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Explainer — sensing
Solar motion lights: PIR vs radar sensing, explained
Every sensor solar light answers the same question — is someone there? — but the two technologies in this catalogue answer it differently, and the difference decides where each light belongs. PIR (passive infrared) sensing watches for moving body heat. Radar sensing emits microwaves and reads the reflection. Both appear in the PENYA range: PIR in the wall and security formats, radar in the corridor line. This post explains each, with the recorded models as examples.
How PIR sensing works
A PIR sensor sits behind a faceted lens and divides its field into zones. When a warm body crosses zones, the infrared pattern changes and the light triggers. The strengths are cost, simplicity and very low standby draw — critical when the whole system runs on a small battery and a panel the size of a postcard. The limits are just as physical: PIR needs line of sight, its range shrinks on hot days when body temperature approaches ambient, and it cannot see through a diffuser, so the sensor window must sit exposed on the fitting.
In the catalogue, PIR-class sensing drives the wall family: the solar PIR sensor wall light (IP65, three modes, 270° beam), the motion sensor wall light (IP54, 100 lm, 0.17 kg) and the PIR security model PY-100LED with its monocrystalline panel and 2200 mAh battery. The garden lawn light uses the same principle differently — a motion sensor with a 6–8 m detection range that turns a marker light into an on-demand path light.
How radar sensing works
A radar (microwave) sensor actively transmits and listens for the Doppler shift of movement. Because microwaves pass through plastic and glass, the sensor can sit inside a sealed fitting — no exposed window — and because it reads motion rather than heat, ambient temperature does not blunt it. The trade-offs are higher standby consumption and a talent for seeing movement through thin partitions, which can mean false triggers if the fitting backs onto a busy space.
That profile is why radar shows up indoors in the catalogue: the solar corridor bulkhead light (PY-LS05) pairs a light sensor with a radar motion sensor behind its diffuser, backed by a LiFePO4 20 AH battery — a fitting for corridors where the light must work through an enclosed cover and occupancy is intermittent. A dedicated solar radar sensor corridor light is also catalogued.
Choosing, job by job
| Situation | Better fit | Why |
|---|---|---|
| Exterior wall, gate, yard approach | PIR wall/security light | Line of sight is natural outdoors; lowest standby draw |
| Path crossed at night | PIR sensor lawn light | 6–8 m detection answers actual use; battery lasts |
| Enclosed corridor or stairwell fitting | Radar bulkhead/corridor light | Senses through the diffuser; unaffected by heat |
| Wide corner coverage | Three-head PIR wall light | Three heads widen the watched field in one fitting |
What the spec sheets do and do not tell you
The catalogue records summarise sensing as modes and formats — "3 modes", "3 lighting levels", "light sensor + radar motion sensor" — rather than publishing detection curves. That is normal for supplier records, and it defines the buyer's confirmation list: exact detection range and angle for the chosen model, the mode logic (which modes are sensor, which are steady), and the standby behaviour. Ask those three questions at quote stage and the technology choice becomes a specification, not a gamble.
The shortlist that applies this thinking to a whole garden is best solar lights: a buyer's shortlist; the models themselves are documented on the solar motion sensor lights page. For outage-duty lighting — the other place sensing and batteries meet — read lights for power outages.
Sensitivity, pets and the 3 a.m. problem
The commonest sensor complaint — the light that fires all night — is usually a sensitivity and siting story rather than a defect. PIR fields that include a road, a heat vent or moving vegetation will fire on all three; radar fields that back onto a busy room will fire through the wall. The catalogue's formats answer with placement and format choice: wall formats with defined beams for aimed outdoor fields, the three-head model to bend coverage around a corner instead of widening a stare, enclosed radar fittings where the watched space is the room itself. Where a programme serves homes with pets, the walk-test matters more than the datasheet — trigger height and field shape decide whether the cat owns the light. None of this appears in a specification table, which is precisely why buyers should raise it at enquiry stage, while the answer is still free.
Standby draw: the hidden specification
Sensor lights spend most of their lives waiting, so their standby consumption quietly decides their winter performance. A PIR front end sips; a radar front end drinks more deeply — one reason the corridor bulkhead pairs its radar sensor with a 20 AH LiFePO4 bank while the PIR wall light thrives on far smaller storage. When comparing sensor models for northern or shaded installations, ask for the standby behaviour alongside the headline modes: the light with the cleverer sensor and the hungrier standby can be the one that is dark in February. The records in this catalogue summarise modes rather than publishing standby curves, so the question belongs on the confirmation list — it is asked in one sentence and answered from the model's full sheet.
Cost curves: why both technologies survive
If radar were simply better, PIR would have disappeared; if PIR were simply cheaper at equal performance, radar would never have entered enclosed fittings. The market keeps both because their costs sit in different places. PIR's cost is optical — the exposed lens window and the siting discipline it demands. Radar's cost is electrical — standby consumption that must be fed with battery, which is why radar appears in this catalogue backed by a 20 AH bank while PIR thrives on cells a fraction of that size. The buyer's question is therefore never 'which sensor is better' but 'which cost does my installation prefer to pay' — a question with a definite answer per site, which is what makes the technology choice a specification exercise rather than a taste one.
A field test worth doing
Before committing a programme quantity, run the two-technology field test: mount one PIR format and one radar format in their intended positions for a week and log the triggers that should not have happened. A notebook by the door beats a laboratory — the site itself will reveal the heat vent, the passing traffic, the cat's patrol route and the thin wall behind the corridor fitting, and it will reveal them in the conditions the lights must actually serve. Buyers who run this test reorder with confidence and return almost nothing; buyers who skip it discover the same facts at programme scale. The test costs two samples and seven days, which is the cheapest specification work in this entire category.