Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 24-06-2008, 12:52   #1
Senior Cruiser
 
schoonerdog's Avatar

Cruisers Forum Supporter

Join Date: May 2004
Location: annapolis
Boat: st francis 44 mk II catamaran
Posts: 1,174
Images: 4
30+ amps from solar panels!

4 175 watt panels going to a outback mppt mx60 showing 33 amps by 11am. Runs 110 liter freezer, 130 liter refrig, 17" laptop, anchor light, etc....about 100 amps draw during the night till the panels kick in.
__________________

__________________
schoonerdog is offline   Reply With Quote
Old 24-06-2008, 13:08   #2
CF Adviser

Cruisers Forum Supporter

Join Date: Dec 2007
Location: Wherever our boat is; Playa Zaragoza, Isla Margarita
Boat: 1994 Solaris Sunstream 40
Posts: 2,439
Wow Schoonerdog, way to go! I am just now replacing my single 75 Watt panel with three X 80 watts (plus my Rutland), but will have to look for space to mount anything near what you are carrying.

Brad
__________________

__________________
Southern Star is offline   Reply With Quote
Old 24-06-2008, 13:22   #3
Registered User
 
Stella Polaris's Avatar

Join Date: Apr 2007
Location: Stavanger
Boat: Ovni 445
Posts: 299
I'm in the process of mounting two 215 watt Sanyo panels with a Blue Sky solar booster in addition to the Air Breeze unit. I'm really curious how many amps I'll be able to wring out of them. I think it'll be a good set-up, both for sunny and windy days, because they usually don't coincide.
__________________
~~~~~~~~~~~~~~~
Our blog
Stella Polaris is offline   Reply With Quote
Old 24-06-2008, 13:47   #4
Senior Cruiser
 
colemj's Avatar

Cruisers Forum Supporter

Join Date: Oct 2005
Location: Presently on US East Coast
Boat: Manta 40 "Reach"
Posts: 10,049
Images: 12
Schoonerdog,

Are those 24V panels? It seems like you should see more than that out of 700W, particularly with a MPPT controller. We have 4 Kyocera 120W panels regulated by a conventional Trace 40 regulator and see ~30A in direct sun in CT.

If these are 17V panels and if it was just early in the day, or not direct sun, then you are going to be even more happy later in direct sun!

Mark
__________________
colemj is offline   Reply With Quote
Old 24-06-2008, 13:53   #5
Registered User
 
Latitude9.5's Avatar

Join Date: Jun 2006
Boat: CAL 3-46
Posts: 441
Send a message via AIM to Latitude9.5
I have 4 85 watt panels, outback mppt, I see 25 to 30 all day, (during the summer) but then again I am in south florida and it's hotter then hell today lol
__________________
Latitude9.5 is offline   Reply With Quote
Old 25-06-2008, 14:25   #6
Senior Cruiser
 
schoonerdog's Avatar

Cruisers Forum Supporter

Join Date: May 2004
Location: annapolis
Boat: st francis 44 mk II catamaran
Posts: 1,174
Images: 4
good comments, the most I've seen is 33 amps, but it could definitely give more. It's just by the time it hits 11am (which in the way the panels are facing is no where near directly overhead) the batteries are typically topped off. I wanted to have enough solar I could completely rely on it, even on cloudy days. My freezer and refrig are the biggest draws by far, pulling around 80 amps during the night (hot muggy night at anchor). I'm going to look at more effectively venting the compressors which should help.
__________________
schoonerdog is offline   Reply With Quote
Old 25-06-2008, 17:23   #7
Registered User

Join Date: Sep 2006
Location: Right now, Australia
Boat: Lagoon 420
Posts: 587
Images: 4
Are you guys wiring your panels in serial or parallel? I have looked long and hard at this and am finding the conventional advice, to wire the panels in parallel, out of whack with my current set of conclusions. The kyocera 135W panels I am ordering have bypass diodes built in so I figure I can wire the panels in series and then run the higher voltage (same Amps) into the MPPT and make the full use of it's capabilities. Am I missing something in my assessment?
__________________
Dignity on the web
ess105 is offline   Reply With Quote
Old 26-06-2008, 23:45   #8
Senior Cruiser
 
schoonerdog's Avatar

Cruisers Forum Supporter

Join Date: May 2004
Location: annapolis
Boat: st francis 44 mk II catamaran
Posts: 1,174
Images: 4
parallel, I didn't want to go much over 48 volts for the shock factor. I think the phone company came to the same decision when they chose a voltage for the phone lines a long time ago. My panels are running 36 volts actually when you measure it, so any series could put the line voltage up to 72 volts, which is seen as pretty dangerous. When I was doing a bit of research I saw that in industry DC voltage is very tightly regulated because unlike AC it doesn't have a self extinguishing arc. 48 volts is pretty much the upper limit and mine are now at 36 volts as measured at the MPPT. Anyway, I ran two sets of 10/2 ga wiring back where they are combined at the MPPT. From there they go in 4 ga cable to the batteries about 5 ft away. MPPTs aren't ignition protected, so they can potentially ignite the offgas from batteries so the MPPT must be located away from the battery compartment. That was a really big pain.
__________________
schoonerdog is offline   Reply With Quote
Old 27-06-2008, 03:50   #9
Senior Cruiser
 
Alan Wheeler's Avatar

Cruisers Forum Supporter

Join Date: Dec 2003
Location: Marlborough Sounds. New Zealand
Boat: Hartley Tahitian 45ft. Leisure Lady
Posts: 8,038
Images: 102
The danger with DC is, it won't allow you to let go. It retracts your mussels and holds you there so you can not let go. And you don't feel the belt that you get with AC. AC hurts because the pain comes from the muscle spasm of 50/60Hz.
As for series connecting panels, you have to ensure your panels do not produce a voltage higher than what the controller can handle. I don't know of one that can handle 72V. There are 36 and 48V for domestic installations, but you need a regulator that is rated for the voltage.
__________________
Wheels

For God so loved the world..........He didn't send a committee.
Alan Wheeler is offline   Reply With Quote
Old 27-06-2008, 05:08   #10
Registered User

Join Date: Sep 2006
Location: Right now, Australia
Boat: Lagoon 420
Posts: 587
Images: 4
Very good point about the arcing and separation from the batteries. I'll have to think about that. With respect to the dangers of the higher volatage I intend to use regulation wiring and put that inside tubing to prevent chaffing. I'll put the wiring/tubing on my periodic inspection list - perhaps once every six months. I've ordered the Flexmax 80 MPPT which has a 145V open circuit voltage maximum. The panels I have put out around 19V unloaded so I figure I have enough margin - even if I add a fifth panel at a later date.
__________________
Dignity on the web
ess105 is offline   Reply With Quote
Old 27-06-2008, 05:38   #11
Senior Cruiser
 
schoonerdog's Avatar

Cruisers Forum Supporter

Join Date: May 2004
Location: annapolis
Boat: st francis 44 mk II catamaran
Posts: 1,174
Images: 4
the popular outback mppt 60 that I have will also handle up to 120V DC and step it down but you also need to keep an eye on the rated maximum amps out. For me with 700 watts that's very close to the 800 watt maximum for the outback. You can also wire in series within two sets of 4 panels and then combine the two sets in parallel and run that back, so the voltage coming back through the line would be something like 38 volts. That's high enough to give you efficiency for your wiring, but not high enough to seriously hurt you.
__________________
schoonerdog is offline   Reply With Quote
Old 27-06-2008, 05:46   #12
Registered User

Join Date: Sep 2006
Location: Right now, Australia
Boat: Lagoon 420
Posts: 587
Images: 4
I considered (and am still considering) the two in series/parallel combo for four panels. What I couldn't work out is what happens when part of one of the four panels is shaded. If they are all in series, I am assuming the power from the other panels is routed around the shaded (now resistent) panels via the bypass diode and the overall voltage drops. This would happen with one of the set in series and now I'd have two different voltages in parallel. The best I can think is this would be like wiring a 12V battery in parallel with a 9V battery. I don't understand what happens in this scenario.
__________________
Dignity on the web
ess105 is offline   Reply With Quote
Old 27-06-2008, 05:53   #13
Moderator Emeritus
 
GordMay's Avatar

Join Date: Mar 2003
Location: Thunder Bay, Ontario - 48-29N x 89-20W
Boat: (Cruiser Living On Dirt)
Posts: 31,579
Images: 240
Quote:
Originally Posted by Alan Wheeler View Post
The danger with DC is, it won't allow you to let go. It retracts your mussels and holds you there so you can not let go...
I’ve personally experience this phenomenon. As a young electrician, I got “hung up”, when I cut into a 120 Volt Direct Current (DC) line, and was absolutely unable to either cut through (#10 AWG) the wire, nor let go. The pain was excruciating, and I decided that I was not going to die “this way”, so I ended up throwing myself off the 80 Ft. high structural steel beam (upon which I was working), expecting my body weight to break my grip on the wire (or break the wire). Fortunately, it did, and I only fell about 12 - 15 Ft. To a catwalk (not the 80' to the floor).

However:
Low-frequency AC (50- to 60-Hz) can be more dangerous than high-frequency AC, and is 3 to 5 times more dangerous than DC of the same voltage and amperage.

Low-frequency AC produces extended muscle contraction
(tetany), which may freeze the hand to the current's source, prolonging exposure.

DC is most likely to cause a single convulsive contraction, which often forces the victim away from the current's source, except if the victim contacts an energized conductor with his hands.

The forearm muscles responsible for bending fingers tend to be better developed than those muscles responsible for extending fingers, and so if both sets of muscles try to contract because of an electric current conducted through the person's arm, the "bending" muscles will win, clenching the fingers into a fist. If the conductor delivering current to the victim faces the palm of his hand, this clenching action will force the hand to grasp the wire firmly, thus worsening the situation by securing excellent contact with the wire. The victim will be completely unable to let go of the wire, as happened to me.

AC's alternating nature has a greater tendency to throw the heart's pacemaker neurons into a condition of fibrillation, whereas DC tends to just make the heart stand still. Once the shock current is halted, a "frozen" heart has a better chance of regaining a normal beat pattern than a fibrillating heart.
__________________
Gord May
"If you didn't have the time or money to do it right in the first place, when will you get the time/$ to fix it?"



GordMay is offline   Reply With Quote
Old 27-06-2008, 06:11   #14
Registered User

Join Date: Jun 2008
Location: St. Louis, MO; Grenada
Boat: Lagoon 420
Posts: 144
I spoke recently with the technical people at a MPPT manufacturer. If the panels are of different size, manufacturer, or likely to be shaded at different times, then the panels should be hooked up in series.
__________________
Bradley is offline   Reply With Quote
Old 27-06-2008, 06:45   #15
Registered User

Join Date: Sep 2006
Location: Right now, Australia
Boat: Lagoon 420
Posts: 587
Images: 4
Gord - thanks for pointing out the risks. At the end of the day we must choose to either avoid, manage, assume or ignore risks. If we always avoid them we'll never get out of bed in the morning. 80V DC is a risk that I believe can be managed well if one is aware of the risks.

Bradley - your comments are in line with my own conclusions. I'm assuming you're implying the panels have suitable bypass diodes when you make that statement. On a sailboat with masts and rigging (not necessarily on your own boat) all conspiring to partially shade arrays of panels I think it is impossible to guarantee a balanced array.
__________________

__________________
Dignity on the web
ess105 is offline   Reply With Quote
Reply

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
No amps from solar controller Jumbyway Electrical: Batteries, Generators & Solar 5 16-06-2008 07:23
Controller for solar panels dennisjay Electrical: Batteries, Generators & Solar 1 13-03-2008 22:09
A GENERATOR AND SOLAR PANELS....... High Cotton Electrical: Batteries, Generators & Solar 20 06-03-2008 19:43
Where to mount solar panels? Rhythmsmith Electrical: Batteries, Generators & Solar 21 16-12-2007 13:52
Do You Need Solar Panels? StoutWench Electrical: Batteries, Generators & Solar 3 15-12-2005 21:33



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 06:24.


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.