Solar Panels - Series or Parallel ?

[careka]

Float is 13.2v on my batts so then a easy way to go is just to put in a switch. and turn them off when i leave the boat.

[colemj]

I don't understand - won't that turn off all charging to your batteries? I don't think that was the point being discussed above - I think the point was how to keep the solar charging the batteries without having them go through unnecessary absorption voltages continually.

Mark

[careka]

Yes, and i don't need any charging, as the boat is not used. i can go down after some days or weeks and give them a day of charging,
You did tell me what i needed. thanks. if i am out sailing then solars will be on al time, but when back home, i will turn it off after batts have been fully charge back up.

[colemj]

Oops! I forgot you were the one with the question! Yes, if there are no loads on the batteries, then turning off the controller and going down once/month and putting them through a charge routine will work just fine.

Mark

[bill good]

A comment on series V parallel. In 2008 I installed two 38 V panels as used on house installations in series with a MTTP controller. One of the panels has two of the three strings producing reduced output & I really don't know how long ago this failure occured except longer than 30 days ago. The system continued to function because of the internal bypass diodes in these cells even though ithe voltage is down from the 80 V to 65 V. Trying for U/W claim currently & will report back on that one!! Not 25 yrs on boats though for info.

Regards Bill

[Tacmed]

I have been playing with solar for a while now. Mostly on the land. One thing I have noticed is that there is no single method that works. Mainly due to differences in equipment.
I have a different configuration which works for me. I have cheap solar panels in Parallel going into an MTTP controller,with their own battery. Then another identical config with its own battery.
I have added a high current diode to the output of each battery output into a common positive rail. This means that the charger only looks after its own battery.
In my case, reliability was more important that squeezing that last milliamp out of a panel.
My original degree was in electronic engineering and reliability was a habit.
Having access to different chargers, i did find that with the configuration I had worked just as well as using really expensive equipment. Just using basic recordings, a $200 kit worked just as good as a $1000 dollar kit.
I am only running equipment and LED lighting 24/7. No cooking or inverters involved.
When I had shading on a panel, the other systems just took over.
In effect, I cam lose two complete systems or have faults on something and the other two keep working.
I did notice a few solar systems had the regulator stuck to the underside of the panel.
I moved the regulator close to the Battery. From an engineering point of view, this is a must. The higher voltage from the panel meant smaller cable worked fine.
Sometimes, theoretical losses dont really make a practical difference.
My testing over 6 months was only for my config. I am also only running 5 x 120amp(12v) systems. Reliability would be about 500% higher than most other configs though.

[Tacmed]

Just to follow up several months later.... all going well. I have noticed pelican poo really messed up eficiency . Had to put cable ties near the edges pointing into the air

Sent from my SM-T800 using Cruisers Sailing Forum mobile app

[sparrowhawk1]

Originally Posted by Tacmed

Just to follow up several months later.... all going well. I have noticed pelican poo really messed up eficiency . Had to put cable ties near the edges pointing into the air

Sent from my SM-T800 using Cruisers Sailing Forum mobile app

Did the cable ties keep the pelicans off?

[travellerw]

Quick question... Instead of series or parallel, is anyone running their panels with individual controllers for each panel? Its seems like this would be the perfect solution (aside from cost).

I've been testing (on a very small scale) a new MPPT Tracer controller from EPSolar that is very affordable. Its affordable enough that running one for each panel would be feasible.

I have an EE background and the hardware on this controller looks very well built. Proper potting and heat syncing. Of course, there are some off brand components so longevity is a question. Its cheap enough that carrying a spare would not be an issue though.

[hellosailor]

Tacmed-
There are bird spike strips, often sold in larger hardware stores, that may be easier and cheaper than zip-ties. But there are also glue guns powered by butane, just like refillable lighters, that allow you to set a blob of glue anywhere, to hold the zip-tie in place. Damn useful tool on a boat!

[noelex 77]

Originally Posted by Tacmed

Just to follow up several months later.... all going well. I have noticed pelican poo really messed up eficiency . Had to put cable ties near the edges pointing into the air

Sent from my SM-T800 using Cruisers Sailing Forum mobile app

It sounds like you have a lot of excess solar capacity which is easy to do on land, but not so easy on a boat.
However, I would be wary of shadow from cable ties. It does it take much to reduce solar output significantly.

What about some fine monofilament fishing line strung up above the panels?

[zboss]

Originally Posted by s/v Jedi

You will find it is very hard to find a case for parallel connection on a boat, except when the controller does not support it.

ciao!
Nick.

Or you have one controller per panel, as I do. This is neither a series or parallel connection then.

Originally Posted by travellerw

Quick question... Instead of series or parallel, is anyone running their panels with individual controllers for each panel? Its seems like this would be the perfect solution (aside from cost).

I do, using four Genasun controllers. I have a love/hate relationship with these controllers. Love them because every panel is completely independent, so if one controller or panel goes out, I don't lose the whole system. They are also cheap, I paid just a slight bit more for four controllers over a single ganged controller.

I hate them because they are not adjustable and give you zero feedback on voltages, amps, etc. They are just basic MPPT controllers.

[OceanPlanet]

Originally Posted by zboss

Or you have one controller per panel, as I do. This is neither a series or parallel connection then.



I do, using four Genasun controllers. I have a love/hate relationship with these controllers. Love them because every panel is completely independent, so if one controller or panel goes out, I don't lose the whole system. They are also cheap, I paid just a slight bit more for four controllers over a single ganged controller.

I hate them because they are not adjustable and give you zero feedback on voltages, amps, etc. They are just basic MPPT controllers.

You could add inexpensive watt meters, which can be placed/wired somewhere easy to see. The Genasun MPPT should be close to the batteries for temp compensation (if Pb batts). Scroll down this page to the "SkyRC watt meter:
Energy Management - System Monitoring & Control

[sparrowhawk1]

Originally Posted by stevensuf

that is what i did, took 2 panels connected in parallel to the mppt controller, measured current/voltage then shaded half of one with a towel, battery was pretty dead, then did parallel comparison, much more output in parallel with one half shaded and the panels have 3 bypass diodes . try it yourself its easy to do.

as others have said if your panels are never shaded, series is better, but if partial shading then parallel is better.

That's what I thought but there's several on this thread that says it's just the opposite and show graphs. Has anyone else done this test and gotten a different result? What about with four panels? Or just 1/4 panel shaded? Of course it must be done on a cloudless day. Thanks in advance to anyone that's willing to do this. Ok just reread the thread starting from the beginning I realize this is basically what the original poster was asking sorry

[OceanPlanet]

Re series vs. parallel, here is something to read...