Last updated: 2026-11-04
A solar panel for a GPS tracker is sized from daily energy use: panel watts equal daily watt-hours divided by peak sun hours and a loss factor. On the example assumptions in this guide, an hourly reporter needs about 0.04 W and a five-minute reporter about 0.40 W.
A buyer sends a reference drawing for a trailer tracker, and the panel in it is much larger than the tracker needs. The tracker inside wakes up, sends a position, and sleeps again, so most of that panel area would never be used. Choosing a solar panel for a GPS tracker starts with the daily energy the tracker consumes, then moves to voltage, shape and the paperwork around repeat orders.
How much solar a GPS tracker actually needs
A GPS tracker needs a panel whose daily energy output covers the daily energy of its sleep current plus its reporting bursts, and for most reporting patterns that is well under one watt. A peak sun hour is one hour of sunlight at 1,000 W/m2, so peak sun hours equal the daily insolation in kWh/m2.
The formula has three steps. Daily battery use in mAh is the sleep current times 24 hours plus the burst current times burst seconds, divided by 3,600, times the number of reports. Multiply by battery voltage and divide by 1,000 to get watt-hours, then divide by peak sun hours and a system factor that covers charger loss, panel angle and dirt to get panel watts.
The inputs below are example assumptions, not data from any real tracker: a 3.7 V battery, a sleep current of 0.1 mA, a report burst of 100 mA for 20 seconds, 3 peak sun hours and a system factor of 0.5. One report then costs 0.556 mAh and the sleep current costs 2.4 mAh per day. No market figure for tracker consumption is given here, so replace each assumption with the datasheet value of your own tracker.
| Reporting pattern | Reports per day | Battery use (mAh/day) | Energy (Wh/day) | Panel needed (W) |
|---|---|---|---|---|
| Once a day | 1 | 3.0 | 0.011 | 0.007 |
| Hourly | 24 | 15.7 | 0.058 | 0.039 |
| Every 5 minutes | 288 | 162.4 | 0.601 | 0.40 |
On one past project, a trailer tracker buyer sent a reference panel much larger than the load needed. The pattern is common: average consumption is low, so measure the mounting space first, then send the voltage and current your charge circuit expects. A sustained load is the exception, because then usable area, not price, limits the design, and the sizing must use the worst-weather daily use and local sunlight.
Match panel voltage to the tracker battery and charge circuit
The panel voltage must fit the input window of the tracker charge circuit, because the panel specification follows the tracker electronics and not the other way round. Read the charger datasheet for its minimum and maximum input voltage before you choose a panel.
A single crystalline silicon cell produces roughly half a volt (the mini solar cell guide covers how cell size sets current and voltage), so one large cell has plenty of current but too little voltage for a charger. Series strings of smaller cells reach the window: at about 0.5 V per cell, a 5 V module needs roughly ten cells and a 12 V module roughly twenty-four. A single lithium-ion cell charges to 4.2 V, so a 5 V panel is the usual feed for a small tracker with that battery.
The panel also needs a charge-control stage. A solar module generates power in sunlight and does not store energy, so a rechargeable battery needs a suitable charge-control circuit between the two. The comparison in MPPT vs PWM for mini panels shows when a simple linear or PWM stage is enough at these power levels.
- Write down the charger input window and the battery full-charge voltage.
- Choose a panel working voltage inside that window.
- Convert the daily watt-hours from the sizing step into panel watts.
- Divide panel watts by working voltage to get the current the charger must accept.
- Check polarity and wiring before the first connection.
The wiring side is covered in how to connect mini solar panels. The listed mini panels show how the numbers line up.
| Listed module | Working voltage | Output current | Footprint | Connection |
|---|---|---|---|---|
| 0.25 W polycrystalline, epoxy coated | 5 V | 0 to 50 mA | 30 x 60 x 3 mm | Rear solder pads |
| 1.2 W polycrystalline, epoxy coated | 5 V | 0 to 240 mA | 100 x 100 x 3 mm | 12 to 15 cm red and black leads |
| 4.2 W polycrystalline, PET laminate | 12 V | 0 to 350 mA | 200 x 130 mm | Rear solder pads |
Against the worked example, the 0.25 W module covers the once-a-day and hourly patterns, and the 1.2 W module covers the five-minute pattern with margin. The 12 V module suits a tracker whose charger takes a 12 V input.
Which panel shape and surface suit vehicle, trailer, asset and animal trackers
The best panel shape follows the mounting surface: a rigid small panel for a flat vehicle or asset housing, a flexible panel for a curved trailer or container, and a narrow thin-film strip for an animal collar. Compare the options by footprint, flexibility, surface and the voltage they deliver.
For a vehicle or asset tracker with a flat face, a rigid epoxy-coated or PET-laminated module is the simplest choice, and the footprints in the table above show the range from a 30 x 60 mm strip to a 200 x 130 mm module. For a trailer roof or container wall, a flexible laminate can follow a gently curved surface, though crystalline versions bend only over a large radius. The ETFE vs PET comparison sets out how the two common front surfaces differ.
An animal collar is the hard case. A narrow strip there is normally built from thin-film amorphous cells, and the buyer should know early that its cost per watt and its efficiency differ from crystalline silicon. Its advantages are the narrow, flexible form and good output in weak light, which suits a collar that spends time in shade.
A low-power node uses little energy per day, so the real limit is the module outline, and a long narrow panel is the usual answer. A trade-off summary by measurable attribute helps the decision.
- Rigid crystalline module: flat mounting face, simplest wiring, fixed footprint.
- Flexible laminate: curved or vibrating surface, panel thickness and bend radius to agree on the drawing.
- Thin-film strip: narrowest width, weak-light output, different cost per watt and efficiency.
What to customize and what to buy from stock
A listed mini panel is enough when its voltage, current and footprint already fit the tracker housing and charger, and customization is worth it when size, leads, connector or surface must match your enclosure. Check the stock range in the mini solar panel collection first.
A drawing can specify four items, to be confirmed in the quote: the outline size, the lead length and color, the connector, and the surface material. The 100 x 100 mm listed module, for example, has attached leads of 12 to 15 cm, while the 30 x 60 mm and 200 x 130 mm modules have bare rear solder pads, so a tracker that needs a plug has to specify one. The custom mini solar panel capability datasheet lists which of these can be changed.
Sensor makers often arrive with a finished drawing. The usual route is a small first order, checked in the product, then small-batch repeat orders. Panels for devices tend to become long-term repeat business when the first order is specified fully.
A short decision rule works for most trackers. Use a listed panel when the footprint, voltage and current in the table above already meet your sizing result. Customize when the panel must fit an enclosure cut-out, a specific cable exit or a curved surface, or when the surface must change.
Fixing the first order so repeat orders stay the same
The first order fixes the drawing, cable, packing and paperwork format, and every repeat order is then checked against those same items. LinkSolar is a China-based B2B supplier of custom & OEM solar panels, solar cells and mounting hardware, and partner production lines build to the buyer's drawing.
Put these items on the drawing and the order record, using the custom mini solar panel drawing RFQ checklist as the template.
- Dimensions, thickness and tolerance of the panel outline.
- Rated power, working voltage and current at the point your charger uses.
- Cable type, length, color and connector, or the solder pad layout.
- Packing format.
- Shipping and export paperwork format for the destination market.
Before each repeat order, confirm these items against the last shipment and ask for a current quotation, because material costs can move between orders. Pre-shipment checks then compare the batch with the agreed drawing rather than with memory of the previous one.
FAQ
Can a solar panel power a GPS tracker without a battery?
A tracker normally needs a rechargeable battery because a solar module generates power in sunlight and does not store energy. At night, in shade or during a report burst, the battery carries the load while the panel tops it up when light returns.
What size mini solar panel does an asset tracker need?
An asset tracker needs the panel watts that the daily energy formula returns for its own reporting pattern. With the example assumptions above, that is 0.007 W for one report a day and 0.40 W for a report every five minutes, so replace the example numbers with your datasheet values.
Can I use a thin-film strip instead of crystalline silicon?
A thin-film strip works when the available width is narrow, as on an animal collar. Plan for a different cost per watt and a different efficiency than crystalline silicon, and send the strip's real size so we can say what is practical.
Is a 5 V or a 12 V panel better for a vehicle tracker?
The better voltage is the one inside the input window of the tracker charger. A 5 V module suits a small lithium-ion charge stage, while a 12 V module suits a charger designed for a 12 V input, as in the listed 4.2 W module.
What should I send to get a custom panel for a solar IoT device?
Send the power, size, quantity and target market, with the charger input window and the mounting drawing. The same details apply to a solar GPS tracker, a solar panel for an asset tracker or any other solar panel for an IoT device.
Next step
Once your sizing result and charger window are known, the next move is to prepare the power, size, quantity and target market so the panel can be specified against your drawing. Send your requirements