Solar panels in series or parallel?

[y22man]

Hello All,

It has been a while since I have been here. I need to come back more often. I have a 2016 fuzion 345. Love the tech but man does it eat power. I did put 6 6 volt batteries and that will get me through a weekend, not much more. I have an onboard gen but I get away for peice and quiet.

Because I use power I have bought 2 - 280 panels and all the trimmings. Last item I need to know. Which is better parallel or series. I know that pannenels in parallel is more volts, series is more amps. I just don’t know which set up I should do. Which is better for battery health? Which is better for quicker recharge. I will be adding an inverter later.

I would like your thoughts.

[Lwiddis]

"You can over-panel the MPPT controller somewhat with no ill effects, because the controller self-limits the amps to its rating. (40 amps)"

This may depend on the manufacturer of the MPPT, BFL. WindyNation says a big "NO." I ask about five 100 watt panels for their 30 amp MPPT...four only.

[y22man]

Here are the photos. I don't have a pic of the roof. It is pretty straight forward up there.

Battery box. 4x6 volts and charge controller.




Main connections off these 2 6V batteries.




Routing of cables from roof to basement.




Remote monitor just inside the door in the hallway to master bed room.

[time2roll]

y22man wrote:
I would like to have the inverter installed, but finding documentation on that install is limited. By that I mean, nothing with an existing T-52 transfer switch. I want to provide all the 110 outlets but the ac, fridge, fireplace, and microwave with the inverter.

What wattage? 350 watts or less is fairly simple.

Yes you will need to possibly put the converter and fridge on a separate circuit. Then use a small transfer switch to power the branch circuit of choice. Possibly 2 switches to power two branches.

[CA_Traveler]

y22man wrote:
With the smoky skies we had due to wild fires the output was severely down.

Lucky you! I was just east of Seattle and it was downright unhealthy+ as in red+ from the monitors. Two days ago it cleared up and steady drip drip last night. But headed south today.

I love those night rains and clear air the next day. :B

[mountainkowboy]

let see if that works....



Great link....THANKS.

[red31]

y22man wrote:

I wish I could post pic directly on here without a url.

This site will let you create a url from a pic on your computer, ya just copy the created url and past it in a message.

http://photoposting.is-great.net/

[y22man]

The system has been installed for a little over a month. Works great. Clear sky’s are important. With the smoky skies we had due to wild fires the output was severely down. The last week or so the performance has been much better.

Even with the smoky skies this system charges to full every day. We are still in the conserve power mode. Kids are respectful of power and water use when we camp. We have been out 3 times since the install. Last week I finally ran the control wire inside.

The real test is when we pull the trailer to the Utah Utes football games tailgating. I would like to have the inverter installed, but finding documentation on that install is limited. By that I mean, nothing with an existing T-57 transfer switch. I want to provide all the 110 outlets but the ac, fridge, fireplace, and microwave with the inverter.

I wish I could post pic directly on here without a url.

[CA_Traveler]

Here’s another illustration for bypass diodes showing how they operate.This is for 3x 24V 60 cell panels in series with 3 bypass diodes per panel. This shows 20+30+20 = 70V. The available amps are dependent upon the available light as shown in the typical IR curves. There is actually a small voltage drop for a conducting diode of about 0.5V. So 19.5+30+19.5 = 69V available to the MPPT controller at the given amps.

[red31]

looking at a ole irradicace plot of 2013 from Cedar city UT, @ 9am a flat panel should be collecting only 600w/m^2 (60%) peak of ~1000 should be 12-12:30.

https://midcdmz.nrel.gov/apps/plot.pl?site=USEPCC;start=20100713;edy=31;emo=12;eyr=9999;year=2013;mo...

[y22man]

I am doing a test. I ran the batteries down this week. I then turned on the panels today at 9:00 am. Clear blue sky, 76*. It seems to me I am only generating half of my potential. 30.1v and 9.7 amps.

Panels are connected to a Y split cable with a single positive and negative run to the charge controller.

I am sure this is more than enough but seems low.

Ok, so I am a dope, or a slow learner. It looks like it is working as installed. The panels are 30.4v and 14.2a. learning, learning, learning.

Jay

[CA_Traveler]

I've posted this before and the graph clearly shows the advantage of series panels with bypass diodes. Virtually all 60+ cell panels have bypass diodes because they protect the panels in the larger series/parallel arrays found on houses, buildings, off grid arrays, etc.

This graph shows the positive effect of bypass diodes with clouds and leafy shade. There are 3 30V (about) serial panels with 3 bypass diodes each which results in each bypass diode controlling about 10V of panel output.

The morning starts with overcast clouds and full solar panel array voltage output (about 90V) in the limited light.

At 8:37 the clouds departed leaving leafy shade covering the panels resulting in 6 bypass diodes conducting and 3 of the panel sections producing power at 30V. As the shade changes on the panels the panel voltage increases to 40, 50, 60 and 70V.

At 9:27 all of the shade is off of the panels and the panel voltage is 90V. The MPPT controller continues to optimize the panel output as the sun continues to rise.




The panels are flat mounted and the sun is rising.

Note: Bypass Diodes have the effect of 9 independent serial panel sections. When there is a shadow on one section that section is bypassed – ie the effect is like a short for that section and it bypasses the amps of the other sections. One bypassed section results in 8/9 of the voltage, two sections in 7/9 of the voltage, etc, however the panel amps are not effected. I’ve seen charging with only 2 sections or 20V. Bypassed sections do not have to be in the same physical panel.

[Almot]

Almost full at 13.7V - maybe.
Could've been almost full before the sunrise already.
Could've been just approaching the Absorb - most likely, considering his "20-30 minutes". Hence, "floating" they are likely not, after 30 minutes of charging.
He said was "40 amp controller". Would've been easier to tell more if the current was known.
Too much data missing. I am out.

[Boon_Docker]

beemerphile1 wrote:

y22man wrote:

...One question I have, what is the load terminals used for....

A load such as a light or radio or whatever can be powered directly from the solar power rather than the battery if you wish.

Not quite.
The load terminal does use battery power when the sun isn't shining. It is a terminal that you can set a time for on and off. It also has a low voltage cutoff so the battery does not drain too low.

[BFL13]

12.4 is say 75% SOC of 6-sixes at 225 a pair so bank is 675AH so was down by 169AH going in. Allow 35 amps for likely charging rate based on OP info.

35 amps is a 5% charging rate so would reach say 95% before Absorption starts and then if it is a Tracer it will hold at 14.6ish for two hours more before dropping to 13.6v

The Bulk is to do 169-34 = 135AH at 35 amps = almost four hours, then another two before dropping to 13.6v = almost six hours.

OP says he was at 13.7v after half an hour. So only another five and a half hours to go before it drops to Float. That would not signal the batts are truly full of course, but almost full.