Trebor English said:
This does get close to the experiment I proposed....thanks for the idea...
MPPT vs PWM test
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This does get close to the experiment I proposed....thanks for the idea...
The Victron series with dongle built in is about $20-$25 more than the older ones.
The old 75/15s can be found $75-90 now, and functionally the same, fully adjustable, so IMO not worth using PWM except for super-frugal types.
The old 75/15s can be found $75-90 now, and functionally the same, fully adjustable, so IMO not worth using PWM except for super-frugal types.
jimindenver
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So I will try to respond without a lot of quotes or multiple posts.
First I was not saying that PWM could NOT charge batteries. Should your PWM system work well for you then great. There is no reason to defend your decision. Does that mean a MPPT system can not provide more power out of the same array, not at all. The charging happens faster due to being able to use all of the panels power no matter what the voltage of the battery. A PWM system will only provide the same amount of power as a MPPT system IF the battery is at the working voltage of the panel. Should you want to run your battery at the 17 or 18 working volts of a 12 volt panel, good for you.
Are the controllers I used reliable? I started using the Eco-worthy controllers in 2012 and never had one fail on its own. I did short one out once and Eco-worthy was quick to offer to repair/replace it. The Solar30 has been a known controller at least that long and is used by many. They were chosen for their reliability and low cost for videos that Bob wanted to shoot. The PWM vs MPPT test was my idea to show the differences in the systems.
Would a better PWM system provide different results? Again you are not understanding the basic concept of how a PWM system works. The power from the panel is limited by the voltage of the battery not the controller. The controller keeps the battery from gaining too much voltage and boiling by holding the voltage down to absorb or float. The excess voltage is shed meaning that a battery at 12v turns a 100 watt panel with a working voltage of 18 volts into a 66 watt panel.
The Bogart system does not change how much power is usable from the panel. Its advantage is that it uses a amp counter to decide when to shut off the charging. The same principle would improve the control of the charging of a MPPT system with the difference being that it would be faster to bring up the voltage of the battery and provide more amps in absorb and float for running loads. Is the concept perfect? No because it does not take into account that batteries degrade and lose capacity over time no matter how well you take care of them.
Will a newer MPPT controller be able to solve the mixed panel issues which is the same issue caused by partial shading on panels in series? Boy wouldn't that be sweet! To test that I would need access to the workings of the controller like I have with my Morningstar's via MSview. There I can see things such as the controllers program trying to settle on a voltage with mixed panels and never stopping.
Does one MPPT controller brand have a advantage in charge management over another? Only side by side testing would prove that to be the case but it may be possible. I would not put anything into the claim unless proven. Most claims of this is better are either bravado or advertising. Look to those that have nothing to sell for real world results. In Victrons case I saw a number of systems not functioning because the owners were not told they needed to spend more money on the dongle to get the ability to upgrade the firmware and change the set points. Until that was done the controller could not properly charge and batteries were damaged. Those controllers simply were not ready to be released nor should they have been sold without the knowledge that the dongle was needed. The new series is a better product and more expensive for it.
Would a higher voltage grid tied panel provide more power than two 12 volt panels in series or even parallel for that matter? That would be a interesting test to set up but I do not have the room to carry the gear around. Add to that as much as I enjoy setting up and running the test to show the results, my enthusiasm is tempered by those that find the need to discount them. So in the end I decided not to accepts Bobs generous offer of the gear to continue running test.
I am not here to tell you what to do or even which is best. I try to show the options so that a person can make a educated decision. Can MPPT provide more power from the same panels? Yes. Does PWM have a advantage with the ability to use varying panels? Yes Is there a Cost difference? Yes. Is the option to accept the info into your decision making process yours? Always
First I was not saying that PWM could NOT charge batteries. Should your PWM system work well for you then great. There is no reason to defend your decision. Does that mean a MPPT system can not provide more power out of the same array, not at all. The charging happens faster due to being able to use all of the panels power no matter what the voltage of the battery. A PWM system will only provide the same amount of power as a MPPT system IF the battery is at the working voltage of the panel. Should you want to run your battery at the 17 or 18 working volts of a 12 volt panel, good for you.
Are the controllers I used reliable? I started using the Eco-worthy controllers in 2012 and never had one fail on its own. I did short one out once and Eco-worthy was quick to offer to repair/replace it. The Solar30 has been a known controller at least that long and is used by many. They were chosen for their reliability and low cost for videos that Bob wanted to shoot. The PWM vs MPPT test was my idea to show the differences in the systems.
Would a better PWM system provide different results? Again you are not understanding the basic concept of how a PWM system works. The power from the panel is limited by the voltage of the battery not the controller. The controller keeps the battery from gaining too much voltage and boiling by holding the voltage down to absorb or float. The excess voltage is shed meaning that a battery at 12v turns a 100 watt panel with a working voltage of 18 volts into a 66 watt panel.
The Bogart system does not change how much power is usable from the panel. Its advantage is that it uses a amp counter to decide when to shut off the charging. The same principle would improve the control of the charging of a MPPT system with the difference being that it would be faster to bring up the voltage of the battery and provide more amps in absorb and float for running loads. Is the concept perfect? No because it does not take into account that batteries degrade and lose capacity over time no matter how well you take care of them.
Will a newer MPPT controller be able to solve the mixed panel issues which is the same issue caused by partial shading on panels in series? Boy wouldn't that be sweet! To test that I would need access to the workings of the controller like I have with my Morningstar's via MSview. There I can see things such as the controllers program trying to settle on a voltage with mixed panels and never stopping.
Does one MPPT controller brand have a advantage in charge management over another? Only side by side testing would prove that to be the case but it may be possible. I would not put anything into the claim unless proven. Most claims of this is better are either bravado or advertising. Look to those that have nothing to sell for real world results. In Victrons case I saw a number of systems not functioning because the owners were not told they needed to spend more money on the dongle to get the ability to upgrade the firmware and change the set points. Until that was done the controller could not properly charge and batteries were damaged. Those controllers simply were not ready to be released nor should they have been sold without the knowledge that the dongle was needed. The new series is a better product and more expensive for it.
Would a higher voltage grid tied panel provide more power than two 12 volt panels in series or even parallel for that matter? That would be a interesting test to set up but I do not have the room to carry the gear around. Add to that as much as I enjoy setting up and running the test to show the results, my enthusiasm is tempered by those that find the need to discount them. So in the end I decided not to accepts Bobs generous offer of the gear to continue running test.
I am not here to tell you what to do or even which is best. I try to show the options so that a person can make a educated decision. Can MPPT provide more power from the same panels? Yes. Does PWM have a advantage with the ability to use varying panels? Yes Is there a Cost difference? Yes. Is the option to accept the info into your decision making process yours? Always
B and C
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jimindenver said:
Please explain what a mixed panel system consists of.
My buddy has a MPPT controller and does not want to buy another one for a second set of panels to run controllers in parallel on the same set of batteries as GotSmart suggested. His MPPT controller is large enough to handle more panels. I am trying to help him pick panels as his are no longer available.
His existing panels are in series and he wants to add a second series set in parallel with the first set before the controller.
As long as the voltage from the second set ='s the first set, everything should be fine? Right?
Wattage can be different. Yes?
If you choose to connect multiple panels per controller, they should all be the same model panel.
Especially with a true MPPT SC.
If you decide to mismatch, yes the voltage being very close is the most important spec to match, but you will lose some output power.
Just buy a separate controller if you have unmatched sets.
A big expensive SC can be connected to a new bigger set, and get a cheap SC for the smaller old ones.
Especially with a true MPPT SC.
If you decide to mismatch, yes the voltage being very close is the most important spec to match, but you will lose some output power.
Just buy a separate controller if you have unmatched sets.
A big expensive SC can be connected to a new bigger set, and get a cheap SC for the smaller old ones.
jimindenver
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Matching panels really are best BUT.....
Same wattage, voltage and type as best as you can. Honestly I would take a meter with me and test each new panel to find some that were as close as possible. The type part is because monos and polys react to varied light differently so what matches up in bright light will not in lower light conditions.
This is the biggest advantage PWM has over MPPT, the ability to fill in holes on the roof or add panels at a later date without messing with the controller. Adding a second controller will fix it or as I have done in the past is sell off the older panels and buy all matching new panels to expand my system.
Same wattage, voltage and type as best as you can. Honestly I would take a meter with me and test each new panel to find some that were as close as possible. The type part is because monos and polys react to varied light differently so what matches up in bright light will not in lower light conditions.
This is the biggest advantage PWM has over MPPT, the ability to fill in holes on the roof or add panels at a later date without messing with the controller. Adding a second controller will fix it or as I have done in the past is sell off the older panels and buy all matching new panels to expand my system.
Canine
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B&C, like what has been said, MPPT doesn't like mismatched panels. If he has old panels and wants to add different ones to his individual charge controller, then that will be difficult. He will have some losses for sure unless he wins the lottery and finds a good match. The best solution by far when using mismatched panels is to add additional charge controllers especially ones that are made to be networked together. Using networked controllers even with brand new, perfectly matched panels will give him great results. I have two networked charge controllers and am super happy with the results. I wish I had been more detailed and scientific with my process going from one controller to two, but it without a doubt the upgrade made a big improvement.
Canine
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jonyjoe303 said:
That is an odd result. An MPPT should give fewer amps with higher voltage and more amps with lower voltage. The results seem to violate Watt's Law.
A higher voltage will push harder, but will push fewer amps; a lower voltage will not push as hard, but will push more amps.
We may need to start another thread to pursue this.
I have a portable Cynergy 160 watt system, I saw a huge difference by doing two things, swapped the cheap pwm controller for a Victron 75/15 MPPT and wiring the two panels in series (double volts/half amps) instead of parallel from the factory (2 x 80 watt panels). I saw a difference of 120 watts PWM to 168 watts for the MPPT (cold winter sunny day).
One thing I noted, as previously mentioned by another poster, when the batteries are really low, the MPPT systems put out significantly more wattage at the time it is needed the most.
JonyJoe303 - My LiFePO4 on MPPT this last weekend was actually up to 980 watts - 70 amps @ 14V (which is where I have bulk set to on my controller), my amps seem to stay steady as the voltage rises as it charges up. I could see the total wattage goes up as the voltage rises.
Also my main panels are only 915 watt rated, but on really icy cold winter days with a lot of white clouds not covering the sun but reflecting light too I see some amazing power outputs (like 980 this weekend). I am seeing a swing of 200 watts depending on temperature alone in my main solar system. I think on a hot summer day my max is around 760 watts.
The three different PWM controllers I have had never got better than 80% of panel rated outputs.
One thing I noted, as previously mentioned by another poster, when the batteries are really low, the MPPT systems put out significantly more wattage at the time it is needed the most.
JonyJoe303 - My LiFePO4 on MPPT this last weekend was actually up to 980 watts - 70 amps @ 14V (which is where I have bulk set to on my controller), my amps seem to stay steady as the voltage rises as it charges up. I could see the total wattage goes up as the voltage rises.
Also my main panels are only 915 watt rated, but on really icy cold winter days with a lot of white clouds not covering the sun but reflecting light too I see some amazing power outputs (like 980 this weekend). I am seeing a swing of 200 watts depending on temperature alone in my main solar system. I think on a hot summer day my max is around 760 watts.
The three different PWM controllers I have had never got better than 80% of panel rated outputs.
> That is an odd result.
No, comes from trying to push too much power into an already full bank.
With LFP will mean only getting a fraction of the bank's potential life, IMO a huge mistake.
As you say best pursued in a separate thread.
No, comes from trying to push too much power into an already full bank.
With LFP will mean only getting a fraction of the bank's potential life, IMO a huge mistake.
As you say best pursued in a separate thread.
ltripper yes very cold and extra light will do that, but IMO "long tail" outlier cases like that are best ignored when doing capacity planning, matching panels to SC etc based on overall averages, or even worst case scenarios.
why SCs like the Victrons that have a lot of safety headroom in their input specs are so great, overpanelling can really improve overall charging inputs without risking breaking the SC
Yes lots of "excess power wasted" when things are ideal, but that's par for the course.
With some SCs though you have to be careful pushing the limits, maybe even tossing a tarp over the panels when it gets like that
why SCs like the Victrons that have a lot of safety headroom in their input specs are so great, overpanelling can really improve overall charging inputs without risking breaking the SC
Yes lots of "excess power wasted" when things are ideal, but that's par for the course.
With some SCs though you have to be careful pushing the limits, maybe even tossing a tarp over the panels when it gets like that
GotSmart
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John61CT said:ltripper yes very cold and extra light will do that, but IMO "long tail" outlier cases like that are best ignored when doing capacity planning, matching panels to SC etc based on overall averages, or even worst case scenarios.
why SCs like the Victrons that have a lot of safety headroom in their input specs are so great, overpanelling can really improve overall charging inputs without risking breaking the SC
Yes lots of "excess power wasted" when things are ideal, but that's par for the course.
With some SCs though you have to be careful pushing the limits, maybe even tossing a tarp over the panels when it gets like that
A solar CONTROLLER is there to CONTROL.
Set it right, and let it do its job.
Fact. North west Washington gets 1/2 the solar potential that Quartzsite does over a years time.
Fact. At winter solstice there is much less solar potential than at summer solstice.
Fact. Useing a tarp as a solar controller would only be suggested by someone that has never actually worked on solar. You match controller to panels. If the batteries are full the controller stops putting power in. It CONTROLS the power.
Back to overpaneling. I have photos of a 6KW mobile system. The designer only has about 600 ah of battery. During the day he charges his electric car and heats his water as well as any other possible use. Is he over paneled?
Insufficient information.
The term does not mean 'have lots of solar power relative to needs'.
It means 'peak panel output (SC input) is higher than SC needs to produce **its** peak output when conditions are ideal'
Depending on panel vs SC pricing doing so may be wasteful, but sometimes great panel deals come along and doing so can greatly improve **average** output.
And obviously my point about the tarp was to avoid that scenario.
The term does not mean 'have lots of solar power relative to needs'.
It means 'peak panel output (SC input) is higher than SC needs to produce **its** peak output when conditions are ideal'
Depending on panel vs SC pricing doing so may be wasteful, but sometimes great panel deals come along and doing so can greatly improve **average** output.
And obviously my point about the tarp was to avoid that scenario.
jimindenver
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Over paneling was first officially sanctioned by Morningstar, before that it was considered that a buffer of 20% was prudent. I have never over paneled my Eco-worthy MPPT controllers but I have seen it done. A 250w poly panel produced 18.5a on the Eco-worthy (the morningstar too) and I have seen people run 300 watts on them. The amps stopped at 20.1 in that case and you have to make sure that proper wiring and a fan is used, even spacers behind the controller to keep it from getting too hot and self limiting itself. Eco-worthy dropped the rating from 300w to 275w which made it so that people didn't have to take measures to keep it from over heating.
I have over paneled my Morningstar TS-MPPT-60 during the mixed panel test. Even though it was shaded and has a huge heat sink, it also got very hot. Hot enough that it too self limited the output and I did not want to pick it up. Heat is the result of over paneling and heat is the bane of electronics. What made it worse was the fact that the over paneling was in series and using a Voc 10 volts under the controllers 150 Voc limit. That gave it a very high conversion rate and the higher the conversion the more heat is produced. Interestingly enough when the controller self limited itself, it did so to the same 660w that I am use to seeing from my three flat mounted 250w panels so really there was no benefit at all in the end.
The concept behind over paneling is that early on or in winter when the sun is low and your panels are below their peak output, you are able to get more production to charge your battery faster. By the time the sun is up high your battery will already be in absorb or float and not accepting peak amps making the over paneling a non issue. My systems do charge my bank but the main objective is as a true solar generator meaning I use the most power mid day when the sun is high to run my A/C, water heater, stove and other appliances. Were I to over panel it would be pushing my controller daily and I just do not believe in stressing my systems for nothing. I get my early and late power via the tilting 435 watt panel on my truck following the sun. It produces more power on its own controller than a forth flat panel on the trailer would. I also get all of the power available all of the time.
I have over paneled my Morningstar TS-MPPT-60 during the mixed panel test. Even though it was shaded and has a huge heat sink, it also got very hot. Hot enough that it too self limited the output and I did not want to pick it up. Heat is the result of over paneling and heat is the bane of electronics. What made it worse was the fact that the over paneling was in series and using a Voc 10 volts under the controllers 150 Voc limit. That gave it a very high conversion rate and the higher the conversion the more heat is produced. Interestingly enough when the controller self limited itself, it did so to the same 660w that I am use to seeing from my three flat mounted 250w panels so really there was no benefit at all in the end.
The concept behind over paneling is that early on or in winter when the sun is low and your panels are below their peak output, you are able to get more production to charge your battery faster. By the time the sun is up high your battery will already be in absorb or float and not accepting peak amps making the over paneling a non issue. My systems do charge my bank but the main objective is as a true solar generator meaning I use the most power mid day when the sun is high to run my A/C, water heater, stove and other appliances. Were I to over panel it would be pushing my controller daily and I just do not believe in stressing my systems for nothing. I get my early and late power via the tilting 435 watt panel on my truck following the sun. It produces more power on its own controller than a forth flat panel on the trailer would. I also get all of the power available all of the time.
Yes why I was saying it's great to find SCs that set the max input spec much higher than the max output, leaves the user in the driver's seat which way they want to go.
Same with accepting a wide range of input voltages, greater freedom to choose panels rather than being locked into a particular type.
Same with accepting a wide range of input voltages, greater freedom to choose panels rather than being locked into a particular type.
frater secessus
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tx2sturgis said:
I have some questions about shunts related to this. I started a thread for it to avoid threadjacking.
I'd appreciate your input on it.I love the Victron 75/15 with bluetooth (I have an older model with separate dongle). The extra cost was totally worth it to me for longer battery life and more efficient operation.
I fully intend to get a larger version for the larger panel system I am planning for the cargo trailer conversion.
I fully intend to get a larger version for the larger panel system I am planning for the cargo trailer conversion.
"Fact. Useing a tarp as a solar controller would only be suggested by someone that has never actually worked on solar. You match controller to panels. If the batteries are full the controller stops putting power in. It CONTROLS the power. "
My controller is fine for 99% of my use, I really did not want to blow another $200 to get a controller that will handle the extra volts in below freezing max conditions. If money was not a consideration I for one wouldn't be on this forum and yes I would have gotten a 250v version instead of 150 volt
1 of my Victrons is definitely over panel'd, the 75/10 is running a 160 watt panel, however that panel I have hooked up with really long runs of wiring and tapped into the RVs wiring at a non optimal point so it never achieves the full 10 amps anyways (7 max around 100 watts).
My large Victron 150 (volt)/85 (amp) never gets hot even at (my 70 amps/14V) max capacity, however in theory it will over voltage if I leave it running on a sunny day at noon when below freezing, I have tested out putting a square of duct tape over one cell and it reduces the voltage enough so I do not have to worry about the controller frying. I would only do this if camping in freezing temps. Victron says their controllers can handle the overcurrent but cannot take over voltage at all. The voltage climbs pretty fast as it gets colder.
My controller is fine for 99% of my use, I really did not want to blow another $200 to get a controller that will handle the extra volts in below freezing max conditions. If money was not a consideration I for one wouldn't be on this forum and yes I would have gotten a 250v version instead of 150 volt
1 of my Victrons is definitely over panel'd, the 75/10 is running a 160 watt panel, however that panel I have hooked up with really long runs of wiring and tapped into the RVs wiring at a non optimal point so it never achieves the full 10 amps anyways (7 max around 100 watts).
My large Victron 150 (volt)/85 (amp) never gets hot even at (my 70 amps/14V) max capacity, however in theory it will over voltage if I leave it running on a sunny day at noon when below freezing, I have tested out putting a square of duct tape over one cell and it reduces the voltage enough so I do not have to worry about the controller frying. I would only do this if camping in freezing temps. Victron says their controllers can handle the overcurrent but cannot take over voltage at all. The voltage climbs pretty fast as it gets colder.
DLTooley
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With lead acid systems peak charging results in a voltage drop (volts not watts). As such panels are engineered to produce near optimal voltages during peak charging. ( I believe this is the functional definition that f the absorb state.). On that THEORY I would not upgrade from a PWM on a lead acid bank. Two exceptions would be overpaneling on a bank(the voltage drop will be less) and when you are using non battery power post absorb. I suspect MPPT may hav additional benefits in cloudy conditions but can’t figure out how to test.
