Solar street lights are a practical and convenient solution to replace old public lighting, and they are the future of public lighting. Solar street lights reduce costs in the long run, require low maintenance, can be installed in areas with no electrical infrastructure, and deliver many other benefits.
Knowing how solar street lights work and compare to traditional public lights, is key to understanding the benefits of this technology. In this article, we cover the basics for each type of street light, compare them to consider the benefits of solar street lights, and we even give you some key tips to choose the best solar street light for your project.
Basics #1: What is a traditional street light?
Traditional street lights are grid-connected sources of lighting that use fossil fuel power. These have been the norm since the 19th century when the light bulb was first discovered, and they usually operate at 120-240 volts for most models.
Traditional public lights have experienced modifications to the shape of their poles, the inclusion of electronic controllers, and even different fixture technologies, going from High-Pressure Sodium (HPS) to LED. Traditional street lights are composed of the post, the fixture that emits the light, and the lens magnifying the effect of the fixture.
Basics #2: What is a solar street light?
Solar street lights are regularly replacing traditional street lighting systems. Here we explain the basics of these modern public lighting systems.
What are the components of a solar street light?
Solar street lights are composed of the following components:
The solar panel is the main component of solar-powered street lights. This is a small photovoltaic (PV) module with the right size to charge the battery, powering the street light with an autonomy of nearly 3-4 days.
The Energy Management System (EMS), manages battery charging with the solar panels and the energy flow supply of the fixture with the batteries. Some models include EMS with motion sensors, timers, or different control systems.
The lighting fixture is commonly referred to as the bulb. To make better usage of solar energy, solar street lights use LED technology, because they are 68% more efficient than HPS fixtures.
The energy produced from solar panels is stored in the batteries, and later on at night, is used by lighting fixtures, to illuminate public areas. For precaution and considering rainy days, the battery is usually designed to last for 3-4 days with one charge.
The pole is where all the components are held in place. Solar panels are installed at the top of the pole, then the EMS and battery are generally installed at the bottom on a box underground, and finally the lighting fixture. The overall height of the pole might vary between 9-50 feet, depending on the need for the installation.
What are the different types of solar street lights?
Currently, there are three types of solar street lights. These are the following:
All in Two Solar Street Light
All in two solar street lights, have the battery and LED fixture integrated, while the solar panel is separated from them.
Split Solar Street Light
Split solar street light is a more simple option, where all components are separated at a certain distance from each other. The solar panel is installed at the top of the pole, the LED fixture extends around 3 ft. from the pole, while the battery is installed at the pole or placed underground.
All in One Solar Street Light
The all-in-one solar street light has every component combined into one simple and fully integrated design. This solar street light is simple and practical, but it has the downside: the angle for the solar panel cannot be adjusted.
How to install solar-powered street lights?
Installing a solar-powered street light is much easier than traditional models. Here is a simple installation guide to help you set a public solar lighting system in place.
Step 1: Plan ahead, use safety gear and clear the area
First, you should plan the site, ensuring that the solar street light gets enough sunlight during the day without the panels being shaded. You should also remember to wear safety gear, gather necessary tools in one place, and set a working perimeter of at least 250 sq. ft., to avoid unnecessary accidents with passersby.
Step 2: Prepare the foundation for the pole
Prepare the foundation for the pole by digging a 35 cu. ft. with a 2 ft. depth. Here you will install the steel cage working as an anchor for the solar street light, leaving the metal bolts outside. Some solar-powered street lights require extra underground space for batteries.
Step 3: Wire and test LED fixture and solar panels
Before setting the pole in place, do the wiring for the LED fixture and solar panel. Every wire should meet where the solar controller will be installed. Finally, put the fixture and panel in place with bolts or the designed mechanism by the manufacturer, before setting the pole in place.
Step 4: Set the pole in place and Install the solar controller
Setting the pole in place should be relatively easy, these structures are relatively light, but to be cautious, look for help for this step. After this is done, connect every wire to the solar controller and configure it properly.
Step 5: Test the solar street light
Before filling every hole with concrete and performing finishing touches, test the solar streetlight for at least 48 hours. If everything is working according to plan, close everything up and finish the installation.
What are the benefits of solar street lights? (When compared to traditional lights)
Solar street lights have many benefits, here are some important ones:
Relatively longer lifespan for most components
LED traditional street lights have an average lifespan of 15 years, or less if they are using HSP technology. Solar-powered street lights tend to have a longer lifespan of around 15 to 30 years for most components like LED fixtures and solar panels. The only component requiring changing before that time is the battery, which has a 10-year average lifespan.
Low installation cost (does not require an electrical infrastructure)
Installing a traditional public lighting system requires a dedicated step-down AC to AC transformer if there is not a previous electrical connection. Traditional lighting systems also require wiring for grid connections, generating another cost.
Installing solar street lights is much cheaper since it does not require grid connections, having the extra advantage of being able to be installed virtually anywhere. The major cost for solar LED Street lights is the price for components and materials to install the pole.
Reduced overall cost during its lifetime
While the upfront investment for all-in-one solar street lights tends to be twice the cost of traditional models, the electricity consumed by traditional options during their lifetime, makes them more expensive in the long run.
A traditional street light costs on average $8,000 during 10 years. This considers costs for components, installation, maintenance, and electricity bills. During the 15-year lifespan, traditional lampposts cost around $12,000. Solar street lights with motion sensors or different models, only cost around $5,000-$6,000 for that same period, making them cheaper and more cost-efficient.
Great overall performance
Traditional street lights have several limitations, but the main one is the requirement for electrical infrastructure. These public lighting systems also cannot emit light during blackouts, making them less than ideal for emergencies. The performance time for street lights depends mainly on the electricity from the grid.
All-in-one solar street lights do not require grid connection, which is why their performance relies entirely on the installed components. Since these lighting systems are designed to deliver power for 3-4 days with one battery charge, they will provide light during blackouts and unfavorable weather.
The U.S. government has many solar incentives to promote solar technology. States like California, have different incentives providing rebates and tax credit returns for solar street light investors. Due to these incentives, the price for components and installation of solar street lights can be highly reduced. Check out the programs available by state, to know more about solar street light incentives for you.
Buying solar street lights for your project
Here are some key tips to help you choose the best solar street light for you.
The lumen is the level of brightness you will get from a LED fixture. Depending on how much light you require for a certain area, consider the number of lumens for your solar LED street light. Most public areas require 20 to 50 lumens every 10 sq. ft. For a 100 sq. ft. area, you might need 200-500 lumens.
When sizing a solar panel for your solar-powered street light, you need to consider the solar radiation in your state. This radiation is measured in kWh/m2/day, with this number being equivalent to the number of hours the panel will generate power at full capacity. Check out the irradiance maps at NREL for specific radiation in your state.
Most solar LED street lights are designed to last 4 days with a single battery charge. Considering this oversized parameter will help you prepare for extremely bad weather when the panel is not producing for a day or two. If the area is not highly transited, consider a solar street light with a motion sensor, which saves battery by reducing light usage on the street light.
The durability is a key element for a solar street light. Some components like the solar panel and pole can last for 30 years to a lifetime, while the battery lasts for around 10 years. Consider performing regular checkups of the streetlight and cleaning the panels at least once a year, to ensure a longer lifespan for the solar street light.