oldtrack123 wrote:

---

Jaahn wrote:

---

Hi

It is hard to reply to such home grown ideas as Terry puts out to support his methods. I do not intend to write any more on this either.

ALL roof top solar systems that I have seen use MPPT controllers for the solar panels in their grid connect or stand alone systems. Go out and look at the specs of the systems offered. Why Terry is the only person in the world who thinks a PWM system is better and produces more power is a mystery to me. He may be the salvation of the solar world. But obviously there are some who support him. Good luck to them !

Jaahn

-- Edited by Jaahn on Friday 1st of December 2017 07:36:26 AM

---

 A BIG DITTO 

All the world is wrong according to T1

The full facts of Terry's set ups is that the panels he generally uses have  MPPs  that are closely matched to the lithium batteries  voltage under all SOCs.

I have tried to point this out to him in the past

After many experiments he has a specifically matched set up that does perform well for JUST THAT ARRANGEMENT

 

They have no real extra output to convert 

One needs a fair bit of  ELECTRICAL knowledge & theory to understand why that is so, . but some people simply hate Theory

Standards 36 cell panels with higher MPP used with LA Batteries with a substantial range in voltage over SOCs is a totally different situation

Particularly when most needed ,when the LAs are in a low SOC!!! 

THAT is when the greatest advantage occurs.

The often mentioned conversion losses with MPPT regs,  is overexaggerated with high quality  MPPS.

The real problem is ensuring that you have a REAL MPPT reg

-- Edited by oldtrack123 on Saturday 2nd of December 2017 05:22:21 PM

---

 Back to the attacks Peter, you do need to actually do the tests to prove or disprove theories, just because you read it some where doesn't make it correct or relevant for Australian conditions. If you don't factor in the reduced Vmp as the panel heats when exposed to the full sun then the theoretical gains are simply theoretical, they can not be reproduced under the Aust sun on the roof of an RV. Simply using the STC figures publish with the panel is silly nonsense, STC conditions can not be duplicated outside the lab, real operating Vmp figures fed into the formula will show the claimed gains simply don't exist.... but you actually need to do the hard yards and test the theory and over days/weeks, not a 5 sec flash from a light box with the cell held at 25*C

 

T1 Terry 

meetoo wrote:

---

T1 Terry wrote:

---

-snip-
The nonsense 70% efficiency limit for a PWM controller is just that, nonsense, battery charge acceptance and cabling has far more effect of charging efficiency and will effect the MPPT controller just as much as the PWM controller, so correct wiring is essential and a far better investment than a rather expensive controller.

T1 Terry

---

 Terry, if not 70%, what might a more realistic figure be please?

Cheers, John.

---

Hi John, finally found your post. A well set up and correctly wired PWM controller will harvest around 80% and sometimes higher efficiency from the solar panel, as long as there is not a silly voltage mis match between the panel Vmp and the battery nominal voltage and the panel is actually correctly angle to the sun. An MPPT controller can't alter the panel angle either so a flat mounted panel on the RV roof will not achieve its optimum output over the full days sun no matter which type of controller used, but a PWM controller will start charging the battery first and still be charging the battery after the MPPT controller has stopped charging, it might still be running but it isn't charging the battery.

I am still yet to see an MPPT controller outperform a correctly wired and panel matched PWM system over a full days solar harvest, it has now been well over 10 yrs of hands on trials and a few hundred systems installed so my knowledge is based on a very large bank of data, not a single system that the owner has never actually tried and other controller to see if their theory holds out..... but that is the world of forum knowledge and I guess it will never change. 

 

T1 Terry

aussie_paul wrote:

---

I am probably having to upgrade the controller now as we more than doubled the roof panel area.

Aussie Paul. 

---

 So according to Terry, unless you chuck all your panels out and start again with new ones that are matched to his favourite controller, you should fit an MPPT controller to your existing panels to get best performance.

Yep, I agree with that. I am currently looking at increasing my solar from 600W to 1,000 or 1200W. I have one of Terry's favourite brand controllers, but to avoid replacing it I need to be very careful with my panel selection otherwise I will be wasting my money.

Cheers,

Peter

-- Edited by Peter_n_Margaret on Saturday 2nd of December 2017 07:13:34 PM

T1 Terry wrote:

---

oldtrack123 wrote:

 

 

 

 

---

 HMmm 

It seems the argument for Pwm is now changing tack

 It is now diverging from a  output efficiency discussion to specific  set upss 

as in my previous post explaining why  "experimenting"  to find the best set up for a particular panel / regulator/ battery types set up  can favour a particular type of regulator

But that has nothing to do with output/set up efficiency. of MPPT versa  PWM regs

---

 Hi Peter, I think the days of simply throwing a heap of bit together and hoping for a good result are well into the history books now. The new method is to design a system to achieve the desired result and if that means matching panels to batteries to controllers to gain the optimum solar harvest then so be it. An RV energy system is an integrated unit these days so inefficiencies are minimised and the max "bang for buck" is achieved.

The modern RV user isn't the tent camper who stepped up to an RV like it was once, roughing it isn't what they want so simply throwing a few components together isn't going to provide their energy needs.

An MPPT controller might get a very poorly set up system operating better, but it will not outperform a properly designed system and suggesting it will is some what misleading

 

T1 Terry 

---

 

Hi Terry 

You are simply verifying what I have posted ,even though you do not probably understand

Your have experimented until you found panels & regulators that where good for use with an  almost constant back EMF as with LI batteries

The system would not be the same with  LA  batteries operating over a voltage range from say 12V to  14+V

The technical term is IMPEDANCE matching the source to the load 

A practise that has been widely known for many many years

I was first learnt  about the basic principles involved , when I was around 12 Years old ,from my father.[77years ago ]

I only fully understood it after I finished my Electrical/radio  apprenticeship   & did advanced courses in radio & Electronics. [60 years ago]

I then realised that it in many ways  ,it applied to the most efficient use of ALL power sources.

Your system would not be so efficient with  LA batteries,. unless they were not discharged over their normal operating range. 

 

In simple words, your system works due to the near constant output voltage of the LIs

It is the BATTERY / PANEL combination that makes your system  work so efficient with a simple PWM controller.

-- Edited by oldtrack123 on Sunday 3rd of December 2017 01:41:47 AM

It is sometimes quite dissapointing that personal views on a subject such as solar and batteries turns what might be a very informative topic into a giant "Peeing Contest"

From the observations of someone just lurking is that what Terry T1 is basically saying is that if you plan your system around your requirements then you will achieve the desired result without having to upgrade panels, controllers etc.
I assume when you go to T1 for an installation the individual requirments would be assessed and the collective information would be used to build YOUR individual system.
There are many variants of what may be required as a free camp or off the grid system. It will all depend on what appliances you need to run and how long you need to camp. There are other factors as well such as where you will be operating and even the seasons of the year. What may suit one person or group may not work for the next person or group.

As a poster commented earlier in this thread with reference as to what type of controller Holden V Ford which is probably a great description.
Some people contributed fact and good advice backed up by technical information and others just attacked a contributor the sells a system that they consider too expensive or they attack just because they have built a different system that works for them.

Any good and honest person in business for themselves is going to offer a product and service that suits the clients requirements, not something that MIGHT work in some circumstances. This method of conducting business should not be attacked or criticised on a technical forum when it detracts from the original enquiry.

This post from me could be placed in almost any topic under solar or tech forums and it is a shame that some contributors withdraw what maybe accurate and informative posts containing details which may help others that are not so tech savvy.

I have no affiliation with T1 or anyone else on this forum apart from a couple of members who I am friends with so can the majority of us just have the fact in technical enquiries without the personal attacks.

To be honest, the silent majority are sick of it.

 

Terry 

One simple question 

Did you EVER do the same "exhaustive" ? testing  of MPPs against PWMs using LA  batteries @  different stages of discharge ,similar light & temp conditions.?????

Even the panel specs can play a big part in which will be the best over a range of conditions.

It would be very ,very  difficult to maintain similar & repeatable test conditions over a large range of tests for the average experimenter .

The actual conditions need to be carefully controlled over the full range of testing,

How did you do THAT???

Did you use  a  temp controlled light box with a controllable range of light spectrums  & intensity similar to sunlight in various conditions?

Hi

I am puzzled about this discussion about this new technology. In the old days PWM reg were the norm and there were quality ones and cheap ones but the difference was mainly the extra ability to change settings and reliability. Then 'they' invented MPPT and all the rooftop solar moved to that, and still does AFAIK. But the Chinese have geared up making cheap and sometimes nasty PWM regs very cheap. Usually copies of something good. We are addicted to cheap so we buy them no matter what.

It is not a comparison of "Ford V Holden" as that is a comparison of similar style and technology state. Buyer preference is quite acceptable as a choice. Here the preference seems to be more complicated to me. A caravan roof is a challenging environment in mid summer. The flat mounted panels do not cool much by air currents as do the angled roof ones. Every day the location and direction may be different, and there are other reasons too. So for these reasons it may not be as straight foward to see the best answer to everyones questions. So going to an experienced installer may give the best result. BUT we all know there is a lot of charlatans in the caravan business so ??? go to the forums. No charlatans there are there 

What I fail to see though is why people on here fail to accept new technology in the solar area when they accept it in the motoring area. They 'all' drive in the new common rail diesel vehicles which were all designed overseas for countries that are vastly different to here and the conditions are vastly different. They are not really designed to do the job they are being used for towing huge caravans but they became accepted quickly, despite faults, because the new technology works well.

But with solar nah sh*t, this new stuff is no good, better living in the past 

Jaahn           

 

-- Edited by Jaahn on Monday 4th of December 2017 08:20:18 AM

dorian wrote:

---

Could anyone point to circuit diagrams for MPPT and PWM controllers so that we could see how they actually work at the nuts-and-bolts level?

---

 Hi Dorian

Numerous circuits are available on line

https://www.google.com.au/search?q=circuit+diagrams+solar+mppt+regulators+12v&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwj--PTh9-7XAhUBoZQKHXS_Ak

 

Put simply

A PWM is basically a voltage sensitive  relay

Depending on type , it simply:

[a]connects or disconnects the panels from the battery ',"ON" or " OFF"

it may also shunt the panel output current from pos to neg[earth] instead of just open circuiting  the panel output

They are always all or nothing

They pull the panel voltage down to the battery voltage but as the panel  generate current is constant,does not increase much even under short circuit conditions, the charge current is simply the  panel's available output, never higher!!

  The good ones have additional features

A MPPT. is a power converter plus a voltage sensor.

Converts power @ one voltage  to power @ a different voltage

It constantly samples the battery voltage,converts the panel available output  to more match the optimum voltage to more fully utilise the available panel output

The charge current can be more than the panel output current

There are numerous circuit diagrams available on line  .

Some for very basic MPPTs  & others with more features

 

Simple equation for 100W panel with a PPP @18v using a PWM[neglecting conversion losses which will depend on the quality of the reg]

100 /18V = 5.55A

Simple equation for with samel panel with a MPPT

battery SOC voltage at  12V :100/12 = 8.33 A

battery voltage @14V:100/14=7.14A

The actual current output of the MPPT will be lower depending the efficiency of the MPPT ,which is highly dependent on quality

Of course  If the panel voltage @their PPP closely matches the battery SOC voltage there will be little advantage for a MPPT

Such is the case with Lis whose output voltage is pretty constant over full operating range,using panels whose PPP was only a little above that SOC voltage

A MPPT would have little advantage !

-- Edited by oldtrack123 on Monday 4th of December 2017 09:51:59 AM

-- Edited by oldtrack123 on Monday 4th of December 2017 10:01:26 AM

Thank you oldtrack 123 and Peter and Margaret,

Your last posts have explained at least to me, what the differences are between the two..

Some time ago I asked a solar installer which was the best and what were the differences and unfortunately he did not explain how each type of controller worked however he did say that in most cases he installs the PWM type with reasonable results. In this case my enquiry was regarding AGM batteries.

We need a "Like" button at times.

oldtrack123 wrote:

---

dorian wrote:

---

Could anyone point to circuit diagrams for MPPT and PWM controllers so that we could see how they actually work at the nuts-and-bolts level?

---

 Hi Dorian

Numerous circuits are available on line

https://www.google.com.au/search?q=circuit+diagrams+solar+mppt+regulators+12v&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwj--PTh9-7XAhUBoZQKHXS_Ak

 

Put simply

A PWM is basically a voltage sensitive  relay

Depending on type , it simply:

[a]connects or disconnects the panels from the battery ',"ON" or " OFF"

it may also shunt the panel output current from pos to neg[earth] instead of just open circuiting  the panel output

They are always all or nothing

They pull the panel voltage down to the battery voltage but as the panel  generate current is constant,does not increase much even under short circuit conditions, the charge current is simply the  panel's available output, never higher!!

  The good ones have additional features

A MPPT. is a power converter plus a voltage sensor.

Converts power @ one voltage  to power @ a different voltage

It constantly samples the battery voltage,converts the panel available output  to more match the optimum voltage to more fully utilise the available panel output

The charge current can be more than the panel output current

There are numerous circuit diagrams available on line  .

Some for very basic MPPTs  & others with more features

 

Simple equation for 100W panel with a PPP @18v using a PWM[neglecting conversion losses which will depend on the quality of the reg]

100 /18V = 5.55A

Simple equation for with samel panel with a MPPT

battery SOC voltage at  12V :100/12 = 8.33 A

battery voltage @14V:100/14=7.14A

The actual current output of the MPPT will be lower depending the efficiency of the MPPT ,which is highly dependent on quality

Of course  If the panel voltage @their PPP closely matches the battery SOC voltage there will be little advantage for a MPPT

Such is the case with Lis whose output voltage is pretty constant over full operating range,using panels whose PPP was only a little above that SOC voltage

A MPPT would have little advantage !

-- Edited by oldtrack123 on Monday 4th of December 2017 09:51:59 AM

-- Edited by oldtrack123 on Monday 4th of December 2017 10:01:26 AM

---

 

Sounds great in theory, but does it stack up in practice?

Bit like Premium Diesel - sounds great but does it actually do anything?

I have asked previously in the thread for any side by side real world tests and so far nobody has responded, have you done any Oldtrack?

Looking on youtube there are some, but they don't stack up for me here in Australia, I don't live in the arctic circle, put umbrellas over my panels etc.

I did get one response from a Facebook member which I posted earlier, he seemed quite thorough and was using AGM's and the result was a better than 20% better charge from the PWM?

(attached below) - comments?

Now I'm not saying your wrong, or even that the theory is wrong, but that's just it isn't it, it's just theory until proven in the real world.

So, any chance you can point me to any real world tests that bear out the theory, tests in tropical/temperate zones I mean.

I would be particularly interested in seeing tests done by the manufacturers, but I can't find any, all they show is their claimed improvements.

 

Cheers,

Hi
No , I have not done any, nor could any amatuer .
Simply because maintaining all the various conditions through multi tests including differing light intensity on the actual panel face [replicating various actual conditions],panel temp ,various battery voltages ,{[SOC voltages] different types of batteries LAs or Lis , battery charge acceptance rate ,[internal resistance] panels with differing specs /characteristics & recording the results would be beyond any backyarder experimenter

As for that link I would suggest that it no better than the info you get on any forum.
About the only thing I agree with is that, IF you have the space ,it would be probably cheaper to fit another panel than buy a good quality MPPT

As for the rest of Docs Statements
Perhaps he should indicate what the voltages are he is talking about:
If Open circuit Voltages, they mean nothing , as it is the voltage @PPP that matters ,even with PWMS.
If they are load voltages,where are they taken ,they certainly are not battery voltage
If they are taken @ the regulator's panel input ,they do not make sense with a PWM. but could with a MPPT.

I noted that he now does use MPPTs

I am not disputing Terry's claims with LI batteries AND the PANELS that he has selected to get the best result & those using LI would be well advised to follow that advice in DETAIL,.
Especially with regard to panel Specs

A difference of  even  1V @PPP in the panels specs , will make a difference in the results between the two systems ......

I am still waiting to see if he claims he did the same extensive testing using LA batteries with different SOCs from say 12v to 14V

-- Edited by oldtrack123 on Monday 4th of December 2017 04:22:05 PM

 

The conditions throughout Australia  vary widely  depending on location  & throughout the year, 

That is one of the reasons  why a simple test ,such as yours, really does not prove anything !!

I repeat It would be near impossible to do proper comparison testing except under closely controlled conditions , simulating the conditions found throughout the year , all over Australia 

There are many reasons, even based just on theory , why your tailor made set up with LI batteries works well.

But LEAD acids are a totally different situation,  higher internal resistance , SOC voltage covers a greater range 

For instance, the worst thing one could do with a MPPT is use 30 Cell panels paralleled ,for charging a 12v LA 

-- Edited by oldtrack123 on Monday 4th of December 2017 04:50:14 PM

Hi El Gringo
I do not accept Terry's as being valid simply because even from his latest reply ,they were NOT carried out under controlled conditions!!
[ & .With LA batteries in various state of charge]

It seems that you do not like theory, just like Terry, but without knowing & understanding Electrical Theory [Well proven now over many many years] you have no chance of sorting it out.

I have seen various claimed specs of many brands/types

Why should the makers divulge their testing methods on line??

But there are worldwide INDUSTRY STANDARDS/requirements for such testing
Yes, those good old STANDARDS which help to ensure that such products must be tested in the same way.

The Regulator & panel Specs will /should quote the STANDARD they conform to, as well as other relevant information such as: open circuit voltage,. PPP voltage Rated current at PPP & short Circuit current
All those should be based on tests done in accordance with the Standards

Buy the relevant Standards & you will see the required testing methods

Not sure who is really one eyed!!!

But it is really hard to help one see facts ,if the do not understand the theory

The reputable makers make both types & you can be assured they ARE TESTED under closely controlled conditions to the STANDARDS, something that an amatuer non eletrically qualified experimenter who hates theory would never achieve..

 

Plenty of information on line if you spend a little time searching

Just try searching "Solar Regulators"

https://www.solar-electric.com/learning-center/batteries-and-charging/mppt-solar-charge-controllers.html

insovoltaics.com/learning-center/certifications/iec-62509-and-iec-62093/

-- Edited by oldtrack123 on Monday 4th of December 2017 06:29:53 PM

oldtrack123 wrote:

---

Put simply

A PWM is basically a voltage sensitive  relay

Depending on type , it simply:

[a]connects or disconnects the panels from the battery ',"ON" or " OFF"

it may also shunt the panel output current from pos to neg[earth] instead of just open circuiting  the panel output

They are always all or nothing

They pull the panel voltage down to the battery voltage but as the panel  generate current is constant,does not increase much even under short circuit conditions, the charge current is simply the  panel's available output, never higher!!

  The good ones have additional features

A MPPT. is a power converter plus a voltage sensor.

Converts power @ one voltage  to power @ a different voltage

It constantly samples the battery voltage,converts the panel available output  to more match the optimum voltage to more fully utilise the available panel output

The charge current can be more than the panel output current

There are numerous circuit diagrams available on line  .

Some for very basic MPPTs  & others with more features

Simple equation for 100W panel with a PPP @18v using a PWM[neglecting conversion losses which will depend on the quality of the reg]

100 /18V = 5.55A

Simple equation for with samel panel with a MPPT

battery SOC voltage at  12V :100/12 = 8.33 A

battery voltage @14V:100/14=7.14A

The actual current output of the MPPT will be lower depending the efficiency of the MPPT ,which is highly dependent on quality

Of course  If the panel voltage @their PPP closely matches the battery SOC voltage there will be little advantage for a MPPT

Such is the case with Lis whose output voltage is pretty constant over full operating range,using panels whose PPP was only a little above that SOC voltage

A MPPT would have little advantage !

---

 Hi,  That description of the voltage boosting is correct for the function which takes the panel power and matches it to the power which the battery needs. That is one function they should do but the fakes do not.

BUT they also do Maximum Power Point Tracking which is described too but not in such detail. This is the function where it tries various changes of the input impedance to obtain the maximum voltage/current combination to get the maximum power out of the panel. This is the biggest difference IMHO between the good units and the cheaper pretenders. The good brands do it often and get more output. Electronic jiggeery pokery, so you would not trust that would you. Just the same as an FM radio tracks the station  Nah couldn't be that simple could it. 

Jaahn 

PS sorry about the odd bold font. Seems to be some sabotage 

-- Edited by Jaahn on Monday 4th of December 2017 07:05:14 PM