Solar Panel

[markopolo]

I'd like to put a solar panel on my current RV to charge the batteries. I had one on my Roadtrek. More info on that here:

http://classbforum.com/phpBB2/viewtopic.php?t=501

Some of our favorite camping spot don't have hookups. My rig has an Onan generator but it is noisy. I don't like running it.

So I've been looking into solar panels. They're still very expensive.

Earlier this year I bought a generator from eBay seller wonderfulidea

http://stores.ebay.ca/Wonderful-Gift-Ideas

Wellington was really good to me. The first generator arrived on a Monday with extensive shipping damage but he sent a replacement immediately and I got it on Friday of that same week.

I see he is selling solar panels now and he offers the following info on his Xtreme Gadget website http://www.xtremegadget.com

There are three types of Solar Cells on the market.

Amorphous or Dual Junction Solar Glass - Cheapest but only 7% energy efficiency and 5 years service life. It is big and heavy. If the seller didn't specify, it is the Amorphorus. It is black solid sheet in appearance. It is about half the price per watt compare to Mono-Crystalline. Most of the solar panels on Ebay are of this type.

Poly-Crystalline - 25 plus years service life under direct sunlight and 13% efficiency. It is blue color circular or semi-circular silicon wafer form in appearance.

Mono-Crystalline - 25 plus years service life and up to 20% efficiency. This is the same type use in solar car racing. This type of solar cells is now in worldwide shortage because only a few companies can manufacture this type solar cell. The raw material which is a special kind of silicon sand ore is also in great shortage. It is in black color circular or semi-circular silicon wafer form in appearance

From it's appearance the solar panel on my Roadtrek must have been Poly-Crystalline.

Looks like a 40 watt Mono-Crystalline panel will cost me a little over CDN$300.00 from eBay by the time I get it. I have to think this over. I'll have to figure out how and where to mount it and how to run the wires etc. I'd have to purchase a good controller.

The Morningstar controller http://www.morningstarcorp.com in my Roadtrek seemed to do a great job maximizing the output of the small (maybe 20 watt) solar panel I had.

[julievojo]

Let us know how it works out for you Marko. We'd love to be able to give this a try as well. It would be nice to be able to keep the laptop and cell phones charged up even if we're parked in the boondocks somewhere for a couple of days.

[markopolo]

I've still got a lot of research to do.

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Nice package here:

http://www.solarpanelstore.com_RV

A basic package including one Shell 75W solar panel and one Morningstar 10a SunSaver controller, 1 set of UniRac RV Feet, 20' 12-2 Tray cable, and 1 tray cable grip. This is a great 75W package for keeping your 12V RV or boat batteries charged. We can customize if you need a different length of wire or different style of rack.

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Some info here:

http://www.rpc.com.au/products/panels/p ... dules.html

What to expect from a Solar Panel
A single 83 watt solar panel should produce about 5 amps under sunny conditions. Each day of reasonable sunshine you should expect about 23.6 amp-hours from one such panel (based on solar radiation data for north coast NSW). You need to take into account the number of consecutive days when you may not see much sun, and allow for this by having a large enough solar array and battery bank to tide you over through such periods.

So, with a 40 watt panel I might get 10 amp-hours per "good" day. That might be OK for me because I can use LED lighting at night. See my post re: 50% LED lighting here:

http://classbforum.com/phpBB2/viewtopic.php?t=580

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An adjustable rack will allow you to increase efficiency by angling the panel to face the sun.



A swivel base under such a rack would make it better

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A panel mounted on a crank up, rotating arm controlled from inside the RV would be great. My TV antenna cranks up and rotates and is controlled from inside my RV I wonder if anyone make something like that for a solar panel?

I saw one automated tracking solar panel mount complete kit at $4,500........... not in the budget

[markopolo]

I've been reading about Uni-Solar's products. It uses Amorphous Triple Junction silicon solar cells.



Their "Peel & Stick" flexible panel is very interesting.



I wonder if I have 9 1/2 feet of space on my RV roof?

[markopolo]

Well, I picked up a used 40 watt Mono-Crystalline panel (4 or 5 years old) and a new Morningstar SunSaver 6 Charge Controller on eBay tonight. The sellers feedback indicated other purchasers are quite happy with theirs. I wanted a narrow panel so I can mount it away from the shadow of my roof-top air conditioner. The solar panel I got measures 38.38" x 17.13". Originally the panel had a 20-year, 80% power output warranty.

[julievojo]

So, Marco....I'm totally ignorant electonically speaking...

Will that be enough to power a lap top and cell phone charger? How much power will that provide to your B?

JV

[markopolo]

I'm no expert in this area, but here's how I'd calculate it:

Basically, you’ll be running from your house batteries. Van alternator, generator, solar panels – are used to charge your batteries.

Laptop - most probably use 100 watts or so. Unless you can get a 12v connection for powering the laptop you'll need an inverter. Inverters are maybe 90% efficient and some laptop power bricks get really warm when connected to Modified Sine Wave inverters. Heat is probably energy wasted in this case. So, conservatively, divide AC watts by 10 to get DC amps. 100/10 = 10 amp hrs. A Pure Sine Wave inverter would be better but it costs more.

(I get a little mixed up with amps, amp hours, amperes)

How many hours will you run it? How many days would this activity take place? I think you’ve mentioned that Chino will be working. (Chino has to take break once in a while!) 4 hours per day will take 40 amp hours from your battery. If you only have a single 100ah battery it'll be pretty much depleted. You're going to need more than one battery.

A cell phone won't use much.

Add lights, fan, pump, TV/DVD, C02 and propane detectors etc. to heavy laptop use, and you'll want to replace 50 to 60 ah per day. From info I've read, one 150 watt panel or two 80 watt panels should do it. Two 100 watt panels like what Cathy has on her Roadtrek should allow you to be independent of grid and generator power.

Link:
http://www.classbforum.com/phpBB2/viewtopic.php?t=717

High voltage panels with a MPPT controller (costly) can give you more amps for your batteries than what the solar panels are rated for. Maybe 25% more.

The panel I purchased has a max amp output of 2.4. I'm more North than you so I can only really hope for 7 amp hrs per day from my small panel with a PWM controller. Maybe 10 on a really good day. My project will cost $300 (maybe $350 tops).

$5 per watt + a controller + bits & pieces + two new batteries to replace one older battery + inverter = $1,300 DIY (shop for bargains) average quality/performance to $3,000 good quality/performance (maybe all installed for you).

Lots of online sellers have RV Solar kits for sale. Here's one from Mr. Solar:

http://www.mrsolar.com/page/MSOS/PROD/rv/MSC-200

Some have kits that come with inverters.

You could of course combine a smaller solar array with some generator use. With a Class B you'll probably have to drive to get fresh water and empty tanks maybe twice per week when dry camping. Driving will also help recharge your batteries.

[markopolo]

There's a solar sizing calculator for RV's here:

http://www.carmanah.com Solar sizing

I think their figures are too high for the propane detector and fridge circuit board though. 4.8 amps per day for the Propane alarm and 9.6 amps per day for the Refrigerator circuit board (fridge on propane) can't be right. I hope they are not right anyway!

Using their calculator, with no laptop use, minimal incandescent light use, water pump and watching one DVD per night it shows I'll need 34 amps per day.

I plan on having three 95ah deep cycle batteries.
95 x 3 = 285 / 2 = 142ah's (50% discharge max)

34 (amps needed) - 7 (amps from my panel) = 27

142 / 27 = 5 days before I'm out of power.

That would be really stressing the batteries. One hour of generator runtime every other day (or every third day maybe) would probably keep everything and everybody happy.

It does confirm that I won't have to run the generator at all for a two day or three day long weekend.

[markopolo]

Another calculator here:

http://www.where-rv-now.com/Notes/Solar/

It lets you enter your location latitude.

[markopolo]

After using all these calculators......... I went ahead & bought a matching 40 watt panel. This project will probably go over $500 now

The 40 watt panels were $169.99 here:
http://search.ebay.com/_W0QQsassZno1underground7

The seller lists them one at a time.

[julievojo]

Thanks Marco, that's alot of great information. Hopefully we'll get around to doing it this summer.

Please let us know how your project turns out!

[markopolo]

Yes, I'll keep you up-to-date re: my solar project

I'll move it to Tweaks, Mods & Projects or the B+ Motorhome Forum when I get started on it.

I want to keep this thread going for solar information etc.

[markopolo]

Concise explanation of MPPT (maximum power point tracking) charge controllers here:

http://www.solar-electric.com/charge_controls/mppt.htm

Maximum Power Point Tracking - this is electronic tracking, and has nothing to do with moving the panels. Instead, the controller looks at the output of the panels, and compares it to the battery voltage. It then figures out what is the best power that the panel can put out to charge the battery. It takes this and converts it to best voltage to get maximum AMPS into the battery. (Remember, it is Amps into the battery that counts). Most modern MPPT's are around 92-97% efficient in the conversion. You typically get a 20 to 45% power gain in winter and 10-15% in summer. Actual gain can vary widely depending weather, temperature, battery state of charge, and other factors.

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Lengthy explanation of PWM (Pulse Width Modulation) charge controllers here:

http://www.morningstarcorp.com/support/ ... wm-1.shtml

What is PWM?
Pulse Width Modulation (PWM) is the most effective means to achieve constant voltage battery charging by switching the solar system controller’s power devices. When in PWM regulation, the current from the solar array tapers according to the battery’s condition and recharging needs.

1. Ability to recover lost battery capacity and desulfate a battery.
2. Dramatically increase the charge acceptance of the battery.
3. Maintain high average battery capacities (90% to 95%) compared to on-off regulated state-of-charge levels that are typically 55% to 60%.
4. Equalize drifting battery cells.
5. Reduce battery heating and gassing.
6. Automatically adjust for battery aging.
7. Self-regulate for voltage drops and temperature effects in solar systems.

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Then of course there are also basic on off charge controllers. They'd be the least expensive followed by PWM then MPPT controllers.

My understanding of all this is that MPPT controllers are the best, followed by PWM controllers. I chose a PWM controller because of cost, a new - in box- Morningstar for $40 on eBay.

[paulm]

Marco, I didn't notice mention of the furnace, or did I miss it. It's fan really hurts the battery. And of course your fridge is on propane...

Solar will give you plenty of lights at night, run the radio for a while maybe a laptop (but PDA for sure LOL). But watching TV/DVD for hours is a big drain (not sure with LCD). But camping all summer I only watched 2 movies, unless the grand kids are around. (love camp fires)

Your project will be a great help, if you don't watch TV and it's free. Do you still use inverters that you shut off? The standby drain probably hurts me. I'm not sure how they rate Panels, but pointing my panel straight at the sun in summer, I can never get whats spec'd.

I just got a couple of Deep Cycle used batteries from a floor swipper. I hope they are still good. Magnum Deep Cycle type 31DC-900 245R.C. / 135 AH

Now if we can just get 24hr of sun, 7 days a week...

[markopolo]

Good point re: the furnace paulm.

I listed Amps used by common RV items here:

http://classbforum.com/phpBB2/viewtopic.php?t=345

Some of the current draws are surprising.

Yes, I put a small (300 watt) inverter in last year and I turn it off when it's not in use. Canadian Tire sale $29.95 I'll be looking at the flyers for the Christmas / Boxing Day sales. I want to put a 1500 watt inverter in.

My plan is to have three group 24 deep cycle batteries. 95ah each. My battery holders will only hold group 24's.

Your two group 31 135ah batteries will equal my three group 24's!

I hope they're in good shape. If not, I don't know if you have or can borrow a BatteryMINDER charger - they claim that their chargers can help recover lost battery capacity. Just leave them on a BatteryMinder for the winter.

I've upped my 80 watt solar array output estimate to 20 amps per day. The combined panels rated max output is 4.8 amps. I figure on a sunny day 5 hours x 4 amps = 20 amps

[markopolo]

I'm starting to think about how to install my solar panels. My RV is still under a cover but I think I know where on the roof they'll go.

I read through a Go Power ( http://www.gpelectric.com ) RV Kit manual for ideas. I didn't buy a kit and didn't get any mounting instructions when I bought these used panels on eBay.



Good advice:

Cover the entire module with paper to prevent the danger of shock during installation. Do not remove the paper until the installation is complete.

I'll use the Well Nuts listed in their parts list. Yes, I'm going to have to drill holes! I'm not worried leaks. Dicor lap sealant will seal everything up nicely.

Got these #10/32 Well Nuts from Home Depot:


They're rubber with a brass threaded insert. They expand when you tighten them.

Gently insert the well-nuts into the drill holes so that only the topmost flange part remains above the roofline. Be careful not to push well-nuts through the holes.

Insert screws with lock washers and tighten. Do not overtighten.

They suggest 4 of these Well Nuts to fasten a 50 watt panel to the RV roof. I think I'll use 8 on each of my 40 watt panels! I guess I could try 4 & see how strong it feels but I don't want these to blow off when I'm going along at highway speeds.





Z brackets are commonly used to flat mount solar panels to an RV roof.

My RV roof is curved.

Flat panel, flat brackets, right angles, curved roof. There'll be stress on one or more components if I try that.

I think I'll make my own "Z" brackets out of two "L" brackets. That way they'll be adjustable to the angle required.

Rough sketch:



It'll be easy to tilt the panels this way. I'm not sure if I will tilt them but at least I'll have the option.

Go Power ( http://www.gpelectric.com ) suggested that one way to get the wires from the panels through the roof is to feed them down through the refrigerator vent.



I might do that. I haven't figured out where to run the wires or where to mount the controller yet.

[markopolo]

I found a water resistant fitting that will secure the wires that connect to the solar panel:









They're at Rona and Home Depot.

[markopolo]

I've finished making my custom solar panel mounts / brackets.











One side of the mount is higher so that the panel will sit fairly level on my curved roof.

The photos show bolts but I also bought clevis pins. By using the pins with my mounts I'll have the option of tilting the panels in two directions without having to undo bolts.

[markopolo]

I moved this topic from General to Tweaks, Mods & Projects.

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I installed the panels this weekend.





It was a lot of work and I'd consider having someone do it next time. I do enjoy these projects though.

I used 10 gauge wire. The only 10 gauge connectors that I could find wouldn't fit in the slots on the solar panels. The slots were made for 14 /16 gauge connectors. I guess you wouldn't normally use 10 gauge on 40 watt panels.

I had to make my connectors out of 10 gauge spade terminals



My Dremel tool made that job pretty easy.

Normal 10 gauge connectors fit the solar controller no problem.