There are many aspects that can impact the performance of a solar flood light which you need to consider before making a purchase. From solar panels to casings, bulbs and batteries, there are lots of options to choose from, that’s why we have made this guide to clear things up and help you make the right decision when purchasing a solar flood light. You can use the table of contents below to quickly navigate to a certain section.
Why solar flood lights?
When looking for an outdoor flood light, you might be facing a choice – whether to install a regular, wired flood light or go for the solar option. Some time ago, the decision was easy – install a wired flood light, as there were very few reliable solar lights on the market. But now the situation has changed a lot due to the growing popularity of solar panels and renewable energy and you might find that electronics stores and internet shops even offer more solar flood lights than regular fixtures.
So why should you choose solar flood lights instead of regular, wired outdoor flood lights?
- More options where to install the lighting. Solar flood lights run purely on energy collected from the sun using a solar panel, so it can be installed practically anywhere where the sun can reach the panel.
- Free energy. This one is pretty obvious as solar energy is free for everyone. Solar lights will definitely reduce your electricity bills because you won’t need to pay for electricity to run solar lighting.
- Fast and easy installation. Because solar lighting usually consists of two (lighting fixture and solar panel) or three (lighting fixture, separate motion sensor, solar panel) parts that all are connected with a single cable, installation of these lights is super easy and takes a little time.
- Less hassle to reinstall the light in other places. Based on the previous point, it is also easy to reinstall solar lighting in another place because the lighting isn’t attached to the grid.
- Use renewable/green energy. Using renewable energy not only helps you save some money in the long run but also is good for the environment.
- Lots of different options to choose from. Solar lighting product range has grown rapidly in the previous years, and now you can choose from small solar accent lights, motion-activated security lights, and landscape lights, to powerful solutions for large areas such as sports stadiums.
What you need to look for when purchasing solar flood lights?
Solar panel is one of the key parts of a solar flood light, it collects solar energy, converts it into electricity and stores into a battery to power a flood light.
- Types. Basically, there are three types of solar panels used for solar lighting – monocrystalline solar panels, polycrystalline solar panels and amorphous (thin-film) solar panels. Monocrystalline panels are considered the most effective, with their cell efficiency (how much solar energy can be collected and converted into electricity) ranging from 15-21%, but they are also the most expensive ones. You will see monocrystalline solar panels mostly used in powerful solar flood lights. Polycrystalline panels also provide good cell efficiency up to 16% but are cheaper to manufacture. Polycrystalline panels usually have solar cells in a dark blue color which makes it easy to differ these panels from others. Both monocrystalline and polycrystalline panels are also used on large solar systems to provide electricity to houses and commercial buildings because of their high cell efficiency and these panels are also used in more powerful solar lights. Amorphous panels provide the lowest efficiency of 10% and below and are mostly used to charge different low power electronic devices. You will find these types of solar panels in cheaper, lower power solar lights. All in all, if you are buying a lower power solar flood light for less than $100 to illuminate your front door or driveway, you shouldn’t worry much about which type of solar panel is used on the light. Because these panels come in a very small size (when compared to ones used to provide electricity for entire buildings), difference in their efficiency practically won’t be noticeable. If, however, you are investing in a powerful flood light that will produce thousands of lumens of light, I would suggest getting a light with either a monocrystalline or a polycrystalline solar panel.
- Wattage. One of the most important measurements of a solar panel is wattage. It shows how much power the panel produces in ideal conditions, for example, a 10-watt solar panel will output 10 watt-hours of electricity every hour. The more powerful the lighting is, the higher wattage panel will be required to power the lighting. For example, lower power lights that produce a few hundred lumens of light can be run by a 1 to 5-watt solar panels, while larger lights will require 10-20 watt solar panels. Most of the time, larger solar panels will produce more wattage, because there simply is more surface area on the panel to collect the sun’s energy. You will sometimes see that high power outdoor flood lights are equipped not just with one, but with two or more solar panels to be able to produce enough energy to recharge their high capacity batteries.
- Size. As mentioned above, the size of the solar panel will depend on how powerful the light is and from what material the panel is made of. Monocrystalline solar panel can produce the same amount of power from a smaller panel than a thin-film solar panel. Before purchasing a solar lighting you should consider not only if the area you wish to install the light has enough sunlight during the day, but also if there is enough physical area to install the solar panel if you are going for a high power flood light.
Fixture & Casings
Outdoor flood lights must be properly weather-proofed to withstand any conditions all year round.
- Build materials. Flood light casings are usually made from two materials – plastic or aluminum. The majority of high power flood lights have aluminum casings to maximize the protection of inner parts of the light against any outer impacts that could damage the light. Plastic casings, however, are used on cheaper flood lights to cut down the price. But plastic doesn’t always indicate lower quality, because most manufacturers make their lights with really durable plastics housings that not only protect the light from impacts and water damage but also are pretty tolerable against high and low temperatures. And don’t think that you have found a great deal if you see a low priced solar flood light with an aluminum casing because these lights usually have poor water-proofing which means that the light can get damaged in a heavier downpour.
- IP ratings. Probably the most important specification you need to watch for when considering the durability of the fixture is IP rating (Ingress Protection). IP rating shows how much protection the fixture has against contact with solid elements (such as dust) and water. IP rating consists of two numbers, for example, IP65, where the first number indicates the level of protection against solid objects and the second – against liquid damage. There are 6 levels of solid protection (1 meaning lower protection and 6 high) and 8 levels of liquid protection. You can read more about IP ratings here.The most important thing to note here is that different parts of the flood light may have different IP ratings. For example, a fixture itself may have as high as IP66 or even IP68 rating, while the solar panel or the motion sensor might have just an IP44 rating, which means a much lower level of protection against solid and liquid damage. Generally speaking, the more parts a flood light has, the lower the IP rating is going to be, that’s why you will practically never see a motion-activated solar flood light with the maximum IP68 rating. Most solar flood lights with motion detectors have IP ratings from IP44 – IP64 which offer a pretty good level of protection against solid (dust) and liquid (rain) damage. These lights are good in areas with mostly calm weather conditions with occasional downpours and higher winds. Majority of higher end dusk to dawn solar flood lights will have an IP65 rating, which means that all parts of the light are fully dust protected and can withstand water jets projected by a nozzle. In other words, this means that the light can be used outdoors practically in any weather conditions all year round.
- Mounting hardware. There are different types of solar flood lights from wall mountable units to ground-mounted and pole mounted lights. Check out if the flood light you want to purchase comes with the correct mount for the area you want to install the light. Some manufacturers provide an option to purchase various types of mounting hardwares for the fixture separately.
- Cable lengths. Another common thing to check is the cable lengths of the fixture, and by cable length, I mean the length of the cable that connects the solar panel to the fixture. Consider the area where you will install the lighting and if the supplied cable length will be long enough. Of course, you can always purchase an extension cable, however, be careful with these, because longer cables can impact the performance of the solar panel.
Bulbs, Brightness & Power
The main function of solar lighting is to illuminate a certain area at night and depending on the size of this area, you should choose appropriate light with enough power and brightness.
- Bulb types. The part of a solar flood light that is directly responsible for illumination is light bulb. There are various types of bulbs used in regular, wired outdoor flood lights – from halogen and CFL, to HID (high intensity discharge) and LED bulbs (diodes).In solar powered flood lights, however, the situation is a bit different. If you have ever looked at solar flood light stand in a shop, you must have noticed that almost every solar fixture is equipped with a LED bulb and there is a good reason for that. LEDs are the perfect type of bulbs for solar lighting because:
- They are the most energy efficient, meaning that they will produce most light consuming less energy which is perfect for solar and other battery powered lights;
- Diodes are a lot more durable than other types of bulbs with glass envelopes, which is great for outdoor lighting;
- LEDs have a very long lifespan up to 50000 hours, which means that they will run maintenance free during all life span of the fixture;
- LEDs have small form factor, allowing to produce more compact fixtures.
Will a flood light with more LED diodes always be brighter than one with less diodes?
Manufacturers of solar flood lights often don’t specify how many lumens or lux a lamp produces, but they often list how many LEDs a fixture has, so one may think that a fixture with more LEDs will output more light than a fixture with less LEDs. In reality, this isn’t always the case. Of course, if we take two completely identical solar lights and one has 60 LEDs and other has 80 LEDs, the one with 80 LEDs will be brighter, but because each manufacturer uses different components for their lamps including LED diodes (the efficiency of these diodes can vary) and all these components can impact how bright the fixture is going to be, you cannot completely judge the brightness of the flood light just by the number of LED diodes it has.
Moreover, there are many other characteristics of a fixture that impacts its brightness, such as the color temperature and color rendering index of bulbs, light spread, angle and direction and many other specifics.
- Lumens and Watts. Lumen is a measurement of light output of a fixture and it can be used as an indicator of how bright a lighting fixture is going to be. Watts measure the work done by electricity in a second, for example, 100W of energy would light a 100W lamp for one hour. When considering how bright a solar flood light is going to be, it is more important to look at the lumen rating of the fixture rather than the wattage, because if we take two 10W solar lights one with LED diodes and other with Halogen bulb (LEDs are 3x more efficient), they will consume the same amount of energy but one with LEDs will produce significantly more lumens (will be a lot brighter). An important thing to note is that a special equipment is required to precisely measure the lumen output of a lamp, so often these lumen ratings listed by manufacturers are not exactly precise, especially for solar lights by less known and reliable brands. When talking about solar lighting, the lumen rating starts at about 100 lumens for smaller, all in one fixture accent lights, to about 300-600 for most motion activated solar flood lights and up to 1000-3000 thousand and more lumens for high power outdoor solar flood lights. On average, the lumen rating of solar powered flood light is going to be 300 – 800 lumens.
- Color temperature. Color temperature describes a color appearance produced by a lamp, or in other words, the color of light produced by a lamp. It is measured in Kelvins (K). Color temperature is more important in indoor lighting, as it helps to set the mood of a living room, bedroom or office by choosing bulbs with certain color temperatures. Bulbs with lower color temperature will produce warmer, more orange looking color (like a candle, or an incandescent bulb) and bulbs with higher color temperature will produce cooler, bluish color (daylight CFL bulbs or LED diodes).
Sensors, such as motion detectors and photosensors, have a significant role in solar lighting, as they help to conserve battery and switch the light on only when it’s necessary.
- Motion sensors. A motion sensor is responsible for detecting motion in a certain range around the flood light and turning the light on when motion has been detected. Three of the most common motion detector types are active sensors (detects motion by sending microwaves and monitoring changes in wave response time), passive infrared sensors or PIR (detects motion by scanning infrared heat changes in the monitored area) and combined sensors. Practically all motion activated solar lights will use PIR sensors to detect motion, because they are easily adjustable and don’t pick up motion of random objects such as tree branches or windblown objects which is a common situation outdoors.
- Adjustable PIR sensors. If you need a security flood light, an adjustable motion sensor is a must-have feature to look for. Most motion activated solar flood lights will allow to adjust various specifications of a PIR sensor such as detection range and distance, delay time and light sensitivity. Range and distance setting determines the angle in which the motion can be detected, most motion sensors allow to detect motion in a 180-degree angle around the sensor, while some special sensors can pick up motion even 360 degrees around. Distance allows to adjust how far away the detector can pick up motion. Delay or detection time setting determines the amount of time a light will be illuminated after motion has been detected. The light sensitivity setting determines the level of darkness required for the sensor to start picking motion. This setting allows to control if the sensor will work also during the daytime, at dusk or only at night when its dark outside. Most solar flood lights have motion sensors that can pick motion in a 120-180 degree wide-angle and in about 15-40 feet long distances.
- Dusk to dawn (photosensor). Photosensor or dusk-to-dawn sensor is a must have feature in every solar flood light. It detects when it gets darker outside and automatically turns the light on at a certain level or darkness and in opposite, turns the light off in the morning when it is bright outside, so it doesn’t waist battery illuminating during the daytime. Without this sensor you would need to manually turn the light on when it gets dark and off in the morning. How to know if a solar flood light is equipped with such sensor? If the description of the light says that it is a “dusk-to-dawn light” or “automatically turns on at night”, you can be sure that it is equipped with a photosensor. I would advise to stay away from any solar flood light that doesn’t have either a motion sensor or a photosensor because that flood light would simply waste energy by illuminating during the day or you would have to turn it on and off manually, which practically eliminates the purpose of solar lighting.
Because solar panels cannot collect energy at night, they store energy during the day into rechargeable batteries to power the light during the night.
- Types. You will find 4 different type of rechargeable batteries used to power solar flood lights – li-phosphate (LiFePO4), lead acid, nickel-metal hydride (Ni-MH) and nickel-cadmium (Ni-Cd). Cheaper, lower power solar lights are powered by either Ni-Cd or Ni-MH batteries in standard AA or AAA battery size. These batteries are small, light, cheap and easy to replace, perfect for low power solar lighting. If choosing between a light with Ni-Cd or Ni-MH battery, the Ni-MH one provides numerous advantages over Ni-Cd such as higher capacity and longer work time with one charge, which is very useful for solar lighting. The only type of battery that has more capacity based on weight than Ni-MH is Lithium-ion battery, which also costs more. While you will find Ni-Cd batteries practically only in low power solar lights, Ni-MH batteries are used in much wider range, including some higher power solar security lights. On the other hand, high power solar flood lights are powered either by lithium-ion (usually by lithium iron phosphate which has the most advantages for solar lighting from all lithium-ion batteries) or lead acid batteries. Li-phosphate (LiFePO4) is much more popular battery for wide range of solar flood lights than lead acid battery, because it has very high specific energy, meaning that batteries can carry more energy while keeping the size and weight smaller, decent cycle life of up to 2000 cycles and they run completely maintenance-free. The only real disadvantage of these batteries is high manufacturing cost, although lithium-ion batteries are getting cheaper for some time now. Lead acid batteries (best known for being used as car batteries) are also a common rechargeable battery option for high power solar flood lights. While you will see li-phosphate batteries used in practically all range of solar lights from small front door lights to powerful outdoor flood lights, lead acid batteries are only used for really high power lighting. In opposite to li-phosphate, they have very low energy density, so the battery must be made a lot bigger and heavier to provide the same capacity as other rechargeable batteries. The main advantage of lead acid batteries is their cheap price, which helps to cut down the total cost of a solar lighting fixture. In solar and portable lighting special valve-regulated Gell Cell and AGM lead acid batteries are used, because they can run practically maintenance-free during their lifetime.
- Capacity. Rechargeable battery capacity shows the maximum amount of energy that can be stored in the battery and is measured in ampere-hour (Ah) or milliampere-hour (mAh). Generally, the more Ah a battery has, the longer it can run. On average, Ni-Cd batteries have the smallest capacities for solar lights – approx. 600 mAh, followed by Ni-MH batteries with 2000 mAh. Lithium-ion batteries come in wide range of capacities for solar lights, starting from 2000 mAh up to 6000 mAh. Lead acid batteries, as previously mentioned, are only used for high power lighting, so they require higher capacity batteries to power the fixture. Usually lead acid batteries come in capacities from 4000 mAh up to 7000 mAh. Battery capacity alone won’t tell you how long the light can be powered using just the battery (factors such as brightness, solar panel wattage, presence of motion sensor and other factors are also important), but it can give you a more in-depth information about the overall quality of the lamp. If you are looking at a high power solar flood light which it is equipped with a small capacity (less than 2000 mAh) Ni-MH or li-ion battery, better look at other models, because this fixture won’t be able to store enough charge during the day to provide illumination from dusk to dawn. To increase the illumination time solar lights are equipped with motion sensors that turn the light on for a given interval (usually up to few minutes) when motion is detected in front of the light and after the preset period the light is turned off which helps to conserve energy and provide illumination only when it’s needed. Sometimes manufacturers even list the “provided illumination time” for the fixture or “how many times the light can be triggered with full charge” for motion-activated flood lights.