Series v parallel solar panels.

[noelex 77]

There is always great debate on the forums regarding which connection type produces the highest yield on a yacht (although the vast majority of members support parallel connection as the better option).

Personally, I use one controller per panel, which was not tested in this experiment. One contoller per panel is considered the best option for installations subject to shade. Nevertheless, this option is not always practical so tests between series and parallel connection in shaded conditions are helpful.

The video below was only released a day ago and shows the type of difference that will be experienced even on relatively low voltage panels. They could have added an extra external bypass diode around each panel during the series test, but very few people do this in practice.

https://www.youtube.com/watch?v=-59v...polpSiQWBmVyY8

[Zonker]

Expensive: each panel should have its own MPPT "charger".


Affordable: a separate step down / up regulator for each panel. Can then feed a regular whatever charger.

[wholybee]

Originally Posted by Zonker

Expensive: each panel should have its own MPPT "charger".


Affordable: a separate step down / up regulator for each panel. Can then feed a regular whatever charger.

MPPT chargers aren't that expensive if you stay away from the expensive brands. A cheap PWM controller would be much better than a step up/down regulator into a regular charger-which probably wouldn't work at all.

The cheapest "controller" is just a voltage controlled relay that directly connects the panel to the battery, and disconnects it when the battery reaches a set voltage. And they work fine, although don't produce as much power as a real controller would.

[Zonker]

Originally Posted by wholybee

MPPT chargers aren't that expensive if you stay away from the expensive brands. A cheap PWM controller would be much better than a step up/down regulator into a regular charger-which probably wouldn't work at all.

The cheapest "controller" is just a voltage controlled relay that directly connects the panel to the battery, and disconnects it when the battery reaches a set voltage. And they work fine, although don't produce as much power as a real controller would.

Nah ... below - this is working pretty well. For step up you don't have to buy Victron or such. AliExpress totally does.


Important is that you have a proper charger or you shorten the life time of you battery.

[noelex 77]

Originally Posted by Zonker

Nah ... below - this is working pretty well. For step up you don't have to buy Victron or such. AliExpress totally does.


Important is that you have a proper charger or you shorten the life time of you battery.

How do you track and adjust the maximum power point?

[wholybee]

Originally Posted by Zonker

Nah ... below - this is working pretty well. For step up you don't have to buy Victron or such. AliExpress totally does.


Important is that you have a proper charger or you shorten the life time of you battery.

You would do better to skip the converters and the charger, and simply use a relay to directly connect the panels to the battery. That would be about $5 to setup.

A PWM controller is only $20 or an MPPT for about $40 (or either for much less but I'm not looking that the very cheapest). You could upgrade from "pretty well" to "great"

[Zonker]

Originally Posted by noelex 77

How do you track and adjust the maximum power point?

You have to split the "problem" in 2 parts if you have multiple solar panels.


1. define a "bus" ... like your AC line at home at 110V or 220V. In order to achieve this, each panel needs "mppt" controller. They are also called step up or step down converters. To make it cheaper you can decide to step up only meaning you define a bus (for ex. @ 48V) so that each panels voltage has to be "step upped" / converted to a higher voltage. You might lose a couple of percentage off the generated wattage.



2. And since you have now a 48V "bus" you can use a step down converter, which fits to your charger. For example for a PWM charger you can set the voltage to like 14..15V, so the "stupid conversion" loss would be small. Or you could use an MPPT charger.


The point is - with multiple panels on a boat ... the voltage and wattage can change non-stop. To add them in serial or parallel order in order to feed a single charger, the loss is just too high.

[Zonker]

Originally Posted by wholybee

You would do better to skip the converters and the charger, and simply use a relay to directly connect the panels to the battery. That would be about $5 to setup.

A PWM controller is only $20 or an MPPT for about $40 (or either for much less but I'm not looking that the very cheapest). You could upgrade from "pretty well" to "great"

Well I can recommend some basic literature about such stuff ... says a EE.

[noelex 77]

Originally Posted by Zonker

You have to split the "problem" in 2 parts if you have multiple solar panels.


1. define a "bus" ... like your AC line at home at 110V or 220V. In order to achieve this, each panel needs "mppt" controller. They are also called step up or step down converters. To make it cheaper you can decide to step up only meaning you define a bus (for ex. @ 48V) so that each panels voltage has to be "step upped" / converted to a higher voltage. You might lose a couple of percentage off the generated wattage.



2. And since you have now a 48V "bus" you can use a step down converter, which fits to your charger. For example for a PWM charger you can set the voltage to like 14..15V, so the "stupid conversion" loss would be small. Or you could use an MPPT charger.


The point is - with multiple panels on a boat ... the voltage and wattage can change non-stop. To add them in serial or parallel order in order to feed a single charger, the loss is just too high.

The maximum power point changes with changing conditions. The "T" in MPPT stands for tracking. The input voltage to the controller is constantly adjusted to maximise the output of the solar panel. This is one of the major functions of a MPPT controller. I don’t see how your system achieves this.

[wholybee]

What happens as the insolation decreases? Walk through it, what happens to the voltage and current from the panels? What happens at the input of the 48V converters? How does the charger react when there is 48V at the input, but the input can't sustain the required current?

I generally ignore people that through out their credentials in a conversation/argument. It usually means their ego is bigger than their knowledge.

[barnakiel]

"Ideally" also the panels nominal should be well above battery voltage nominal.


So 12V panels should be avoided on a 12V battery bank. (unless you wire two in series )



b.

[s/v Jedi]

No, not again.



Matching impedance and adjusting when conditions change is completely omitted by pwm or the boost/buck converter methods, resulting in an immediate 7% less production for the average setup on an average day.

There is a reason why moot is so popular: in all but very few cases it is far superior than all other methods.

[smac999]

Originally Posted by barnakiel

"Ideally" also the panels nominal should be well above battery voltage nominal.


So 12V panels should be avoided on a 12V battery bank. (unless you wire two in series )



b.

A 12v panel means it works on a 12v battery with a pwm controller. Which means the panel is 20v. But that wording isn’t really used anymore since now everyone uses mppts.

[Zonker]

Originally Posted by wholybee

What happens as the insolation decreases? Walk through it, what happens to the voltage and current from the panels? What happens at the input of the 48V converters? How does the charger react when there is 48V at the input, but the input can't sustain the required current?

I generally ignore people that through out their credentials in a conversation/argument. It usually means their ego is bigger than their knowledge.

As I said you have no clue about EE ...



Panel producing 20W @ 20V.


1) totally shaded -> 0W => what is the voltage achievable
2) partially shaded -> 10W => how much current can "a regulator" deliver @ 40V


-> this is at high school level ...


So what if we have a MPPT for each panel and all MPPTs going to the same battery bank -> kinda gets difficult since the sensors which affect each other.

So what is the cheap solution to avoid the issues with multiple panels and multiple MPPT controllers ...


Yea ... some ppl read and learn, some ppl just throw bs.

[Zonker]

Originally Posted by s/v Jedi

No, not again.



Matching impedance and adjusting when conditions change is completely omitted by pwm or the boost/buck converter methods, resulting in an immediate 7% less production for the average setup on an average day.

There is a reason why moot is so popular: in all but very few cases it is far superior than all other methods.

Sure ... again for you, multiple panels and multiple MPPT controllers.


Also have a look INSIDE a MPPT controller ... how is this built ... ... using old fashined switching regulator.