Which Solar Panel Belongs on a Street Light?

The efficiency map

All efficiency figures are standard-test-condition ratings. Real output on your site will be lower; treat the ratios between rows, not the absolute numbers, as the selection signal.

Monocrystalline: the default

A single silicon crystal sliced into wafers gives a uniform structure and the familiar black cell color. Above 20% efficiency means more watts from a small pole-top area, which is exactly the street-light constraint. These panels carry 25-year-or-longer warranties and hold up better in low light than the alternatives.

Two honest limits. They cost more per watt to manufacture. And like all crystalline silicon, output drops as cell temperature climbs, which matters in desert projects where the panel itself sits in full sun all afternoon.

Polycrystalline: the legacy choice

Multiple crystals melted into one ingot produce the bluish, speckled look and a slightly lower efficiency band of 15–20%. The manufacturing footprint is smaller per watt, and for years that price gap made poly the budget answer. The gap has largely closed. We still fit polycrystalline panels when a client's existing fleet standard demands them, but we no longer spec them for new designs.

Thin-film: weight and flexibility buy the efficiency back

Depositing photovoltaic material onto a substrate yields panels at 10–13% efficiency. You need roughly twice the area for the same watts. In exchange you get weight, flexibility, and better behavior in high temperatures.

That trade wins in exactly one street-light scenario: panels that wrap the pole or ride on structures that cannot carry a glass laminate. Everywhere else, the area penalty costs more than the panel saves. Thin-film also carries a shorter lifespan and shorter warranty periods than crystalline silicon.

TopCon: what we spec when autonomy is tight

TopCon (Tunnel Oxide Passivated Contact) adds a thin tunnel oxide layer on the wafer, improving light absorption and cutting electron recombination. Cells now exceed 24% efficiency, and they hold their output better at high temperature and in low light than conventional monocrystalline cells.

For a pole with a fixed footprint feeding a multi-night autonomy requirement, that combination is why TopCon has become our default for high-autonomy units. It is a newer technology with a shorter field history than monocrystalline, which we weigh against the energy gain.

Orientation and tilt: the free efficiency

The panel only performs if it faces the sun. Three rules we apply on every site:

1. Tilt roughly equal to the site latitude for year-round balance. Go steeper (latitude plus 10–15°) in winter-heavy projects, flatter (latitude minus 10–15°) where summer load dominates.
2. Face the equator (due south in the northern hemisphere, due north in the southern) unless a shading survey says otherwise.
3. Survey shading before you buy. One branch shadow across part of a single panel drags the whole string's output down; on multi-panel arrays, bypass diodes limit the damage but do not eliminate it.

What we spec, and the rule behind it

1. Fixed pole-top area with a hard autonomy requirement → monocrystalline or TopCon.
2. Weight or flexibility is the binding constraint → thin-film, sized with the efficiency penalty priced in.
3. Polycrystalline only when a fleet standard mandates it.

What this page does not cover

This page compares panel technologies for street-light duty. It does not cover how the cells themselves are made — that is here — and it does not size arrays. For panel and battery sizing on a specific project, use our solar panel sizing calculator, or start from our all-in-one solar street lights line, where the panel grade is documented per unit.