Cruisers Forum
 


Join CruisersForum Today

View Poll Results: What panel voltage should be supported?
under 30v (keep price low) 3 12.50%
up to 40v (compatible with most panels) 9 37.50%
up to 100v (allow large panels) 12 50.00%
Voters: 24. You may not vote on this poll

Reply
 
Thread Tools Rate Thread Display Modes
Old 26-03-2015, 16:06   #76
Marine Service Provider
 
OceanSeaSpray's Avatar

Join Date: Aug 2013
Location: New Zealand
Boat: Custom 13m aluminium sloop
Posts: 414
Re: Open Source MPPT

Here is an interesting paper about GaN FETs, some of you might already be familiar with it. They do have some notable difference from MOSFETs. They are more sensitive and not always as forgiving. They (those?) are not (cannot be?) avalanche-rated either and so not exceeding VDS is even more important.

We shouldn't let any charge control issues come in the way of the MPPT project, there is time to find pathways.

Regarding specs and after looking into GaN FETs, I would be increasingly tempted to favour a design intended for say ~300W. There are lots of smaller installations that would have no use for a large unit and would incur unnecessary cost. Even just cost+complexity aspects could well warrant designing a more modest converter and installing two instead of one large one, splitting the solar capacity.
Of course, that also means 300W panel max, but realistically, on a boat...?

I can see that an interleaved buck converter of that capacity could be small and low cost compared to a large unit, it would look like two of the power stage of the small Genasun unit, off-the-shelf toroidal inductors hopefully and within the thermal capabilities of the GaN FETs without having to deal with significant heat removal. GaN FETs are not as well set up for heatsinking compared to MOSFETs.
__________________

__________________
"The case for elimination: the only equipment that never needs maintenance and never breaks down is the one you don't have on board."
OceanSeaSpray is offline   Reply With Quote
Old 05-04-2015, 13:54   #77
Registered User
 
whiskthecat's Avatar

Join Date: Mar 2015
Location: Texas
Boat: Bruce Roberts Spray 36
Posts: 57
Re: Open Source MPPT

Okay, well I have the panel now, so that's a pretty decent start.
__________________

__________________
whiskthecat is offline   Reply With Quote
Old 06-04-2015, 11:21   #78
Registered User
 
whiskthecat's Avatar

Join Date: Mar 2015
Location: Texas
Boat: Bruce Roberts Spray 36
Posts: 57
Re: Open Source MPPT

Could a mod please remove the poll? Going with 100v.
__________________
whiskthecat is offline   Reply With Quote
Old 08-04-2015, 13:05   #79
Registered User
 
thomasow's Avatar

Join Date: Dec 2011
Location: Salish Sea & North
Boat: Monk/McQueen 45' - 1961 Trawler
Posts: 39
Re: Open Source MPPT

Quote:
Originally Posted by whiskthecat View Post
Okay, well I have the panel now, so that's a pretty decent start.
Pictures

And how are you looking to mount this, 96" or so isn't it?

-al-
__________________
Viking Star
45' Monk Sr. / McQueen
mvVikingStar.blogspot.com
thomasow is offline   Reply With Quote
Old 08-04-2015, 17:57   #80
Registered User
 
whiskthecat's Avatar

Join Date: Mar 2015
Location: Texas
Boat: Bruce Roberts Spray 36
Posts: 57
Re: Open Source MPPT


It's sitting on a ping pong table which is sitting on a pool table just to give a reference for scale in addition to the soda cans. I've been having nightmares about how I'm going to mount it but none of them have been all that useful. Any suggestions beyond what I'm seeing on google images would be more than welcome.


So it looks like during our discussion the next gen gan fets are now available for purchase but in 10qty at $10 per unit, ouch. They are substantially better though.
__________________
whiskthecat is offline   Reply With Quote
Old 13-04-2015, 12:05   #81
Registered User

Join Date: May 2011
Location: Toronto
Boat: Sandpiper 565
Posts: 2,941
Re: Open Source MPPT

here's a MPPT project using Arduino
__________________
Lake-Effect is offline   Reply With Quote
Old 29-04-2015, 23:55   #82
Registered User
 
whiskthecat's Avatar

Join Date: Mar 2015
Location: Texas
Boat: Bruce Roberts Spray 36
Posts: 57
Re: Open Source MPPT

Thought you guys might wanna check this out. Quite impressive.

http://www.gansystems.com/_uploads/w...0converter.pdf
__________________
whiskthecat is offline   Reply With Quote
Old 02-05-2015, 14:07   #83
Marine Service Provider
 
OceanSeaSpray's Avatar

Join Date: Aug 2013
Location: New Zealand
Boat: Custom 13m aluminium sloop
Posts: 414
Re: Open Source MPPT

Thanks for posting it. It is impressive, especially the lack of ringing considering the slew rate of the signals. The PCB layout might have given them a bit of work. The inductor on the photo must be hiding some HV capacitors.
One difference is that it is a low current application, very suited to GaN FETs.
__________________
"The case for elimination: the only equipment that never needs maintenance and never breaks down is the one you don't have on board."
OceanSeaSpray is offline   Reply With Quote
Old 08-05-2015, 10:07   #84
Registered User

Join Date: Nov 2013
Location: Nice, France
Boat: Hunter Marine 38
Posts: 281
Re: Open Source MPPT

whiskthecat: This is the way i mounted my solar panels on the SS tubing of the frame. The model depends on the tube diameter, you can find them in several sizes.
Attached Thumbnails
Click image for larger version

Name:	Solar panel clamps.jpg
Views:	89
Size:	366.6 KB
ID:	101604  
__________________
sailormed is offline   Reply With Quote
Old 08-05-2015, 23:34   #85
Registered User
 
whiskthecat's Avatar

Join Date: Mar 2015
Location: Texas
Boat: Bruce Roberts Spray 36
Posts: 57
Re: Open Source MPPT

Nice mount. I just need to figure out how to get my stainless railing from waist height to above head height.
__________________
whiskthecat is offline   Reply With Quote
Old 09-05-2015, 07:51   #86
Registered User
 
whiskthecat's Avatar

Join Date: Mar 2015
Location: Texas
Boat: Bruce Roberts Spray 36
Posts: 57
Re: Open Source MPPT

Okay, a couple of updates. I've yet to make the plunge and order any parts but in the meantime I have acquired a large 11 inch pulley for a prop shaft alternator and I've repaired my old Rutland wind generator and will probably replace it with a newer model. So, the need to MPPT things is increasing fast.
__________________
whiskthecat is offline   Reply With Quote
Old 20-05-2015, 16:23   #87
Registered User
 
whiskthecat's Avatar

Join Date: Mar 2015
Location: Texas
Boat: Bruce Roberts Spray 36
Posts: 57
Re: Open Source MPPT

It seems I will be putting this off for quite a while now as I've found a workable solution. I was messing around with a 20$ 385 watt PlayStation power supply to make a cheap 13.2v (Adjustable) battery maintainer for my bilge pump when I had the realization that 90V DC from the solar panel wasn't too far away from 100VAC that the supply was intended to run on. Sure enough I hooked the panel to it in bright sunlight and it worked. For now I will just use a couple of these units on my panel and prop shaft generator to at least maintain battery voltage and I'll likely add on a microcontroller and some current sensing to handle charge and maybe even MPPT. You can't beat 20$

Here is a link to what looks to be the same model I am experimenting with.
__________________
whiskthecat is offline   Reply With Quote
Old 23-05-2015, 21:31   #88
Registered User
 
whiskthecat's Avatar

Join Date: Mar 2015
Location: Texas
Boat: Bruce Roberts Spray 36
Posts: 57
Re: Open Source MPPT

If anyone is interested I can document the process. It appears these power supplies have over current protection so I can likely tap in to current sensing that is already present for mppt. Right now all I have done is modify a resistor value near the 2.5v feedback reference. This allows me to adjust from the default 12.4v up to about 13.7v when the over voltage protection kicks in. This can easily be disabled to allow any voltage up to the 16v the output capacitors are rated for. I suppose it would be best to modify the OVP to kick in at 15v or w/e would be appropriate for flooded lead acid charging. I have access to a lot of these power supplies to experiment with.
__________________
whiskthecat is offline   Reply With Quote
Old 23-06-2015, 19:57   #89
Registered User
 
whiskthecat's Avatar

Join Date: Mar 2015
Location: Texas
Boat: Bruce Roberts Spray 36
Posts: 57
Re: Open Source MPPT

Just a quick update. My modified ps3 power supply has been keeping my battery floating nicely at 13.4v with the bilge pump running every 3 hours for 3 minutes. (The magnetic water level sensor failed closed circuit so I wired up a small 16 bit MCU as a timer) I've just ordered a 48v alternator @ 266rpm (192v @ 960rpm) that I will be using as a propshaft generator and I'm fairly sure a ps3 power supply will work nicely here as well. I will report back when I know more. For now the plan is to modify a few more of these power supplies and get all of my power sources (solar, hydro, wind) attached to keep the battery held at float voltage.
__________________

__________________
whiskthecat is offline   Reply With Quote
Reply

Tags
mppt

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
Navico BR24 Radar - Open Source protocol implementation maxxflow OpenCPN 23 30-07-2012 05:20
Open Source CPN , Mexico - Pacific Coast Cranston OpenCPN 1 08-12-2011 18:38
Garmin Colorado 400c as NMEA data source for Open CPN elleandi355 Navigation 2 16-03-2011 23:11
Looking to Use Open Source Charting Software SquireDude Navigation 6 10-03-2011 10:47
Open Source Navigation MaineCub Navigation 28 16-01-2011 04:37



Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 07:17.


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.