Before you pick a solar panel for street lights, run three numbers, LED watts, hours per night and your worst-month peak sun hours, because they size everything else on the pole.
A solar panel for street lights should produce the LED's nightly watt-hours (Wh) within the worst month's peak sun hours, plus 20 to 30% for losses. Multiply LED watts by hours per night, divide by worst-month peak sun hours, then multiply by a typical loss factor of 1.2 to 1.3. Size the battery for a typical 2 to 5 nights of autonomy.
The sections below explain what the panel does on a street light, walk through panel and battery sizing step by step, and show when a 12 V or 24 V battery fits. They then compare a separate pole-top panel with an all-in-one head, line up panel specs in one table, cover installing the panel on the pole and answer common questions. LinkSolar supplies the panel side, stock or custom, plus pole mounts and brackets for street-light makers, integrators and contractors, including custom street-light panels built to a target Vmp, the panel's voltage at maximum power.
What does the solar panel on a street light actually do?
A solar street light panel is the photovoltaic panel that charges the light's battery by day through a charge controller, so the LED can run from stored energy at night. The panel never powers the LED after dark.
Every solar street light, in one housing or spread along the pole, has five parts:
- Solar panel: Rated in watts (W) and Vmp, the voltage at which it delivers maximum power, which has to suit the battery.
- Charge controller: The controller charges the battery by day, switches the LED on at dusk for dusk-to-dawn operation and cuts the load when battery voltage falls too low.
- Battery: The battery stores the night's energy, and its capacity in watt-hours (Wh) equals its voltage multiplied by its amp-hours (Ah).
- LED head: The head draws set watts for set hours, giving the nightly energy the system is sized around.
- Pole and bracket: The pole holds the head at height, and the bracket holds the panel at a fixed angle and direction toward the sun.
The LED head is the reason a modest panel can light a road. According to the U.S. Department of Energy, LED lighting is the most energy-efficient lighting technology, with efficacies up to 150 lumens per watt or more in some specialized products. LEDs also perform well in cold temperatures and can be dimmed, which lets a controller lower the load in the quiet hours after midnight.
The panel's task each day is to refill the watt-hours the LED used overnight. If it cannot do that in the shortest, cloudiest days of the year, the battery drains a little more each winter night until the light cuts out early. For solar lighting beyond roads, see this guide to sizing solar for signs and area fixtures.
How do you size the solar panel and battery for a street light?
A solar street light panel is sized from daily energy: LED watts multiplied by hours per night gives watt-hours per day (Wh/day), and the panel and the battery both follow from that one number and the site's worst month. Watt-hours measure the energy the LED draws across a night, so every later step divides or multiplies this figure.
The second input is sunlight. According to PVEducation, average daily insolation in kWh/m² per day is called peak sun hours, because peak solar radiation is 1 kW/m², so 8 kWh/m² per day equals 8 hours at 1 kW/m². Use the figure for the darkest month, since a street light has to run every night of the year.
- Daily energy: Multiply LED watts by hours per night, and use the controller's dimming profile if it dims after midnight or on motion sensing, because nameplate watts over a full night overstate Wh/day.
- Worst-month sun hours: Find the site's peak sun hours for its darkest month, typically around 2 to 5 depending on latitude and climate.
- Panel watts: Divide Wh/day by those sun hours, then multiply by a typical loss factor of 1.2 to 1.3 for controller, wiring, temperature and dirt losses.
- Autonomy nights: Choose how many nights the light must run with no recharge at all, typically 2 to 5 for street lighting.
- Battery watt-hours: Multiply Wh/day by autonomy nights and divide by the usable depth of discharge (DoD), the share of capacity you can draw, typically around 80% for lithium iron phosphate and around 50% for lead-acid.
- Amp-hours: Divide battery watt-hours (the daily watt-hours multiplied by the autonomy nights and adjusted for depth of discharge) by the battery voltage to get the Ah rating for the order.
Illustrative example: a 20 W LED running 12 hours uses 240 Wh/day. At 4 worst-month sun hours that is 60 W, and 60 W × 1.25 for losses gives 75 W, so a 100 W-class panel leaves margin. Round the result up to the next panel class, because winter recharge depends on that surplus.
For 3 nights of autonomy at 80% DoD, the battery needs 240 × 3 ÷ 0.8 = 900 Wh, which is around 75 Ah at 12 V or around 37.5 Ah at 24 V. These figures show the method and are not a product specification.
Leave headroom on both sides of the calculation. Add margin for wiring, controller and temperature losses on the panel, and if uptime matters through long cloudy spells, add battery reserve first, the same order used for panel and battery sized together for winter. To set the number of nights for your site, read the guide on choosing nights of battery autonomy.
Should a street light panel charge a 12 V or a 24 V battery?
A street light panel should have a Vmp matched to the battery voltage the light uses: a panel with Vmp around 18 V is the typical match for a 12 V battery, and a 24 V battery typically needs Vmp around 36 V or two 18 V-class panels wired in series (series wiring adds the voltages and keeps the current).
Vmp (maximum power voltage) is the voltage at which the panel delivers its rated watts. Voc (open-circuit voltage) is the panel's voltage with nothing connected, and it is the figure a controller input must tolerate. On the live LinkSolar flexible collection, the 100 W flexible panel lists Vmp 18.05 V and Voc 21.63 V at standard test conditions, a typical 12 V-class panel.
For the same watts, a 24 V battery carries half the current of a 12 V battery. Lower current means smaller losses in the cable, so larger heads and longer runs down the pole typically favor 24 V.
The charge controller sits between panel and battery and handles the voltage match; this guide covers how a panel charges a battery through a controller. MPPT helps in winter, in partial shade and with higher-voltage arrays, while a quality PWM controller can work on a simpler 12 V system (see when MPPT beats PWM on a small system).
Before the first connection, check these points against the controller's label:
- Array Voc: Confirm the panel or series string Voc stays below the controller's input voltage limit.
- Current limit: Check that the controller's rated charge current covers the panel's output current.
- Battery voltage and chemistry: Set the controller to the battery's nominal voltage and to lithium iron phosphate or lead-acid as fitted.
- Polarity: Verify panel and battery polarity with a meter before closing any connection.
- Cable size: Size the cable for the charge current and the full run length from the pole top to the battery.
- Charging profile: Match the controller's charging profile to the charge settings specified for the battery.
Separate panel on the pole or all-in-one light head: which format fits the project?
A separate panel on the pole suits street-light projects that need more panel than a light housing can carry or a tilt set for the site's latitude, while an all-in-one head suits lighter loads where one fixture per pole keeps installation quick. An all-in-one head, also sold as an integrated solar street light, puts the panel, battery, charge controller and LED in one housing. A split solar street light puts the panel on the pole top and the battery in a box or at the pole base.
The formats typically differ on four points.
- Panel size: The housing of an integrated head caps the panel size, while a split system sizes the panel to the load and the worst month.
- Panel angle: An integrated head usually fixes the panel angle, while a pole-top panel on an adjustable bracket is tilted for the site's latitude.
- Battery location: The integrated format carries the battery in the head, while the split format puts it in a box on the pole or at the pole base.
- Service access: A split system lets the panel, battery and controller be replaced one at a time, while an integrated head is typically serviced as one unit.
The usual separate panel is rigid framed glass monocrystalline, and the panels in LinkSolar's packaged remote systems list 21% or higher efficiency with an aluminum frame. Specify the junction box position, a cable length matched to the pole height, and the connector: MC4, bare tails or custom. Glass lamination fits where rigidity and lifetime matter more than weight, and brackets for framed panels on arms and posts cover the mounting side.
A flexible panel fits where weight on the arm is the limit. LinkSolar's lightweight flexible panels with published Vmp are frameless with an ETFE front and weigh roughly a fifth of a glass module of the same output: the 100 W panel weighs 1.0 kg and the 135 W panel 1.8 to 2.0 kg. Trade-offs are compared in flexible versus rigid panels outdoors.
Makers fitting a panel to their own housing or arm can specify a custom panel from 3 V to 48 V in any outline. Ask the supplier for the test report that covers the panel you order.
Specs to compare before you order a street light panel
A street light panel should be compared on rated power (rated W), Vmp and Voc against the battery and controller first, then on panel dimensions, weight and frame against the pole and bracket. The table lines up four panel options for a split solar street light, with live LinkSolar figures on the flexible rows and typical values on the rest.
| Panel option | Rated W | Vmp | Voc | Size | Weight | Frame and front | Best fit |
|---|---|---|---|---|---|---|---|
| Flexible 100 W | 100 W | 18.05 V | 21.63 V | 1247 × 418 mm | 1.0 kg | Frameless, ETFE, MC4 | Weight-limited arms, 12 V battery |
| Flexible 135 W | 135 W | About 19 to 20 V | About 26 to 30 V | 545 × 1180 to 1374 mm | 1.8 to 2.0 kg | Frameless, ETFE, MC4 | Larger heads where weight matters |
| Framed glass monocrystalline | To spec | Around 18 V (12 V) or around 36 V (24 V), typical | To spec | To spec | To spec | Aluminum frame, glass front, ≥21% efficiency on the packaged systems | Standard pole-top panel |
| Custom panel | To the load | Set by cell count, 3 V to 48 V range | To spec | Any outline | To spec | Glass-laminated, ETFE, PET or fiberglass | Fixture makers fitting a housing or arm |
Once a row fits the load, choose from pole mounts matched to pole diameter and panel size so the bracket carries the outline and weight you picked.
Flexible figures are at STC, the standard test conditions of 1000 W/m² light, AM1.5 spectrum and a 25 °C cell; rigid figures are typical until specified. Read the columns this way:
- Rated W: The output at STC, which should meet or exceed the panel W from your Wh/day, sun hours and loss factor.
- Vmp: The voltage at maximum power, which must sit around 18 V for a 12 V battery or around 36 V for a 24 V battery.
- Voc: The voltage with nothing connected, which, added across panels in series, must stay under the controller's input limit.
- Size: The outline that has to fit the bracket's mounting range and clear the LED head.
- Weight: The load the arm and clamps carry, which matters more on tall or exposed poles.
- Frame and front: Glass with an aluminum frame gives rigidity, while an ETFE front on a frameless laminate saves weight.
- Best fit: A starting point to confirm against your own load and pole.
The price of a solar panel for a street light follows four inputs: rated W, framed glass or flexible build, the cable and connector specification, and the order quantity.
Installing the panel on a solar street light pole
Installing the panel on a solar street light pole means fixing an adjustable pole bracket, tilting the panel toward the equator, keeping it clear of the LED head's shadow and running the cable down the pole to the controller and battery. Pole erection, footings and lifting work are covered in the pole and footing installation steps.
- Measure the pole: Record the pole's outside diameter rather than the nominal pipe size, because a universal pole kit covers 50.8 mm to 114.3 mm (2.0 to 4.5 in) while a 30 W to 60 W bracket fits 2 in poles.
- Choose the bracket: Match the bracket to the panel's rated W, its frame and its dimension across the mounting axis, since the wrong clamp style lets the panel rotate, drift out of alignment and loosen.
- Set the tilt angle and azimuth: Turn the bracket around the pole so the panel faces the equator (the azimuth), then set the tilt angle at roughly latitude plus 15° for a light sized on the worst month, a little steeper where snow needs to slide off.
- Clear the head's shadow: Mount the panel at the pole top above the LED head and its arm, so neither casts a moving shade line across the cells on short winter days.
- Route the cable: Run UV-resistant cable from the junction box down the pole to the controller and battery box, with no sharp bend near the frame and a service loop secured to the pole.
- Torque-mark the clamps: Tighten each clamp, mark the fastener with a paint line as a torque mark, and check tightness again after installation and after the first wind exposure.
The tilt step carries the most energy, because according to PVEducation the power density on a module is at its maximum when the module is perpendicular to the sun. A pole-top bracket has no roof pitch to follow, so the angle can be set for the low winter sun when the battery is under the most strain.
Wind is the site-specific part of the job. A mount that holds in a sheltered backyard may fail on an exposed roadside, and wind load matters more as panel size increases, so choose the bracket for the panel and the site together. Browse adjustable pole brackets for the panel by pole diameter and panel size.
Solar street light installation cost is set per pole more than per panel. Pole height and the need for lifting equipment set the crew time at each pole, and the bracket type affects fitting and alignment time. A new pole with a new footing adds civil work that a reused pole avoids.
FAQ: solar panels for street lights
What size solar panel does a street light need?
A street light needs a solar panel rated for the LED's nightly watt-hours divided by the worst-month peak sun hours, then raised by a loss factor of around 1.2 to 1.3. Step 3 of the sizing method in this guide works through the numbers.
Can one solar panel run an LED street light all night?
One solar panel can run an LED street light all night when it refills the nightly watt-hours in the worst month and the battery holds it until dawn. The panel produces nothing in the dark, as covered in what a panel does after dusk. A controller that dims the LED after midnight or on motion sensing lowers that load.
How many days of autonomy should a solar street light have?
A solar street light typically carries 2 to 5 nights of autonomy, the number of nights the battery runs the LED with no charge from the panel. Cloudy climates and critical roads need the upper end. If uptime matters through long cloudy spells, add battery reserve before adding panel watts.
What voltage do street light solar panels use?
Street light solar panels typically have a Vmp, the voltage at maximum power, of around 18 V for a 12 V battery and around 36 V for a 24 V battery. A 24 V system can also use two 18 V-class panels in series. Custom panels span 3 V to 48 V, with the cell count set by the target Vmp.
How is a solar street light installed?
A solar street light panel is installed on an adjustable bracket sized to the pole's outside diameter, tilted toward the equator and placed above the LED head, clear of its shadow. The cable runs down the pole with a service loop to the controller and battery box. Recheck the clamps after installation and after the first windy spell.
Next step
Size from the worst month and the battery voltage first, then pick the panel format and the bracket.
Send the LED W, hours per night, autonomy nights, site latitude, battery voltage, pole diameter and quantity, and LinkSolar returns a matched panel and bracket specification. To request a quote, use panel quotes for street-light projects.
Related resources
- Bracket materials: Read about aluminum bracket alloys and finishes for pole and arm mounts.
- Other pole loads: See power design for a pole-mounted camera for the same method on another load.