PWM VS MPPT TROPICS

[deckofficer]

Well Nick if you never have noticed interference while operating HF during the day, I'd say your Outback isn't generating any RFI.

[s/v Jedi]

Originally Posted by deckofficer

Well Nick if you never have noticed interference while operating HF during the day, I'd say your Outback isn't generating any RFI.

No, I just hooked it up, I didn't use a controller for a long time. I'm rewiring panels to series connection 3x2. My panels are still like new but the cabling is far gone after 9 years...

[deckofficer]

Originally Posted by s/v Jedi

No, I just hooked it up, I didn't use a controller for a long time. I'm rewiring panels to series connection 3x2. My panels are still like new but the cabling is far gone after 9 years...

Your usage always exceeded your production?

[s/v Jedi]

Originally Posted by deckofficer

Your usage always exceeded your production?

Yep, always.

[deckofficer]

No need for any controller in that situation. What has changed?

[Caribsailors]

Originally Posted by daddle

Ahhh ... Just get some reasonable 18v panels, wire them in parallel with a controller, maybe MPPT, and go cruising. It's what everybody is doing. Try to keep the panels in the sun and the beer in the fridge.

Ditto....Has worked form me in the tropics

[ChuckSK]

Originally Posted by s/v Jedi

No, I just hooked it up, I didn't use a controller for a long time. I'm rewiring panels to series connection 3x2. My panels are still like new but the cabling is far gone after 9 years...

Because a shaded panel in one series string will pull down the voltage in the parallel unshaded series string, thereby causing a double loss, it would be better to use a separate controller for each string.

Chuck

[s/v Jedi]

Originally Posted by ChuckSK

Because a shaded panel in one series string will pull down the voltage in the parallel unshaded series string, thereby causing a double loss, it would be better to use a separate controller for each string.

Chuck

Only if your panel is 30 years old without blocking diode....

[s/v Jedi]

Originally Posted by deckofficer

No need for any controller in that situation. What has changed?

We bought a motorhome

So last summer in storage I disconncted my solar and use a shorepower cord... big mistake!

[ChuckSK]

Originally Posted by s/v Jedi

Only if your panel is 30 years old without blocking diode....

Modern panels have bypass diodes but not blocking diodes. It is the operation of the bypass diodes that will cause the voltage in a shaded series string to be lower than in an unshaded series string. When these two series strings are then connected in parallel, the total voltage is the voltage of the shaded string. A single controller will see only one input voltage.

[s/v Jedi]

Originally Posted by ChuckSK

Modern panels have bypass diodes but not blocking diodes. It is the operation of the bypass diodes that will cause the voltage in a shaded series string to be lower than in an unshaded series string. When these two series strings are then connected in parallel, the total voltage is the voltage of the shaded string. A single controller will see only one input voltage.

Sure. I assume you tested this with your solar array. Please tell us which brand and type of panels you used, how many and how they were connected. ?

[ChuckSK]

Originally Posted by s/v Jedi

Sure. I assume you tested this with your solar array. Please tell us which brand and type of panels you used, how many and how they were connected. ?

I have 4 Kyocera 130 panels in series connected to a Xantrex XW-MPPT-60.

Here are charts of series-parallel studies I did before deciding on a series configuration. You will notice that shading 1 cell reduced the series-parallel array output by 120 watts. If there had been a controller for each series string the loss would have been 65 watts.

[s/v Jedi]

Originally Posted by ChuckSK

I have 4 Kyocera 130 panels in series connected to a Xantrex XW-MPPT-60.

Here are charts of series-parallel studies I did before deciding on a series configuration. You will notice that shading 1 cell reduced the series-parallel array output by 130 watts. If there had been a controller for each series string the loss would have been 65 watts.

Where is the voltage drop? I think you wrote that the array voltage would go down to the low voltage of the shaded string?

[ChuckSK]

Originally Posted by s/v Jedi

Where is the voltage drop? I think you wrote that the array voltage would go down to the low voltage of the shaded string?

Observe that the voltage at MPP dropped from 35 volts to 27 volts.

[s/v Jedi]

Forgot: an easy way to check if your panel has a blocking diodeis directly attaching to a battery; if the battery get charged during the day but discharges into the panel at night, you have no blocking diode. This is how it was 30 years ago.

Now, I know for sure that my Shell/Siemens panels have blocking diodes and I'm sure somebody will come up in this thread to tell us if the Kyocera 130's have one. I'm pretty sure they do since the last 30 years...