By Rusty Latenser
Purpose of Analysis
This report compares Portable Changeable Message Sign (PCMS) units using their standard solar panel configurations. The central question is: can these units reliably recharge in winter conditions? Why does this matter? If a deployed unit loses power more than a few days, it triggers an unscheduled maintenance trip.
Key Determinants of Recharge Performance
The solar charger controller
- PWM (most manufacturers use this controller
- MPPT (Only INEX and Wanco use these on their full-sized units)
2. Tilted Solar Panels
- Even a smaller 15° tilt increases production by 8–36%, depending on orientation.
- The Spyder Platform’s Opposing Tilt Solar system averages a average 10% gain over flat panels across all deployed orientations.
Solar Panel Area (Square Footage)
- The largest driver of power output.
- Insufficient daylight means additional panels must be purchased.
- Some manufacturers do not offer optional panel expansions, limiting flexibility.
3. Battery Type
- Lithium Iron Phosphate (LiFePO4): Charges 3–5 times faster than lead-acid.
- Full charge: 2–4 hours.
- Lead-Acid: Requires 6–12 hours or more under similar conditions.
- Why it matters: Winter daylight hours are significantly reduced, so faster charging is critical to restore autonomy.
5. Daylight Hours in Winter
- Average difference between June and December: 7 hours fewer daylight, a 44% drop.
- This seasonal reduction directly impacts recharge capacity.
6. Overcast Conditions
| Condition | Average reduction vs clear sky |
| Thin overcast (bright clouds, sun disc visible) | 20–40% |
| Heavy overcast (uniform gray, no sun disc) | 60–80% |
| Rain (dark clouds, precipitation) | 70–90% |
Myth: Contrary to common belief, solar panels do produce power under overcast conditions, though at reduced levels.
Assumptions
- Configuration: INEX configured with the Spyder Opposing-Tilt Array (two sets); all other message boards are delivered with flat panels..
- Loads: INEX 62 Wh/day; Competitors 50 Wh/day.
- Orientation and month: East (090°) or West , (270°) January. This is the worst-case scenario for the INEX opposing tilt configuration. Orientation has no impact on flat panel configurations (all other manufacturers).
| Message Board | Spyder Platform | PCMS #1 | PCMS #2 | PCMS #3 | PCMS #4 | PCMS #5 | PCMS #6 |
| # Solar Panels | 4 × 120 W | 1 x 330 W | 1 × 85 W | 1 × 140 W | 1 × 140 W | 1 x 160 W | 1 × 80 W |
| STD Total Power | 480 W total | 330 W total | 85 W total | 140 W total | 140 W total | 160 W total | 80 W total |
Method synopsis for report
- Daylight hours (approx. mid-January): Boston 9.3 h; Chicago 9.6 h; Atlanta 10.2 h; Phoenix 10.1 h; Seattle 8.6 h; Anchorage 5.5 h.
- Daily energy basis: Results use full-day energy yield (morning through dusk), it is not a single-time snapshot. They’re derived from daily kWh simulations based on NREL PVWatts and NSRDB data for each orientation and location.
- Scaling approach: Document kWh/day at 2 kW is scaled to each unit’s array wattage and configuration.
- Excess hours available: Daylight hours − Hours to restore daily load.
- Minimum Output Required: Output must cover sign operation and replenish the batteries at the same time.
Weather-adjusted winter outputs for all locations (east-facing, January)
- An asterisk (*) indicates output below daily load
- INEX Spyder (LiFePO4, 62 Wh/day load): must produce ≥112 Wh/day to operate signage and recharge batteries.
- Competitors (Lead-acid, 50 Wh/day load): must produce ≥110 Wh/day to operate signage and recharge batteries.
An Asterisk indicates the solar output is insufficient to perform both functions: operate sign and recharge batteries.
Boston, MA
| PCMS Unit | Clear sky output (Wh/day) | Light overcast (60% of Clear Sky) | Heavy overcast (20% of Clear Sky) | Rain (10% of Clear Sky) |
| Spyder Platform | 504 | 302 | 101 | 50* |
| Competitor #1 (330W) | 330 | 198 | 66* | 33* |
| Competitor #2 (85W) | 85 | 51* | 17* | 9* |
| Competitor #3 (140W) | 140 | 84 | 28* | 14* |
| Competitor #4 (140W) | 140 | 84 | 28* | 14* |
| Competitor #5 (160W) | 160 | 96 | 32* | 16* |
| Competitor #6 (80W) | 80 | 48* | 16* | 8* |
Chicago, IL
| PCMS Unit | Clear sky output (Wh/day) | Light overcast (60% of Clear Sky) | Heavy overcast (20% of Clear Sky) | Rain (10% of Clear Sky) |
| Spyder Platform | 576 | 346 | 115 | 58* |
| Competitor #1 (330W) | 363 | 218 | 73* | 36* |
| Competitor #2 (85W) | 94 | 56* | 19* | 9* |
| Competitor #3 (140W) | 154 | 92 | 31* | 15* |
| Competitor #4 (140W) | 154 | 92 | 31* | 15* |
| Competitor #5 (160W) | 176 | 106 | 35* | 18* |
| Competitor #6 (80W) | 88 | 53* | 18* | 9* |
Atlanta, GA
| PCMS Unit | Clear sky output (Wh/day) | Light overcast (60% of Clear Sky) | Heavy overcast (20% of Clear Sky) | Rain (10% of Clear Sky) |
| Spyder Platform | 768 | 461 | 154 | 77 |
| Competitor #1 (330W) | 512 | 307 | 102 | 51* |
| Competitor #2 (85W) | 132 | 79 | 26* | 13* |
| Competitor #3 (140W) | 217 | 130 | 43* | 22* |
| Competitor #4 (140W) | 217 | 130 | 43* | 22* |
| Competitor #5 (160W) | 248 | 149 | 50 | 25* |
| Competitor #6 (80W) | 124 | 74 | 25* | 12* |
Phoenix, AZ
| PCMS Unit | Clear sky output (Wh/day) | Light overcast (60% of Clear Sky) | Heavy overcast (20% of Clear Sky) | Rain (10% of Clear Sky) |
| Spyder Platform | 1,320 | 792 | 264 | 132 |
| Competitor #1 (330W) | 891 | 535 | 178 | 89 |
| Competitor #2 (85W) | 230 | 138 | 46* | 23* |
| Competitor #3 (140W) | 378 | 227 | 76* | 38* |
| Competitor #4 (140W) | 378 | 227 | 76* | 38* |
| Competitor #5 (160W) | 432 | 259 | 86* | 43* |
| Competitor #6 (80W) | 216 | 130 | 43* | 22* |
Seattle, WA
| PCMS Unit | Clear sky output (Wh/day) | Light overcast (60% of Clear Sky) | Heavy overcast (20% of Clear Sky) | Rain (10% of Clear Sky) |
| Spyder Platform | 288 | 173 | 58* | 29* |
| Competitor #1 (330W) | 182 | 109 | 36* | 18* |
| Competitor #2 (85W) | 47 | 28* | 9* | 5* |
| Competitor #3 (140W) | 77 | 46* | 15* | 8* |
| Competitor #4 (140W) | 77 | 46* | 15* | 8* |
| Competitor #5 (160W) | 88 | 53* | 18* | 9* |
| Competitor #6 (80W) | 44 | 26* | 9* | 4* |
Anchorage, AK
| PCMS Unit | Clear sky output (Wh/day) | Light overcast (60% of Clear Sky) | Heavy overcast (20% of Clear Sky) | Rain (10% of Clear Sky) |
| Spyder Platform | 72 | 43* | 14* | 7* |
| Competitor #1 (330W) | 50 | 30* | 10* | 5* |
| Competitor #2 (85W) | 13 | 8* | 3* | 1* |
| Competitor #3 (140W) | 21 | 13* | 4* | 2* |
| Competitor #4 (140W) | 21 | 13* | 4* | 2* |
| Competitor #5 (160W) | 24 | 14* | 5* | 2* |
| Competitor #6 (80W) | 12 | 7* | 2* | 1* |
Key takeaways
- INEX Spyder (LiFePO4): Passes clear and light overcast in most regions; fails heavy overcast and rain everywhere except Phoenix (heavy passes). Anchorage fails across all conditions.
- Competitors (Lead-acid): Only pass clear/light in mid- and southern latitudes (Atlanta, Phoenix). Fail heavy and rain everywhere. Anchorage fails across all conditions.
- Operational reality: Winter overcast and rain conditions push nearly all competitor units below viability. INEX maintains margin longer but still requires auxiliary charging or panel expansion in northern regions.
