Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 16-06-2015, 15:01   #1
Registered User

Join Date: Sep 2005
Posts: 229
Do you cool your solar panels to get more power?

I've been monitoring performance of my solar panels for last two months and on two occasions my panels produced more power than they are rated. I have two Schott Poly 230W (made in USA) panels. On typical sunny day here in PNW they produce around 370-380 W around noon this time of year. But, on two occasions I got peek of 520 W, for short period of time, than they stayed around 480-495W for extended period of time, slowly coming down as they warm up. On first occasion I thought it was something wrong with my OutBack FM60, as it started acting up around that time. Controller eventually failed completely and I replaced it with TriStar MPPT60. Everything went back to normal, except last week the same thing happened: it was rather cold morning (52 F?), cloudy, with thick marine layer, when around noon sun broke through openings in marine layer, allowing full sun at cold panels. I again saw over 500W coming out of these panels, staying above 460W for next couple of hours. I think clear skies with low humidity helped as well. This time I have no reason to believe that controller had a problem. I know for sure that cold panels produce more power. Mine are rated at -0.44% per deg C, but that helps only partially. Anybody else observed something similar? Opinions? Would it make sense to cool solar panels somehow? Do you know of any working, effective cooling?
__________________

__________________
BambooSailor is offline   Reply With Quote
Old 16-06-2015, 15:26   #2
Senior Cruiser
 
FSMike's Avatar

Cruisers Forum Supporter

Join Date: Aug 2009
Location: Bahamas/Florida
Boat: Solaris Sunstar 36' catamaran
Posts: 2,654
Images: 5
Re: Do you cool your solar panels to get more power?

In warmer climes it's recommended to elevate the panels a bit if you are installing them flat on a solid surface. Just enough to allow air flow beneath them. Don't know how much it helps, but that's what I've been told.
__________________

__________________
Sail Fast Live Slow
FSMike is offline   Reply With Quote
Old 16-06-2015, 16:18   #3
Registered User
 
travellerw's Avatar

Join Date: Jan 2014
Location: Martinique
Boat: Fortuna Island Spirit 40
Posts: 1,726
Re: Do you cool your solar panels to get more power?

I've wondered about this myself. There are couple of videos on youtube where water is run over an array. The rise in power was higher than I thought it would be. Had me wondering if it was worth while rigging up a flood system on a boat.

In the end, I didn't think it would be worth it as you would need to use fresh water (salt buildup would reduce output). You would use more energy making the fresh water then the gains.
__________________
travellerw is offline   Reply With Quote
Old 16-06-2015, 17:27   #4
Registered User
 
irwin37's Avatar

Join Date: Oct 2009
Location: Gettysburg Pa
Boat: 1981 Irwin 37
Posts: 193
Re: Do you cool your solar panels to get more power?

Keeping your panels cool will definitely help in output power but you will use that same extra power pumping water, and water on the front of the panel may actually reduce power production if the water is at all murky.

Now what you saw has nothing to do with the temp of the panel, the is a thing call cloud edge effect, in some cases as the sun comes out from behind a cloud the edge of the cloud and the water droplets in it tend to concentrate the sun slightly. This effect will only last a few seconds to a few mins based on how fast the clouds are moving and are sometimes followed by a short period (Seconds to mins) of lower output.

Google solar cloud edge effect.

John Collins
__________________
irwin37 is offline   Reply With Quote
Old 16-06-2015, 18:20   #5
Registered User
 
Paul54's Avatar

Join Date: May 2015
Location: Neuse River, NC
Boat: 1984 Catalina 36
Posts: 126
Re: Do you cool your solar panels to get more power?

Cloud edge effect is a factor, a big factor. But panels will produce higher than rated voltages when it is cold. If possible keeping some air space beneath the panels is a good idea, both for the panels operation and for providing shade underneath. Underneath is usually the Bimini or the cabin where people are. Trying to cool the panels is probably not worth it, but hosing dirt and dust off from time to time is.
__________________
Paul
1984 Catalina 36
Paul54 is offline   Reply With Quote
Old 16-06-2015, 18:21   #6
Registered User
 
El Pinguino's Avatar

Join Date: Aug 2013
Location: Punta Arenas ahorra
Boat: 39' Westerly Sealord
Posts: 3,959
Re: Do you cool your solar panels to get more power?

Edited..is a response to #4......Hmmmmm... maybe... I wouldn't expect an instant power spike when the sun comes or goes in so maybe that is cloud edge effect... I found a bit about that effect which was something I hadn't heard of before.... however it would appear that cold is good regardless.
'The edge-of-cloud effect is only going to be a problem when it is very cold outside and passing clouds. You can use this sizing tool for SMA Sunny Boy Products. Also, solar panels have a Voc (open circuit) and a Vmp (max power). for a 12VDC panel Vmp may actually be 17VDC and Voc around 21VDC. Since the edge-of-cloud effect normally occurs when the inverter or controller is running you already have some extra wiggle room.

(I guess you could have a rolling black during the day and have your grid-tie inverter shut-off. But then you would also have to have record cold temperatures. But then it would be winter and you would have less transmitted light because it has to travel though more atmosphere at an oblique angle. Plus you would have to have perfectly clean panels. As you can see, not likely to happen any time soon.)'
El Pinguino is online now   Reply With Quote
Old 16-06-2015, 18:44   #7
Registered User
 
Paul54's Avatar

Join Date: May 2015
Location: Neuse River, NC
Boat: 1984 Catalina 36
Posts: 126
Re: Do you cool your solar panels to get more power?

The higher voltage when it is cold is only a problem when the input to the charge controller is close to being maxed out. Acquaintances in Alaska and Northern Canada have learned to leave extra head room on the charge controllers max voltage input rating since the panels will exceed their rated output when cold.
__________________
Paul
1984 Catalina 36
Paul54 is offline   Reply With Quote
Old 17-06-2015, 08:41   #8
Senior Cruiser

Cruisers Forum Supporter

Join Date: Dec 2010
Location: Cruising Indian Ocean / Red Sea - home is Zimbabwe
Boat: V45
Posts: 1,282
Re: Do you cool your solar panels to get more power?

As FSMike says, don't mount them totally flat, leave a ventilation gap as this improves cooling significantly. I am not aware of anything else that is worthy of doing - just keep them clean. We clean ours every morning with a soft cloth with fresh water (we also run our 12v water maker daily) - one of the routines you get adopt - my job after putting the kettle on!
__________________
Bulawayo is offline   Reply With Quote
Old 17-06-2015, 10:05   #9
Moderator
 
noelex 77's Avatar

Cruisers Forum Supporter

Join Date: Jul 2007
Location: Living on dirt waiting for our new yacht to be built.
Boat: Half built Bestevaer.
Posts: 10,619
Re: Do you cool your solar panels to get more power?

The first thing to be careful of is that the displays on the charge controllers can sometimes be quite optimistic, but panels can and do put out more than their rated power on occasions. There are several reasons for this:

1. Illumination level:

The panels are measured at 1000w/m2. While this is very bright, it is not exceptionally bright. In some situations particularly with direct sun and reflected sun from cloud the illumination levels can be higher, especially briefly.

2. Rating /Age:

Solar panels do age slightly, particularly when very new. The better manufacturers offer a guarantee regarding future output. Often when brand new they will exceed the rating slightly.
The better manufacturers also provide some idea of variance: 0 to +5%, -5 to +10% or -5 to+5%. For the first couple of examples, on average you should get a panel that exceeds the nominal wattage.

3. Temperature:

The panels are rated for a cell temperature of 25C. In full sun they will generally be much hotter than this, but in cold climates especially when the sun briefly pokes out the temperature can be below 25C and the output will be higher.


Your higher panel output will be a combination of these factors, but I think it likely your meter is over reading. They generally do.

Cooling the panels by leaving an air gap is important. If you can come up with a better method of cooling the panels (pumping seawater for example) this has potential to be useful. Invent away . I suspect the complication and required pump power means that it not really viable. There have been some suggestions of heating hot water for showering etc that could be combined with cooling the panels. I think this is promising. Cell temperatures are often around 45C in summer conditions. This is warm enough to generate shower water, but pumping shower water temperature water around the panels would not cool them much.
__________________
noelex 77 is offline   Reply With Quote
Old 17-06-2015, 13:25   #10
Registered User
 
hamburking's Avatar

Join Date: Feb 2013
Location: Kingston Ont Canada
Boat: Looking for my next boat!
Posts: 2,149
Re: Do you cool your solar panels to get more power?

You could keep the panels cooler by putting them in the shade.
__________________
hamburking is offline   Reply With Quote
Old 17-06-2015, 15:19   #11
Registered User
 
Miz Pea's Avatar

Join Date: Jul 2008
Location: St. Petersburg, FL, USA
Boat: under construction
Posts: 42
Re: Do you cool your solar panels to get more power?

Rolling on Floor LMAO!!!

"You could out them in the shade."
__________________
Miz Pea is offline   Reply With Quote
Old 17-06-2015, 18:20   #12
Senior Cruiser
 
s/v Beth's Avatar

Cruisers Forum Supporter

Join Date: Oct 2008
Location: Coos Bay, Oregon
Boat: Valiant 40 (1975)
Posts: 4,066
Re: Do you cool your solar panels to get more power?

I'm kinda surprised you guys are not thinking outside the box. Why not liquid cool the solar panels, and use that heat for one of your hot water sources?
Solar Energy Advantages - DX3 Here is a crude example.
You might be able to custom fit some thermal collectors behind the solar using this technology:
Build your own flat panel solar thermal collector
Then you would have both cool panels and hot water.
Just an idea....
__________________
s/v Beth is offline   Reply With Quote
Old 17-06-2015, 20:32   #13
Registered User
 
tstano's Avatar

Join Date: Mar 2012
Location: NH
Boat: Pearson 530
Posts: 98
Re: Do you cool your solar panels to get more power?

Quote:
Originally Posted by s/v Beth View Post
I'm kinda surprised you guys are not thinking outside the box.
Build your own flat panel solar thermal collector
Then you would have both cool panels and hot water.
Just an idea....
How about a 12v fan under the panel? Low tech and would use some of that excess energy.

All U Get
__________________
All U Get
tstano is offline   Reply With Quote
Old 17-06-2015, 21:01   #14
Registered User
 
Privilege's Avatar

Join Date: Oct 2009
Location: Bermuda
Boat: Privilege 435
Posts: 362
Images: 12
Re: Do you cool your solar panels to get more power?

One thing that you may have to consider when calculating your output is this; if your panels are putting out 500w for a few hours then your batteries are getting charged quite well. The more your batteries become charged, the less they need and your controller will change from bulk charge to ABS or float charging which will be at a much less rate that the bulk charge. You will only get a true maximum output reading if you batteries are somewhat depleted.
__________________
Privilege is offline   Reply With Quote
Old 17-06-2015, 23:47   #15
Marine Service Provider

Join Date: Oct 2011
Posts: 1,205
Re: Do you cool your solar panels to get more power?

I use a little trick I developed in 1979. Freon, and fun with thermodynamics, called a co-generator.

Lloyd


Quote:
Originally Posted by BambooSailor View Post
I've been monitoring performance of my solar panels for last two months and on two occasions my panels produced more power than they are rated. I have two Schott Poly 230W (made in USA) panels. On typical sunny day here in PNW they produce around 370-380 W around noon this time of year. But, on two occasions I got peek of 520 W, for short period of time, than they stayed around 480-495W for extended period of time, slowly coming down as they warm up. On first occasion I thought it was something wrong with my OutBack FM60, as it started acting up around that time. Controller eventually failed completely and I replaced it with TriStar MPPT60. Everything went back to normal, except last week the same thing happened: it was rather cold morning (52 F?), cloudy, with thick marine layer, when around noon sun broke through openings in marine layer, allowing full sun at cold panels. I again saw over 500W coming out of these panels, staying above 460W for next couple of hours. I think clear skies with low humidity helped as well. This time I have no reason to believe that controller had a problem. I know for sure that cold panels produce more power. Mine are rated at -0.44% per deg C, but that helps only partially. Anybody else observed something similar? Opinions? Would it make sense to cool solar panels somehow? Do you know of any working, effective cooling?
__________________

__________________
FlyingCloud1937 is offline   Reply With Quote
Reply

Tags
panels, solar, solar panels

Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Some Cool Advances in Generating Solar Power Ocean Girl Electrical: Batteries, Generators & Solar 9 16-04-2014 06:57
AC72....Crazy Cool and Cool Crazy Ocean Girl General Sailing Forum 6 30-08-2013 06:22
To Keel Cool or Not to Keel Cool, that is the question swdreams88 Plumbing Systems and Fixtures 3 26-06-2012 14:45
I Wonder - If You Install a Wind Gennie or Solar Panels, Can You Get a Tax Credit? chuck711 General Sailing Forum 4 09-01-2010 08:09



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 23:45.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.