Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 03-03-2015, 13:26   #16
֍֎֍֎֍֎֍֎֍֎

Cruisers Forum Supporter

Join Date: Apr 2006
Posts: 13,022
Re: Realistic Solar Panel Output in Carribean

A nominal 860 Watts. If they were angled to the sun, a full day in an average place further from the equator would give you five effective hours of full output, so maybe that's more like 4 with the panels being flat. (An MPPT controller would also boost the output.) About 3300Wh or 860 Ah per day, as a first fast rough idea.


For a better number, you need to know cable losses, controller type, battery state, latitude and time of year, and then go look for Sandia National Labs or one of the other sites that will tell you how many "hours" or what output you can expect from the panels, based on your exact latitude and time of year.


Or you can add a wattmeter or battery meter into the circuit and find it out the old-fashioned way. Even do that with just an ammeter, noting the amperage every 15-30 minutes and then averaging the numbers at the end of day, say, from 8AM to 4PM. Noon to 2PM is usually peak, with an additional 10% loss every hour before/after that, compounded every hour.


Rough numbers but they'll get you in the ballpark pretty painlessly.
__________________

__________________
hellosailor is offline   Reply With Quote
Old 03-03-2015, 15:53   #17
Registered User
 
clownfishsydney's Avatar

Join Date: Mar 2014
Location: Sydney, Australia
Boat: Lightwave 38' Catamaran
Posts: 304
Re: Realistic Solar Panel Output in Carribean

We have 520 watts. Over the New Year period, we were getting up to 100 Ah net increase in a day from what the batteries were in the morning. As we were probably using 100 Ah during the day, this meant we were making about 200 Ah during the day. Of course, once you get your batteries closer to full, the input drops off dramatically, no matter the sun available.

A tip, if you want to charge things or use heavy use items (eg 110/240 v thru inverter), do this in the mid-afternoon if you can when the sun is still high and your batteries are fuller. Your solar controller will up the output to compensate for the extra usage.
__________________

__________________
Michael and Kelly
Catlypso - Web Site
Lightwave 38' cat
clownfishsydney is offline   Reply With Quote
Old 03-03-2015, 17:08   #18
Long Range Cruiser
 
MarkJ's Avatar

Cruisers Forum Supporter

Join Date: Dec 2007
Location: Australian living on "Sea Life" currently in England.
Boat: Beneteau 393 "Sea Life"
Posts: 12,828
Images: 25
Re: Realistic Solar Panel Output in Carribean

It might be a surprise to get a response from someone actually in the Caribbean!!

Doing the theretics is bs... So I will give u what I get and you can then sail down here are correct for your boat.

I have 320 watts of solar it puts in about 70 amp hours in total over a day whilst I am running a fridge and a seperate freezer, and the computer etc.

But this it up to 100%. So if I start the day on -70 amp hours on the battery monitor it should bring it back to pretty well fully charged.

If its a bad day and its down to -90 then its 2 days to get back to 100%.

One of he things that few people take into account is the trade winds clouds. Its not sunny here, its sunny with a nother cloud every 15 minutes. In the sun I might pull down 15 amps but a cloud will cut it back to 3 to 6 amps.

Then theres a few squalls each day that probably take out another half hour or so.

I have recently bought a wind generator to run at night and it probably averages 2 amps. Not much but keeps the batteries to that -70amp hours. If people tell you they get 20 amps from wind its all wind. They need a very stable wind to be effective because unless they are spinning at high speeded the deacceleration and acceleration takes the tine of most gunts. Your 15 ampos is only for seconds. The average is quite low.

Its really just trial and error. But with the OPs battery bank you should be able to have a fair draw before you get into trouble.

My only advice is to quit work, cast the bloody lines off and come down here and see!!
__________________
Notes on a Circumnavigation.
OurLifeAtSea.com

Somalia Pirates and our Convoy
MarkJ is offline   Reply With Quote
Old 03-03-2015, 17:34   #19
Registered User

Join Date: May 2008
Location: daytona beach florida
Boat: csy 37
Posts: 2,844
Images: 1
Re: Realistic Solar Panel Output in Carribean

In florida/bahamas, 225 to 270 amps per day.
__________________
Take two at low eight
onestepcsy37 is offline   Reply With Quote
Old 03-03-2015, 17:41   #20
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
Re: Realistic Solar Panel Output in Carribean

Although MarkJ doesn't think we are in the Caribbean, I can give you our results from around 9N 79W.

480W of solar averages 120-150Ahr on sunny days and 60-80Ahr on cloudy days.

Mark
__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 03-03-2015, 18:40   #21
Registered User
 
zboss's Avatar

Join Date: Sep 2011
Location: On a boat
Boat: Cabo Rico 38
Posts: 3,426
Re: Realistic Solar Panel Output in Carribean

I've noticed that if you take the watts people say they have and divide by 4 you end up with about the same number of amps as are being reported. Give or take.
__________________
zboss is offline   Reply With Quote
Old 03-03-2015, 18:57   #22
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
Re: Realistic Solar Panel Output in Carribean

Quote:
Originally Posted by MarkJ View Post
It might be a surprise to get a response from someone actually in the Caribbean!!

Doing the theretics is bs... So I will give u what I get and you can then sail down here are correct for your boat.

I have 320 watts of solar it puts in about 70 amp hours in total over a day whilst I am running a fridge and a seperate freezer, and the computer etc.
Mark - Thanks for "real world" experience - Only clarification is the 70 amps total produced or net of the daily consumption loads?

Quote:
Originally Posted by colemj View Post
Although MarkJ doesn't think we are in the Caribbean, I can give you our results from around 9N 79W.

480W of solar averages 120-150Ahr on sunny days and 60-80Ahr on cloudy days.

Mark
Having lat/long data is useful.

People over and underestimate and maybe report their data. It would be nice to have someone do some controlled testing. MPPT series vs. parallel. Hourly tracked output, battery SOC, panel temp, ambient temps yada, yada, yada...

Lots of confounding in the data seems to be the norm. I am sure someone could define a testing regime.
__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 03-03-2015, 19:06   #23
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
Re: Realistic Solar Panel Output in Carribean

Quote:
Originally Posted by Ex-Calif View Post

People over and underestimate and maybe report their data. It would be nice to have someone do some controlled testing. MPPT series vs. parallel. Hourly tracked output, battery SOC, panel temp, ambient temps yada, yada, yada...
Our data represent averages of MPPT with panels in series/parallel in a part of the world which basically has no change in daylight hours and air temps in the 80's and 90's. The panel temps are too hot to touch most of the day. The output numbers assume little throttling due to high battery SOC.

On very good sunny days we will see 170Ahr and less good sunny days 100Ahr, but the 120-150 is a good all-round average for a typical sunny day here.

Mark
__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Old 03-03-2015, 19:22   #24
Moderator Emeritus
 
Ex-Calif's Avatar

Cruisers Forum Supporter

Join Date: May 2007
Location: Singapore
Boat: Maxi 77 - Relax Lah!
Posts: 11,514
Images: 4
Re: Realistic Solar Panel Output in Carribean

Quote:
Originally Posted by colemj View Post
Our data represent averages of MPPT with panels in series/parallel in a part of the world which basically has no change in daylight hours and air temps in the 80's and 90's. The panel temps are too hot to touch most of the day. The output numbers assume little throttling due to high battery SOC.

On very good sunny days we will see 170Ahr and less good sunny days 100Ahr, but the 120-150 is a good all-round average for a typical sunny day here.

Mark
I am sure your experience is real. I am not questioning you.

But my engineer horns are coming out. Controlled data testing is not what you are reporting. You are reporting observed data. No problem - that's what it is.

My comment was more specifically aimed at a lot of the assumed truths and folklore that gets tossed around in every solar thread.

One example - Panels too hot to touch - OK - what's the output at 35C, 40C - what variables affect the output - current load, battery temps, battery bank size, battery bank SOC. Controller type, controller make and model, panel brand, wiring sizes. Lat/Long, date, periods of shade, percent shade per period, sun azimuth, panel angle. Many of the parameters may be useless but some very interesting correlations can be made statistically and with data.

Anyway - I know I won't get what I am after until I do it myself. That's why OP question was good and the initial responses are good. He asked for a swag and he's getting them. I am kinda liking the 25%-50% multiplier - the 80% one has always seemed high.

Practical application is key. Most people are getting 300-500W on their boats without making them look like a solar farm so you fit the energy budget (1st step anyhow) into the solar array and you get the biggest array you can live with aesthetically.
__________________
Relax Lah! is For Sale <--- Click
Click--> Custom CF Google Search or CF Rules
You're gonna need a bigger boat... - Martin Brody
Ex-Calif is offline   Reply With Quote
Old 04-03-2015, 06:38   #25
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
Re: Realistic Solar Panel Output in Carribean

Quote:
Originally Posted by Ex-Calif View Post
I am sure your experience is real. I am not questioning you.

But my engineer horns are coming out. Controlled data testing is not what you are reporting. You are reporting observed data. No problem - that's what it is.

My comment was more specifically aimed at a lot of the assumed truths and folklore that gets tossed around in every solar thread.

One example - Panels too hot to touch - OK - what's the output at 35C, 40C - what variables affect the output - current load, battery temps, battery bank size, battery bank SOC. Controller type, controller make and model, panel brand, wiring sizes. Lat/Long, date, periods of shade, percent shade per period, sun azimuth, panel angle. Many of the parameters may be useless but some very interesting correlations can be made statistically and with data.

Anyway - I know I won't get what I am after until I do it myself. That's why OP question was good and the initial responses are good. He asked for a swag and he's getting them. I am kinda liking the 25%-50% multiplier - the 80% one has always seemed high.

Practical application is key. Most people are getting 300-500W on their boats without making them look like a solar farm so you fit the energy budget (1st step anyhow) into the solar array and you get the biggest array you can live with aesthetically.
I didn't think you were questioning the data - I thought you were asking for the parameters I collected them under.

I don't even think controlled experiments are meaningful, or even possible. Instead, a lot of actual averaged data can tell everything. We aren't shooting for a precise and accurate "number" here - just an average range for rather largish areas of the world ("Caribe", PNW, USEC, etc).

This only takes a few controlled variables - battery SOC and proper wiring not throttling output being the most important, if not the only ones that really matter.

When I was doing series/parallel experiments with ours, I have months of daily (even hourly) data in each configuration in controlled conditions. However, the endpoint of it all had the data squishing into the fairly tight average ranges I presented - there was no need to know the details of %clouds, daily temps, etc.

The actual brands of panels and controllers don't mean much because any variance here is going to be within the +/- of the averages anyway. The rest of the variables are pretty much uncovered by the long-term averages in largish geographical areas.

When all the variables are controlled, the results will show that high-voltage panels used with MPPT controllers in full sun with no shading in cool weather during the summer months feeding low SOC batteries always outperform everything else.

But they won't tell you what to expect in real use anywhere. For that, rules of thumb and anecdotal data give a range - which one uses to adjust their power usage or add more solar to fit their profile.

Mark
__________________

__________________
www.svreach.com

You do not need a parachute to skydive. You only need a parachute to skydive twice.
colemj is offline   Reply With Quote
Reply

Tags
rib, solar

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
Solar panel output Catalpa1 Electrical: Batteries, Generators & Solar 8 26-09-2012 12:55
Solar Panel output voltage? John Duckworth Electrical: Batteries, Generators & Solar 7 16-08-2012 15:39
Solar Panel Output granche1 Electrical: Batteries, Generators & Solar 6 04-04-2011 17:27
Use Solar Panel Output Directly? ciclon1942 Electrical: Batteries, Generators & Solar 7 23-05-2009 06:40



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 14:51.


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.