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Wattplot Basic — fixed-tilt build (no electronics)

The Basic tier is the same bed, frame, hinges, and panel clamps as the Smart build — but the tilt is set by hand with a pinned prop strut instead of a linear actuator. No ESP32, no PCB, no wiring beyond the panel leads to your charge controller. This is the weekend build and the natural home for a salvaged panel (see upcycling.md).

What you skip vs. the Smart build: actuator, actuator mount blocks, ESP32/PCB, IMU, INA219, soil sensor, all firmware. Everything else in build_guide.md applies — follow it and substitute Phase "actuator install" with the strut below.

The pinned strut

Two 2x4 struts (one per cross-rail end, both cut from a single 2x4x8ft board — square cuts only, per the design rules) prop the frame's north rail:

  • Top end: square cut, butts under the north rail against a 2x4 stop block screwed to the rail.
  • Bottom end: sits in a 2x4 shoe screwed to the bed's north wall.
  • Lock: a ½" steel pin (same rod stock as the hinge pin) through the shoe and strut. One hole per tilt angle.

Tilt stops: 0° (stowed flat), 15°, 25°, 35°, 45° (max) — matching the tilt schedule presets in the sun simulator, so the annual-yield numbers in the sim apply directly. 45° is the structural ceiling: the wind calc passes SF ≥ 2.0 only up to 45° at the design wind. Set it seasonally: steeper in winter, shallower in summer, or just leave it at 25° year-round and lose only a few percent annually.

Storm stow (do this — it's your wind safety)

The Basic build has no auto-fold. You are the fold controller.

Before any forecast of sustained winds above ~40 mph or gusts above ~55 mph:

  1. Pull both strut pins.
  2. Lower the frame flat onto the bed walls (0° stop).
  3. Re-pin both struts in the 0° holes so the frame can't be lifted by gusts.

At 0° the panel carries essentially zero uplift and drag (see ../analysis/wind_load_report.md — the 0° row is the whole story). Deployed, the structure is engineered for the ASCE 7-22 design wind (115 mph, Exposure C) with SF ≥ 2 up to 45° tilt (~125 mph rated at 45°, ~165 mph at 35°, 20" soil fill) — but stowing is free, takes two minutes, and turns a marginal night into a non-event. If a named storm is coming, stow.

Cost

The delta vs. the Smart BOM: subtract the actuator ($40), electronics ($40–80), and PCB. With a salvaged residential panel (often free to $50 on Craigslist), the Basic build lands in the $250–450 range depending on lumber choice (PT pine vs. cedar). See ../bom.md.

Upgrade path

Drill the strut holes even if you plan to go Smart later — a Smart build with strut holes degrades gracefully to a pinned Basic build if the electronics come off, and the struts double as a mechanical backup prop while you're bench-testing the actuator.