Solar Panel Install Ideas

[D Davis]

Hey guys, found this idea "crank up solar panel" on this website, scroll down and you will see it with pictures. The guy is using a rv crank up television stand. Looks good.
If you are not interested in that, there are other great tips. Enjoy
Hints and Tips

[Jon Vermilye]

Mark Nemeth also has written the "Bible" for working with 12V systems: "The 12V Side of Life, Pt 1" & "The 12V Side of Life, Pt 2"

Lots of other good stuff available from his home page.

[Cam A]

Would having solar cells at the end of a 40 foot cord affect their output?

[deryk]

Possibly... but a single 100 watt panel would more then be sufficient for my weekend camping... considering the twin batteries would be charging while I drive. During the winter its the heater that eats the batteries... the fantastic fan isn't as much of an energy pig.

deryk

[Thomas G.]

Originally Posted by Cam A

Would having solar cells at the end of a 40 foot cord affect their output?

You can calculate the power wasted in the cord exactly.

It is the current in amps squared times the cord resistance in ohms. With a set up like this you should try to keep the controller near the battery.

Resistance of Wire (Wire Resistance Calculator)

[multi-task]

You will see noticeable voltage drops with 40ft of cable unless it's big, especially with lower voltage panels usually found on rv/trailers. Shorter is always better, but it's much more important to be short from the controller to the battery. However this always depends on your needs. If you never see your batteries reach their proper charging voltage (usually between 14.4 and 14.8) it's likely either the cable run is way too long or the panel can't sustain enough voltage or amperage to properly charge a battery. That also presumes your controller works properly.

For long runs, a higher voltage panel works best, but then you'd need an mppt controller.

[Otters]

Originally Posted by Ron F

Here are a couple of photos of my install. I added 185 watts total

Ron, Do you have one or two batteries. I have only one battery and I'm looking at a 100 Watt solar. But then wondered if there is such a thing as too much solar. Thoughts??

[Perry J]

The only time I have camped in a campground with power was 3 years ago when I spent a week in Yellowstone.
The trees in the Camp Ground are all at least 80 ft. tall.
It was freezing every night so I used my furnace.
I had a flat roof mounted 50 W panel and a group 27 deep cycle battery.
In the sun the battery is usualy at full charge by 10 am. In the trees at Yellowstone
it was at full charge about 1 pm.
My camping is all in Fire safe Areas in National Forests and ocassionally in the Arizona Desert.
I have 12V TV/DVD player which I use almost every night for DVDs.
I have never been short of power.
John

[Ron F]

Linda,
I have one Trojan T-1275, 12v, 150 AH deep cycle golf cart battery, which gives me about 75 amp hours to work with. It just fits (tight) into a group 27 battery box, but it is heavy, weighing in at 84#.

My major energy drains are the lighting, fridge, fans in summer, and furnace when colder. None of the energy drains are on all the time. So, you need to determine, realistically, the duty cycle (how much of the time they are actually draining the battery) for your appliances. All my lighting is LED and only used in the evening. The fridge is a Norcold DC0040, compressor type and pretty efficient. It only runs about 25% of the time. The two fans are from MaxxFan and the furnace is an Atwood 8012II, both the most efficient that I could find.

I was determined to place as much solar on the roof as the real estate would allow, 185 watts in all (one 85 watt Solartech multi-crystal and two 50 watt mono-crystal). I kept the wiring as short as possible to eliminate losses due to wire resistance. 10 gauge from the panels to the controller and 6 gauge from the controller to the battery. I used a PWM type controller, so the panels are wired in parallel. If I were to do the system over, I'd use flexible panels (similar to panels from http://www.sunflexsolarhk.com ), attached directly to the roof (without mounting hardware) and spend a bit more for a MPPT type controller and wire the panels in series.

You really cannot have too much solar. The solar controller regulates the rate of charge to the battery. The more solar you have, the faster your battery is restored. Once the battery is fully charged, the controller shifts to a maintenance (trickle) charge. So, if you top off the battery by 10 am, as Perry does, then your appliances are actually being powered by the panels for the remainder of the daylight hours, thereby extending your battery's capacity.

Ron

[Thomas G.]

Originally Posted by Ron F

.............I was determined to place as much solar on the roof as the real estate would allow, 185 watts in all (one 85 watt Solartech multi-crystal and two 50 watt mono-crystal). ........
Ron

This is of interest, as I was wondering exactly how well matched solar panels need to be in order to add them in parallel. I had read elsewhere that they should be more exactly matched, but perhaps that is for optimal efficiency as opposed to acceptable efficiency. Glad to hear that yours are working out.

[knighth001]

Originally Posted by Ron F

I was determined to place as much solar on the roof as the real estate would allow, 185 watts in all (one 85 watt Solartech multi-crystal and two 50 watt mono-crystal). I kept the wiring as short as possible to eliminate losses due to wire resistance. 10 gauge from the panels to the controller and 6 gauge from the controller to the battery. I used a PWM type controller, so the panels are wired in parallel. If I were to do the system over, I'd use flexible panels (similar to panels from Solar South USA, Providing the Best in Alternative/Renewable Energy ), attached directly to the roof (without mounting hardware) and spend a bit more for a MPPT type controller and wire the panels in series.

So I understand that wiring in parallel increases amps output but wiring in series increases voltage output. So why the move to series wiring scheme? Wouldn't parallel also better insulate against a situation where one panel may be partly shaded?

[multi-task]

You would wire in series to increase voltage, thus reduce the dependence on larger wire. But as mentioned you’d need an mppt controller to properly charge your batteries. In series you’d need a by-pass diode for each panel in case one is shaded. Some panels have these built in, some do not and you’d have to build it into your wiring, all depends on your gear.


Mismatched panels become bad news when they are different voltages (not watts), as everything is dragged down to the lowest voltage. This is also true for poor charge controllers, they’ll drag your panels down to battery voltage.

[Thomas G.]

Originally Posted by multi-task

............
Mismatched panels become bad news when they are different voltages (not watts), as everything is dragged down to the lowest voltage. This is also true for poor charge controllers, they’ll drag your panels down to battery voltage.

Drew what causes different voltages in solar panels? Is it the basic structure, like amorphous vs crystalline or is it common to have different numbers of cells in each panel?

[multi-task]

Each panel will have a certain number of cells, all which should be at the same voltage, which will be dependent on the manufacturing process. They are then wired in series and parallel to come up with the panels overall voltage. So for example, I have a 75w panel with 36 cells, and I have a 215w panel with 72 cells. The 75w panel is 17 volts, the 215w panel is 42 volts. You wouldn’t use these two together. I bought the 215w panel to replace my 75w.


The type of cell, mono, poly, etc... will affect how large the panel is, and how it handles environmental conditions such as temperature, sun, shade... so overall efficiency.


I’m no expert, but that’s how I understand it, hope that helps!

[Otters]

Originally Posted by Ron F

Linda,

I If I were to do the system over, I'd use flexible panels (similar to panels from Solar South USA, Providing the Best in Alternative/Renewable Energy ), attached directly to the roof (without mounting hardware) and spend a bit more for a MPPT type controller and wire the panels in series.

Ron

Thanks John and Ron for assuring me that I have no worry about Solar overdose. The flexible panels is what I've been looking at and I'm pretty convinced that is the route I will go. I don't use a lot of power, but will be running a new Fantastic Fan I just ordered, one or 2 LED lights, and my big splurge, TV to watch DVDs at night.
Ron, since you mention not skimping on the controller, do you have one you can recommend?
Linda

[honda03842]

Linda the typical Scamp TV uses little power. You should be fine.

[Otters]

Originally Posted by honda03842

Linda the typical Scamp TV uses little power. You should be fine.

That's good to know, that is probably my biggest usage. I'll hopefully run the frige on propane, but with some solar refresh I should be good to go. I read your thread about your solar installation and intend to do the same type setup. I had planned on also installing an 80 watt flexible panel with tape and the marine gizmo you used to wire into the Scamp. But I found what looked like a great deal on a 100 watt flexible, which started me wondering. You've done a great job on your all the mods. It inspires me.
Linda

[honda03842]

100 watts is great. I could only fit 80.

[Ron F]

Linda, The only controller that I have any experience with is the one on my camper, which is a Morningstar Sunsaver Duo (PWM). I haven't had any trouble with this one. When I got it, I was looking for a multi-stage controller, one that would shift the charging rate based on what was needed by the battery, just like some of the smart battery chargers or converters. That's important because, if a high charge current is constantly applied you can damage your battery. A good charger/controller should drop the current to a trickle/maintenance charge once the battery is fully restored.

The Duo also came with a nice meter that can help you keep track of what's happening with you battery. Regardless of what brand you choose, I recommend installing some type of meter to monitor the condition of your battery.

Ron

[Thomas G.]

Originally Posted by Otters

..........
Ron, since you mention not skimping on the controller, do you have one you can recommend?
Linda

I'm not Ron, but here is my $0.02. You can get a Chinese controller for less than $10 off eBay, you can get a quality PWM controller for $50-ish or you can go all out and get an MPPT controller for $200+.

My recommendation would be to go with a brand name PWM controller like Morningstar or Xantrex. Choose by the amperage (and voltage) you need, allowing some "headroom" to add another panel if you want it later without upgrading. Panels are getting cheaper everyday, so it is likely you'll upgrade when it is too cheap not to.

I like this place for panels and controllers.
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