Solar Discussion

[chasd60]

Hi all,
 It seems there has been more interest in using solar power as a method for battery maintenance and charging while drycamping.
 
 There also appears to be knowledge and past experience using solar on this board, feel free to share your experiences.
 
 In the upcoming week I will add numerous links to sites I have found with educational resources, rv applications, home applications and rebates/tax incentives available.
 
 I will also add a little about windpower. It is actually a good source of power used by boaters and has more economic feasibility than solar in many instances. Public acceptance of windpower is not as great due to the windmills and towers being unsightly.

[dthurk]

I will be most interested to see how this thread develops.  Thanks for starting it.  I will be reading to learn.  I don't think I have much to contribute at this point.

[chasd60]

The link that first grabbed my attention and planted the solar seed.
 http://www.where-rv-now.com/Notes/Solar/

[wavery]

I had both solar and wind generator on my sailboat.

I've previously posted about my solar experience and won't belabor it here. If someone would like to transfer that post, that's fine with me.

Wind generators are very efficient. The ones that are sold commercially are very expensive and their efficiency is quite limited. Therefore, I designed and built my own out of a 24v, permanent magnet motor. When the motor is turned backward, it becomes a generator.  I used light weight wood propellers that I made myself (from a pattern that I purchased). I used 4 blades (2 doubles) 40" in diameter. I actually built several of those units and sold them to other cruising yachts. About 2 years ago, I purchased one of these motors on eBay and built a wind generator for a friend. It worked very well:
 http://cgi.ebay.com/AMETEK-38VDC-WIND-MOTOR-GENERATOR-116868-00_W0QQitemZ7595820818QQcategoryZ78195QQrdZ1QQcmdZViewItem

Actually, there are a lot of good ideas for wind generators on eBay:
http://search.ebay.com/ws/search/SaleSearch?sofocus=bs&satitle=wind+generator&sacat=-1%26catref%3DC5&%3Bsspagename=h%3Ah%3Aadvsearch%3AUS&from=R7&nojspr=y&pfid=0&fsop=1%26fsoo%3D1&fcl=3&frpp=50

When it comes to using wind power, the theory is exactly the same as a gas powered generator. The more horsepower that you can produce, the larger the generator you can drive and the more electricity you can generate.

The problem that you run into is, when you select a campsite, you usually try to select one that is out of the wind and sun. Therefore, if you are interested in using these types of alternative power sources, it will change the way that you camp and neither are dependable.

The nice thing about wind generators is that they work 24 hours a day (if you have wind) as opposed to the 3-8 hours that you get from solar (if you have Sun).

I found that the only time that my wind generator was truly effective was when I was at sea, going to windward and in Hawaii, where we had pretty dependable trade-winds in the anchorage. In a 15-20MPH wind, I could depend on getting 10-15amps out of the wind generator. Thats over 200amps per day, on good days. I had a relay in the system that switched the power from charging the batteries (at 14.5v) to heating the water in my hot water heater. I also had 3 - 400amp batteries on the boat.

[wavery]

One small  (but important) thing that I forgot to bring up and hasn't been mentioned here.

When you install solar panels or wind generators, it is vital that you install a diode in the positive feed line to your battery. The diode will break the contact in the line if the charge rate drops below 1/2 amp.

If you don't install a diode, your energy source will work in reverse when no power source is available. In other-words, your battery will over power your solar panel when charging drops past zero (at night). It will turn the solar panel into a heater and drain your battery. Same thing with the wind generator. If there is no wind, the power from the battery will actually turn the propellers backward, thus draining the battery.

[ForestCreature]

One small  (but important) thing that I forgot to bring up and hasn't been mentioned here.
 
 When you install solar panels or wind generators, it is vital that you install a diode in the positive feed line to your battery. The diode will break the contact in the line if the charge rate drops below 1/2 amp.
 .

Isn't that part of the charge controlers job?  We have no such diode inline and have not lost power during the night that wasn't drawn by the furnace or other 12v items.

[wavery]

Isn't that part of the charge controlers job?  We have no such diode inline and have not lost power during the night that wasn't drawn by the furnace or other 12v items.

Yes, it is part of the charge controller the controller has a built in diode. I guess that I should have stated that.

Just didn't want someone to just hook a solar panel directly to a battery without knowing that fact.

Actually, when using a small array of panels or a single panel, you can get about 1/2a more output by wiring directly, with no diode or controller of any kind. You just need to be aware that there are drawbacks.

The only time that I would recommend using a controller is if you have an array big enough to over charge the batteries.

[wavemaker]

this guy has some realy good info...


http://www.klenger.net/arctic-fox/solar/index.html

Yes, it is part of the charge controller the controller has a built in diode. I guess that I should have stated that.

Just didn't want someone to just hook a solar panel directly to a battery without knowing that fact.

Actually, when using a small array of panels or a single panel, you can get about 1/2a more output by wiring directly, with no diode or controller of any kind. You just need to be aware that there are drawbacks.

The only time that I would recommend using a controller is if you have an array big enough to over charge the batteries.

[wavery]

this guy has some realy good info...


http://www.klenger.net/arctic-fox/solar/index.html

His estimates are fairly realistic also. He states that he gets 40-60a from 2-130w panels (260w array).

There is one thing that he leaves out and another thing that I would do differently. He left out the words "On sunny days". That is fairly important IMHO.

I would use a 2500w inverter and a battery charger instead of the 250w inverter (what's that all about?) and the 9100 Series Electronic Power Converter. You can also get inverters with built in battery chargers.

[chasd60]

My panels have the diode on the output connections.
 
My gain is higher than some stated because I have an MPPT controller. I have never pulled my batteries down so low as to require more than 40AH returned and that has been easily achieved in a day during the winter. It is important to realize that the cooler temperatures of the northern latitudes can make up some of what is lost in the winter months and the low sun angle. The hotter a panel gets, the more the output is derated. The cooler the panel gets the higher the output. I have seen many times when my panels output far exceeded the manufacturers stated output because of the cold. The manufacturer typically rates the panels at 20-25C.
 
Every year there is a National Solar Tour, I have been to one of the homes in my area (my doctor) and it is off-grid and powered by 880W worth of panels and 960AH of battery storage. I could not live with that little power, he doesn't even have a television. He heats his home with wood that he cuts from his land. He leaves the wood as long in length as he can and during the summer when he is producing too much power, he uses an electric chainsaw to cut up the pieces less than 4" in diameter.
 
Recently he added a 400W wind generator but it is not set up correctly so the gains are minimal. He does have to use a generator at times during the winter due to the shorter days. he had hoped the wind power would be enough but the rule of thumb is have have the generator 30' above anything within 250'. he has it mounted to the second floor of his garage but there are plenty of trees higher than that. He said the winter production went up some due to the leaf drop but not as much as he hoped for.
 
Solar Tour Info here
http://www.ases.org/tour/index.htm

[wavery]

My panels have the diode on the output connections

It would be easy to put a by-pass toggle switch on the line with the diode and controller. I did that on my boat and it increased the output to the battery by .5A. It doesn't sound like much but you may be talking about an extra 4A per day per panel (assuming a diode on each panel). You just have to remember to switch it back to the diode/controller when the Sun goes down.

[unitydnk]

It would be easy to put a by-pass toggle switch on the line with the diode and controller. I did that on my boat and it increased the output to the battery by .5A. It doesn't sound like much but you may be talking about an extra 4A per day per panel (assuming a diode on each panel). You just have to remember to switch it back to the diode/controller when the Sun goes down.

you know I am coming to SoCal in May with the new PU and I am going to come to your house so you can teach me everything I am going to know to keep me a happy camper for years to come...LOL

[wavery]

you know I am coming to SoCal in May with the new PU and I am going to come to your house so you can teach me everything I am going to know to keep me a happy camper for years to come...LOL

Are you coming down to camp?

[unitydnk]

Are you coming down to camp?

yep kinda...
we are leaving wed May 3rd like at 3am going to the game farm in Or,camping for the night at lake shasta,thur night we are camping just north of LA,fri-wed Disneyland in a hotel. DH is meeting us there then going home.Thur-fri san diego KOA where others are camping from here(it is free on fri)sat night between LA & SF then making our way N up the coast...I will need a vacation when we get back...LOL

[chasd60]

It would be easy to put a by-pass toggle switch on the line with the diode and controller. I did that on my boat and it increased the output to the battery by .5A. It doesn't sound like much but you may be talking about an extra 4A per day per panel (assuming a diode on each panel). You just have to remember to switch it back to the diode/controller when the Sun goes down.

My diode is inside the electrical connection box under the panel. The typical diode voltage drop is 0.7V but I may be dropping that twice if I have another one in the controller.
 
I wouldn't want to bypass my diode and charge controller completely. My panels can crank out over 17V at around 4.5A each. I would feel like I had to watch it too closely. I can understand doing it on a boat, hard to plug in the TV or take the battery elsewhere when you are on the water.
 
Oh yea.......
My $@*#&% laptop died and I think I lost all of my bookmarks. I pulled the HD out and hooked it to my daughters PC through a USB HD box. I clicked on Mozilla Firefox on the drive that came from my laptop and it acted like it was performing a new install. When I looked at my bookmarks, there were only the default ones in there like when you install a new browser. Looks like I should have copied the bookmarks before starting any programs. Will have to get all of the solar sites back that I once had.