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Old 18-10-2012, 23:18   #16
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Re: Be Honest, What do Your Panels Really Put Out...

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Originally Posted by SunDevil View Post
That is very cool. I like it. It looks like you have the same switches that I have to disconnect items too.

I'm not sure how much the wifi antenna support bars and mast are shadowing your panels (and what effect that will have).

I haven't used this at all, but it might be of interest.
Programmable Digital AH meter. Ideal for battery monitoring
The switches came from Defender or a surplus store, can't remember which. The computer works great, I'm typing this on it now. I move it from boat to boat and take it home, where we are now, and hook it to an old 12 volt battery under the computer table with a charger on it. This way I have all of my files always with me to work on our web site and such. Use a laptop on the road.

I never considered the shading from the antenna to be much, but I'm starting to see that it doesn't take much to effect things. I think I'll leave things alone for now as on the trips I mentioned we had 180 watts and now 200 and we were keeping up with things. We also still have the gen-set ....

Macgregor 26S Outside Mods page 13

...I made if we ever need to fill in and I really should run it every once in a while.

Thanks for the meter link. I took a fast look and it looks like it might have some features I'm might like. I would like to hook an hour meter on the new fridge to get some actual numbers on it vs. the guessing I've been doing. Anyone know of a cheap 12 volt clock I could wire to the fridge controls so that when it came on the clock would run and then stop when it went off. I could then just see how many minute/hours it ran in say 48 hours,

Sum
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Old 18-10-2012, 23:46   #17
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pirate Re: Be Honest, What do Your Panels Really Put Out...

Well... I can't come out with fancy formulas and figures.. just experience..
In June '01 I solo'd a Bendi 321 from St Martin to the UK non stop.. I had a Plastimo tiller pilot and for this I bought a standard car battery and a 10watt solar panel to act as a stand alone unit dedicated to the pilot... kept me powered all the way..
In 2010 I bought a Raymarine 1000 TP and 2x20watt panels... this for a 21ft boat... they were woefully inadequate.. the pilot would die 3-4hrs after sunset... and they were sunny days..
I've since learned that the mineral used in the originals has run out and the makers are using substitutes that have nowhere near the efficiency of the old.. for me wind power is the only way to go today... for the price of those two plus one more I could have bought a basic wind generator... live and learn..
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Old 19-10-2012, 01:09   #18
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Re: Be Honest, What do Your Panels Really Put Out...

Solar panel output is very dependent on location and time of year.

Rules like wattage /3=AHrs are often quoted and can be useful, but its important to realise there will be considerable variation.

If you look up the insolation values for the area and time of year you will have a much better idea of the expected output.

In my own case 330w gives me an average of 175 AHrs in summer dropping to about 60AHrs in the middle of winter.this is in the Mediterranean.
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Old 19-10-2012, 01:19   #19
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Re: Be Honest, What do Your Panels Really Put Out...

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The MPPT will only continue to charge you in marginal light if the array voltage is at or above the minimum charge voltage. For this reason, we purchased pannels with open circuit voltage of 54 VDC. Our system is 24 volts so we can charge even as the clouds cover or the sun drops. I have considered a switch system to change the three panels form parallel to series to continue to generate in lower light but the gain might be too small to worry about and the risk of damage to the MPPT is real if we forget to switch back. Our MPPT can handle 118 VDC input.
I would not recommend this. Solar controller are not tolerant of excessive voltage and will usually be rapidly destroyed by a voltage only slightly over the specifications.

Once the panel voltage has dropped below the battery voltage due to low light there is almost no energy that can extracted from the solar panel anyway.
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Old 19-10-2012, 01:33   #20
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Re: Be Honest, What do Your Panels Really Put Out...

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I've since learned that the mineral used in the originals has run out and the makers are using substitutes
Solar panels are getting better, not worse. The modern counterparts are more efficient and much cheaper than their older counterparts.
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Old 19-10-2012, 04:48   #21
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Summers sailing Maine waters our (2) 54 watt panels will put out 7.5 amps at peak. The panels are mounted on "solar trackers" (James Baldwin design) which increases their efficiency somewhat. Our demand is very low at the moment. So I can't say for sure what the total output might be. Watts/3 would give us about 36 amps. That would do us just fine. They are our only source of power and they work great!!!!
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Old 19-10-2012, 05:51   #22
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Re: Be Honest, What do Your Panels Really Put Out...

I'll also mention that wire size between devices has a lot to do with efficiency and getting the power from point A to B. Check the sizes and be sure they are sized properly. There have been a lot of systems with undersized wires found out there.

Steve in Solomons MD
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Old 19-10-2012, 06:08   #23
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Re: Be Honest, What do Your Panels Really Put Out...

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Originally Posted by Sumner View Post
Anyone know of a cheap 12 volt clock I could wire to the fridge controls so that when it came on the clock would run and then stop when it went off. I could then just see how many minute/hours it ran in say 48 hours,
Any hour meter like those sold for engine hours will work. We have a digital one on our fridge from Grainger or McMasterCar (or someplace like that) ~$30.

Here is an example: REDINGTON Hour Meter, Electronic - Hour Meters - 3AE22|3311-2000 - Grainger Industrial Supply

Mark

EDIT: Holy crap! That meter I randomly linked to is being cleared out for $0.99! Just picked up 4 of them and am going to randomly buy a lottery ticket now...
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Old 19-10-2012, 06:22   #24
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Re: Be Honest, What do Your Panels Really Put Out...

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There is never really an "average" solar day; it's all over the map.
I would think San Diego would get as close to a boring average solar day as possible.

In the Caribbean during trade wind season, one can pretty much count on steady, sunny days with the boat facing NE for months on end. During this time, our daily output never really varies more than 10%.

Mark
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Old 19-10-2012, 06:36   #25
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Re: Be Honest, What do Your Panels Really Put Out...

Our app. 285 Watts of solar panels, (= the 4 combined), have individual AND a collective A. meter wired in. Even after 16 years of use, (mostly as full time livaboards), they put out between 9 and 15A. This was confirmed last week.

By using energy efficient versions of everything, even with refrigeration, SSB, water maker, and all the comforts... We get by on about 30 to 40 Ah/day.

Our solar panels have our 340 Ah. Trojan L-14, (6V in parallel) batteries, to 100% full, usually before noon! On a very overcast day, it might be most of the day, but we still get there.

By having the right balance of solar to daily need, (=2X min)... and large high quality 6V batteries, (good for 2X the cycles of their 12V. batteries), we get over 10 years of reliable service from them. With HydroCaps, we water them just once every 3 months...

By topping off to 100% charged daily, and maintaining high V., electrical things work better & longer. Also, by re-zeroing the Link 10, it maintains perfect accuracy.

We are therefore, 100% "solar self sufficient", 95% of the year. The other 5%,. (when doing week long + passages), we need to have the engine's little 55A. alternator, bring us up a bit, just before sun up. (45 min)... This gets us up to 100% again, with solar, by sun down.

The key to solar success, is have over 2X (in Ah. production) the daily usage, separate the panels for some/most of them to always go unshaded, for one to be tiltable, minimize the boat's Ah. need, have large HIGH quality batteries, cycle them shallow, and top them off to 100% charged daily.

I've used solar exclusively since the 70s. Those that have trouble powering their boats with solar, aren't doing it right!
M.
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Old 19-10-2012, 08:32   #26
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Re: Be Honest, What do Your Panels Really Put Out...

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My panels get a daily scrub, and are shadow-free most days until the sun is too low on the horizon to worry about.
This is more important than most people realize. Just a little bit of shadow falling across a solar panel reduces its output by a LOT!

In the picture in the original post, it appears that there might be a brace that could cast a shadow on one of the panels for a good bit of the day (if not all of it). This would have a significant effect.
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Old 19-10-2012, 09:00   #27
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Re: Be Honest, What do Your Panels Really Put Out...

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This is more important than most people realize. Just a little bit of shadow falling across a solar panel reduces its output by a LOT!
Yep. I recently went below and glanced at the charge controller, and it showed I was only getting 12 amps output in the middle of the day. Went up to check the array, and sure enough a gull had splattered the panels. Rinsed them with a bucket of freshwater, and right away they were back up to 14 amps.
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Old 19-10-2012, 09:09   #28
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Re: Be Honest, What do Your Panels Really Put Out...

We have 795 Watts of solar and a Blue Sky 60 amp Controller, which accepts incoming voltages betweem 36 and 48 volts. This allows me to run the panels in paired series. The house bank is 968 Amps.

I have not done a log, but what I can tell you is my Catalina 47 with two 12v refrigerators, computers and radios has sat on the anchor for 7 days without running the gen set, which I think is what we are trying to accomplish.

Down here in Panama the rainny seaason is hell on solar, but on a nice sunny day my solar panels are making between 45 and 48 amps per hour.

Even right now as I type this, it is drizzling with overcast skys at 10am and I am generating 15 amps output charge current to the batteries!

I guess-t-mate I am making about 300-320 amps per day, again on clear sunny days.

Someone once told me buy as much solar as you can fit on deck and afford. They were right!
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Old 19-10-2012, 09:15   #29
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Re: Be Honest, What do Your Panels Really Put Out...

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Originally Posted by colemj View Post
Any hour meter like those sold for engine hours will work. We have a digital one on our fridge from Grainger or McMasterCar (or someplace like that) ~$30.

Here is an example: REDINGTON Hour Meter, Electronic - Hour Meters - 3AE22|3311-2000 - Grainger Industrial Supply

Mark

EDIT: Holy crap! That meter I randomly linked to is being cleared out for $0.99! Just picked up 4 of them and am going to randomly buy a lottery ticket now...
Thank you, thank you . I just ordered 6 myself (can't get lottery tickets here ). All the hour meters I found before were up in the $60 range.

Quote:
Originally Posted by Mark Johnson View Post
....The key to solar success, is have over 2X (in Ah. production) the daily usage, separate the panels for some/most of them to always go unshaded, for one to be tiltable, minimize the boat's Ah. need, have large HIGH quality batteries, cycle them shallow, and top them off to 100% charged daily.

I've used solar exclusively since the 70s. Those that have trouble powering their boats with solar, aren't doing it right!
M.
Great post Mark. I hope we are about the same place with the panels on the Endeavour and more batteries. I think we will be there easily with the "over 2X (in Ah. production)" and storage you recommended.

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...Someone once told me buy as much solar as you can fit on deck and afford. They were right!
Yep, I'd rather be in the too much vs. not quite enough group,

Sum
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Old 19-10-2012, 09:31   #30
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Re: Be Honest, What do Your Panels Really Put Out...

i have 6 panels--i dont always use them all at one time. i have seen everything from 1.7 to 10.8 amps per hour coming into my boat here in sunnyland...it depends on how much i use over night and how much sun there is to use. is very very sunny here, so i am using only 1-2 panels every day, no problems. some charging happens, i have noticed, when sun lights thru my tarps--is a wonderment.
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