Solar Powered LED Yard Lighting Made Cheap & Easy

In this Instructable I'll be sharing some of the outdoor solar powered LED lighting projects that I currently have up and running. I'll be covering how I put these projects together, why certain items were chosen over others, sourcing the stuff you need for the projects, and how to calculate what you need panel and battery wise to have a reasonably reliable setup.

I try to lean towards the "make do with what I can re-purpose or get cheaply" mindset. You can buy outdoor solar lighting setups that are turn key and ready to go but I've found I can build my own for much less and make it better from a utilitarian point of view.

These are all projects done by a hobbyist with a tech background. Different municipalities have different building codes. Some places have stricter codes than others. This is all low voltage (12v) stuff. It's up to the reader / builder to adhere to any local building codes that may apply.

What's needed on your part to duplicate what I have done?

Basic knowledge of hand tools, power tools, electricity, wiring, and of course that ever elusive common sense. Gear wise you'll need solar panels, batteries, a charge controller, and cable to hook it all up with. For years I have been a big fan of using 12-14ga outdoor lighting cable like what's used in Malibu light setups. The stuff has a heavy sun resistant insulation and will last for years outdoors.

What to expect from one of these systems?

A fairly reliable solar lighting system that can illuminate part of your yard without reliance on the commercial power grid.

What limitations will a solar powered lighting system have?

To put it simply, no sun = no power. Without getting into an oversized panel and battery setup, you just have to accept that on cloudy days your system may not run as many hours as expected. In this instructable we're all about keeping it simple enough so it works reliably on sunny days. Scaling things up so your system can get through a day or two of lousy sunlight is covered later in the instructable.

Step 1: Why Go Solar?

Because it's free and doesn't make noise.

I've been playing around with solar power for amateur radio applications for over 20 years but the recent visit from hurricane Irma gave me a push to convert some of my outdoor lighting to something that wasn't grid dependent. Unfortunately we live in a world were some folks look at a power outage as an opportunity to acquire that which is not theirs. After a widespread power outage, places with lights tend to convey the message that there is someone home and trespassing may not be a good idea. It was also nice to have illumination without the constant drone of a generator.

Will this save you money? At this scale it's highly doubtful but if you're somewhere that is known for power outages every time the wind kicks up, the peace of mind is well worth it.

Aside from getting off the grid, solar is a great way to get lighting in places where it may prove expensive or impossible to have an electrician run a power drop. What I did here can be easily applied to a remote hunters cabin or other location in which commercial power is just not an option.

If you buy everything new and are a thrifty shopper, you can assemble a reliable system for under $100. If you're a good scrounger, you can save a bit of cash. The priciest parts are the battery and the solar panel. I'll cover sourcing the different parts in the next few pages.

Step 2: Batteries, What Will Store Your Power.

The battery is your "gas tank". It stores the power you have generated during the day. For a simple dusk till dawn setup (on at night, off during the day), 10Ah per 10w of LED lighting is right at the minimum. If you can afford a little more battery capacity then go for it! Is 10w of LED lighting bright? Yes, a modern 10w LED floodlight can easily light a driveway for example. A 10w LED bulb in a lamp can illuminate a room.

The type of battery I use is called an SLA, Sealed Lead Acid (pics 1-3). This battery is commonly found in UPS systems for computers, adult mobility scooters, and kids ride on toys like Power Wheels. 6V and 12V are common. They will be rated in voltage and amperage. For example an SLA battery could be marked 12V 10.5Ah (pic 1). This means it's a 12v battery that can hold up to 10.5Ah of current. If you are pulling 1 amp from this battery and it's fully charged and in good shape, you should be able to run up to 10 hours off it. The higher the Ah rating, the more capacity the battery has. These types of batteries are typically rectangular or little cubes. They can be mounted upright or on their sides but I prefer to run them upright just in case the seals aren't up to snuff.

sourcing them..

These can be bought new from all the usual online vendors like ebay, Amazon, Walmart, etc. Hardware stores and specialty battery stores will also carry them. I've found the best deals on these new are currently at the Walmart website. They often have free shipping deals if you spend a certain amount of money. I purchased 20Ah 12V SLA's from walmart.com for $25 shipped but those deals don't come often. That price is very hard to beat and if there's an issue with them (I received a damaged one) they can be returned at any Walmart store.

Used batteries can be had cheap / free but it's a crapshoot. If you know anyone that deals with UPS (uninterruptible power supply) systems on a commercial scale, you can often get your hands on used batteries for next to nothing. Even dead, all lead acid batteries have scrap value due to their lead content. Some places don't want to deal with them and may let you have them just to get them hauled off. I've picked up a few lots of used batteries like this and have been able to score a few good batteries out of the pile. The bad ones go to the scrap metal place and end up as some extra pocket cash.

A quick way to cull out bad SLA batteries in a used battery lot is look and shake. Cracked or bloated cases are bad. Batteries that sound like there's something loose in them when shaken are usually dried out and no good. Corrosion around were the terminal enters the battery case is also bad. Like I mentioned before, these are no good for our project but still have scrap value.

Once you've culled out the obviously bad ones, take a multimeter and measure the voltage on the remaining batteries. 12v batteries showing less than 10.5v are probably done for and not worth messing with. On 6v batteries pass on anything reading under 5v. Once batteries are deeply discharged and left that way they can be damaged.

Take what's left in your "possibly good" pile and charge them on a slow charger. Small batteries in the 20Ah size or less should be charged at around 2Ah. All the small car battery chargers I have seen have a setting that is comparable to this. Any higher and you risk cooking the battery. If you have any 6v batteries you'll need a 6v capable charger.

Charge a used battery on slow charge over night. Take it off the charger and let it sit for about an hour to stabilize. Measure the voltage, write it on the battery with a permanent marker and let the battery sit disconnected over night and re-measure it's voltage the following day. If it's dropped under 12v it's bad and has an internal short of some kind. If it's voltage is above 12v chances are it's usable. On 6v batteries the test is the same but pass on any that drop below 6v after sitting for a day. There are actual battery capacity testers for this purpose but we're keeping it cheap and simple here.

How much battery capacity do you need?

Take the number of lights running, add their wattage, multiply by the number of hours they will be on, finally divide by 12 which is our system voltage. this will give us the amount of amps we will draw for one day of operation.

There's always that one battery question everybody getting into solar always asks... Can I use a car battery? Yes you can but car batteries have some shortcomings. They are intended for a quick massive draw from the starter motor and then immediately recharged. They don't work well for long discharge applications. Car and truck batteries are also what is referred to as a wet cell battery. They are filled with liquid acid so must remain upright at all times and emit fumes when charged. SLA's are much better suited for enclosed electronics boxes and indoor applications.

Step 3: Solar Panels, What's Going to Generate Your Power

Solar panels come in all shapes, sizes, ratings, and prices. You can spend a bunch of money but don't need to if you're an educated shopper. We're keeping it thrifty remember?

Amorphous Vs Silicon.

Amorphous solar panels (pic 1) are what's usually found in little solar powered yard lights and trinkets. The panels have a brownish look. This is a low cost technology that is the most inefficient (requires more panel to produce the same power when compared to silicon) and has a shorter lifespan. There are some discount tool vendors that sell solar kits made up from amorphous panels. They do have one benefit which is they perform better in "shaded" applications, cloudy days for example. Pass on these unless you got them for free or darn near free. The one benefit doesn't outweigh all the negatives.

Silicon panels (pic 2) have a blue look to them and that's what you want. Silicon solar cells can be made from mono or poly crystals. This results in a dark blue even color or a blue color that seems to be made up of slivers. Either one is fine for our needs. There is a difference in mono Vs poly crystal panels but for our purposes either one is fine. Mono crystal panels tend to produce more power per square inch but it's a minimal difference on the scale that we're working at.

So we're looking for silicon cell panels, what else do you need to physically look for?

Solar panels can be framed or unframed. They can be rigid or flexible. they can have a glass face or an epoxy sealed face. Aluminum framed, glass faced silicon panels have the longest lifespan. It's not uncommon for one to last 20+ years as long as it's not physically abused.

Unframed panels need to be framed to protect them and give you a way to mount them. Epoxy faced panels work well for a few years but the epoxy sealant will slowly begin to darken over time and diminish the panels output. Eventually the epoxy gets so dark, the panel is useless. Flexible panels are convenient for portable installations but have short lifespans due to the flexing of electrical contacts and the epoxy sealer they use to keep the whole assembly flexible. Glass faced aluminum framed silicon is the way to go.

Solar panels come in many different output variations. In order to keep it simple, stay with panels that have an open circuit voltage in the 17-20v range. These would be considered 12v system panels and will match up nicely with the ultra cheap regulators we'll be talking about later. Can you use panels with higher voltages? Yes but it will require a more expensive MPPT regulator. Can you use panels with lower open circuit voltages? Not without some electronics ingenuity that is simply not worth the effort. The exception is if you have multiples of the same panel and you connect them in series to raise their operating voltage. There's an additional electrical spec to worry about but we'll come back to that.

New or used?

New is obviously better as solar panel tech is improving constantly. A panel that was $4 per watt 20 years ago is now $1 or less a watt. Solar panels live outdoors, cook in the sun, get rained on, and depending where you live, freeze on a cold night. In short, they have a hard life. $100 shipped for a 100w glass faced silicon panel for a 12v system on ebay is not uncommon. For a two 10w LED light setup in a sunny place, 60w is about ideal. If you can afford new panels, go that route.

Going used?

There's a few things to look for. Skip the epoxy faced panels unless they are darn near free. The epoxy has a limited lifespan before it starts to darken and diminish the solar panel's output. If the epoxy sealant is visibly turning a honey color, it's on it's way out. These epoxy panels can be identified by simply digging your fingernail into the face of the panel. Epoxy panels will have some give, glass won't.

Amorphous panels are not worth getting used unless darn near free. Just like epoxy faced panels, they have a limited lifespan. As they age, the output will diminish. Expected useful lifespan for amorphous panels is about 7-10 years. With the prices coming down on silicon, the limitations of lowered output and decreased lifespan make amorphous panels almost not worth dealing with.

This leaves us with glass faced silicon panels. These are clearly the best option for any solar project. A well built glass faced aluminum framed silicon panel can easily last you 20 years. When buying these used skip any with glass damage. They may still produce but not for long. Bent aluminum frames can usually be fixed by disassembling the frame and straightening the rails. One other defect to look for on silicon panels is humidity damage. You can get humidity inside the solar panel assembly if it's seal has gone bad. This will look like a white haze over the solar cells (pic 3). While not an immediate killer, it will shorten the life of the panel and definitely lower it's output.

What about electrical testing of used panels? If your looking at panels of less than about 400w each you can do all your testing with a common multimeter. Your meter should be able to handle up to 10a of current (most do).

Place panel to be tested in direct sunlight. Set multimeter to DC voltage and measure output. If panel is in direct sunlight the voltage reading should be very close to the open circuit voltage on the manufacturers label located on the underside of the panel (pic 4). Next we will test current output. Set your meter to amps (some require moving leads) and test just like you did voltage. When a test meter is checking amps this places a dead short across whatever you're testing. This is a big no-no on most electronics but ok for testing solar panels providing your meter can handle the output of the panel. The amp reading you get should be close to the max amps rating on the panels label. If you get zero, check your meters internal fuse before condemning the panel. It's not uncommon for folks to accidentally blow those fuses and forget too change them.

Step 4: How Much Panel Capacity Do You Need?

Figuring out how much solar panel capacity you need isn't hard but you do need to know some data about how much of an electrical load you're going to run and how good the sunlight is in your area. Solar panels are typically rated in watts. This number is derived by multiplying the panel's operating voltage times it's current. This info is found on the label on the backside of the panel.

This instructable is intended to help folks set up a cheap lighting solution while keeping things simple. So far we've been sticking with 12v 10w LED bulbs as a load. This gives us an easy number to work with and those bulbs are cheap and easy to find online.

Calculating the long way...

On a dusk till dawn system we're looking for a operating time of about 10-12hrs every day for most places. This means our solar panels have to produce enough electricity to run the lights overnight and overcome any losses from charging. No system is 100% efficient.

(1) 10w bulb running for 12hrs = 120w of power consumption every night.

(2) 10w bulbs running for 12hrs = 240w of power consumption every night

So, if we want to run (2) 10w LED floodlights for 12hrs every night we need to produce 240w of power from our system. This number is in a perfect world though. No battery charging system is 100% efficient. Add to this you may have a cloudy day or a bird that decided to camp out on your panels. A good rule of thumb in sunny places is to consider that your system 80% efficient in a perfect world.

So our math tells us we need 240w of power for (2) 10w LED lights. Our system is 80% efficient at best so we need to come up with 300w per day to keep the battery charged enough to run our lights that evening. This is cutting it close though. One day of lousy weather and you have taken a big hit on how much power you put into your battery for the day. I prefer to have a bigger safety blanket and at least double the number of what I need to produce. So for (2) 10w LED lights running 12hrs I'd like to have 480w minimum of daily production. This looks like a big number but it really isn't as you will see.

Anywhere you go in the world, you can look up what an area's average solar insolation number is. This is the number of hours of good strong sunlight an area averages. Where I'm at, that magic number is 7.5. So knowing that number I can easily calculate what my panels will produce on a daily basis in clear weather.

30w panel multiplied by 7.5 = 225w of production from good strong sunlight. This is close enough to my target of 240w (120w x 2 safety margin) for a single 10w LED lamp to run 12hrs a day reliably.

Why am I calculating solely on the solar isolation number? This leaves me a little safety margin at the start and the end of the day where the solar panel is still producing something but it's not at peak output.

Solar capacity needed for dusk till dawn system = wattage of lamps multiplied times hours of operation and then doubled.

To calculate what a panel produces for the day find out solar insolation number and multiply that by panel's rated wattage.

There's lot's of variables here. Do your panels really produce what they claim? If your system more inefficient than typical? etc. This will get you in the ballpark.

Now the easy way based on my experiences in sunny South Florida...

30w of panel and 10Ah battery will run a 10w LED floodlight all night but you have no safety margin.

20w of panel and a 10Ah battery will run a 9w LED lamp all night but you have no safety margin.

To buy yourself some margin in case of overcast days double both the panel size and battery size. What happens if you don't produce enough electricity and don't have some safety margin in your setup? Simple, the lights go out till the next day when the battery can recharge. Of course, if you live somewhere that isn't as sunny as South Florida then my experience is meaningless to you and you'll have to revert to the insolation data and do the math.

A word about system reliability...

In order to keep costs and size down I've kept things to a scale that will be very reliable on sunny days and somewhat tolerant of a partially cloudy day. As I said before, no sun = no power. If you are absolutely in need of a setup that can handle a completely overcast day without leaving you in the dark, I suggest you multiply your battery and solar capacity by the number of cloudy days you expect to get through before the system has a chance to recharge. Don't forget to upgrade your regulator as well. A 10A charge controller (regulator) can only handle 120w of panel in a 12v system.

Step 5: Charge Controllers, What Regulates the Power From the Sun

Next to the solar panels themselves, the next biggest price drop in solar has been the cost of regulators. The regulator or charge controller is what takes the power coming from the panel and keeps it within a safe range to charge your battery with. Some charge controllers can also provide you with a low voltage disconnect (LVD) and the ability to automatically turn the lights on at dusk and back off at dawn.

In the not too distant past, a 15amp charge controller would easily set you back $50 or more. Granted these were high quality American made units. Like most everything else electronic, the Chinese have figured out how to make them dirt cheap and keep all the features. These cheap regulators are PWM technology which is not the most efficient but dirt cheap right now and more efficient than shunt type regulators.

Avoid older shunt type regulators as they can wreak havoc on electronics. The way they work is by connecting the panels directly to the battery and watching the voltage. Once it hits a predetermined value they shut off and wait for the battery voltage to drop again. This on/off up and down voltage swing can upset some electronics.

There's one more charge controller tech called MPPT which is the most efficient and has some benefits over the PWM type but they do cost more money, hence out of the scope of this instructable.

In pics 1, & 3-5) you see a few different options from China. These range from 10a to 20a and all cost me less than $10 ea shipped. They all have LVD and dusk till dawn light control ability. The trade off is cheaper construction but I haven't had any failures yet and am quite pleased with them.

What is the LVD?

The Low Voltage Disconnect is a circuit within the charge controller that detects when your batteries have run very low and disconnects the load (whatever is being powered) from the battery. This is important because running a lead acid battery dead will drastically shorten it's life. This is a failsafe to prevent battery damage. Once the battery is charged back up the LVD resets and everything works again.

What is the dusk till dawn feature?

This feature uses the solar panels as light sensors. If the panels aren't seeing light, they aren't producing power. If no power is being produced, this means it's dark and we should turn on the lights. That's how it works. In the case of a lighting system being used inside a cabin or shed for example, you'll want control of the light via a switch. The dusk till dawn feature can be bypassed via button programming on every single charge controller I have seen that has an LCD display of some sort. Some very basic charge controllers retain the LVD but do away with the dusk till dawn feature.

Resist the urge to bypass the LVD by connecting your lights straight to the battery. If your battery is run flat, it will ruin it.

My experience with the recent crop of Chinese charge controllers (regulators) is you connect the battery FIRST, then the panels, then the load. Some of these controllers can operate on 24v systems and connecting the battery first is what tells it that you are using a 12v or 24v system.

Charge controllers are rated in amps (pic 2) they can handle. A little overkill is not a big deal but for a basic light setup like we are building here, a 10A unit is plenty. A 20A unit is more than you'll need for a basic system like we're discussing here.

USB charging - added bonus!

Seems the latest trend in Chinese charge controllers is to provide you with a USB charge port for phones and such. For folks building a setup for use in a cabin or workshop this charge port can be a welcome addition.

Step 6: Lighting, Keeping It Cheap, Efficient, and Effective

When it comes to solar lighting projects, there's one way to go and that's LED!

LED tech has really been one of the best things to happen to off grid power. It's efficient, rugged, cheap, and there's a ton of options ranging from sterile bright white to bulbs that can change color via remote control. If it wasn't for LED bulbs, none of my setups would be worth doing.

In pic 1 you see my latest floodlight setup for the backyard. Those two lights are enough to illuminate a sizable portion of the yard yet only consume 20w of power. In pics 2 and 3 you can see what the fixtures look like when they aren't powered up. These particular fixtures are 10w warm white LED floodlamps for outdoor use. Cost? An unbelievable $39 for 10 of them shipped via Chinese ebay vendor at time of writing. They run off 12v making wiring a breeze since it's all low voltage.

In pic 4 you see another wonderful option for retrofitting conventional 110v fixtures. These are 12v LED Edison based bulbs. They screw into a regular fixture so you can re-purpose nice looking yard fixtures intended for 110v bulbs. The one pictured is a 9w warm white LED e27 base bulb. It's a whopping $1.50 shipped at time of writing via Chinese vendors on ebay. The catch with these is they fit regular sockets so you need to make sure they dont accidentally get put into a regular 110v lamp. if they do you will have a poof and some smoke for your $1.50 expense.

In pics 3-5 you see the e27 base bulb inside a regular fixture and a couple of shots of the fixture. I absolutely love these bulbs for yard lighting as they produce enough light to be useful but not annoying. Since they can fit any standard fixture, you can do like I did and grab some nice fixtures off the clearance table at the local home improvement store and use them with your solar setup without any mods. The same wiring that works for 110v can be used for 12v since the current draw is so minimal in our application.

One thing to consider with these bargain bulbs though is they are typically not weather proof. Whatever you put them in must shield the bulb from the environment. The exception is outdoor rated floodlights you see in pics 2-3.

As I mentioned before, these LED bulbs can be purchased in a multitude of colors. My preference for white light is warm white (aprox 3000k on the color temp scale) which closely matches the light from a conventional incandescent. The comforting warm white color comes at the expense of slightly reduced light output. Cold white bulbs (6000-7000k) produce a sterile bright white light and can achieve more lumens (light output) per watt but some folks find it annoying for anything other than task lighting. I'm one of those folks and have delegated all my cold white bulbs to places like the workshop or laundry room.

Remember LED bulbs are much more efficient at producing light than their old incandescent predecessors. A 10w LED floodlight can easily light up a 2 car driveway. The 9w bulbs I used in the outdoor fixtures do a great job of lighting the yard without being obnoxiously bright.

LED's are polarity sensitive. If your light doesn't work, flip around the wires to the lamp. I haven't seen any that get damaged by being connected backwards but most DC LED bulbs won't turn on if the polarity is incorrect. The rare exception is some 12V ac/dc bulbs that don't care about polarity.

Step 7: Protecting the Gear From the Enviroment

While your solar panel needs to be outdoors, your charge controller and battery need to be protected from the environment. The goal here is to keep it out of the weather and safe from critters. The charge controller can get warm during normal operation, this can attract bugs and reptiles. While SLA batteries are sealed, low priced charge controllers typically are not. Bug or reptile droppings can ruin the electronics if they get inside.

Plastic outdoor electrical boxes are easy to work with and fairly cheap. In pics 1-3 you see some of my choices for enclosures. In pic 1 I'm using a $10 plastic electrical junction box from Home Depot to house the regulator. The battery, which is sealed anyways is sitting on sheet metal shelf brackets. The battery is stuck to the shelf brackets using VHB tape which is a high grade double sided stick tape often used for automotive applications. The whole setup lives under an outdoor roof.

In pics 2-3 you see a setup I did to illuminate a 2 hanging light fixtures that are strung between 2 trees in the yard. The box is an outdoor rated plastic communications box like those used by cable companies on customer homes.

Plastic outdoor boxes are cheap and easy to work with but remember it is plastic. The sun will eventually win and the box will fail. If you're going to go this route check your enclosure every so often and make sure it's holding up to the weather. For the best in outdoor protection get an outdoor rated metal box but these can be pricey.

Step 8: Some Cost Effective Panel Mounting Options

Remember the goal here is to keep it cheap and useful. You can opt for more professional mounting options but these worked for me.

In the first pic you see my solar powered back yard light. The floodlamp is a 10w warm white LED like I pictured before. The panels are glued to the roof of the plastic shed using RTV silicone adhesive. The charge controller and battery are mounted inside the shed. This system survived hurricane Irma, pic 2 is an after Irma shot. The shed looked like a giant sat on it and someone threw a grenade in it after the storm but the solar light setup kept working. The fact that I had run long wood screws into all mating panels kept it from blowing away in pieces. I snapped all the plastic panels back together on the shed and reorganized all the stuff inside that got blown around. The solar setup was unscathed. The RTV'd panels didn't come off. The trick was to clean the surfaces to be bonded using denatured alcohol. Those panels are on tight.

In pic 3 you see my most recent addition in the quest to completely convert all my yard lighting to solar. What you see is a 55w panel supported on $10 shelf brackets from Lowes. The lamps used are the same 10w LED floods I used on the shed. The charge controller is mounted in a weather proof box and located under the wooden roof between the rafters along with the battery.

Pics 4 and 5 require a little more explanation. Hurricane Irma knocked over my two mango trees. They were successfully raised and held up by cribbing. Those wooden supports will be there for a while so I decided to mount another 55w panel and an outdoor box for the regulator and battery on them. This setup will eventually be moved to a more aesthetically pleasing location but for know its working fine. It powers two 9w LED bulbs in hanging lantern type fixtures which are suspended by stainless steel cable.

In pic 5 you see the setup I came up with to make the panel easily removable. On the wood plank that holds the panel there are two stainless steel eyelets like those used for boat bimini tops. The eyelets line up with holes in the panel frames. Dropping a pin top and bottom hold the panel in place. In case of a tropical storm or worse, I can pull 2 pins and quickly release the panel for safe storage.

Step 9: Some of My Finished Installs

These four systems are operational at my home at time of writing. They all use glass faced silicon panels, some of which are about 20 years old.

Pic 1 is a single 110v glass and metal lantern I repurposed as a 12v accent light. It hangs from a fancy looking shelf bracket. Inside is a 9w LED warm white bulb. The setup consists of a 20w panel, a used 12Ah SLA battery, and a Chinese 10A charge controller. it has been running reliably from disk till dawn since installed.

In pic 2 we have 2 of the 110v glass and metal lanterns repurposed as yard lights around my firepit area. Yep, I have an "interesting" back yard as most other self respecting tinkerers do so please forgive the mess! The lanterns are fitted with 9w warm white LED bulbs and suspended from a stainless steel cable across two trees. Tension on the cable is kept by repurposing a screen door spring and chain assembly (pic 3). The system charges from an old 55w panel via Morningstar charge controller and runs off a 10.5Ah SLA battery. This system has proven reliable so far from dusk till dawn.

In pic 4 is the latest system I have setup. It consists of (2) 10w LED warm white floodlights, a old 55w panel, Chinese 10A regulator, and a 20Ah battery. This system works great at lighting the backyard but with both floodlights on, I can't recoup a full charge the following day. The panel itself is damaged due to moisture intrusion and not putting out full power. I will likely replace that panel but for now it works flawlessly for a single floodlight. I did install a switch that lets me select single or double lamps.

Pic 5 was mentioned earlier. I needed lighting in the far back yard and decided to give solar a whirl. It was the inspiration to move forward with the other projects. This setup consists of a 10w warm white LED floodlamp, 10A Chinese regulator, 20Ah SLA battery, a 10w panel on one side and a 20w panel on the other. This setup has proven reliable from dusk till dawn. It's Achilles heel though is a tree that needs to be kept trimmed so it doesn't shade the panels. Shaded panels don't produce peak power.

I hope these builds inspire you to try going solar. With some basic calculations and frugal shopping, it can be both reliable and inexpensive.