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Any solar panel gurus out there?

Aviator

Registered User
Canada (Legally)
I plug a 1A solar panel into the 12V cigar lighter that takes its pwr from the starter button, and turn the master sw. ON, but leave everything else OFF (no master relay) to keep the battery trickle charged on the ground.

The voltage in the lighter socket with the master OFF is normally zero. With the master ON, it's 12.4V.

The solar panel has a built-in reverse-current flow diode. It puts out 25V with no load - i.e. not plugged in to anything. When plugged in w/master OFF, it drops to 12V, but recovers to 16V w/master ON. The battery is about 75% charged. (The ammeter doesn't move. (+or- 1A presumably wouldn't show anyway)

Q: Why is the voltage so low w/master OFF? The wiring to the starter button isn't grounding anywhere, and the battery doesn't discharge when on the ground, even for weeks.

Q: Shouldn't the voltage be lowest with the master ON and charging the battery?

Anyone have experience with this?

Thanks.
 
you are energizing the buss, might have some loads/losses you cant turn off(you just think you are), that master just turns buss/batt off... maybe like alternator/generator field
 
In order to charge a battery a solar panel must have a voltage higher than the battery. 25 volts is good.

When a solar panel is connected to a battery with a good connection the panel voltage and the battery voltage should appear identical. In reality there will be a few hundreths of a volt difference. This is because the panel voltage is "clamped" by the battery. The few hundredths of a volt difference is caused by wire resistance. (There will be a 0.2 volt difference if you test the panel between the blocking diode and the solar cells)

When the master is off there must a path for the current to flow elsewhere or the panel voltage would remain at 25 volts. The current will be flowing to something electrical between the socket and the master switch. (Radio, beacon energizer, intercom or similar) and this is not really a good practice as these devices can "see" 25 volts when they are 14 volt devices.

With the master on the battery is connected and should act as a voltage stabilizing device. Unfortunately in your case there must be something else that is diverting the panel power and causing a resistance between the panel and the battery. If the connection was good with the master on, the panel and battery voltage would be identical and slowly rising as the battery took power. Remember: Panel and battery voltage will be identical when there is a good connection.

Ideally if you can, you should fit a small socket directly to the battery with an inline fuse and plug the panel into this with the master off. Unfortunately this may ot be legal. I did this to my old 172 and my battery problems and a short battery life was cured. My mechanic ignored it.
 
Thanks for the advice, guys. I turn the generator field sw. ON only in th air. For the test, I pulled all fuses and C/B's, x-cept the master; nothing is powered by the master bus. When I clamp the panel output cables directly to a spare odyssey, the voltage drops from 25 to 18V (the cable is about 12' long). Should I be looking into a $40 controller?
 
A normal 12v solar panel is capable of 17v output in optimum sunlight. The panel is configured to supply a useful charge in "average" sunlight conditions. If your panel is putting out 25v something's wrong. Voltage isn't ultimately what you're concerned with anyway. Amperage is what you want for charging a battery. I don't remember where the output limit is before needing a charge controller. Something like 5w.

SB
 
How many watts is the solar panel? There is some info on solar panels on my web site, link in signature.
 
I agree that an open circuit voltage of a "12 volt" module of 25 volts is high, most "12 volt" panels are more like 17 to 21.5 But that's not your problem probably. As others have mentioned, go direct as possible to the battery, leave the master and cigar lighter out of it. We don't care where the issues are going through the lighter/master, going direct to the battery will solve them. Use a cheap auto type inline fuse, 5 amps would be about right, or just follow the directions with the controller, always good practice.

A great little controller for that small of panel is the MorningStar Sunguard, it's a quality unit, not Harbor Freight junk. 33 bucks and it'll last forever.
 
A regulator is a good idea if you put the solar panel in direct sunlight for any period of time. Like if you put it on a hanger roof or put it on the top of your airplane.
If you are putting the panel on the plane dash under perspex where it will only get an hour or so of sun per day then a regulator is not needed.
If you have a flooded cell battery (one you can add water to) then no regulator is needed.
If you have a sealed battery then a regulator is a good idea because overcharging sealed batteries can separate the electrolyte from the lead plates or use liquid that cannot be replaced.

For my installation I would have the panel on the hanger roof and a long lead going to a regulator. From the regulator i would have a short lead ending in a small Anderson plug. I would hard wire another Anderson plug to the aircraft battery with a 5 amp inline fuse.

Unfortunately some regulators do not like being disconnected from the battery while the panel is still connected ... so a switch on the panel positive may be needed.
 
I love solar energy. I've run my cabin off it for 15 years or more. My snowgo trailer has a 5w panel to maintain a deep cycle battery. It runs through a controller. Works great. I used to use a 2w panel in a no-electric boat to keep a battery charged to run the bilge pump. No controller on that one. Google battery "equalizing" for overcharging info. Most of us with battery banks for homes and/or cabins are used to sustained charging at 15v to boil the batteries every few months. It's a specific process. Not recommended for every day, though. Better yet, use a good alternator and an Odyssey battery. They hold their charge like no other battery I've ever used. Not even close. Maintainers aren't necessary. They bounce back from excessive discharging. They sit outside all winter in Alaska and still spin the motor easily in spring. I'll never go back to flooded batteries in an airplane. Solar power is awesome when applied correctly. I just can't figure why an airplane would need it.

SB
 
DSC_0343.jpg
 
Grid intertie or on-site storage? If storage, how much capacity? How is it distributed? 48v, 24v, other? I'm nursing one more summer with my current batteries and will upgrade to new Surrettes this fall. Any opinion on Surrette vs Trojan?

SB
 
This was installed for a feedlot operation, and was way off grid. The battery was a 3,000 lb. DEKA, sealed, and all contained in one crane liftable unit, 24 VDC. I got a deal on them, lightly used, they are very expensive new. Two Outback inverters provide 7,000 watts of power, both 120 and 240 VAC. Loads are yard lights, electric branding irons, misc. tools,and a 2 1/2 horse hydraulic squeeze chute. Plus we have a 17,000 gallon buried tank, supplied by a 120' deep well with a Grundfos SQ Flex pump moving about 10,000 gallons a day into 15 different water troughs some distance away, these are supplied by a separate pressure pump as we had no gravity flow to play. That's the power shed on the left, half buried so it stays warmer.

Surrettes are the premium, top of the line, get as big as you can. By that I mean the last small install I did for an off grid place used just three batteries, but each weighed 423 lbs! So, a simpler easier to maintain battery, plus fewer cells means they get less out of whack with each other chemically over time, much better then a long string of L-16's for a similar total amp storage.

More importantly, I see in this picture about a half dozen of my landing sites in the background, and the valley is 60 miles long! What a fun job, I'd work and then go play, or sometimes the other way around, and I had a great place to tie up when done! I was carrying out a few hundred feet at a time of PVC conduit on this job, and generally using the plane like a work rig, 2 1/2 drive min, or 1 hour flight, a no brainer.
 
Thanks for the description. Sounds interesting. My system is small (800ah) but with some adaptation of appliances and reduction in wasted energy it's more than adequate. The solar component has offered a very effective alternative to burning diesel during the sunny months. Wifey's really curious about adding a grid contributing array on the Texas roof. In a climate where air conditioning demand and sunshine share the same hours it makes some sense.

Solar power continues to gain momentum. http://money.cnn.com/2011/06/14/technology/google_solarcity/index.htm?hpt=hp_t2

SB
 
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Problem solved: Nothing wrong with the panel or the wiring. The fault was with the user. It seems there's some kind of a controller or load limiter in the panel that cycles ON-OFF, depending on the battery charge. When ON, the voltage drops to about 13V. When OFF, it's 25V. When the battery's charged, it comes ON for a few secs every 5-6 minutes. Live and learn - I guess... Thanks to all. (Neat setup, c-guy. Wish I had that kind of independence.)
 
@StewartB Go with the Surrette batteries, they are great. I was so happy when I replaced by deep-cycle golf cart batteries. On my 10th year, and they hold charge and recharge like the day installed. I have 4 for a 12v bank at the cabin. My controller does a great job maintaining and equalizing them. I run a 1kw pure sine inverter for my electronics and Toyo stove, cabin wired with both 12v and 120v circuits.
 
Scooter,

Are you leaving the Toyo running all winter? How do you manage battery recharging? I use a non-electric Efel oil stove for heat. Northern Lights genset for winter battery charging. The well runs on generator power only, not through batteries. I really enjoy seeing and hearing about Alaskan cabin power and water systems. There are some really clever guys and really interesting equipment around the state. But on the flip side, I gave my wife a Paloma water heater for mother's day about 10 years ago. It's still in the box. Wifey likes heating water on the oil stove. Life in the slow lane. Just right.

SB
 
@Stewart, I have two 100w solar panels for charging. I will run the Toyo for a day or two if I am not around, but see no reason to leave it on for a week, that would be just a waste of fuel. I use it more if I am out on long snowmachine rides or doing some flying and leaving the dog at the cabin and during the night so I have a nice even heat control as compared to woodstove.
 
An intersting discussion to follow. Does anyone have a recommendation for a small portable type panel that could be used to charge batteries used in small electronic devices, like a sat phone, that would have a 12 V lighter type recepticle?
 
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Thanks Stewart for the links. The third one had exactly what I was looking for showing the Iridium phone and the second link offers an identical kit at about 1/3 the cost. It looks like the solstarenergy outfit is marketing theirs specifically for Iridium phones but seeing what the watt and voltage output was helped me find the same panel through batterystuff.com
 
I'm surprised Roger Peterson has not chimed in here. He has the most awesome solar installation at his retreat in Canada that I have ever seen.

sj
 
Am in the process of tearing down an older cabin (gas lights) and thinking instead of the Humphrey mantle lights I'm thinking of installing solar. Been doing some looking on line...anyone have recommendations regarding a kit or supplier? Not sure if I should stay 12v or go the inverter route. Appreciate thoughts from those who have done this. The cabin will be a log cabin 16 x 24.
 
My system started small and evolved with my needs. I have 200w of solar panels routed through an MPPT controller into 750ah of storage. The inverter is 2500w and includes a 120A charger built-in. The charger is temperature sensing and is powered when necessary by a 6kw diesel generator. Along side my inverter is a 12v distribution panel that uses automotive fuses. It powers several 12v high efficiency lights, two on-demand water pumps, and a separate small point-of-use inverter to power a bedroom TV when the main power is turned off. Long ago we converted all 110v incandescent lights to fluorescent and saw a significant reduction in power consumption. When we added 12v lights we saw another reduction. We use the 110v and 12v systems equally. 12v for lights and water and 110v for the microwave, stereo, vacuum, blow dryer, etc. During summer the solar panels easily stay ahead of our needs. The batteries are always full. During winter the generator is necessary for a couple of hours a day. Inverters don't like ceiling fans or any appliances that produce electric heat. Forget about the electric coffee pot or toaster oven if you stay with a small system. Large systems can run electric dryers and dishwashers without any problem. On cold Friday nights in winter expect the batteries to be lazy. Once they warm up they're much happier. That's true no matter how big the system is.

When I started I found Northern Arizona Wind & Sun to be very helpful. There are many internet sites with good info. When you go to buy I recommend finding a local alternative energy store. They'll know your local conditions and will have good advice for you. The Arizona folks laughed at me when I went solar saying it would never work. They were wrong about that. Still, their site has lots of good information. If nothing else going alternative will make you aware of what energy pigs most of us are. You tend to use electricity more carefully when you make your own. It sure is satisfying to roll out of bed to see the solar charge meter at 6a first thing in the morning! Have fun.

This link is their education site. Scroll down to see the topic index. There's a link to their web store if you want to estimate costs. http://www.windsun.com/

Stewart
 
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Led lighting has a low power consumption compared to incandescent and fluorescent. They come in both AC and DC voltage. I have LED 4' tubes in my kitchen and LED lamps in my bedroom and living room at my camp, running on a solar system. I have everything running on AC. It really is amazing how much of a difference in the load this lighting is. Some LED's have warranty's of up to 10 years. They last longer so the inital cost is offset by not having replacement cost, plus less power consumption.
Tony
 
www.backwoodssolar.com These guys are good also, not too small and not too big, the personal touch. Just don't buy your stuff through the internet and then ask your local solar guy for free advice and help, I can't believe the people who do just that! Try and find a solar guy who will FLY INTO YOUR PLACE, for free of course, like I do. Good luck with that!
 
I bought a solar panel from one of the vendors Stuart had linked. This one is a 12 volt, 12 watt model that folds up into a neat little package that weighs very little too. The delivered price was about $165.

solar_sat.webp

Kinda neat what we can do with technology today. I took this image of the panel charging the Iridium phone with my cell phone, sent the image to my e-mail address, downloaded it with my e-mail this morning and uploaded it to SC.org. Guys with smart phones could go directly from phone to SC.org too.
 

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Laura's son Billy just had a project where he had to make a solar cooker for school. I did a little internet research and was surprised to find out how widespread their usage is worldwide, how easy they are to make, and how many different variations there are. My brother Mark said that when they were in India a few years ago, there were lots of folks using solar teapots.

http://www.solarcooking.org/plans/

http://en.wikipedia.org/wiki/Solar_cooker

sj
 
I bought a solar panel from one of the vendors Stuart had linked. This one is a 12 volt, 12 watt model that folds up into a neat little package that weighs very little too. The delivered price was about $165.

View attachment 2733

Kinda neat what we can do with technology today. I took this image of the panel charging the Iridium phone with my cell phone, sent the image to my e-mail address, downloaded it with my e-mail this morning and uploaded it to SC.org. Guys with smart phones could go directly from phone to SC.org too.

just need a plastic baggie to put phone in with cord comming out bottom, in case that rain shower rolls by.....
 
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