In series or parallel

[CarterKraft]

Originally Posted by cru-in

I ran two panels, in series and on one side of the roof, to one Morningstar MPPT Controller and a second set of panels, in series and on the other side of the roof, to a 2nd Morning star MPPT controller.

It worked great. Each MPPT maximizing for each set of panels and sun conditions. It was interesting to watch, throughout the day, the different production from the left and right side panels as the sun moved across the sky.

With MPPT controller prices coming down, I am surprised more folks do not do this.

Great point and one that I have noticed on large off grid installations. They use many smaller controllers for each solar plane.

I didn't break it down that far but the pricing on the Victron controllers is such that expanding your system above 600w it doesn't really make sense to buy a larger controller as cost wise you are better off with two 30 amp controllers. Much like the 75/15 @ $118 each would give you the same capacity as the 100/30 at nearly the exact same cost with double redundancy and increased gains over a single for the AS roof layouts that are common.

Of course then would you parallel each pair or put them in series

[cru-in]

Originally Posted by GMFL

Neat idea!

Thanks, with a Masters Degree in Electrical, I tend to over design the electrical stuff in our trailer.

[AirMiles]

I don’t even know how to reply to Pteck. He’s all over the place and making worthless assumptions about why I moved to 600W.

I moved to 600W to prove that it will work on the factory prewire. I moved to 600W to see if I could power my DC fridge with solar. I moved to 600W because it fit on the roof. I use series-parallel initially to use the factory pewire with minimal voltage loss. I found out it works great. I used series-parallel with 600W because it’s required because of the amperage that will move across the 10G prewire. I was perfectly happy with my 400W performance. I haven’t charged with a generator in two seasons with hundreds of documented dry camping days. I didn’t move to 600W because my 400W underperformed.

I haven’t had the opportunity to push my new 600W system yet. I had a good clear morning this morning. So I turned on the DC fridge at 7 am and cranked the power usage so I could see what the system could do full out on a clear day. The system did over 1.2kWH in the morning with a peak of just over 400W. Then the clouds moved in by 1pm. I turned the DC fridge back to propane and turned everything off except the fantastic fans. We will see where it ends up, but now it’s nearly overcast again so I still won’t know what the system is capable of producing on a sunny day. Maybe Pteck doesn’t care what his system is capable of producing, but I want to know.

It’s not easy to do these tests. It takes time and effort. I do them for myself and share them so others can learn too. But it’s disheartening when others twist and spin things out of context and make bad assumptions to put down others. Sometimes I wonder if it’s worth opening myself up for abuse by sharing the good, bad, and ugly performance of my solar system.

For what it’s worth, here’s the pictures of today’s aborted test. Morning clear skies to the east. Afternoon cloudy skies to clear the west. Production through 1:30pm. I’m parked at a suboptimal position with the curbside to the north. My maximum solar and least shade potential is rear to the south. I like to sit on the north side with the awning out. I’m sure Pteck will spin this test as a negative too. I don’t care. I did this for me and I share it so others others might learn something too.

My 400W series-parallel system met all my power needs. My 600W system will far surpass my needs. The 600W system cannot power the refrigerator on DC 24/7 like I hoped. With 600W, I can run the refrigerator on DC on sunny days. That’s what I’ve learned from my tests. I hope others have learned something too.

[pteck]

Originally Posted by AirMiles

I don’t even know how to reply to Pteck. He’s all over the place and making worthless assumptions about why I moved to 600W.

I moved to 600W to prove that it will work on the factory prewire. I moved to 600W to see if I could power my DC fridge with solar. I moved to 600W because it fit on the roof. I use series-parallel initially to use the factory pewire with minimal voltage loss. I found out it works great. I used series-parallel with 600W because it’s required because of the amperage that will move across the 10G prewire. I was perfectly happy with my 400W performance. I haven’t charged with a generator in two seasons with hundreds of documented dry camping days. I didn’t move to 600W because my 400W underperformed.

I haven’t had the opportunity to push my new 600W system yet. I had a good clear morning this morning. So I turned on the DC fridge at 7 am and cranked the power usage so I could see what the system could do full out on a clear day. The system did over 1.2kWH in the morning with a peak of just over 400W. Then the clouds moved in by 1pm. I turned the DC fridge back to propane and turned everything off except the fantastic fans. We will see where it ends up, but now it’s nearly overcast again so I still won’t know what the system is capable of producing on a sunny day. Maybe Pteck doesn’t care what his system is capable of producing, but I want to know.

It’s not easy to do these tests. It takes time and effort. I do them for myself and share them so others can learn too. But it’s disheartening when others twist and spin things out of context and make bad assumptions to put down others. Sometimes I wonder if it’s worth opening myself up for abuse by sharing the good, bad, and ugly performance of my solar system.

For what it’s worth, here’s the pictures of today’s aborted test. Morning clear skies to the east. Afternoon cloudy skies to clear the west. Production through 1:30pm. I’m parked at a suboptimal position with the curbside to the north. My maximum solar and least shade potential is rear to the south. I like to sit on the north side with the awning out. I’m sure Pteck will spin this test as a negative too. I don’t care. I did this for me and I share it so others others might learn something too.

My 400W series-parallel system met all my power needs. My 600W system will far surpass my needs. The 600W system cannot power the refrigerator on DC 24/7 like I hoped. With 600W, I can run the refrigerator on DC on sunny days. That’s what I’ve learned from my tests. I hope others have learned something too.

It's not worth my time to try to teach you what you don't understand. Nor can I make you learn what you insist on ignoring.

However, you're agenda impacts others that are following your lead. Engineering is not social engineering which you have a lot of time to do. Engineering is based on hard science and data.

What you're not understanding is the nature of a series-parallel system and how the panels are cross constrained in either current or voltage, such that shade on a single panel greatly impacts and reduces the overall potential output of the system.

cru-in's strategy is the only way I would setup multiple series strings. Not intertwine and constrain the array in a series-parallel fashion.

As he mentions, there is always a difference in production even at the same instant of the day. Imagine a setup where it takes the min of each string as the overall output of both strings. That my friend is what you've got.

[AirMiles]

Data. That’s what I provide. Make your own conclusions

2kWh of production with an afternoon of mostly cloudy to overcast conditions.

Months and months of actual dry camping with floating batteries nearly every day from all over the country in tree canopy, clouds and overcast, Series-parallel works great for me.

[pteck]

Data is great, but the title of this thread is to help us answer whether series vs parallel.

Originally Posted by CarterKraft

Of course then would you parallel each pair or put them in series

If optimizing for shade which is a common theme of when there's a production shortfall... I'll let these videos do the talking.

https://www.youtube.com/watch?v=ofo1HQyGG8s&t=305s

https://www.youtube.com/watch?v=1qD3mN8VotQ

[GMFL]

AirMiles and pteck guys..... Love you both, but we gotta agree to disagree. You guys are arguing over which car is faster a red on or a black one.
You passion is great and I’m sure you both get great results from your individual solar set ups, but these Hatfield/McCoy feud is becoming nonproductive. No one is listening to either one of you because you both have overstated your point.
There is no right or wrong answer here.
Guys being “Right” at all cost is wrong. No matter how smart y’all are you have lost any postive educational benefit to the entertainment of the argument.
You both have solar and it works for each of you. Congratulations.

[blacklab]

To the OP, in the interest of education as per your question, if you've not seen it, here's a video from AMSolar that describes the differences among series, parallel, and hybrid.

Not trying to prolong the "debate" here, just passing along a video that may provide additional info for your decisionmaking.

Lots of info presented in the video. Using "Pause" and "Rewind/Replay" helps.

https://www.youtube.com/watch?v=Z1ur3kSHuBU

Cheers,

Bryan

[FC7039]

Thanks to all who shared informative information and too bad others, whether right or wrong, used this post for nonsense.

[gcarter]

400 watts of series parallel. MPPT controller. Lithum 100ah battery. 20 years of usage.


18 year's parallel.


2 years ago rewired for series parallel. The panels show about 35 volts under brite sun and about 9 amps input to the controller. The voltage starts out at about 14v in the morning and charging at .5 amps. I even got 1 amp charging under a full moon one time. I will never go back to straight parallel.


What is shade. I live in the desert SW with no shade, no trees, and seldom have clouds.


So my vote is series.

[Tony Lee]

Originally Posted by pteck

This is a fallacy promoted by non-technical individuals on these boards. Even when disproved, they continue the spread of false information.

Truth is, all panels are rated at a nominal voltage higher than system voltage. i.e. 19V vs 12V system voltage.

If there's insufficient sun or shade enough that a panel is not producing near nominal voltage, there's simply not enough solar energy to be had to produce meaningful watts/power. Series connected panels won't change that fact.

That said, in a 2x panel setup, it won't matter as much if it's series or parallel with an MPPT controller, yet parallel still has a distinct edge in overall production.

Not my understanding, but perhaps you could give us your reasoning

[billrector]

I have a series, parallel configuration similar to Airmiles (I consulted with him for my installation). I have 400 watts of solar on the roof and am currently in Southern Utah. I also have 2 Fullriver AGM batteries providing 224 Ah. My batteries are fully charged by typically 1pm. Disclosure: I am in full sun every day. I don’t see what difference it would make if I am all parallel or series-parallel as fully charged is fully charged.