Light from the Sun?- Mtbr.com

# Thread: Light from the Sun?

1. ## Light from the Sun?

Has anyone tried charging their batteries using solar power?

This Idea may seem off the wall or impractical - but then again, maybe it has merit...

So, the other night when I was 'thinkin' while drinkin'' (possibly smokin' ), I was looking at my shi++y solar powered walkway/landscape lighting. It had been dark for two hours and they were already off. And when they were on, they wern't bright to begin with.

So that got me thinkin, "why not DIY some yard lights?
The lights wouldn't need to be anywhere near as bright as your lights that you build, so you could get longer run-times (and still brighter light) with less current necessary.

That idea further led to myself as a commuter..."what about solar power to charge my battery as the bike sits all day at work?"
The run-time wouldn't need to be that long - say an hour if I throw in some shopping after work or go on a beer run after I get home.
(I use a MS 1400 currently)

whaddya think? feasable?

2. You would need to carry a REALLY big solar panel

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3. Yep. Been done.

I use solar Christmas lights on my house. I also decorate some cedar trees with the solar Christmas lights in the woods at my main mountain bike trail.
I like a festive ride while in the woods.

4. Originally Posted by scar
You would need to carry a REALLY big solar panel

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how big you reckon?

5. Math is a wonderful thing....

You can pick a number (hours) for your runtime. You know the battery voltage of your pack. Measure the current drawn from the battery pack with the light on and at the level you plan to use.

Multiple the 3 numbers and you have watt.hours used on your ride home in darkness.

Now, pick a solar panel than can put that many watt.hours + 50% back into your batteries during your day at work. Is this panel indoors or outside? Indoors you'll get pretty dismal power from fluoro's etc, outside you have to deal with cloud cover, shading, magpies that will steal your panel, aiming/re-aiming the panel to keep it pointed at the sun etc etc.

Personally it would be a heck of a lot easier to have a battery charger at work and use that stuff that comes out of a wall socket in your office/cube.

cheers,
george.

6. OK Maybe not THAT big.

7. Originally Posted by georges80
Math is a wonderful thing....
I can handle the math, (ex-avionics tech - F-14D/SH-60 radar), I just don't know squat about the efficiency of photo-cells...

Still seems like you could improve on the crappy yard lights

8. Originally Posted by highdelll
I can handle the math, (ex-avionics tech - F-14D/SH-60 radar), I just don't know squat about the efficiency of photo-cells...

Still seems like you could improve on the crappy yard lights
Google is also a wonderful thing (google for solar panel efficiency )

Efficiency of common solar cells is 10 - 20% typical. 20% at the higher end and 10% at the cheap/junk end.

Most solar yardlights are more limited by the charging technology and you'll find the nicad/nimh cells are usually low quality/capacity and then abused by the solar charge circuitry in the cheap lights. Basically if you can get a season or two out of them you're doing pretty good. Combined with plastics that deteriote in the sun and the panel will be lucky to get much light. Then the panels are typically horizontal versus tilted towards the sun.

Anyhow, the majority of solar garden lights are basically junk that ends up in the landfill. So, in terms of their 'green quotient' it would be better to run low voltage lights off the grid or from a decent panel/charger/battery combo.

cheers,
george.

9. Originally Posted by georges80
Google is also a wonderful thing (google for solar panel efficiency )
.
ha
ha

10. Cateye Hybrid:
Panel charges NiMH
https://www.cateye.com/en/product_detail/575

11. Originally Posted by highdelll
Has anyone tried charging their batteries using solar power?.....

That idea further led to myself as a commuter..."what about solar power to charge my battery as the bike sits all day at work?"
The run-time wouldn't need to be that long - say an hour if I throw in some shopping after work or go on a beer run after I get home.
(I use a MS 1400 currently)

whaddya think? feasable?
Be sure, you're not the first one to consider solar. I think the main obstacle is , "The Money". You need a solar panel big enough to run your battery charger. Unfortunately most chargers run off of 110-120volt AC. Likely you need a Solar panel that can provide about 50-75watts....enough to power a small DC/AC inverter plus the charger. A cheap 12v DC/AC inverter runs about \$30. The Solar panel is where the big money comes in. Maybe in the \$100 to \$300 range. You need one that can provide 12v DC with enough current to run the inverter. The inverter needs to power the charger which requires about (est.) 13.5 watts of power. Total power required would be that needed for both the inverter and the charger combined. I would be thinking a Solar Panel in the 75watt range to be safe. Anyway, just food for thought.

Frankly what Georges80 said makes more economic sense. Just buy an extra charger and plug it in at work. Either that or carry an extra battery and charge every thing at home. ( Note: there are some chargers designed to work with a 12V DC car plug as well as 110v AC. People who have those don't need an inverter, a big plus. I doubt the MS charger has an extra 12vDC input plug. )

12. Originally Posted by Cat-man-do
Be sure, you're not the first one to consider solar. I think the main obstacle is , "The Money". You need a solar panel big enough to run your battery charger. Unfortunately most chargers run off of 110-120volt AC. Likely you need a Solar panel that can provide about 50-75watts....enough to power a small DC/AC inverter plus the charger. A cheap 12v DC/AC inverter runs about \$30. The Solar panel is where the big money comes in. Maybe in the \$100 to \$300 range. You need one that can provide 12v DC with enough current to run the inverter. The inverter needs to power the charger which requires about (est.) 13.5 watts of power. Total power required would be that needed for both the inverter and the charger combined. I would be thinking a Solar Panel in the 75watt range to be safe. Anyway, just food for thought.

Frankly what Georges80 said makes more economic sense. Just buy an extra charger and plug it in at work. Either that or carry an extra battery and charge every thing at home. ( Note: there are some chargers designed to work with a 12V DC car plug as well as 110v AC. People who have those don't need an inverter, a big plus. I doubt the MS charger has an extra 12vDC input plug. )
I know I'm not the first to think of it.

But what's with this 120V, inverter, battery charger...The solar panel would be the "charger" - a trickle charger that is already putting out DCV that needs no inversion.

13. http://www.sparkfun.com/products/7845 is a .45W pannel at about 6*9 cm
http://www.sparkfun.com/products/7840 is a 2.5W pannel at about 11*18 cm

You would need to work on how to use the suplied voltages sencibly.

14. Originally Posted by highdelll
I know I'm not the first to think of it.

But what's with this 120V, inverter, battery charger...The solar panel would be the "charger" - a trickle charger that is already putting out DCV that needs no inversion.
The idea would be that the Solar panel is outputing 12V DC. Since most chargers require 110-120V AC to operate, hence the need for an inverter. Now if you have a way to disassemble your charger and by-pass the built in power rectifier circuit ( the circuit that converts AC to DC ) more power to you.

Yes, basically you have to go from DC to AC and back to DC. No need for a AC inverter if you know how to build a charger that operates directly from 12V DC. Like I said before, some chargers are designed to operate using both. Owning one of those is a big plus as it means you can plug into your car lighter plug when going places. ( Comes in handy when camping when no electric is available. ) The rest of us just buy a cheap Radio Shack car adapter plug inverter and we're good. The one I own will handle 75watts and plugs into my lighter plug. More than enough for a 13.5 watt charger.

There are Solar panels designed to charge lap top batteries however I believe most lap tops are designed to operate in cars with lighter plug adapters so they already have a circuit built in to handle it. I don't own a lap top so I can't swear they all will plug into a car plug. I would not recommend connecting 12V DC directly to your bike battery without a charging circuit to monitor the charge. Sure would be nice if someone would sell a ready to go set-up like that. If someone knows where to buy to buy one I sure would like to know. On the up-side, if you use a standard DC to AC inverter you can operate anything that runs on AC up to the max power output ( watts ) of the inverter. ie...My car inverter will power any Li-ion charger I own. It should power a portable radio ( up to 75watts ) It WON'T run a micowave or an electric heater. That would require something like a 2000+watt inverter, much more expensive...not to mention you would need a car with a two battery setup to drive the inverter.

QUOTE=ifor]http://www.sparkfun.com/products/7845 is a .45W pannel at about 6*9 cm
http://www.sparkfun.com/products/7840 is a 2.5W pannel at about 11*18 cm

You would need to work on how to use the suplied voltages sencibly.[/QUOTE]

...That is why you need to use a charger to control both voltage and input current to the battery. That is what a charger does. Those panels would not work unless used in series to bring up the voltage...then you need a circuit to control the voltage and current which will flucuate with the change in sun light.

15. -the idea is to BYPASS any standard AC charger...
happens all the time AKA my yard lights

16. Originally Posted by highdelll
-the idea is to BYPASS any standard AC charger...
happens all the time AKA my yard lights
You can't charge a battery without a charger unless you want to blow it up. If you have one that operates on DC voltage then you're good. You can run a DC bulb or LED from a DC solar cell or battery without control circuitry, however do not expect them to last long. You can operate stuff out of designed parameters but doing so can be extremely dangerous. Charging a Li-ion battery without a control circuit could be done as well but VERY, VERY DANGEROUS. FWIW, none of those solar sidewalk lights impress me much. Very low output. Highdell, I can't speak to your yard lights (?) Most peoples yard lights are using AC voltage although some newer lights use converters ( AC to DC ) to power different kinds of lights ( Like Led or fluorescent )...Those screw-in fluorescent bulbs...Yep, DC converter/ballast inside the bulb.

17. Let’s take an idea I have been shooting around (in my own mind, of course) for a while now. That idea is around the basis of taking a cross country bike ride, relying on the resources one finds along their route. Well, sunlight is a commodity for such tours. If one were able to capture an AFFORDABLE 500mAh of energy in their batteries then everything would be peachy keen (thanks Jan Brady). The facts right now are that the efficiency of solar cells, after more than 45 years of development (thank the United States space program), is still leaving a lot to be desired. I think ”we” are finally “up to” an “amazing” 28% efficiency rating. Got craploads of money??? (think along the lines of thousands) No problem, just cover yourself in flexible solar cells, and get some really efficient charging circuit to keep your (assumedly expensive-assed Li-Po) batteries topped off. Yes, folks, one step forward (GM EV-1, I think that was back in 1993), and twenty steps back (when the “threat” of immeasureable oil reserves under the Shrub Jr. administration really f°cked things up—anyone remember vividly paying more? Oh nevermind). We are back at square one until a REAL global crisis (non artificially implemented) comes about.

Oh carp. Yes, not salmon, CARP. I ranted.

18. Originally Posted by highdelll
Has anyone tried charging their batteries using solar power?
If you live in Sahara, that's good idea. Otherwise, it's crap.

19. LP, no reason why solar can't work. It's just expensive. I would love to see an affordable Solar charger designed to charge a Li-ion 4 cell battery ( 7.4V ). Not sure you could carry it easily on a bike though. Depends on the size of the array. Could work for car camping though without too many problems. I think for bike commuting the Dynamo is the best bet right now for people who don't want to rely on batteries.

After some extensive web surfing I found a couple solar arrays that would work with the set-up I proposed. Unfortunately all of these go for about the same amount of money, roughly \$300 to \$400 ( just for the panels ) The only affordable solar solution I see for bikes is with the ones sold to charge loose NiMh AA cells. If you use a bike light that runs off of loose NiMh AA's, solar rechargers for about \$30-\$50. They do require a full 8hrs of good sun light for recharge though.

20. I charge at home, where we have 3KW of panels.
Or, I can use the 7.5KW of panels at work.

Gotta love the Ontario MicroFIT solar program.

21. Originally Posted by georges80
Efficiency of common solar cells is 10 - 20% typical. 20% at the higher end and 10% at the cheap/junk end.
39.2% cells just about to ship:

http://www.gizmag.com/boeing-to-mass...r-cells/17028/

When it comes to solar cells, everyone is chasing the highest conversion efficiency. Although we’ve seen conversion efficiencies of over 40 percent achieved with multi-junction solar cells in lab environments, Boeing subsidiary Spectrolab is bringing this kind of efficiency to mass production with the announcement of its C3MJ+ solar cells which boast an average conversion efficiency of 39.2 percent...Boeing hopes to transfer that success to the terrestrial solar cell market with the new high-efficiency solar cells that are expected to be available from January.

22. Everyone is forgetting about the cheap and high end balance chargers all over eBay or hobby stores that work extremely well on 12v from a battery. This would be a plug and charge option with the solar.

I just ordered one for my light build. Doesn't even come with the 110/120 adapter. Have to buy it separately or use an old laptop charger.

23. Originally Posted by syadasti
10-20% is still the typical range of COMMONLY available panels/cells that you can buy TODAY without paying through the nose - especially since the OP is looking at small panels for yardlights and bikelights. You really think the average yardlight is using premium solar cells?

I still think small scale solar isn't feasible when combined with junk batteries and junk chargers - aka the stuff in yardlights or DX type bike lights with built in solar panels...

Then factor in that most folk need bike lights in the winter months when the sunlight is less, cloud cover is more, sun angle is nearer the horizon and you have all the cards stacked against you for small scale solar to work well.

For the OP, you may as well use a dynamo and charge controller on your bike to help top up your battery while riding or have 2nd charger at work or 2nd charged battery pack or a larger pack to start with to cover the ride both ways with margin.

Anyhow, just call be a very skeptical engineer when it comes to small scale solar combined with winter time. And solar yardlights are just a dumb idea that catches the impulse buyer or person that is too lazy to run some low voltage wiring around their front yard

cheers,
george.

24. Originally Posted by Ofroad'bent
I charge at home, where we have 3KW of panels.
Or, I can use the 7.5KW of panels at work.

Gotta love the Ontario MicroFIT solar program.
I was reading about the Solar buy-back programs in Canada just last light. That is a really great program.

Originally Posted by syadasti
Interesting website this gizmag.com
I had no idea there were organic versions of Solar cells. Low efficiency but cheap and flexable. One of the commentators on gizmag mentioned the lack of full disclosure when it comes to solar technology. Apparently solar cells have a defined lifetime of use. I really don't know too much about that but I did notice that one seller disclosed a 6-8 year lifetime on the one that he sold. Hopefully technology will continue forward and there will be better disclosure on new technology.

25. Originally Posted by Cat-man-do
I was reading about the Solar buy-back programs in Canada just last light. That is a really great program.
If you check the market, NJ has the best renewable energy credit program in the US. This year they went for about \$650 a credit (our system will produce about 300 a year):

https://markets.flettexchange.com/

We just installed a 1196 panel (each panel is 235 watts) 281 kW system - it will pay for itself in 5-6 years and after that its all profit (the entire system has a 20 year warranty too). We get SRECs for 15 years and we can also sell power back to the grid - nice since the summer time when we'd make more power is the low season for our business. The panels will probably work for at least 25-30 years if they aren't replaced due to being obsolete.

To keep this on forum topic we have a very efficient T5HO 48" 49W/bulb 5000K light system in our new building. Each court uses about 5000 watts and the 96 bulbs put out over 450,000 lumens - about 90 lumens/watt including the ballast (better than LED systems which aren't mature in this segment). These are over 60% more efficient than 2001 minimum standard for our type of building.

You can probably afford a single 25 kW suncatcher unit if your lawn has the space - \$75,000 and its the most efficient solar option on the market (right now, Boeing may challenged that, but not at this pricepoint). Downside is the moving parts and more frequent mirror cleaning making maintenance higher compared to PV cells:

https://www.youtube.com/watch?v=-evkuwvKJ-c

26. ## Light from the Sun?

Crazy notion! I've never heard of such nonsense. That shining thing in the sky is just a gaping hole in the ether.

It lets the global warming gasses out too!

27. Solar powered flashlights! What is next, submarines with screen doors?

28. Here are some of the latest that I have seen - http://store.goal0.com/index.php?p=c...parent=29&pg=1

They do a couple of LED lights also - http://store.goal0.com/index.php?p=c...parent=30&pg=1

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