Solar install on a Trailer, newbie questions

[curly5759]

Hi, I just got a solar panel and controller for my TT. I want to install the panel on the roof laying flat but am unsure of how to attach it.

Q#1 Should I run some screws or bolts into the roof and seal, or ?? (It's a 07 Fleetwood Orbit 18' if that helps)

Q#2 How do I run the power cables inside, drill a hole in the roof, follow the roof antenna cable or ...?

Q#3 With the controller mounted inside, can I attach the charging cables to the power panel (+) and (-) or do I have to run another set of wires out front to the battery?

Q#4 Can I hook to shore power and leave the Solar connected?

Thanks for any and all help.

[babock]

mike-s wrote:
I'm not the one who thinks that when you put 20 A into one end of a wire, less than that can come out the other end. I don't believe your EE claim.

I never said that was the case.

When we design our power distribution in our chassis, we never allow a 10% voltage drop. Why would you do that with your charging system? It's also why I am moving my converter within a few feet of my batteries so I don't get voltage drop with that either.

Been an EE since 1982 when I got my bachelors degree. Masters a few years later with an emphasis on digital signal processing. Currently do FPGA design for a company that does internet protocol testing.

[mike-s]

babock wrote:

mike-s wrote:
If you think that, you think wrong. Come back when you understand how electricity works, including the relationship between voltage, current and power, and Ohm's and Kirchhoff's laws.

LOL...not sure what you do for a living but it isn't electrical engineering which is what I do.

I have gone back and looked at a bunch of your posts. Are you really this arrogant in your normal life? Only one seat at your table? LOL

I'm not the one who thinks that when you put 20 A into one end of a wire, less than that can come out the other end. I don't believe your EE claim.

[babock]

mike-s wrote:
If you think that, you think wrong. Come back when you understand how electricity works, including the relationship between voltage, current and power, and Ohm's and Kirchhoff's laws.

LOL...not sure what you do for a living but it isn't electrical engineering which is what I do.

[noteven]

Some info here:


https://handybobsolar.wordpress.com/2014-solar-ideas-batteries-other-things/

[magicbus]

Also, you might consider a service disconnect switch so you can cut power from the panel to the controller so your 12V system and controller aren't always "hot".

Dave

[mike-s]

babock wrote:

mike-s wrote:
If the controller has remote voltage sensing, it's mice nuts

I would love to see a controller that has remote voltage sensing. Care to share the info on one?

Most of the Morningstars. Prostar and Prostar MPPT are two in specific. They also have remote temperature sensing.

Limiting the voltage drop actually does make a huge difference. If you have a length of cable that had a 10% voltage drop at 20A you would likely get half the charge current than you would if you limited it to 1%.

If you think that, you think wrong. Come back when you understand how electricity works, including the relationship between voltage, current and power, and Ohm's and Kirchhoff's laws.

[babock]

mike-s wrote:
If the controller has remote voltage sensing, it's mice nuts

I would love to see a controller that has remote voltage sensing. Care to share the info on one?

Limiting the voltage drop actually does make a huge difference. If you have a length of cable that had a 10% voltage drop at 20A you would likely get half the charge current than you would if you limited it to 1%.

[mike-s]

pauldub wrote:
it's far from optimum. You want to minimize the voltage drop between the controller and the battery.

Define "far".

If the controller has remote voltage sensing, it's mice nuts. Which it is anyway, since you only get significant voltage drop with high current so it doesn't keep the battery from getting fully charged. It can cost a few percent in efficiency. But if a few percent is critical, one should just add another panel and be done with it - don't worry, be happy.

And, if charging while there's a power draw, sending current to the battery then back to the converter/distribution is also a loss. The wire between the solar controller and the battery would need to be significantly larger than the stock wire from converter to battery for there to be any advantage even with no power draw during charging.

A lot of the common knowledge about solar is based on the days of $5+/watt panels, where spending $50 in time and material for bigger wire provided a meaningful return on investment. Things have changed, and other than space limitations, putting another panel up is a much better deal these days, in addition to providing more capacity for overcast days, etc.

[Lwiddis]

Controller connected to and close by battery is the ideal set up such as controller in front pass through storage and batteries on trailer tongue. Don’t skimp on wire size. Why only one panel? General guide is one solar watt for every battery amp hour. I’m 300 for 240.

[pauldub]

3. You could but it's far from optimum. You want to minimize the voltage drop between the controller and the battery.

If you want to use solar for your primary source of charging, there's lots of reading ahead of you. Here's a good place to start.

[mike-s]

1: yes, but get some angle aluminum and cut it into 3" chunks. Drill holes. Four pieces on the roof, four on the panel, and bolt them together. Much easier to remove for maintenance in the future than the common mounts.

2: Down the refrigerator vent is a common method - no drilling or sealing, and a natural drip loop is created.

3: Yes.

4: Yes.

Hint: for most controllers, connecting a panel without already having a battery connection can/will damage the controller. DC breakers make good dual-purpose switches.