Portable solar for limited current draw

[ohhell10339]

I want to be able to generate enough power to run my laptop and keep a couple of lights inside the RV lit.

1. Will a 100 watt portable solar array do it? Or will I need 200? (Let's assume that I'll usually have sunlight.)
2. What's the easiest way to use the DC output of the panel(s) to light the interior of the rig (and maybe run things like a fan and/or the water pump)? In a rig that doesn't have a generator, where would the interface be? (I assume it would be horribly inefficient to run the output through an inverter and then connect the inverter to the shore power plug.)
3. Likewise, what would be the mechanism I would use to charge the house batteries with the panels' output? Keeping in mind I want all this to be portable, so no permanent hard wiring.

[Harvey51]

Ohhell, perhaps you will have my surprising experience. Since I installed a 100 watt panel flat on the roof about 4 years ago, I have never plugged in or used a generator. That 5 amps for a few hours is completely sufficient. I have never seen the batteries (2) below 80%. We don't have a laptop aboard very often but two iPads are running every evening, often using cellular internet shared by one of our iPhones.

Don't fear installation. All I did was run a pair of wires down to ground and the positive (through the controller) to the terminal on the battery monitor where engine and converter current are connected. I know the horizontal panel is much less efficient but it does deliver those 5 amps when driving, too. I expected to need a second panel and will get one if we ever "need" a TV or can't manage without a microwave or electric coffee pot. I might well choose portable for the second one but I'm very glad the first one is fixed. Solar is magic when you don't require air conditioning.

I did fear installation until I looked into the fridge vent. It is not like a chimney pipe; rather a huge opening with plenty of room for the exhaust pipe from the little propane flame, air flow from the warm parts of the cooling mechanism and any solar panel wires.
Securing the panel frame to the roof was concerning because in our MH only a part of the roof below it had heavy plywood - I had to locate a crosspiece joist to be sure it was safe. I did the stud finder thing, then narrowed it down via nail into the ceiling inside a cupboard. No big problem.

I'm sure you will love solar, especially if you understand it through installing yourself.

[SoundGuy]

red31 wrote:
So to restate the question, is 100 watt panel enough power for some unknown laptaop usage and 2 x unknown watt lights for 4 hrs of use. Assume all lights and laptops are the same. Unknown location, unknown time of year, unknown panel tilt, unknown wiring losses, unknown ...

Sure, give it a try and report back!

Sort of belies the OP's SIG. :W

[Almot]

I want to be able to generate enough power to run my laptop and keep a couple of lights inside the RV lit.1. Will a 100 watt portable solar array do it? Or will I need 200? (Let's assume that I'll usually have sunlight.)

You mentioned "fan" later in the post. A good fan on High for 12 hours will need 100W solar just for itself. Portable solar more than 120W becomes a pain. Better to permanently install 200 or 300W on the roof.

2. What's the easiest way to use the DC output of the panel(s) to light the interior of the rig (and maybe run things like a fan and/or the water pump)?

You don't understand how 12V system works. Your lights, fan and water pump are 12V wired to the battery. All you need is "more" 12V power at the battery. This is done by clipping crocodiles of solar output to the battery. There will be a small box - controller - between the panel and battery, to regulate the panel output. That's all.

If you're not sure how to, spend more and buy one of 100W solar suitcases. If you feel more confident, spend less and get 100W "kit" from Solar Blvd. Either one will include all solar parts - panel, wire and controller. With Solar Blvd kit you might have to make "legs" of PVC pipe to prop the panel up.

[red31]

my laptops's 40 wh battery could recharge from dead to full with the energy harvested in one hr of full sun with a 100 watt panel. A full charge might last longer than 3-4 hrs of use.

2 x 25watt lights would consume 50 watts/hr or 200 wh in 4 hrs of use.

So to restate the question, is 100 watt panel enough power for some unknown laptaop usage and 2 x unknown watt lights for 4 hrs of use. Assume all lights and laptops are the same. Unknown location, unknown time of year, unknown panel tilt, unknown wiring losses, unknown ...

Sure, give it a try and report back!

[ohhell10339]

TomG2 wrote:
OP: The question is, "Do you want to go camping or become a solar hobbyist?"

I have a friend who travels full time and uses a fifty watt portable unit to replenish his battery between visits to full hookup campgrounds.

On the other hand, some like to diddle with switches and monitor usage and output every few minutes. They will never have "enough" solar or gadgets.

I go with the former.

Believe me, I'm not a gadget person. Everything inside my RV, and the RV itself, is a means to an end. It's not a hobby, it's not something to finker and tiddle with, and if I never have to take it apart, modify it, fibulate it, renoberate it, or flammulate it, that's just great with me.

That's why I like the idea of a portable solar unit. I won't have to "install" it, "configure" it, or "adapt" it. The existing gauges inside the coach will do fine for monitoring the house battery level. I'm not going to be running an entertainment center or a rotisserie grill. I just need some watts so I can run my laptop and see what I'm doing, as I'm not crazy enough to pay some clown $65 a night for a concrete slab with an electrical plug and a water spigot.

[TomG2]

OP: The question is, "Do you want to go camping or become a solar hobbyist?"

I have a friend who travels full time and uses a fifty watt portable unit to replenish his battery between visits to full hookup campgrounds.

On the other hand, some like to diddle with switches and monitor usage and output every few minutes. They will never have "enough" solar or gadgets.

I go with the former.

[SoundGuy]

red31 Link That Works. 😉

[red31]

Seamutt wrote:
Question, if one has two portable solar panels each with its own controller, is it okay to connect each separately to the battery.

yes, but it would be better to permanently mount the CC inside out of the weather but close to the batt, the grape controller makes that a breeze with Bluethooth and free app, it program-ability and data retrieval. proper charge profile for storage, usb charge port.
https://www.homedepot.com/p/Grape-Solar-40-Amp-PWM-Solar-Charge-Controller-with-Bluetooth-GS-PWM-40B...

[Seamutt]

Question, if one has two portable solar panels each with its own controller, is it okay to connect each separately to the battery.

[Lwiddis]

"Keeping in mind I want all this to be portable, so no permanent hard wiring."

Why portable? So you can set it up, watch it to prevent theft and take it down daily? All RVs have "permanent hard wiring." Why don't you want charge your house battery all day long and your computer, phone whenever you plug it in?

My system...most RV solar systems...just work without you working. Don't over think a solar system.

[SoundGuy]

ohhell10339 wrote:
Hooking the panels' output directly into the RV batteries with alligator clips or something seems kludgy, but maybe it's the simplest alternative.

2oldman wrote:
It's not recommended as the voltage is too high.

He means - or should mean - hooking a portable panel with a built in charge controller to the battery, which is exactly how these smaller folding panel systems are designed to be used. 😉

[SoundGuy]

ohhell10339 wrote:
Hooking the panels' output directly into the RV batteries with alligator clips or something seems kludgy ...

Then install a 2-pin connector on the battery box. Several manufacturers offer them, this one from Furrion being an example.

Given that the panel itself is only part of the setup, I would imagine that 200 watts would not cost twice as much as 100 watts, so that might be the way to go.

Sure, but do you really want to fool around with a large 200 watt panel when a 100 to 130 watt folding panel is so much easier? Many portable panels of this size even come with a padded carrying case as well. :B

[2oldman]

ohhell10339 wrote:
Hooking the panels' output directly into the RV batteries with alligator clips or something seems kludgy, but maybe it's the simplest alternative.

It's not recommended as the voltage is too high.

[ohhell10339]

MrWizard wrote:
the typical 100w panel puts out a 5amp charge rate
your laptop probably draws 2-3 amps, then there are the lights

i would recommend 200w

your use may be different, but only you can judge the specfics of the situation

what do you do at night ?
TV/DVDs, PC streaming video, or set with one light and read a book

people often come here and only ask one side of the question
every watt, amphr of power used at night also has to be replaced in the batteries during those solar hours

Well, obviously. I didn't posit a distinct amount of use or a particular number of charging hours because those are variables that will be different from day to day. The only "side of the question" I asked, and the only one I was interested in, was whether the charge from a 100 or 200-watt panel would be sufficient to compensate for the current drawn by a laptop and a couple of lights. I would probably be using each for 3-4 hours a day.

Hooking the panels' output directly into the RV batteries with alligator clips or something seems kludgy, but maybe it's the simplest alternative. In that scenario, I still need an inverter to run the laptop, but I have one already and have been using it in my car now and then--works fine.

Given that the panel itself is only part of the setup, I would imagine that 200 watts would not cost twice as much as 100 watts, so that might be the way to go. As far as security goes, well, I would probably just stow the panel(s) whenever I was away from the campground. Also, I have an attack cat.

[MrWizard]

the typical 100w panel puts out a 5amp charge rate
your laptop probably draws 2-3 amps, then there are the lights

i would recommend 200w

your use may be different, but only you can judge the specfics of the situation

what do you do at night ?
TV/DVDs, PC streaming video, or set with one light and read a book

people often come here and only ask one side of the question
every watt, amphr of power used at night also has to be replaced in the batteries during those solar hours