100 plus 200 watts

[sonar]

Is it better to join two solar panels of same voltage but differ in watts. Like a 200 watt and a 100 watt solar panel

in either series or connected parallel .

a question I have not found an answer for

 

[Lenny HB]

Always best to parallel pa els on a Motorhome because if you connect in series if eith panel gets any shade you will lose all output. Doesn't matter if the panels are a differentsize.

 

[I2C]

It’s better to join 2 panels of the same wattage and voltage, a 100 and a 200 panel will not give you 300 watt’s.

Personally I have my panel’s connected in series (smaller wires to the controller), never had a problem with shade, if I did it would affect both panels anyway as they’re close to each other.

 

[sonar]

So this is the way to go then .

It could be a question a few others Would like to know maybe at a later date. If others decide to go down the solar route.

 

[I2C]

This site will give you reasons on why not/how to connect different sized panels

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[andy63]

its been well covered over the years
panels are best matched so that the voltage characteristics/specifications are the same if you are connecting in parallel
if connecting in series the current specifications should be the same...
if you connect panels in parallel that have different voltage specifications then the panel with the lowest voltage capability will limit the max voltage of the array and therefore the max power harvested
similarly if they have different current ratings then if connected in series the max current that will flow is governed by the panel with the lowest current capability and again limit the power of the system...
so in short its best to match panels if you want the max output from the system , but if you have mis matched panels the system will still produce..
Andy

 

[Guigsy]

Always best to parallel pa els on a Motorhome because if you connect in series if eith panel gets any shade you will lose all output. Doesn't matter if the panels are a differentsize.

If you parallel two panels, you end up with equal voltage on them both. Even if they have similar open voltages, they can behave quite differently for any given load. You can end up with poor efficiency. Might find you only get 250w out of the pair of them.

The best option is just to add another solar charger with the new panel. But that obviously adds cost and wiring. It's often cheaper just to buy a bigger panel and replace the smaller one.

 

[sonar]

I have two 95 amp habitation batteries.
and one cab battery. Fiat duca don,t know the amps as I have not yet renewed it.

with a mppt controller it will handle 350 watt total input power 8 mm wires to the batteries.
two mismatched solar panels 1 x 100 watt and 1. X 200 watt. And a solar panel monitor.
it is what I have to use.

parallel is my option well for the mismatched system according to what I have read and a few comments here on the forum.
Getting a bigger solar to match there is no more roof room unfortunately the roof is not totally flat.
sweeps up at the front so would not possible be the best place to place a larger panel unless someone has already done this.

 

[Jimbohorlicks]

This site will give you reasons on why not/how to connect different sized panels

That's really enlightening,thanks for the link

 

[dash300]

To be quite honest my brain is not in series or parallel with any of that. I will leave it to a professional not far from me!

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[Tombola]

I have two 95 amp habitation batteries.
and one cab battery. Fiat duca don,t know the amps as I have not yet renewed it.

with a mppt controller it will handle 350 watt total input power 8 mm wires to the batteries.
two mismatched solar panels 1 x 100 watt and 1. X 200 watt. And a solar panel monitor.
it is what I have to use.

parallel is my option well for the mismatched system according to what I have read and a few comments here on the forum.
Getting a bigger solar to match there is no more roof room unfortunately the roof is not totally flat.
sweeps up at the front so would not possible be the best place to place a larger panel unless someone has already done this.

Darren has a simlar van, flexi panels

 

[Raul]

Is it better to join two solar panels of same voltage but differ in watts. Like a 200 watt and a 100 watt solar panel

in either series or connected parallel .

a question I have not found an answer for

In this particular case, your best choice is parallel. The amps will add up, and you will loose 0,25 volts from the higher one to match the lowest. Perfectly ok.

 

[sonar]

In this particular case, your best choice is parallel. The amps will add up, and you will loose 0,25 volts from the higher one to match the lowest. Perfectly ok.

Thanks that’s how I saw it as well if the smaller panel had been 0.25 higher they would have matched in voltage.

hence higher amps same voltage.

 

[Pausim]

I used to use 3 100W portable panels and played around with parallel and series connection. Firstly although all 3 were identical and rated at 100W they did not all have identical outputs. When they were in series they all seemed to be dragged down by the one with the poorest performance and the output was always better in parallel.

 

[Raul]

That’s how it works in a series string. The hole string of 2-3 or more panels, will flow current limited by the lowest panel. If you have a string of 3 with 8-6-5A, the max that string can carry is 5A. When you parallel, the amps just add up, and the voltage equalises. Series has advantage when panels are equal in amps per string, and long run of cable. When long run, then you want high voltage (hence series), to compensate for voltage drop losses.

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[cyberyacht]

When I upgraded my system, I removed a framed 100W and replaced with 3x100W semi flex in series. That keeps the voltage up enough to continue charging longer at both ends of the day.

 

[sonar]

When I upgraded my system, I removed a framed 100W and replaced with 3x100W semi flex in series. That keeps the voltage up enough to continue charging longer at both ends of the day.

That was something I did think about but the words flex or flexy just seems so temp to me.
there will be lots that say no.

I did think flexible overtop of the cab . It a shape similar to an airplane wing and then decided maybe not.
fiat ducato sundance 2003

 

[Raul]

The only flexible worth fitting are CIGS, or SunPower.

 

[Billy192]

I believe semi flex are known to burn out cells after 12-18 months. if you buy from big name like Renogy who has a good warranty they will swap like for like. i was going to put 4 of the 100w on my roof (limited with sky lights) but watched several Utubes ( )

so i am going for solid 2x100w in series and 1 x 250w with 2 Victron mppt and a 300AH lith.