you can stand reasing it, the Sandia lab PDF says enough to say it all. http://www.nrel.gov/docs/fy01osti/29245.pdf

They used dual-axis mounted photocells, to keep them aligned with the sun in two axis not just one, and the kicker comes around page 43 when they note that the total average daily power output (daily POWER, as in watt-hours) ran about 4.8x the maximum rated power output (plain WATTS) for the panels.

IOW a 100-W rated panel could be expected to produced about 480 watt-hours of power under year-round average conditions. At 14 volts, that would be some 34 amp-hours of power. Regardless of the panel type, and assuming 100% power utilization, i.e. an MPPT controller.

For those of you looked at the PDF and ran away screaming (and I don't blame you) they also tested five "standard" types of days and locations, and there don't appear to be any situations that would allow for getting twice that much power out of a panel during any given day on this planet.

The Florida results seem to echo Sandia very nicely, and additionally confirm that pretty much every panel on the market, regardless of maker or type, varies only a few percent from the rated output, which again is going to be higher than the real world output--any where, any time, any conditions, that the panels will be on this planet.

Cam-
The NC results seem to echo Florida's results, and Sandia's, and California's, very nicely. Tracking increases output, sure. Look at some of the figures for dual-axis panel output versus time of day, and you'll see that even with tracking--outside of the four-hour "noon" slot, output is still going way down, making it simply impossible to get "eight hours" at the panel's rated output, unless it is mounted on an aircraft and chasing the sun.


But...I'm still willing to see if PS, or SS, can demonstrate an error in these ways. Kinda like the guys who proved that with sufficient thrust, even a brick outhouse can be made to fly. Honest.

[sailingdog]

Originally Posted by hellosailor

Okay, if you can stand reasing it, the Sandia lab PDF says enough to say it all. http://www.nrel.gov/docs/fy01osti/29245.pdf

Thanks for the link... Just what we needed more to read...

They used dual-axis mounted photocells, to keep them aligned with the sun in two axis not just one, and the kicker comes around page 43 when they note that the total average daily power output (daily POWER, as in watt-hours) ran about 4.8x the maximum rated power output (plain WATTS) for the panels.

IOW a 100-W rated panel could be expected to produced about 480 watt-hours of power under year-round average conditions. At 14 volts, that would be some 34 amp-hours of power. Regardless of the panel type, and assuming 100% power utilization, i.e. an MPPT controller.

To look at a device that is designed to charge batteries, without bringing battery charging into the context of the discussion is pointless, and we all know that charging batteries, even with an MPPT charge controller is going to be considerably less than 100% efficient.

Brian, from SolarStik, indicated that they are using batteries at an 11.5 volt level, which as Cam has pointed out is essentially completely discharged. Given that completely draining the batteries vastly shortens the lifespan of the batteries, using that as a voltage point for the batteries is somewhat dishonest IMHO.

The testing should have been done with the batteries at the 50% charge level, which is the most that an intelligent user will generally allow their batteries to get down to. As the charge level of the batteries goes up, their ability to accept current goes down drastically. By using the voltage level of 11.5 Volts for their testing, SolarStik is artificially inflating the amount of energy stored by the batteries as compared to what the actual real-world usage would be.

For those of you looked at the PDF and ran away screaming (and I don't blame you) they also tested five "standard" types of days and locations, and there don't appear to be any situations that would allow for getting twice that much power out of a panel during any given day on this planet.

Seriously considered this... but been at it too long to give up now.

The Florida results seem to echo Sandia very nicely, and additionally confirm that pretty much every panel on the market, regardless of maker or type, varies only a few percent from the rated output, which again is going to be higher than the real world output--any where, any time, any conditions, that the panels will be on this planet.

That makes sense... from a purely economic viewpoint the manufacturer has no incentive to make panels that are rated more than their stated output under the STC conditions. The production run of any given panel should average out to the stated power rating. This appears to be something the SolarStik people don't understand.

Cam-
The NC results seem to echo Florida's results, and Sandia's, and California's, very nicely. Tracking increases output, sure. Look at some of the figures for dual-axis panel output versus time of day, and you'll see that even with tracking--outside of the four-hour "noon" slot, output is still going way down, making it simply impossible to get "eight hours" at the panel's rated output, unless it is mounted on an aircraft and chasing the sun.

This also implies that on any day that has more than 12 hours of daylight, you won't get (Length of day-4) hours of full output—ergo, you won't get 10 hours of full output on a 14-hour day. This means that most of the best case estimates in this thread are very optimistic and generous.

But...I'm still willing to see if PS, or SS, can demonstrate an error in these ways. Kinda like the guys who proved that with sufficient thrust, even a brick outhouse can be made to fly. Honest.

Again, we should see when PS publishes their testing results. I would also be interested in having PS do a longer term study, since it is known that solar panels drop output after their initial "break-in" period. BTW, the Space Shuttle proves that every time it goes up and comes back...

[hellosailor]

"Brian, from SolarStik, indicated that they are using batteries at an 11.5 volt level," Did he really?! And I missed that one?

Actually, if he uses batteries that are discharged to 11.5 volts that's a very good thing. Most battery makers will tell you that cycling a battery that low even dozen times can kill it. So, if that's his test parameters? Let him repeat his test three or four dozen times--and he'll "prove" the Solar Stik kills batteries and provides no useful charge at all.

"since it is known that solar panels drop output after their initial "break-in" period." Yeah, and some of the PDFs account for that as well, with "break in" cycling before the testing began.

You don't suppose...Someone at PS has invented the whole SolarStik controversy in order to boost subscription sales this spring?

Look out, my Evil Twin Brother has gotten to the computer again!

[camaraderie]

Let me clarify that last point. Brin said that his most recent days testing produced about 63AH's (due to a partly cloudy day) on an 11.5 volt reading battery. As pointed out...this is not a fair test as no one would do THAT to their battery to get a good A/H result. On the other hand, Brian has not said how ALL his testing has been done or what the other test conditions were so I would be careful about extending what he reported about a single test universally.
Nevertheless...the tracking data HS reports appears remarkably similar and even if you could get 2X the input hours (clearly ridiculous) from reflections (as Tomaz points out could be a factor) you still come up short of 10 hours of full output.
HS...thanks for the data and the new reading material.

[hellosailor]

Originally Posted by xort

seems I remember conky joe was going to get back to us early this week with some new info.

Instead they've moved the 'conversation' to another forum and bash this forum in the process...

The Solar Stik... fact or fiction? ...the debate: - Ask All Sailors Forum

xort-
A funny thing:

"Oops!
The topic you're looking for is not in our active forums. This may be due to... "

Apparently the thread has been moved to their Hunter Owner's Forum *archive* if anyone is looking for it:

http://archives.sailboatowners.com/p...07096173139.65

And locked (?) no replies can be added.

[sailingdog]

Hmmm. Interesting that they've locked that thread.

[xort]

The SBO board administrator admitted to me that the thread was 'pretty much in violation of forum policy to begin with' and when it turned ugly he pulled it. Seems to me to be a fair handed administrator, a tough job.

Practical Sailor told me the test is due in June or July.

As the starter of this thread I'd like to thank you all for the information. It's been very educational although not in exactly the way I envisioned it.
I'd like to ask that lets set aside the solar stik specifically for the time being and discuss the general issue of the effectiveness of solar & wind, especially for eliminating or drastically reducing the need for engine or generator recharging when at anchor for extended periods. My personal needs, hopefully soon, will be while cruising the Bahamas and the east coast US.

Do I get a gold star for the longest thread on sailnet?

[sailingdog]

Xort-

I think Fight Club has you beat. That thread is currently almost five times as long as this one... so you're not even a contenda...