LED lighting plus solar panels

I have been considering using Solar Panels to drive High power LED lights. By using the output of a solar panel to both charge a small battery bank and drive LED lights I could avoid the whole Inverter plus driver issue. Basically I would Configure the Solar array to run 48 volts, then connect them to a 48 volt charge controller to a string of 4 12volt batteries. From there to a Fuse array. Then run 48 Vdc to each light. Since voltage drop in the cable would be an issue I expect to home run each light to minimize voltage drop issues. The actual voltage the array would be configured at would depend on the lights requirements. Several of the lights I have looked at run at 48 volt, however many places never list the actual Dc voltage used. I am talking high bay 120 watt to 200 watt.


It seems to me that Solar plus LED is such a great fit. You can build your own solar panels and save a bunch of money in parts. Probably not so much in labor. Go to ebay and search 3x6 and 6x6 solar cells. There are a number of videos on You tube that explain how to build them.


A 250 watt panel runs about $250.00 pre-made. So for a commercial install I would use them. But for your home build your own.


Pluses:
No power bill at all from the power company.
No expensive Inverters or driver to buy.
No transfer switches.
Run it in parallel with the existing lights so if any problems develop the old lighting system could be turned back on.
12 to 48 volts is considered Low voltage so wiring rules are less strict. I would use 12/2 jacketed speaker wire.




Questions I have are:


How sensitive are LED arrays to slight variations in voltage? If I have a voltage drop of 2 volts in the cable and I get 46 volts at the light will that be an issue? Assuming a 48vdc light.


I am looking at a service bay with 12- 250 watt Metal halide lights. My calculations indicate that the 120 watt should work well. The existing 250 MH lights put out 14000 to 20000 lumens. While the 120 watt LED does about 10000 lumens. While the Lumens are less as I understand it LEDs are more efficient at projecting light, so less is needed. Am I mistaken about this?


12 lights X 120 watts = 1440 watts


1440 watts / 250 watt solar panels = 5.76


To have enough excess current to keep the batteries charged I would go with 8 panels. Keep in mind solar cells degrade from UV light over time, plus in winter you would have a reduction in output.


8 solar panels X $255.00 = $2040.00
Charge controller ~ $ 150.00
Batteries X 4 ~ $ 300.00
Fuse block $ 25.00
Mounting kits x 8 ~ $ 800.00

I would be curious what some of the experts here would say about this.

KITROBASKIN said:

I would be curious what some of the experts here would say about this.

Click to expand...

The experts are too busy rolling around on the floor laughing to type a suitable response.

But seriously Rondil, go back and do a ton of research and then decide if it is a good idea. You may even want to look at some of the posts on solar lighting on CPF.

Semiman

are there really panels for a dollar per watt? I thought the figure was much higher.

The inefficiencies of solar panels are significant, as well as all of the non-ideal conditions that they will be operated in. A 250 watt panel may only put out that power when ideally aligned with the sun on a clear day and while the panel is still cool (i.e. hasn't been exposed to the sun for more than a few minutes).

I would recommend starting with a single panel and playing around with it. Hook up a light or two, hook up a battery, etc. The cost is relatively small, and you'll get some experience with how much power you can really get from a panel. It'll entertaining and a good education.

Have you considered a skylight? I just spent a few days in a lab with one, and it really does help.

KITROBASKIN said:

I would be curious what some of the experts here would say about this.

Click to expand...

$3300 in solar lighting gear would pay my whole electric bill for almost a year and a half. Lighting is a small part of my power bill - The electric AC, electric water heater, electric vent fans, consume most of my power - and I have about 300W in fluorescents in the kitchen for hydroponic lettuce and herbs.

A window - With or without a reflector on the lawn - would be a great light source. Same for skylights. Heck, a decent heliostat would bring light in for cheaper than that. Check out the SunFlower heliostat, for about $300 you get a volleyball-sized sunbeam to shine into a room. That's a lot of light during the day.

For one I am in the research stage. Part of my research is asking people who may know more than me. I am looking into this for one of my customers who has a 2200 a month power bill. I realize that his copiers, welders, water heaters, computers consume a lot of power and there isn't much I can do about that. A solar array to power all that would be prohibitively expensive. A solar array to take the lights off of Grid power is doable. I have seen NO INFORMATION to suggest that it isn't.
If I can reduce that 500 a month then payback would be a year or so. High wattage Metal Halides consume a lot of power.

It sounds like I will be doing the LED lighting on the grid for now and experimenting with solar. As it looks like none of you have a clue. No one was able to answer my questions.

I talked to the customer about skylights. He doesn't want them due to leakage problems.

As for solar panels being a dollar a watt, just check ebay. I just saw one for 230 bucks for a 250 watt panel. If you build your own you can go a lot less.

If your so smart give me one good reason why it won't work.

An accurate accounting for battery costs (AH capacity = 5 x daily load AH and replacement in 2-5 years) should give you an ongoing cost for free power that is note than twice the cost per kWh that you would pay for utility power. Off grid solar lighting is far from cheap, especially where the light is for visibility and not just decorative.

Also, though, you can get first grade panels from a second tier manufacturer for under $1/watt pretty easily. Mainly as overstock or discontinued, but still good panels. Prices may be rising soon as tariffs kick in.

Rondil I will not waste my precious time responding at length because your post shows you have done almost no research and considering you are getting paid ...... There are so many flaws in your logic that a read of even one half decent article on using off grid solar power seems to have not occurred. Spend a few hours reading about sizing of off grid solar power then come back here.

Semiman

P.s. good solar panels can be had well under $1.00 per watt as pointed out but shipping is not free and can be substantial. Build your own solar panels .... Still rolling.

Ty semi, someone had to say it. Lol

Sent from my SAMSUNG-SM-G730A using Candlepowerforums mobile app

Rondil said:

It seems to me that Solar plus LED is such a great fit.

Click to expand...

Let's start by saying that personally I'm very much into your line of thinking, Rondil. But reality is a complex beast... And there's a number of flaws in your thinking:

1) If you've got sunlight, why not use that directly?
2) If LEDs are so good, cheap and efficient, wouldn't everybody use them? Oh right, most people do! Just to different degrees, and for different applications.

3)

AnAppleSnail said:

Lighting is a small part of my power bill - The electric AC, electric water heater, electric vent fans, consume most of my power

Click to expand...

True - for most of mankind. Sure it matters how you'd power those LEDs, but the same is true for all other equipment. If low-cost lighting is your thing, efficient light sources (like LED) do the trick. If energy saving is your thing, start with the biggest consumers first (heating, airco etc. comes to mind).

4) A 500 Watt-peak solar panel isn't what you need to power up to 500W worth of equipment. A 500 Wp solar panel is a long-lasting energy source, that provides up to 500W under ideal circumstances (and 0 at night!). You shouldn't be asking how much Watt worth of panels you'd need to power everything in your house. You should be asking how much you want to invest in a solar setup right now, and what's the best way to use whatever energy comes out. Reduce your electricity bill, feed a surplus back into the grid, run that airco on hot days, charge the battery on your boat, whatever.

5) Store energy in a battery, and whatever goes through it, has a $/kWh cost attached that's likely much higher than either solar or grid power. So first you'd have to ask yourself if you'd want to use a battery at all. And 2nd you'd have to ask yourself what for. Of course "to cut that LED lighting loose from the electric grid" is one option. But only one of many, and each purpose places different demands on battery type & capacity you need.

Steve K said:

I would recommend starting with a single panel and playing around with it. Hook up a light or two, hook up a battery, etc. The cost is relatively small, and you'll get some experience with how much power you can really get from a panel. It'll entertaining and a good education.

Click to expand...

+1

And indeed, the going price seems to be around $1 / Watt-peak these days. If it hasn't dropped lower in the meantime...

with all the negativity towards solar panels, it almost seems as if you all work or own stock in power companies....lol. dont ever let anyone discourage you from doing something or trying to make something better. we wouldnt even have lights if the inventor got discouraged from people saying you cant, its impossible, your crazy and so on....etc. it is possible.

aw73 said:

with all the negativity towards solar panels, it almost seems as if you all work or own stock in power companies....lol. dont ever let anyone discourage you from doing something or trying to make something better. we wouldnt even have lights if the inventor got discouraged from people saying you cant, its impossible, your crazy and so on....etc. it is possible.

Click to expand...

Feel free to stick your head in the sand but the rest of us live in the real world.

Its nothing against solar panels.... Its panels, 8-10 days of battery storage at end of battery life and cold for where used, batteries killed by heat, hopefully no shading on the panel, the large panel and large projected area for wind loading for pole and footing design, the larger footing to support the panel and batteries , the smaller light due to the limited power available, the increased failure rate due to increased complexity, eliminating the benefits of long LED fixture life by introducing a shorter life product , namely the battery.


Please explain why you think solar lighting is such a panacea?...lol

see what i mean about people trying to discourage?

i never said solar lighting was panacea. there are thousands of people using solar panels and cutting there energy cost in half or more and some are even making money. and batteries can be restored, i have done it, so maybe you need to do a little research on that. there is a reason when you buy a new car battery they want your old one.

solar lighting would only be used during the day, solar panels could be used to charged batteries during the day and lights would be used maybe 3 or 4 hours at night.

solar panels would only be part of energy savings, you would need to stop being such a consumer and be more responsible and learn to use less and have less to save energy just like most people do that are off the grid.

maybe you need to get your head out of the sand.....you sure your not working for the power company?....lol.

With the exception of California and other very high electricity costs, no one saves money with solar panels without subsidies.

No one recovers properly treated lead acid batteries that have simply wore over time. Never been shown to be done in a controlled ... Ie independently observed environment.

They want your old battery back for the core charge. Most of the weight is lead and tin in some and is almost 100% recovered when reprocessed.

Your LOL just makes you look foolish as you hand wave without addressing real issues.

Again , some of us live in the real world ...where we solve real world problems. We don't simple LOL the problems away, we need to solve them as customers are really pissed when the lights fail.

Using solar to exclusively serve lighting makes little sense. Use all that you can on the loads that need it and store nothing as nothing is left makes far more cost and environmental sense.

i guess the power companies should of talked to you before they invested their money in solar panels and wind mills to get energy to the masses......lol. i guess solar panel company stocks are going to plummet now since you have shed the light on their stupidity.......lmao.

and yes i have recovered old 12v car batteries. just because you havent seen it or dont know how doesnt mean it isnt true or cant be done.

I don't think he's saying that it's totally uneconomic, just the fact that unless you want to devote a large investment initially, the cost vs. gain rises considerably.... more than other methods/technology.
A smattering of LEDs and solar panels spread over X.X ft² vs. same land area dedicated to solar power is staggering. You are comparing camp fires to nuclear power.


Sent from my SAMSUNG-SM-G730A using Candlepowerforums mobile app

Well... I can see a couple problems off the bat.


You mentioned 48V, nice... good to see people deviate away from 12V and take advantage of voltage over thicker wires... however...
You might have difficulty finding a commercially available charge controller to charge a 48V battery bank. Typical "12V" solar panels are about 21V open circuit [VOC], 17V max power [VMP], You'll need to daisy chain at least three modules in series to offset the charging differential if you ever did manage to find a charger.


Another thing, if you're getting "48V" from daisy chaining four 6-cell Lead acids I got news for you. "12V" is a nominal figure. The voltage at depletion is about 1.7V/cell, or about 43.2V, voltage at full is about 2.2V/cell, or about 52.4V. While shopping for disconnects, take note on the voltage rating for DC, you'll find that many battery breakers aren't rated that high. My 120A main breaker for the "House battery" is only rated at 42V. You'll see an accelerated oxidation rate on your contacts running the system on voltages way above spec.


Now you mentioned 48V LEDs... if they have internal drivers then they may be constitutionally incapable of compromise when it comes to supply voltage fluctuations. If they are resistor driven they could care less as long as the supply voltage is below their maximum allowable upper limit. If you are using the higher voltage to offset voltage drop I would suggest DC-DC converters and running lower voltage LEDs. As long as the DC-DC converter has a 2:1 [or better yet 4:1] input range your output won't be affected by the voltage drop or fluctuation one bit.


Before you consider any solar project, evaluate where you are standing from a latitude perspective. If you're in an geographic location poorly suited for PV you might end up with a PV array three times it needs to be only to gain maybe a third of its rated production. Best luck to you.

aw73 said:

i guess the power companies should of talked to you before they invested their money in solar panels and wind mills to get energy to the masses......lol. i guess solar panel company stocks are going to plummet now since you have shed the light on their stupidity.......lmao.

Click to expand...

Lmao ...yes I laugh at your ignorant posts. You really need to research before spouting off.

Solar panel stocks are pretty much maybe 1/3 their value of what they were in 2011 when government subsidies dried up and prices and values tanked. The largest solar panel company in the world Suntech declared bankruptcy.

The only reason they invested in solar and wind was due to government incentives and mandates.

That said, large scale solar thermal in California has promise even without incentives .... Ie handouts of taxpayer money.

Wind can have better kW/h costs but incurs large costs in backup generation.


No one has shown the recovery of a lead acid battery that has been treated properly and has aged normally. Never .... Not once under controlled repeatable conditions. Limited recovery of poorly treated batteries has occurred but that is not what we are talking about.

You talk a good story ... Now perhaps stop waving hands and show actual results.

By the way how much solar you out in? .... Me ... Hundreds of solar light and almost a megawatt of solar. How many solar chargers you designed?



Illum ....48v chargers are easy to find and buy.

how much solar am i out in? way more than you, im in the solar everyday all day its called the sun, some people have to work...lol. how much bull do you talk?......mega piles....lol. how arrogant are you?.....giga arrogant!!!!!!

i dont like people like you, your not helpful, your hurtful, know it all, and always negative. you could of left a very helpful and positive post as illum did but, you chose to be a **** and be negative on your very first post on this thread.