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Post Info TOPIC: SOLAR REGULATOR


Chief one feather

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SOLAR REGULATOR


How, everyone,

Please be gentle. 

I am changing from a 30a regulator to 40a. Should I go MPPT or PWM and why. 

Edit. .. I have 3X150W panels on teepee roof.

            2x110AH Batteries. 

 



-- Edited by Dougwe on Tuesday 13th of March 2018 03:14:01 AM

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TUG.......2014 Holden LT Colorado Twin Cab Ute with Canopy

DEN....... "Chief" Arrow CV  (with some changes)

 



Guru

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I can start this one off Doug.

My van has the same - 3x150w panels hooked up to a PWM. It seems to do the job well. Never skipped a beat yet.

Cheers, John.



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Guru

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Iam obviously no expert,but everything I have read and believe me I studied every bit of information available stated that mppt   Was the way to go. Theres a solar expert on the panel who is dead against mppt and fair enough ,I have hooked up a modern mpp to my set up and the difference between its performance and the PWM is amazing...



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Guru

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Hi Dougwe smile

My take on this subject.

If you have a setup that is fully charged by midday then who cares, as it will be charged well anyway. If you need all the help to get charged by the end of the day then MPPT does provide some extra current but mostly when the batteries are down and the voltage is lower. It can use the higher panel voltage and convert it to extra battery current.biggrin 

MPPT is also better when you have panels which are not regular 12V charging panels but put out a higher voltage. The MPPT again will convert a higher panel voltage into more current at the battery voltage. Some advantages there in using sometimes cheaper "house" panels.

However there are lots of fake MPPT regulator/controllers on the market. no Because they are regarded as better, lots of cheap ones sold are labeled as MPPT but do not actually do that and have no parts inside for that function. If you want genuine MPPT then only buy a known good brand. Otherwise just buy a good brand PWM unit.

If you are upgrading then I hope you are upgrading the wiring too. The extra power gained by MPPT will not be realised if the resistance in the wires and connectors from the panels to the reg/controller wastes the power in losses. hmm

Cheers Jaahn

PS all roof top solar charge inverters use MPPT as the industry standard. That will tell you something.hmm 



-- Edited by Jaahn on Tuesday 13th of March 2018 10:28:47 AM

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Guru

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Hi guys

You know all this discussion about different regulators is really moot in my opinion. At the end of the day all that is needed is a good charge on the battery and a regulator that can handle the current from the panels. Now I admit, I know little about this subject so I may be way out of line here, BUT thats all I see as being important.

I have also noticed the great price differential in regulators. I refer back to my first comment in this post.

Cheers

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Homebase is Strathalbyn Caravan Park (now permanent). 2013 Jayco Starcraft 20-62-2, 2012 Ford Ranger  XL diesel. 

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if you can't follow all this just ask me to explain it better, I don't mind a bit. I tend to get over technical some times but hopefully those that can't quite follow it will ask for more explanation, better than boring those who do understand some of it to the point where they don't read any more and maybe miss something that will expand their knowledge. Hopefully those that don't agree will be constructive in their criticism rather than attack for the sake of it smile


It really depends on the solar panels you plan to use. If they are all roughly the same capacity as far as watts, have a voltage significantly greater than the battery voltage you want to charge, then MPPT is the way to go. Ideally with all the panels connected in series, positive from one into negative from the next till you have only one negative at one end of the chain and one positive at the other end of the chain, and this total open circuit voltage is less than the max input voltage of the MPPT controller and that controller can output the total that can be extracted from this combination, then go that way and you will be happy with the outcome.
If you can not make a solar panel single series string with an open circuit voltage less than the max voltage the MPPT controller can handle, then you need to connect all the panels in parallel. This means all the negatives together and all the positive together to add up to the max amps the controller can handle. So you need to look at both the input max voltage and the output max current to be sure you choose the right controller for your set up.
No matter what anyone suggests, forget about trying to make 2 series strings to keep the voltage down and feed that into one controller, the end result is a poor functioning system. The same goes for multiple MPPT controllers or multiple charging devices working along with an MPPT controller unless they are the top of the line linkable type or you have a degree in cabling/ rewiring and programming to trick the individual controllers into becoming master slave controllers. Yes, it can be done, by the average punter ..... highly unlikely to get it to work without ending up paying for someone to sort it. The chances of the user understanding how it works so they can explain to the repair man when it stops working .......?????? Not the best situation to end up in when you are out on the road eh.

This leads to why I recommend avoiding MPPT controllers if you can. If you want to get the best out of a PWM you need to have panels with an open circuit voltage 10v or less than the battery voltage you want to charge. This should mean the Vmp (maximum voltage the panel creates its max amps) should be higher than the highest voltage you expect to need to charge the battery at most temperatures. An example, a flooded cell lead acid battery wants 14.8v to reach the end of the boost charge cycle. This will probably occur close to the middle of the day and this is when the sun will be getting the panels to their highest temperature. A panel with a Vmp marked on the back of 18v says that panel at 25*C in the perfect angle to the sun will develop the most current it can produce at 18v, but, there is absolutely no chance in Australia that a flat mounted panel on the roof of an RV at mid day in full sun will be still at 25*C. Real world Vmp for that panel marked as 18v Vmp would be around 15v to 16v, could be less, but this is still more than the 14.8v required so it will do the job just fine.
PWM controllers don't care if the voltage from the panels is higher, it won't extract the max that maybe could be extracted under certain conditions, but all the panels connected to the controller will put out the best they can produce as long as the cabling is up to spec. It doesn't care if one panel is a 60w and the next is a 300w, the total will still be 360w. It doesn't care if one panel produces 10 amps at up to 30v and the one beside it produces only 5 amps at up to 15v, as long as the battery voltage is less than 15v the panel mix will feed in 15 amps, when the battery voltage gets above 15v then only the 30v panel will be able to put its full 10 amps in, but the 15v panel will still be adding something. This because the 15v panel can only produce its max output at up to 15v, after that, to meet the higher voltage required to push any current out, the 15v panel will not be able to operate at its best output but it will still put out something until the open circuit voltage is reached. No one would try to charge a 12v battery to 20v or more, or a 24v battery to 40v or more, this is the voltage that a 12v nom. or 24v nom. panel can still put out some current so they don't just stop because they reached their Vmp voltage.
PWM controllers don't care if other PWM controllers or any sort of chargers are trying to charge the battery at the same time, they only care about the target voltage and they will do all they can to reach it and maintain it.

So, the choice is back I your court, only you know what you have now and what you want to achieve

 

T1 Terry

 

Edited my terrible typing and tried to make it easier to read by adding a few of the words I missed confuse



-- Edited by T1 Terry on Tuesday 13th of March 2018 03:12:15 PM

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You can lead a head to knowledge but you can't make it think. One day I'll know it all, but till then, I'll keep learning.



Senior Member

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Posts: 158
Date:

Dougwe wrote:

How, everyone,

Please be gentle. 

I am changing from a 30a regulator to 40a. Should I go MPPT or PWM and why. 

Edit. .. I have 3X150W panels on teepee roof.

            2x110AH Batteries. 

 



-- Edited by Dougwe on Tuesday 13th of March 2018 03:14:01 AM


 

I run a Morningstar 30 PWM & my 2 110ah batteries are always charged by mid morning. Also my panels work well in low light, hence why I paid a bit more to get them.

Cannot fault the Morningstar; it has been brilliant & I chose it because it was highly rated repeatedly. Tested, tried & true is usually a good act to follow.



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Bob+Deb


Chief one feather

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Posts: 14111
Date:

Thankyou everyone for your input. As usual everyone has come to the rescue.

T1 Terry, thankyou for such a detailed answer, I understood most of it but now have a case of information overload biggrinbiggrin I have been on this for days now and my mind is spinning around and around and not cos of drinks either.

I have now made a choice. I will go with a 40a PWM. Brand still up in the air at this stage. The MPPT's are way out of my price range, for now anyway. Us old Indians have to watch our penny's ya know. 

Thanks heaps again everyone.



__________________

Live Life On Your Terms

DOUG  Chief One Feather  (Losing feathers with age)

TUG.......2014 Holden LT Colorado Twin Cab Ute with Canopy

DEN....... "Chief" Arrow CV  (with some changes)

 



Guru

Status: Online
Posts: 717
Date:

T1 Terry wrote:

if you can't follow all this just ask me to explain it better, I don't mind a bit. I tend to get over technical some times but hopefully those that can't quite follow it will ask for more explanation, better than boring those who do understand some of it to the point where they don't read any more and maybe miss something that will expand their knowledge. Hopefully those that don't agree will be constructive in their criticism rather than attack for the sake of it smile


It really depends on the solar panels you plan to use. If they are all roughly the same capacity as far as watts, have a voltage significantly greater than the battery voltage you want to charge, then MPPT is the way to go. Ideally with all the panels connected in series, positive from one into negative from the next till you have only one negative at one end of the chain and one positive at the other end of the chain, and this total open circuit voltage is less than the max input voltage of the MPPT controller and that controller can output the total that can be extracted from this combination, then go that way and you will be happy with the outcome.
If you can not make a solar panel single series string with an open circuit voltage less than the max voltage the MPPT controller can handle, then you need to connect all the panels in parallel. This means all the negatives together and all the positive together to add up to the max amps the controller can handle. So you need to look at both the input max voltage and the output max current to be sure you choose the right controller for your set up.
No matter what anyone suggests, forget about trying to make 2 series strings to keep the voltage down and feed that into one controller, the end result is a poor functioning system. The same goes for multiple MPPT controllers or multiple charging devices working along with an MPPT controller unless they are the top of the line linkable type or you have a degree in cabling/ rewiring and programming to trick the individual controllers into becoming master slave controllers. Yes, it can be done, by the average punter ..... highly unlikely to get it to work without ending up paying for someone to sort it. The chances of the user understanding how it works so they can explain to the repair man when it stops working .......?????? Not the best situation to end up in when you are out on the road eh.

This leads to why I recommend avoiding MPPT controllers if you can. If you want to get the best out of a PWM you need to have panels with an open circuit voltage 10v or less than the battery voltage you want to charge. This should mean the Vmp (maximum voltage the panel creates its max amps) should be higher than the highest voltage you expect to need to charge the battery at most temperatures. An example, a flooded cell lead acid battery wants 14.8v to reach the end of the boost charge cycle. This will probably occur close to the middle of the day and this is when the sun will be getting the panels to their highest temperature. A panel with a Vmp marked on the back of 18v says that panel at 25*C in the perfect angle to the sun will develop the most current it can produce at 18v, but, there is absolutely no chance in Australia that a flat mounted panel on the roof of an RV at mid day in full sun will be still at 25*C. Real world Vmp for that panel marked as 18v Vmp would be around 15v to 16v, could be less, but this is still more than the 14.8v required so it will do the job just fine.
PWM controllers don't care if the voltage from the panels is higher, it won't extract the max that maybe could be extracted under certain conditions, but all the panels connected to the controller will put out the best they can produce as long as the cabling is up to spec. It doesn't care if one panel is a 60w and the next is a 300w, the total will still be 360w. It doesn't care if one panel produces 10 amps at up to 30v and the one beside it produces only 5 amps at up to 15v, as long as the battery voltage is less than 15v the panel mix will feed in 15 amps, when the battery voltage gets above 15v then only the 30v panel will be able to put its full 10 amps in, but the 15v panel will still be adding something. This because the 15v panel can only produce its max output at up to 15v, after that, to meet the higher voltage required to push any current out, the 15v panel will not be able to operate at its best output but it will still put out something until the open circuit voltage is reached. No one would try to charge a 12v battery to 20v or more, or a 24v battery to 40v or more, this is the voltage that a 12v nom. or 24v nom. panel can still put out some current so they don't just stop because they reached their Vmp voltage.
PWM controllers don't care if other PWM controllers or any sort of chargers are trying to charge the battery at the same time, they only care about the target voltage and they will do all they can to reach it and maintain it.

So, the choice is back I your court, only you know what you have now and what you want to achieve

 

T1 Terry

 

Edited my terrible typing and tried to make it easier to read by adding a few of the words I missed confuse



-- Edited by T1 Terry on Tuesday 13th of March 2018 03:12:15 PM


Doug, glad you were able to work out a way to go.

 Terry, thanks for that explanation. It increased my knowledge and reinforced some of what I already thought I knew.smile

Cheers, John



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