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

---

 Are the moderators really going to allow these sort of personal, spiteful, vitriolic attacks to continue.

Disagreeing with another's opinion is one think, but these PERSONAL attacks should not be allowed.

Time for some holidays IMHO

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 

T1 Terry wrote:

---

Peter_n_Margaret wrote:

---

In some conditions, there may be little difference between MPPT and PWM, but I suggest that a good quality MPPT will always equal or exceed the performance of a good quality PWM controller.
Also, with a PWM controller, you are constrained to a narrow range of voltage inputs to the controller otherwise there will be losses. These constraints do not apply to MPPT controllers which can accept higher voltage inputs (such as those offered by cheap panels designed for grid connect) without the extra losses.

Cheers,
Peter

---

Agree with the first part, but not all of it Peter. A good quality MPPT controller costs a lot more than a good quality PWM controller and is limited to the capacity of that controller. If you need more capacity you need a second MPPT controller identical to the original and they must be of a type that can be linked in a master/slave operating mode. MPPT controllers with this ability are not cheap, up around the $1,000 mark each so a system expansion requires another $1,000 controller plus the linking kit.

Victron do make MPPT controllers that can be linked together, but they are not the cheaper ones, they are the much more expensive units. Midnite solar make linkable units as well but they are both expensive and huge. MPP solar make an inverter/charger/MPPT controller all in one that can be linked to expand the capacity of the inverter as well as the 2 chargers.... but they only come in 24v and 48v designs, the 12v model can't be linked.

Plasmatronics, a great Aust company that build RV solar controllers for Australian conditions have the ability to be expanded by 100 amps capacity by as many times as you want by using solid state relays. One controller at around $350 plus $50 for a solid state relay and you have a controller that can handle 120 amps, add another $50 and it can now handle 220 amps and so on.... you don't need an economics degree to figure out which is the more cost effective.

 

As for grid connect panels being cheaper than 12v panels, where did you get that notion from, the going price is $1 per watt no matter the voltage output. They only come down in price when the panel size goes well beyond the area the average RV owner has clear to mount a solar panel. Small output 12v panels like the 60w units are more expensive than the $1 per watt, but the advantage is you can fit so many more panels into the available space because they can fit up the sides and between the vents and roof top rattler, big panels won't fit. You can't mix and match panel sizes with an MPPT controller, you can with a PWM controller, you can simply plug in portable solar into the same control system used for the roof top solar, you can't if the roof top solar is a different voltage or series connected to build a higher voltage, the advantages go on and on ..... it really is a no brainer when you compare the flexibility of a quality PWM controller to an MPPT controller when it comes to an RV set up.

 

 

 

 

---

 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

RE [Quote] you can with a PWM controller, you can simply plug in portable solar into the same control system used for the roof top solar, [end Quote]

I suggest you reconsider that  very open ended comment before you get shot down again.

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

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 

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

Peter_n_Margaret wrote:

---

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

---

I think you possibly need to re-read what I posted Peter ..... unless you have already set your mind on an MPPT controller to replace the perfectly good PWM controller you have now. Good luck with finding an MPPT controller that can handle 1200w for charging a 12v battery that will actually fit in the spot where the other regulator was... or even in the same cupboard or wall.

I'll leave this forum to the group of experts who feel their toes have been trodden on because I really do have better things to do than give valueable advice for free only to be attacked in return.

T1 Terry 

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.

This was discussed big time on another very popular caravan forum where Terry's views and another person AGM views were discussed, there both very knowledgeable and it was a very good insight into who's right and who's wrong.

T1 Terry wrote:

---

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

---

 Terry, Thanks for your reply.

BTW I am a Holden bloke.

Cheers, John.

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           

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

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 !Except at the margins of the day when the MPPT can boost the voltage that is otherwise too low, to something higher and useful.

For someone with a battery type whose optimum voltage charge requirements are different from the panel output - a quality MPPT will provide an advantage.

As Terry says, if everything is perfectly matched, MPPT has only minor benefit and the Plasmatronic range of PWM controllers is about as good as they come.

In ALL cases, the benefits require quality products and the "cheapies", whether PWM or MPPT should be avoided if you want good performance and good battery life.

Cheers,

Peter

Dickodownunder wrote:

---

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.

---

 More like a 'dislike' button.

As I suggested in an earlier (page 1) post this thread has gone down the predictable pissing competition path.

Pitty.

So I have unsubscribed & won't be annoyed any longer by the experts trying to win the unwinable.

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

oldtrack123 wrote:

---

 

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?

---

Sorry Peter, I know how much you hate this term but they were in real world conditions. I mounted the panels flat on the patio roof to simulate how they would be mounted on an RV. I needed to know if they could actually do what was claimed and not in simulated conditions but rather in the conditions I would be using them. I was all for spending the extra $$ if it would give me a better solar harvest. The original tests were 2 sets of solar panels with their own controller charging 500Ah of AGM batteries built up from 125Ah 6v Yuasa batteries. After a week of full day harvesting recorded for each set up the solar array was swapped to the other controller and battery pack. If the output/input figures were effected by the array or battery pack it would show in the comparative figures.

Both battery packs powered their own inverter and they powered their own appliances so the batteries were always discharged to approx. 50% SOC over night and the solar was required to return the battery to as close as possible 100% SOC while still providing current for the day time load.  Naturally, some days neither of the batteries made it back to 100%.

Once I switched to Li battery testing things got a lot easier and far more consistent I'll admit that and the efficiency of the PWM controlled panels certainly improved, but that made the gap between the 2 types even greater.

If you really do want to do a theoretical calculation to compare one controller to the other you need to put all the factors into the equation. You do need the controller efficiency at the conversion rate you are attempting to theorise, you do need to factor in the reduction in Vmp as the panel heats up while exposed to the full sun, and you do need to factor in the internal resistance of the battery to take into account the real terminal voltage at each stage of charging.

At least Li batteries make that last one easier, unless the charge rate is kept low the lead acid battery terminal voltage will rise rapidly and not reflect the true state of charge. For instance, anyone taking their batteries below the 50% threshold on a regular bases won't see 10.8v when recharging a battery at anything more than a trickle charge because the internal resistance will increase after the first few excessively deep discharges, so using the 10.8v figure in any calculation is deliberately misleading and will result in a deliberately falsified result if the aim is to fully recharge the battery in the 5 peak sun hrs available.

Use data related to Australian conditions as these are the conditions members are asking which controller will work better, no 100w panel will have a Vmp of 18v when actually out in the sun in the middle of the day and that is when the solar panel is actually at the best angle to the sun and where the advertised figures come from, the best alignment to the light source.

 T1 Terry

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 

oldtrack123 wrote:

---

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

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 So you don't know of any real world tests, but you still maintain the your right...

And, you won't accept T1's testing either.

Seems a bit one eyed?

I know you love your god Theory, but many times theory doesn't stand up when tested properly.

Is it too much to ask the makers of these devices to divulge their testing methods, after all they come up with figures to show how good they are, why no proofs?

Cheers,

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/

Actually I do like theory and even understand the theory of MPPT vs PWM.

As for Australian Standards I have been quite involved in the process of determining new standards, I was a consultant for the Cyclonic Roofing standards some time ago.
I also know how companies flout these standards, and it usually starts with making claims that are unsupported for observable tests in real world conditions.

Also most of the controllers are made overseas and only have a CE standard, not worth the paper it's written on.

The thing with theory is, it's just the beginning of something, an idea put down to see if it might be workable.
That theory has to then be tested to see if it's valid.
Now in our case this theory should be observable in real world conditions even by laymen, not to the decimal point perhaps, but we are talking claims of 15% or so.

My issue is that I think it's all a scam.
Mr Bloggs goes out and buys a $1000 MPPT controller believing that he will get the advertised extra power into his battery.
But how does he know it is doing that?
He has no point of reference to compare.
So, shouldn't we expect that some testing has been done to show whether or not the claims are true.

Therefore I ask again, show me the real world testing to prove the claims for MPPT controllers.
You can't tell me it hasn't been done, so why nothing published?

Yes as mentioned by someone above, it is a little thing in the grand scheme, but if people are being ripped off???
Maybe Choice might be interested.

Cheers,

PS, I had already found that info, just dumbing it down a bit hey.

oldtrack123 wrote:

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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 !

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 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 

Thanks everyone. 

Aussie Paul.