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More on solar panels.

8K views 47 replies 15 participants last post by  sonofasonofasailer456 
#1 ·
Ive been looking for some solar panels to keep the batteries in my Pearson charged up. Now im going to admit right out, im broke so cheap is my only option. Ive been looking at the Sunsei line from WM, but they are still high priced. Ive got one of the $99 SE-500 panels, but it doesnt do alot for keeping up with my useage. Ive been looking at the SE-1500, but at $179 plus another $40 for the controller, its still a bit high for not much power output.

Now ive just found that Costco sells the same panels under the Coleman name for ALOT less. They sell a kit that has three SE-1500 panels and a controller for $289. Now this is alot cheaper than west marine. I know these arnt high output panels, but for what i need, they will do fine. Im going to have 2 Trojan T-105's soon. My power useage isnt that much. Ive got a Davis Megalight for my anchor light, i use maybe 2 hours a night of my cabin lights. Now my cabin lights are the old style house sized bulbs. I know they are high power. I dont have any other way to charge than solar or my generator and that sucker is noisy.

Costco - Coleman® CL3600 Solar Back up Power Kit 54 Watts by ICP
 
#36 ·
Window solar panels

I am looking for a manufacturer of solar panels built into windows, suggest you look at a German firm "asola-power", but they are in development whereas I have heard that a japanese firm is selling them for sunroofs. Anyone encountered this?
fair winds, seanseamour
 
#37 ·
I am looking for a manufacturer of solar panels built into windows, suggest you look at a German firm "asola-power", but they are in development whereas I have heard that a japanese firm is selling them for sunroofs. Anyone encountered this?
fair winds, seanseamour
I couldn't find these panels - do you have a link?

By the way - when at my boat this weekend with Saildog we did some rather extensive looking at my system.

To refresh, I have a Kyocera 80w panel, 3 Optima blue tops with 210 total amp hours. I use a c-80 charge controller for that, and I am not plugged into shore power. My monitor is a Xantex XBM wired on a toggle so I can check house and starter banks.

On a bright day in March, 10% cloud, at noonish with the panel tilted 20 degrees out of plane I was getting 2 amps - the batteries were showing 12.9v and a 99.6% charge.
I re-angled the panel to closer to flat to the sun, and stangely enough dropped to 1.2 amps, 12.9v.
Two hours later - I was at 100%, reading 13.3v and 212ah of capicity, with .9ah coming from the panels. We assumed this meant I was topped off at 210 ah, the extra 2 showing was the capicity available from the panels.
I turned on my anchor light - ah in went from .9 to .2, then built back up over a few seconds to .9 - In short, absolutely dead spot on what should have happened (the light put a load on it, the controller read the load and allowed the panel to pick it up).

How's that for fun. I don't gete that every thing out there says 12.6v is the max. I've seen 13.9 on my monitor - with a load being drawn. I do know about overcharge and equalization - mine is disabled. I also know you can have a higher voltage showing - and it's a 'flash' voltage, not real, and it's supposed to drop as soon as you put a load on. My batteries stay over 13v for hours at a time.

Nuclear engineering?

and a big raspberrry to the solar stick thread - I've read every frigging post and most of the semi-demi-god Nigel Calder has written. Unless it's exactly the same as my question it's not, well, the same. Rasp'emberry, sloppy ones even.
 
#38 · (Edited)
"For me to get only 16 amps (1/3 of 48) I would have to have less than 5 hours of sunlight."
And that's the reason to read the other, older, longer threads. They touch on the difference between amps and watts and amps and amphours, and the fact that "sunlight" is not a fixed or even quantity but one that varies through the day and latitude. And that variation is well known, well-documented, and detailed in the URLs in some of those other articles.

The bottom line is that you need to measure POWER in WATTS not volts or amps alone. And with a loaded circuit (i.e. normal connections) you will see the POWER form a solar array rise closer to local noon, then drop a bit towards 2PM, then plummet somewhere between 3 and 7, depending on the time of year. You'll see about a 10% climb/falloff per hour during the day, outside of the two noon hours, no matter where you are or who has promised you better, with fixed panels.
Add it up, divide the numbers, and it always comes back to "Panel wattage rating divided by 3-4-5-6 coincides with actual panel output rating, in amp-hours at 12-13-14 volts. The exact numbers don't matter, the relationship stands as a general back-of-the-envelope one that will accurately predict performance.
Why does this work? Because panels are all substantially the same, sunlight is all substantially the same, and the only variables (lattitude and time of year) are also about the same all over the world. The 3-4-5-6 numbers are a FUDGE FACTOR. That is, they are chosen--they are the product of the human imagination--because they make the equations work and work consistantly. You take the panel wattage, you multiply by lumens of illumination or however you want to measure sunlight per square meter of panel, factor in atmospherics, height, temperature, angles of incidence...Sure, you can do all that the same way the labs do. And it comes back to "Just divide by four or five" gives you the same result.
But of course, you are welcome to follow the posted URLs, or rediscover them yourself, and do all the math, and when you're done...you'll discover the same fudge factors still work the same way.<G>
 
#39 ·
Chuck...
"I don't gete that every thing out there says 12.6v is the max. I've seen 13.9 on my monitor - with a load being drawn. I do know about overcharge and equalization - mine is disabled. I also know you can have a higher voltage showing - and it's a 'flash' voltage, not real, and it's supposed to drop as soon as you put a load on. My batteries stay over 13v for hours at a time."

By 12.6V...I assume you are commenting on the voltage of a fully charged 12V battery at rest. I believe this is really 12.66V but close enough for government work. You can ABSOLUTELY get voltage readings of higher than 12.6 volts on a recently charged battery and it can take from 12 to 48 hours for readings to fully drop back to 12.6V. This is called a surface charge and reflects additional electrical charge stored temporarlily on the batteries positive plate after charging and does not reflect the actual storage capacity of the battery.

Removal of the surface charge is necessary to check a batteries natural standing voltage. For a 100 amp battery...you can accomplish this with a 25 amp load for 30 seconds. (Extend the time or increase the amp load for larger banks.) Small house loads will not do the job of dropping the Voltage back quickly. Hope this clarifies the issue.


 
#40 ·
Absolutely, couldn't remember the term 'surface charge' (I said 'flash').
I didn't realize it needed to be hit that hard to flush it. I'll flip on the windlass next time, run some chain down and up for 30 and see what it says then.
Thanks.
 
#41 ·
Removing the surface charge is typically done on a car by leaving the headlamps (10A load) on for 3-5 minutes. A larger boat battery will need a larger load, but just hitting everything on the panel for 5 minutes should do it.

Then you still have a false surface depletion voltage showing.<G>

It can take 24 hours for the electrolyte to circulate (remember, there's no pump in there) and even out the charge in a wet cell. A false high voltage will show for at least that long.

12.6-12.8 volts is the maximum any nominal 12v lead-acid battery will ever charge up to, because of the chemistry of the battery. (Which varies a bit from brand to brand.) Anything over 12.8 is an illusion from surface charge, and every battery maker will tell you the same thing. That's also why their warranty test consists of using a LOAD TESTER that pulls high power form the battery--and not doing a simple voltage test. You'll find load testers on sale for $25-100 in "automotive" and "truck" sizes. They'll pull a thousand watts from the battery, emulating a starter motor's load.
 
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