{"abstract":"Incidence angles are nonsense for any tilted panel.","category":"Solar tracker geometry","checks":7,"contract":"Panel tilted by tilt degrees from horizontal, facing pan_az (clockwise from north). zenith = 90 - sun_el. cos(aoi) = cos(zen)cos(tilt) + sin(zen)sin(tilt)cos(sun_az - pan_az), clamped to [-1, 1]. Return [aoi degrees rounded 3, max(cos aoi, 0) rounded 4, 'front' or 'back'], or [None, 0.0, 'night'] when sun_el <= 0.","contract_signature":"tilt, pan_az, sun_az, sun_el","evaluation_group":"w2-solar_tracker_geometry-fixed-panel-incidence","failed_approach":"Measuring tilt from vertical swaps flat and vertical panels.","family":"w2-solar_tracker_geometry-fixed-panel-incidence-tilt-units","id":"FA-93411","implementations":{"attempt":{"sha256":"623957d97c4ddbcbbd92928050405f77e4edc2622fd49110b5afece65f10b502","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(tilt, pan_az, sun_az, sun_el):\n    if sun_el <= 0:\n        return [None, 0.0, 'night']\n    zen = math.radians(90 - sun_el)\n    t = math.radians(90 - tilt)\n    c = math.cos(zen) * math.cos(t) + math.sin(zen) * math.sin(t) * math.cos(math.radians(sun_az - pan_az))\n    c = max(-1.0, min(1.0, c))\n    aoi = math.degrees(math.acos(c))\n    side = 'front' if c >= 0 else 'back'\n    return [round(aoi, 3), round(max(c, 0.0), 4), side]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [30, 135, 0, 10], [101.408, 0.0, 'back']],\n  ['regression: tilt units (partial repair)', [10, 225, 60, 89], [10.969, 0.9817, 'front']],\n  ['control 1', [0, 180, 225, -5], [None, 0.0, 'night']],\n  ['control 2', [0, 135, 150, 45], [45.0, 0.7071, 'front']]],\n [['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [20, 225, 270, 3], [73.101, 0.2907, 'front']],\n  ['regression: tilt units (partial repair)', [90, 180, 250, 45], [76.005, 0.2418, 'front']],\n  ['control 1', [25, 180, 60, 10], [92.907, 0.0, 'back']],\n  ['control 2', [60, 225, 270, 20], [41.716, 0.7465, 'front']]],\n [['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [10, 135, 30, 45], [48.35, 0.6646, 'front']],\n  ['regression: tilt units (partial repair)', [30, 270, 225, 10], [60.095, 0.4986, 'front']],\n  ['control 1', [60, 90, 135, 30], [38.709, 0.7803, 'front']],\n  ['control 2', [45, 270, 60, 89], [45.868, 0.6963, 'front']]],\n [['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [30, 135, 100, 10], [56.376, 0.5537, 'front']],\n  ['regression: tilt units (partial repair)', [20, 225, 270, 3], [73.101, 0.2907, 'front']],\n  ['control 1', [45, 180, 315, 0], [None, 0.0, 'night']],\n  ['control 2', [30, 90, 225, 45], [68.754, 0.3624, 'front']]],\n [['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [10, 180, 100, 30], [58.767, 0.5185, 'front']],\n  ['regression: tilt units (partial repair)', [30, 225, 270, 60], [22.062, 0.9268, 'front']],\n  ['control 1', [45, 180, 0, 75], [60.0, 0.5, 'front']],\n  ['control 2', [45, 225, 270, -5], [None, 0.0, 'night']]]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"80d9672498211989aa4a32efd5bdaba91cfcd6c317b8e1cbc2b910a67698ad91","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport math\nN = 1\nobservations = []\ndef solve(tilt, pan_az, sun_az, sun_el):\n    if sun_el <= 0:\n        return [None, 0.0, 'night']\n    zen = math.radians(90 - sun_el)\n    t = tilt\n    c = math.cos(zen) * math.cos(t) + math.sin(zen) * math.sin(t) * math.cos(math.radians(sun_az - pan_az))\n    c = max(-1.0, min(1.0, c))\n    aoi = math.degrees(math.acos(c))\n    side = 'front' if c >= 0 else 'back'\n    return [round(aoi, 3), round(max(c, 0.0), 4), side]\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [30, 135, 0, 10], [101.408, 0.0, 'back']],\n  ['regression: tilt units (partial repair)', [10, 225, 60, 89], [10.969, 0.9817, 'front']],\n  ['control 1', [0, 180, 225, -5], [None, 0.0, 'night']],\n  ['control 2', [0, 135, 150, 45], [45.0, 0.7071, 'front']]],\n [['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [20, 225, 270, 3], [73.101, 0.2907, 'front']],\n  ['regression: tilt units (partial repair)', [90, 180, 250, 45], [76.005, 0.2418, 'front']],\n  ['control 1', [25, 180, 60, 10], [92.907, 0.0, 'back']],\n  ['control 2', [60, 225, 270, 20], [41.716, 0.7465, 'front']]],\n [['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [10, 135, 30, 45], [48.35, 0.6646, 'front']],\n  ['regression: tilt units (partial repair)', [30, 270, 225, 10], [60.095, 0.4986, 'front']],\n  ['control 1', [60, 90, 135, 30], [38.709, 0.7803, 'front']],\n  ['control 2', [45, 270, 60, 89], [45.868, 0.6963, 'front']]],\n [['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [30, 135, 100, 10], [56.376, 0.5537, 'front']],\n  ['regression: tilt units (partial repair)', [20, 225, 270, 3], [73.101, 0.2907, 'front']],\n  ['control 1', [45, 180, 315, 0], [None, 0.0, 'night']],\n  ['control 2', [30, 90, 225, 45], [68.754, 0.3624, 'front']]],\n [['boundary: sun on horizon', [30, 180, 180, 0], [None, 0.0, 'night']],\n  ['normal: sun normal to panel', [30, 180, 180, 60], [0.0, 1.0, 'front']],\n  ['boundary: sun behind vertical panel', [90, 180, 0, 20], [160.0, 0.0, 'back']],\n  ['regression: tilt units', [10, 180, 100, 30], [58.767, 0.5185, 'front']],\n  ['regression: tilt units (partial repair)', [30, 225, 270, 60], [22.062, 0.9268, 'front']],\n  ['control 1', [45, 180, 0, 75], [60.0, 0.5, 'front']],\n  ['control 2', [45, 225, 270, -5], [None, 0.0, 'night']]]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Deterministic stipulated toy contract for teaching; no claim of conformance with any standard, vendor protocol or production controller. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-solar_tracker_geometry-fixed-panel-incidence-tilt-units","generated_at":"2026-09-29T14:51:54.906766+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Single-axis and dual-axis solar trackers turn a sun direction into actuator commands; a sign, frame or limit mistake points a whole plant away from the sun or into a mechanical stop.","root_cause":"The tilt in degrees is used as radians.","sha256":"94c2c96d120a01eb3a7b70f4b83eed4de1d8f6f7cd7a79e2c6b2b6a3f7a6e191","title":"Fixed panel angle of incidence: tilt units · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verified":true,"visibility":"public","verification":{"attempt":{"elapsed_ms":40.355,"exit_code":1,"observations":[{"actual":[null,0.0,"night"],"check":"boundary: sun on horizon","expected":[null,0.0,"night"],"passed":true},{"actual":[30.0,0.866,"front"],"check":"normal: sun normal to panel","expected":[0.0,1.0,"front"],"passed":false},{"actual":[70.0,0.342,"front"],"check":"boundary: sun behind vertical panel","expected":[160.0,0.0,"back"],"passed":false},{"actual":[121.081,0.0,"back"],"check":"regression: tilt units","expected":[101.408,0.0,"back"],"passed":false},{"actual":[80.966,0.157,"front"],"check":"regression: tilt units (partial repair)","expected":[10.969,0.9817,"front"],"passed":false},{"actual":[null,0.0,"night"],"check":"control 1","expected":[null,0.0,"night"],"passed":true},{"actual":[46.92,0.683,"front"],"check":"control 2","expected":[45.0,0.7071,"front"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: sun on horizon\", \"actual\": [null, 0.0, \"night\"], \"expected\": [null, 0.0, \"night\"], \"passed\": true}, {\"check\": \"normal: sun normal to panel\", \"actual\": [30.0, 0.866, \"front\"], \"expected\": [0.0, 1.0, \"front\"], \"passed\": false}, {\"check\": \"boundary: sun behind vertical panel\", \"actual\": [70.0, 0.342, \"front\"], \"expected\": [160.0, 0.0, \"back\"], \"passed\": false}, {\"check\": \"regression: tilt units\", \"actual\": [121.081, 0.0, \"back\"], \"expected\": [101.408, 0.0, \"back\"], \"passed\": false}, {\"check\": \"regression: tilt units (partial repair)\", \"actual\": [80.966, 0.157, \"front\"], \"expected\": [10.969, 0.9817, \"front\"], \"passed\": false}, {\"check\": \"control 1\", \"actual\": [null, 0.0, \"night\"], \"expected\": [null, 0.0, \"night\"], \"passed\": true}, {\"check\": \"control 2\", \"actual\": [46.92, 0.683, \"front\"], \"expected\": [45.0, 0.7071, \"front\"], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":40.066,"exit_code":1,"observations":[{"actual":[null,0.0,"night"],"check":"boundary: sun on horizon","expected":[null,0.0,"night"],"passed":true},{"actual":[111.127,0.0,"back"],"check":"normal: sun normal to panel","expected":[0.0,1.0,"front"],"passed":false},{"actual":[173.38,0.0,"back"],"check":"boundary: sun behind vertical panel","expected":[160.0,0.0,"back"],"passed":false},{"actual":[44.372,0.7148,"front"],"check":"regression: tilt units","expected":[101.408,0.0,"back"],"passed":false},{"actual":[146.075,0.0,"back"],"check":"regression: tilt units (partial repair)","expected":[10.969,0.9817,"front"],"passed":false},{"actual":[null,0.0,"night"],"check":"control 1","expected":[null,0.0,"night"],"passed":true},{"actual":[45.0,0.7071,"front"],"check":"control 2","expected":[45.0,0.7071,"front"],"passed":true}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"boundary: sun on horizon\", \"actual\": [null, 0.0, \"night\"], \"expected\": [null, 0.0, \"night\"], \"passed\": true}, {\"check\": \"normal: sun normal to panel\", \"actual\": [111.127, 0.0, \"back\"], \"expected\": [0.0, 1.0, \"front\"], \"passed\": false}, {\"check\": \"boundary: sun behind vertical panel\", \"actual\": [173.38, 0.0, \"back\"], \"expected\": [160.0, 0.0, \"back\"], \"passed\": false}, {\"check\": \"regression: tilt units\", \"actual\": [44.372, 0.7148, \"front\"], \"expected\": [101.408, 0.0, \"back\"], \"passed\": false}, {\"check\": \"regression: tilt units (partial repair)\", \"actual\": [146.075, 0.0, \"back\"], \"expected\": [10.969, 0.9817, \"front\"], \"passed\": false}, {\"check\": \"control 1\", \"actual\": [null, 0.0, \"night\"], \"expected\": [null, 0.0, \"night\"], \"passed\": true}, {\"check\": \"control 2\", \"actual\": [45.0, 0.7071, \"front\"], \"expected\": [45.0, 0.7071, \"front\"], \"passed\": true}], \"passed\": false}\n"}},"member_only":{"stages":["fixed"],"fields":["implementations.fixed","verification.fixed","harness","repair"],"note":"The verified repair, its recorded checks, the repair description, and the scoring harness are available to members."}}