Solar panel project for low voltage landscaping lights

I want to put a solar panel to charge a 12V battery which will power my low power landscaping lights. This is my first time working with solar, landscaping lights and electricity, so I am really a newbie in everything. I hope someone can look over my items and see if I got everything that I needed to make this happen.

These are the items I am considering of getting:

1) Morningstar SL-10L-12V SunLight 10 Amp Charge Controller LVD
http://www.amazon.com/gp/product/B007NNRFVO/?tag=cpf0b6-20

2) 12 volt 18 Ah Rechargeable Battery
http://www.amazon.com/gp/product/B002QGZ35S/?tag=cpf0b6-20

3) Instapark® NEW All Black 30W Mono-crystalline Solar Panel, 30 watt
http://www.amazon.com/dp/B004FWW44Y/?tag=cpf0b6-20

4) allen + roth Black Low-Voltage LED Path Light
http://www.lowes.com/pd_357138-2121-4441E_4294719521__?productId=3578998&Ns=p_product_qty_sales_dollar|1&pl=1&currentURL=%3FNs%3Dp_product_qty_sales_dollar|1&facetInfo=

5) Malibu Low Voltage Black 20-Watt Flood Lights (6 Pack)
http://www.homedepot.com/Lighting-F...Id=10053&langId=-1&storeId=10051#BVRRWidgetID


- The 18Ah battery will give me a total of 216W to use between fully charged to empty. 12V x 18Ah = 216 W
- The 30W solar panel will give me about 100W of charge per day, assuming that I got 5 hours of sun. 1.68A x 5 Hrs of Sun x 12V = 100.8 W of charge / day
- I am thinking of putting 11 LED path lights (1W each) and maybe 4 flood lights (will replace the 20W halogen bulbs with 4W LED bulbs). I would like to leave the lights on for about 6 hours, so ((11x1W)+(4x4W))x6Hrs = 162W consumption per day.

I don't have any experience with solar panel, so I don't know if my calculation is accurate of 100W of charge per day. With my daily watt usage, should I get a larger solar panel just to be safe, maybe 50W? Anyone knows if I can plug the LED lights directly to the battery? Do I need a low voltage transformer? If so, that means I need to convert my DC to AC and then back to DC, which don't make sense.

Thanks and sorry for the long post.

Hinzinho

I like the choice of the Morningstar controller and an AGM type battery. I have used both in my camper with good results.

The LED and power budget is optimistic for both the battery and the solar panel. By hammering the battery to 100% depletion everyday greatly reduces the cycle life of the battery. This is explained in the data sheet http://upgi.com/Themes/leanandgreen/images/UPG/ProductDownloads/D5745.pdf Most RV and solar websites say to limit the battery depletion to 40-50% for max cycle life. Notice also from the data sheets the capacity is rated at 0.9A draw for the UB12180, while mentioned LED budget will be between 3-4A which further deflates the capacity.

For only $17 more I would double down on the battery size to the UB12350:
http://www.amazon.com/dp/B001G8AJ92/?tag=cpf0b6-20
http://upgi.com/Themes/leanandgreen/images/UPG/ProductDownloads/D5722.pdf

Similar savings could be realized by going with a 50W panel. If you can find a reputable auction site dealer, the cost of a 50W panel can be had for the same price of the previously linked 30W panel. By the way, those links need to be edited as they are same for the first three items.

The power LED's need to be fed a constant current source as opposed to a constant voltage. There are pre-made 350ma and 700ma led drivers from luxdrive, meanwell, and others that will do the job. No need to go with any sort of inverter or AC voltage, although the wire gauge needs are greater for DC for a given amount of current.

Thanks, I have updated the links.

Thanks for your reply.

I don't quite understand your last statement about LED need constant current. Will I need a LED driver for each fixture? If I went with a LED landscaping lights, should that not have a built-in self regulating driver. If so, to make things simpler, I would get all LED lighting instead of trying to replace the bulbs.

hinzinho,
That's great that you want to take this to the sustainable side. As for your measurements for power draw, you are doing them correctly but as to remember for a 5-10% tolerance for power draw for the system itself as the longer the wire the higher the resistance. I imagine that this setup is going to be ran at least 100ft or more with that many lights.

It sounds like each unit is going to run in parallel so there is no need for a current driver or power regulator, as its self regulated to just run off of 12v. I was thinking of a different application as running unregulated leds off of 12v, but you have a light system that has regulation in it. Totally my bad and just negate(remove) the idea of using such.
Then getting the adequate power driver for whatever consumption. This is just like when you are charging the battery with the controller as you are going to get a known charging rate and thus is predictable. There should be no AC involved as this is presuming that you are going to run this solely off the 12V SLA battery. When in doubt with specs you should always measure for a little more!

Then for the solar panel, the instapark company is great with using high grade mono-crystalline cells. So the panels will do what they spec them out to be a usually more. The mono panels are going to get ypu the highest current of all the other makes(poly, amorphous and CiGs), then again you are only going to get this if the sun is directly out. Polysilicon panels do the same as mono but with less efficiency and cost less. Then for thin films such as amorphous and Copper Indium Gallium Selenide are going to be the best for low levels of light(called diffused) if its going to have overcast a lot where you are at.

You are in the right direction of figuring this out by yourself. Its mainly going to be up to you when you want to source the components of the system, which you are doing great by using morningstar and instapark.

If it were me then I would go with the 50W panel from instapark as they are going to have the highest performance/dollar or $/W.

Then again for the battery, I would just source a good deep cycle or marine battery if you can find one cheap. This is me and just would be able to use it for something else if need be. Shipping is going to be alot when you are talking more than 10lbs being shipped. I am sure you can find a good local dealer for such. Think of 200-400Ahrs vs 20-40Ahrs.

hinzinho said:

Thanks for your reply.

I don't quite understand your last statement about LED need constant current. Will I need a LED driver for each fixture? If I went with a LED landscaping lights, should that not have a built-in self regulating driver. If so, to make things simpler, I would get all LED lighting instead of trying to replace the bulbs.

Click to expand...

The ideal setup would be driving three very efficient LED's (Cree XP series or??? with Vf of 3V or less) in series with the 12V battery. That would be four drivers for up to 12 1W lights, and one each for the 3-4W lights.

I can not speak to what drivers are inside the higher power LED landscape lights, and if they would work with your proposed setup, I would venture a guess they would not. Most of the low power solar landscape lights use a special driver chip or circuit to boost a 0.5V solar cell, to charge a 1.2V nicad battery during the day, and light the 5mm led at night.

On another thread I am building a 10W desk lamp that will be driven off a solar panel/agm battery combo. Going to what I call high power LED's (say 1W or more) there are significant challenges involved, with heat being one, and driving in constant current mode being the other. If it wasn't for the fact that I already have the solar panel (75W Siemans) and the Deka grp31 agm battery, I wouldn't be doing the project. I will have $20-25 in components alone for the lamp, not including a scrounged cpu heatsink, and a $1 yard sale lamp. It would a lot cheaper to just throw in a AC line powered A19 LED bulb, that costs $10, and call it good. But I like to tinker with these things.......

Consider using high efeciency connectors. I use Anderson Powerpole connectors. They are used quite a bit in solar instalations.

Any number of them may may be locked together to create polarized connections. The Anderson line is impressive with a wide variety of wire gauges supported.

They work well enough that they are almost a standard for the ARRL. If you go to a hamfest most of the DC gear will be running on Powerpoles.

I use them for all of my DC powered projects.

The link below goes to a nice Powerpole overview:
http://home.comcast.net/~buck0/app.htm

Lots of Powerpole stuff on Youtube.

You may also have use for a good DC distribution box. RIGrunner has a line of boxes that use Powerpoles. The one I use has a blade fuse for input and an individual fuse for each output line. I've been using mine for a year and I love it.

West Mountain Radio has a wide selection of RIGrunners:
http://www.westmountainradio.com/content.php?page=RIGrunner

Quite a few solar/Rigrunner vids on Youtube:
http://preview.tinyurl.com/cd5gw3x

I made some adjustments to my items (50W solar panel and a larger battery) and now my cost is at $300 for the solar setup.

If my total watt usage from my landscape lights are at most 200W per day and PG&E charges $0.13 per kW, it will take me 31.6 years to break even. This is not even accounting for replacement batteries in the future.


$0.13 / 1000W * 200W = $0.026 cost per day to run my landscaping lights
$300 / $0.026 = 11,539 days or 31.6 years to break even for my solar cost.

It's a nice project to do with my kids but the cost is too high to justify this. Thanks all for the comments. I have a much better understanding now and maybe look at a small project to do just for fun.

Your math assumes perfection. Not going to happen in the real world.

For my free brainstorming, I'm assuming 12v batteries/lights/solarpanels....

Without location, I'd recommend that you'd multiply 3x-4x of your light wattage for panel size wattage and battery amphr to have a reasonable dusk/dawn system with cloudy day reserve.
I do see that you're happy with a 1/2 of dusk:dawn run with that 6hr timer run time so I'd use a 1.5x-3x multiplier. Assuming a 6hr run time, LED watt times 1.5 = minimal panel watt and battery amphr recommendation. LED light watts multiplied by 3.0 for reliable panel watt recommendation and battery amphr choice.

11(11x1w) + the 16(4x4w)= 27w... 6hrs runtime, IMO, 40w-80w solar panel and 40-80amp/hr battery... Always recommend going as big as you can afford. You'll have much longer battery life and some reserve capacity rain/clouds/snow/overgrowth shade trees/.... I'd use at least a group 29/31 deep cycle marine battery from Walmart, SamsClub, Sears, BJs, Costco, as these batteries are usually <$130.

I'd hunt down a 60w+ solar panel from ebay(~$140+), which is definitely more cost effective than Amazon.

I'd consider an MPPT solar charge & lighting controller to squeeze a little more capacity only if you don't go the bigger panel/battery route. If you're stuck on the 30w amazon and 18ah battery, try the MPPT-05 solar charge controller.

You can get a similar non-MPPT dusk:dawn:timer solar charge and lighting controller for <$50 on ebay. Money saved on solar charge controller can go to the bigger battery/panel budget.

I use the waterproof $25 EPRC10-MF since its has an after dusk light delay, whether using the timer or dusk:dawn controller option.

One of my perfect dusk:dawn lights(12 hours) uses a ~120ah battery and ~120w and uses a ~30w bulb. I'm at a similar wattage to what you plan on using. I'm in the northeast USA. If I cut my run time in half to match your 6hr need, you can see that I would be at 60w/60ah for solar/battery power for your 6hr perfect run time, and you'll also have reasonable battery life. I truly don't think that an 18ah battery will last too long, dead at 10 months at 60% discharge daily, or sooner with a 27w load and 30w solar panel.

I've put together a landscape lighting system similar to what you're trying to achieve. Mostly followed an article that was published in Backwoods Home Magazine. http://www.backwoodshome.com/articles2/yago92.html as well as some suggestions from deadrx7conv.

Currently running two Malibu LED Pro-style fixtures from Home Depot (unfortunately discontinued now but you may still find some on clearance). I also tried the Lowes Allen+Roth fixture you posted and although I liked the warm white light they give out, I ended up going with the Malibu fixtures since they drew less power (1.3 watts vs 2 watts for the Allen + Roth. I used the same MorningStar Sunlight-10 controller you mentioned. A feature I like about the SunLight-10 is that you can have it run for a few hours after dark then shut off in the middle of the night and come back on in the morning one or two hours before sunrise. You can use 4/2 setting for a 6 hour run time if you want some light for when you leave the house early in the morning. Energy storage is currently a used 50 amp hour gel battery I got from a company that installs and maintains UPS systems for a local cable company.

Now the solar module I have currently is a 5 watt unit from Harbor Freight which does not seem like much but it just manages to keep up with running the two 1.3 watt LED lights for 6 hours every night with about 5 hours to recharge during a typical summer day in So Cal. I try to put back at least 30% more energy into the battery than what I take out.

hinzinho said:

I want to put a solar panel to charge a 12V battery which will power my low power landscaping lights. This is my first time working with solar, landscaping lights and electricity, so I am really a newbie in everything. I hope someone can look over my items and see if I got everything that I needed to make this happen.

These are the items I am considering of getting:

1) Morningstar SL-10L-12V SunLight 10 Amp Charge Controller LVD
http://www.amazon.com/gp/product/B007NNRFVO/?tag=cpf0b6-20

2) 12 volt 18 Ah Rechargeable Battery
http://www.amazon.com/gp/product/B002QGZ35S/?tag=cpf0b6-20

3) Instapark® NEW All Black 30W Mono-crystalline Solar Panel, 30 watt
http://www.amazon.com/dp/B004FWW44Y/?tag=cpf0b6-20

4) allen + roth Black Low-Voltage LED Path Light
http://www.lowes.com/pd_357138-2121-4441E_4294719521__?productId=3578998&Ns=p_product_qty_sales_dollar|1&pl=1¤tURL=%3FNs%3Dp_product_qty_sales_dollar|1&facetInfo=

5) Malibu Low Voltage Black 20-Watt Flood Lights (6 Pack)
http://www.homedepot.com/Lighting-F...Id=10053&langId=-1&storeId=10051#BVRRWidgetID


- The 18Ah battery will give me a total of 216W to use between fully charged to empty. 12V x 18Ah = 216 W
- The 30W solar panel will give me about 100W of charge per day, assuming that I got 5 hours of sun. 1.68A x 5 Hrs of Sun x 12V = 100.8 W of charge / day
- I am thinking of putting 11 LED path lights (1W each) and maybe 4 flood lights (will replace the 20W halogen bulbs with 4W LED bulbs). I would like to leave the lights on for about 6 hours, so ((11x1W)+(4x4W))x6Hrs = 162W consumption per day.

I don't have any experience with solar panel, so I don't know if my calculation is accurate of 100W of charge per day. With my daily watt usage, should I get a larger solar panel just to be safe, maybe 50W? Anyone knows if I can plug the LED lights directly to the battery? Do I need a low voltage transformer? If so, that means I need to convert my DC to AC and then back to DC, which don't make sense.

Thanks and sorry for the long post.

Hinzinho

Click to expand...

I have solar panels that charge 12 volt batteries that run my LED landscaping lights http://solar.led-guy.com/

Also consider PV on your house? Payback is a lot quicker than 31 years, and with net metering you are effectively using the grid as a battery. [with a time-of-use tariff it can be even better, because your panels generate power when the electricity rate is high, and you use it at night when the price is lower, so in effect you have a battery which you get out more energy than you put in !]

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Never had an outage. Any assumptions of such are false. Calculations and real world don't always coincide.
The only issue is snow which needs to be removed(winter re-angling the panel, rain-x, and a little panel cleaning eliminated issue). Clearing/cleaning panel should be expected and assumed as a non-issue for anyone considering solar, just like inspection/watering of the batteries.
The reserve assumes that there is NO sun for those 2-3 days. Even on overcast/cloudy days, the battery takes 'some charge' so the reserve worked perfectly fine stretching throughout the winter without ANY non-snow outages. It worked fine and perfectly better than 'as calculated'.

Instead of critiquing my working system, why don't you spend your math time calculating the expectation of the OP's build? He's the one that needed help. I only pushed him to 'up-size' to prevent serious short battery life and failure, based on my experience and not 'calculations', and showed what I have that is WORKING so that he doesn't invest in an undersized project that could be miserable.

I wonder how the OP's project turned out.

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Unless you know all variables, your calculations are worthless. So, quit trying to figure out why my systems work perfectly, and why I have updated plenty of failed overpriced 'contractor' built systems. Math vs experience and what does/doesn't work in the real world at the location, for the variables available at the location, within the available budget and expectations, are just not in any calculations. I find that the 'expense' of the contractor is what makes most systems perform pathetically as all are trying to make a weeks pay for a days work and are too hung up on their calculator created spreadsheet. Too many owners get sold on silly mathematical sales pitches and end up with a non-working gee-whiz overpriced systems. The power of simplicity always smacks the so-called professional in the forehead.

No outages here and that is the truth. Sorry if you just can't admit to when you're wrong, and can't accept a system that is working. Enjoy spending your time trying to prove something as not workable, when its actually working perfectly.

"People who say it cannot be done should not interrupt those who are doing it."

The OP hasn't been around since his last post.

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I don't care what, anyone with a calculator, or someone who thinks that they are the greatest professional, thinks. Go out there and BUILD SOMETHING.

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