Flexable solar panels ???

jkjenn

Thanks, @jcfaber1. That pretty much confirms my thoughts. I will look for your other thread.

jcfaber1

Jenn, to give you a reference of the voltage drop of wiring in parallel or in series, the following is from my Southwire voltage drop calculator.  Say we have 2 100 watt PV panels.  Each PV puts out 17.5 volts at 5 amps.  If we wire in parallel then we have 17.5 volts at 10 amps.  For a 50 ft. cable run, you would need 6 kmcil wire (a beast of a cable) and would have a 2.52% voltage loss.  Conversely if we wire in series, we would have 35 volts at 5 amps.  The same 50 ft. run would have 12 gauge wire and a 2.48% voltage loss.  I went with 8 gauge wire for a voltage drop of less than 1%.  Does this help?

John

jkjenn

jcfaber1 said:

Jenn, to give you a reference of the voltage drop of wiring in parallel or in series, the following is from my Southwire voltage drop calculator.  Say we have 2 100 watt PV panels.  Each PV puts out 17.5 volts at 5 amps.  If we wire in parallel then we have 17.5 volts at 10 amps.  For a 50 ft. cable run, you would need 6 kmcil wire (a beast of a cable) and would have a 2.52% voltage loss.  Conversely if we wire in series, we would have 35 volts at 5 amps.  The same 50 ft. run would have 12 gauge wire and a 2.48% voltage loss.  I went with 8 gauge wire for a voltage drop of less than 1%.  Does this help?

John

It does, thanks, John. I ordered most of the stuff I need last night.  Thanks for the input! I found an article last night, while researching something else, that did a great job explaining it and it all finally clicked for me.

The trolling motor plug is a phenomenal idea, by the way. I was thinking of using something along the lines of an Anderson plug, but I like your idea so much better.

Ratkity

Won't running 2x12v panels in series give you a 24V system? I thought I read that panels need to be run in parallel to maintain 12V (or am I confusing battery stuff with the panels?)

jkjenn

Ratkity said:

Won't running 2x12v panels in series give you a 24V system? I thought I read that panels need to be run in parallel to maintain 12V (or am I confusing battery stuff with the panels?)

It depends on how you chain them, In parallel, no, they produce 12v. In series yes, but an MPPT controller would produce 12v.

jcfaber1

Ratkity, the reason that the voltage of the PV is more than 12 volts is that the only way to charge a battery is to give it more voltage and amps than the battery presently has.  The 12v is a nominal charge.  A 12v battery has 6 cells at 2.2V per cell or 13.2 volts.  I have AGM batteries.  To ensure a full charge, they should be charged to 14.4V and held there with a trickle (float) charge for 2 hours.  The charging process is done in a number of stages.  The stages are managed by the charge controller to ensure the batteries are not damaged but can get to a full charge.  My earlier post describes the difference between series and parallel wiring.  If the voltage is much above 17 then you need a MPPT type charge controller which can step the voltage down. 


John

Ratkity

Hi jc,

I'm aware of 12V battery requirements and actual numbers for full charge and how to achieve that while increasing the life of the battery. Most solar systems put out about 17-18V that go to the charge controller, which feeds into the battery at an optimal input depending on the charge state of the battery. I was probably too general when I just said 12V and 24V. There are some RV battery systems with solar input set up for 24V for 24V battery banks and their controller systems step that down to 12V. Some European systems are 24V. I think it's rare to see a 24V RV/camper in the U.S. unless it's custom. Jenn answered my question in that she's using an MPPT charge controller.

Thanks though!

jkjenn

I finally figured out what to do with my solar panels. I used the existing folding legs I was using on the GZ panels and can attach the flexible panels with industrial strength Velcro. I will use tent stakes in the pre-drilled holes in the back of the legs to help stabilize them. Maybe it won't work, but I thought it was worth a try. I could also tie them down with stakes with paracord through the grommets on the corners. When you look at the rear photo, you can see a bow in the middle. I put the Velcro too far towards the edges. I will likely pull path off and move it in a little. It is noticeably less on the other panel where I scooted it in a little.

Pros:

• Very light weight
• Already had the parts
• Can remove panels from legs and store flat and tuck legs away - uses very little storage space

Risks:

• They won't hold up the wind like this
• No way to lock them down.

Verna

Jenn, I've seen the new generation of Harbor Freight solar panels....I'm impressed with the simplicity of the frame holding the panels. It is about 1" to 1 1/2" PVC that uses thing bolts and wing nuts to hold the pieces together.  If you have a Harbor Freight near you, maybe you could go look at the frame. It would give you horizontal support between the ends of the panels

jcfaber1

Here is my "suitcase" and cedar frame.  Works great.  I have drilled holes in the lower cross brace so if I need to screw it into the ground with timber lock 10" screws I can.  John

jkjenn

Verna said:

Jenn, I've seen the new generation of Harbor Freight solar panels....I'm impressed with the simplicity of the frame holding the panels. It is about 1" to 1 1/2" PVC that uses thing bolts and wing nuts to hold the pieces together.  If you have a Harbor Freight near you, maybe you could go look at the frame. It would give you horizontal support between the ends of the panels

Just from looking at it online, it looks like pretty much the exact route I was planning to go if I went PVC.  I thought I could somehow put a stake in the leg to give it more stability. I really like the grey color they use and wish that could be sourced. Hopefully, I can find black.

I found a picture online of the installation instructions, which is basically a parts list and diagram for me.



The irony is that the legs I am using are the ones that were used on the last generation of HF panels.

I do think I like situating the panels horizontal versus vertical as they will be less of a "sail" horizontal. I am not sure why that didn't occur to me some time ago.

Photomom

A couple things - look in the electrical department to see if gray plastic conduit will work for you.

Alsi, invest in an inexpensive PVC cutter. Saves time, avoids mess from sawing, and you won't have to breathe the stinky fumes from sawing. 

jkjenn

Photomom said:

A couple things - look in the electrical department to see if gray plastic conduit will work for you.

Alsi, invest in an inexpensive PVC cutter. Saves time, avoids mess from sawing, and you won't have to breathe the stinky fumes from sawing. 

Yes, on the cutters. Thanks for the tip on conduit.