Cruisers Forum
 


Join CruisersForum Today

Reply
 
Thread Tools Rate Thread Display Modes
Old 28-05-2013, 20:28   #31
Marine Service Provider
 
Emmalina's Avatar

Join Date: Jan 2012
Location: Thailand
Boat: Herreshoff Caribbean 50
Posts: 482
Re: MPPT Controller Explanation For Dummies

Its all about algorithms and the biggest advantage I have found is the ability to series up your panels to 150v VOC so you can reduce cable diameter on big arrays.. Seen a lot of these "cheap" Mppt charges from a certain country and they don’t even weigh enough to make decent paper weights.
Yer gets wat yer pays for !!
__________________

__________________
Steve .. It was the last one that did this !
Emmalina is offline   Reply With Quote
Old 28-05-2013, 20:52   #32
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by Emmalina View Post
Its all about algorithms and the biggest advantage I have found is the ability to series up your panels to 150v VOC so you can reduce cable diameter on big arrays.. Seen a lot of these "cheap" Mppt charges from a certain country and they don’t even weigh enough to make decent paper weights.
Yer gets wat yer pays for !!
There's no particular reason for mppt controllers to be large or heavy though

Dave
__________________

__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 28-05-2013, 20:59   #33
Marine Service Provider
 
Emmalina's Avatar

Join Date: Jan 2012
Location: Thailand
Boat: Herreshoff Caribbean 50
Posts: 482
Re: MPPT Controller Explanation For Dummies

Quote:
Originally Posted by goboatingnow View Post
There's no particular reason for mppt controllers to be large or heavy though

Dave
True but you are dissipating a lot of excess energy so you need a large heat-sink or fans. I prefer a large heat-sink as it has no moving parts. You also require a certain amount of inductors and other fairly heavy passive components to boot.
__________________
Steve .. It was the last one that did this !
Emmalina is offline   Reply With Quote
Old 28-05-2013, 21:10   #34
Marine Service Provider
 
Emmalina's Avatar

Join Date: Jan 2012
Location: Thailand
Boat: Herreshoff Caribbean 50
Posts: 482
Re: MPPT Controller Explanation For Dummies

This vid explains a lot about quality without being too biased...
__________________
Steve .. It was the last one that did this !
Emmalina is offline   Reply With Quote
Old 28-05-2013, 21:13   #35
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by Emmalina View Post
True but you are dissipating a lot of excess energy so you need a large heat-sink or fans. I prefer a large heat-sink as it has no moving parts. You also require a certain amount of inductors and other fairly heavy passive components to boot.
Mppt with switched mode shouldn't be dissipating hardly anything, high frequency inductors are small , and really heat generation should be low.

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 28-05-2013, 21:21   #36
Marine Service Provider
 
Emmalina's Avatar

Join Date: Jan 2012
Location: Thailand
Boat: Herreshoff Caribbean 50
Posts: 482
Re: MPPT Controller Explanation For Dummies

Quote:
Originally Posted by goboatingnow View Post
Mppt with switched mode shouldn't be dissipating hardly anything, high frequency inductors are small , and really heat generation should be low.

Dave
Well alll the main players I deal with are pretty big and heavy that includes outback morningstar BZ etc but then again we go for 45-80A systems
Switch mode power regulation doesn't dissipate much heat !
__________________
Steve .. It was the last one that did this !
Emmalina is offline   Reply With Quote
Old 28-05-2013, 21:23   #37
Registered User
 
nimblemotors's Avatar

Join Date: Apr 2011
Location: Sacramento, California
Boat: Solar 40ft Cat :)
Posts: 1,557
Re: MPPT Controller Explanation For Dummies

Quote:
Originally Posted by goboatingnow View Post
Mppt with switched mode shouldn't be dissipating hardly anything, high frequency inductors are small , and really heat generation should be low.

Dave
This $100 SPV1020 controller board has no heat sink, has 97% efficiency.
In fact, if you read about them, it uses four small inductors, so it doesn't need a larger electrolic capacitor, which tend to have short lifetimes (1-3 years) in the heat.
I see both the circuit boards in the videos have electrolic caps.
Note however, it is JUST a MPPT controller that outputs a fixed voltage,
it is not a battery charger.

__________________
JackB
MiniMPPT Solar Controller
nimblemotors is offline   Reply With Quote
Old 28-05-2013, 21:35   #38
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: MPPT Controller Explanation For Dummies

There are lots of poor quality MPPT regulators.

MPPT can be implemented in many different ways and some of them of very inefficient.
If you want an MPPT it needs to be good quality. If you want a cheaper regulator it is generally better to get to a non MPPT regulator, but make sure it is PWM not just an on off regulator.

There are some moderately priced MPPT such as Gensun, but MPPT circuitry is complex and I would recommend avoiding the cheaper MPPT regulators.
__________________
noelex 77 is offline   Reply With Quote
Old 28-05-2013, 23:09   #39
Registered User

Join Date: Jul 2011
Location: Australia NSW south coast
Posts: 633
Re: MPPT Controller Explanation For Dummies

Quote:
Originally Posted by Emmalina View Post
This vid explains a lot about quality without being too biased...
After actually testing these two controllers, the WellSee didn't perform that well, but it crapped all over the 2 BZ units I had, one MPPT250, the other MPPT250HV. The output display on the BZ units tells very large lies, at a reading of 25 amps it was actually putting out 18 amps. If you could actually get it to output 25 amps the thing would need to be water cooled, it generates that much heat, even mounted in an old inverter case with 2 fans running, the transistors finally failed.

Unless you are charge a big lead acid battery pack or you have a big mismatch between panel voltage and battery voltage, there is bugger all to be gained. If you are charging Li batteries, it's actually a backward step, the energy wasted as heat in the MPPT controller is greater than the gain from impedance matching. Li batteries don't have the big voltage changes between discharged and charged, and there is no bottle neck as far as resistance against current entering the battery, the PWM type controllers work fine, up to 80% conversion efficiency.
Unless you can keep the solar panels below 25 deg C while in full sun, there is not enough difference between Vmpp and Li terminal voltage, but enough to over come wiring resistance.
For those that want to work it out, for ever deg over 25 degC reduce the Vmpp by 0.462%, panels in full sun in T shirt weather will climb to around 75 degC, that brings the 18v Vmpp @ STC (Standard Test Conditions, a light box in a lab with flash readings so the panels don't heat up) down to 14v Vmpp NOCT (Normal operating Cell Temp) not much impedance match to be had there.

T1 Terry
__________________
T1 Terry is offline   Reply With Quote
Old 29-05-2013, 01:06   #40
Marine Service Provider

Join Date: Oct 2011
Posts: 1,205
Re: MPPT Controller Explanation For Dummies

Quote:
Originally Posted by endoftheroad View Post
I used a meter yesterday at mid day and my 140 watt panels were 20 volts each entering each mppt controller. Was I seeing things?
The battery was 14.3 volts (if I remember correctly).

My batteries are full mid morning while I'm running refrig, vhf and 12 volt fans.
I'm charging every electronic gadget possible during this 6 or 8 hour period although it's not necessary.
I'm new to solar and mppt, it's been a better than expected experience.

2-Kyocera 140
2-genasun mppt controllers
4-Trojan T-105's in series.

Victron battery monitor soon to be installed.

It's raining here in Key West at 3:00 pm, grey skies and stormy weather and my panels are 14.4 each and the batteries are 12.7 volts.

Looking forward to the Victron.
Endoftheroad,

I don't want to burst your bubble,

but food for thought.

Solar panels can easily fool a volt meter, especially if you never plug-in to shore power.

It's called surface charge.


If you have a 440 amp-hr bank and draw out 100 amp-hr over-night.

Now add 2 solar panels that generate 12 amp's per hour. Total by 12 noon in your latitude is going to be not more then 48 amp hrs added back...leaving a deficit of about 52 amp hrs.

If your bats are showing 14+ voltage you have a surface charge. And the real state of charge is....something less than 100%

Amps out overnight X 125%, plus amps in from the solar = net re-charge.

So now if this is a day in day out occurrence and you have a negative, then, at some point the deficit is going to come home to roost.

Lloyd
__________________
FlyingCloud1937 is offline   Reply With Quote
Old 29-05-2013, 02:40   #41
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by noelex 77 View Post
There are lots of poor quality MPPT regulators.

MPPT can be implemented in many different ways and some of them of very inefficient.
If you want an MPPT it needs to be good quality. If you want a cheaper regulator it is generally better to get to a non MPPT regulator, but make sure it is PWM not just an on off regulator.

There are some moderately priced MPPT such as Gensun, but MPPT circuitry is complex and I would recommend avoiding the cheaper MPPT regulators.
What do you mean PWM versus on off , the PWMsokar regulators are an on off charger design.

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 29-05-2013, 02:47   #42
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by T1 Terry View Post

After actually testing these two controllers, the WellSee didn't perform that well, but it crapped all over the 2 BZ units I had, one MPPT250, the other MPPT250HV. The output display on the BZ units tells very large lies, at a reading of 25 amps it was actually putting out 18 amps. If you could actually get it to output 25 amps the thing would need to be water cooled, it generates that much heat, even mounted in an old inverter case with 2 fans running, the transistors finally failed.

Unless you are charge a big lead acid battery pack or you have a big mismatch between panel voltage and battery voltage, there is bugger all to be gained. If you are charging Li batteries, it's actually a backward step, the energy wasted as heat in the MPPT controller is greater than the gain from impedance matching. Li batteries don't have the big voltage changes between discharged and charged, and there is no bottle neck as far as resistance against current entering the battery, the PWM type controllers work fine, up to 80% conversion efficiency.
Unless you can keep the solar panels below 25 deg C while in full sun, there is not enough difference between Vmpp and Li terminal voltage, but enough to over come wiring resistance.
For those that want to work it out, for ever deg over 25 degC reduce the Vmpp by 0.462%, panels in full sun in T shirt weather will climb to around 75 degC, that brings the 18v Vmpp @ STC (Standard Test Conditions, a light box in a lab with flash readings so the panels don't heat up) down to 14v Vmpp NOCT (Normal operating Cell Temp) not much impedance match to be had there.

T1 Terry
Yes terry but Vmp also moves with illumination levels , and a small mismatch in voltage can mean you are moved away from the Vmp pointb( which is dynamic)

I don't get your comments re Li at all. Li with its capability of demanding full charge right up to the end is a n ideal candidate for MPPT , whereas for LA , its only useful in bulk charge phase , yet many people buy panels for absorption charging , ie finishing off the battery and with big panels for this use MPPT is useless as the panels arnt delivering anywhere near full power anyway.

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 29-05-2013, 02:48   #43
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: MPPT Controller Explanation For Dummies

Quote:
Originally Posted by T1 Terry View Post
If you are charging Li batteries, it's actually a backward step, the energy wasted as heat in the MPPT controller is greater than the gain from impedance matching. Li batteries don't have the big voltage changes between discharged and charged, and there is no bottle neck as far as resistance against current entering the battery, the PWM type controllers work fine, up to 80% conversion efficiency.
With LI batteries the gains from MPPT controllers will, overall, be higher than for lead acid batteries.

The lower battery voltage during charging that is characteristic of Li will make the gains from voltage conversion inherent in the MPPT process higher.

A suitable algorithm for charging Li batteries can be programmed into the better MPPT controlers, but not all of them.
Many of the medium and low priced controllers are not suitable.

On all the current MPPT and non MPPT controllers the battery voltage hysteresis is a bit too high for my liking, but this will only be a factor near 100% control.
I think we will see controllers released in the future with tighter voltage control which will be better for Li
__________________
noelex 77 is offline   Reply With Quote
Old 29-05-2013, 02:53   #44
Nearly an old salt
 
goboatingnow's Avatar

Cruisers Forum Supporter

Join Date: Jun 2009
Posts: 13,649
Images: 3
Quote:
Originally Posted by nimblemotors View Post

This $100 SPV1020 controller board has no heat sink, has 97% efficiency.
In fact, if you read about them, it uses four small inductors, so it doesn't need a larger electrolic capacitor, which tend to have short lifetimes (1-3 years) in the heat.
I see both the circuit boards in the videos have electrolic caps.
Note however, it is JUST a MPPT controller that outputs a fixed voltage,
it is not a battery charger.
The SPV1020 chip , that's the eval board , is designed as a fully fledged , Just feed that into a PWM solar regulator and hey presto mppt charger ,( well , maybe a buck stage might be useful ) ,

Interesting chip , designed as a mppt per panel application replacing bypass diodes.

Interesting its even a 4 phase switcher , which should mean no nasty failure prone big caps on the output to control ripple

I see a project in my future. !!

Dave
__________________
Check out my new blog on smart boat technology, networking and gadgets for the connected sailor! - http://smartboats.tumblr.com
goboatingnow is offline   Reply With Quote
Old 29-05-2013, 02:57   #45
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: MPPT Controller Explanation For Dummies

Quote:
Originally Posted by goboatingnow View Post
What do you mean PWM versus on off , the PWMsokar regulators are an on off charger design.

Dave
There are three types of solar controllers/regulators. From cheapest to best they are:

1. On/off.
2.PWM
3.MPPT (which are generally also PWM)

There are no suitable collective nouns to describe these different types of regulators, but it is important to distinguish between them.

Calling PWM regulators On/off, or bang bang, is very confusing as it blurs the first two categories of regulators.
__________________

__________________
noelex 77 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




Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -7. The time now is 12:45.


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.