Solar Panel Performance Comparison Across 22-Day Great Lakes Cruises
In previous entries, I documented our solar panel performance on Great Lakes cruises: a 130-watt mono-crystalline panel in August 2011, and a 140-watt poly-crystalline panel in August 2012. This year, I tested a 160-watt mono-crystalline panel under similar conditions. The main variables affecting output were weather and engine usage, as we often motored into headwinds. Each panel’s performance is averaged across four weather conditions: sunny, mostly sunny, mostly cloudy, and cloudy.
Test Setup
- Battery banks: 315 Ah and 105 Ah deep-cycle wet cells
- Refrigeration: 5 amps, ~6+ hours daily due to cooler weather
- Navigation: Laptop drawing 3 amps
- Lighting: LED throughout
- Panel management: Typically connected to the controller while motoring
- Controller: Dual battery bank solar controller, which stops charging when batteries reach full charge
- Tilt and rotation: Panel angle set to ~45 degrees, rotated ~3 times daily for optimal sun exposure
- Anchoring routine: We anchored for 2–4 days at a time and did not use shore power
Results Summary (Average Amp Hours Produced Per Day)
| Condition | 130W Mono | 140W Poly | 160W Mono |
|---|---|---|---|
| Overall average | 54 Ah | 53 Ah | 48 Ah |
| Sunny days | 71 Ah | 69 Ah | 71 Ah |
| Mostly sunny | 51 Ah | 50 Ah | 50 Ah |
| Mostly cloudy | 46 Ah | 35 Ah | 37 Ah |
| Cloudy | 24 Ah | 32 Ah | 28 Ah |
| At anchor | 62 Ah | 62 Ah | 61 Ah |
| Engine in use | 35 Ah | 43 Ah | 44 Ah |
| Min day | 16 Ah | 27 Ah | 28 Ah |
| Max output (amps) | 10.5 A | 10.5 A | 11.5 A |
Note: Fewer sunny days impacted the 160W panel’s overall output.
Analysis
All panels met our power needs, with occasional slight deficits on extended cloudy days at anchor. The 160W panel’s higher maximum output (up to 11.5 amps) and overall efficiency align with its rating, though performance was tempered by fewer sunny days. Interestingly, the poly-crystalline panel was less affected by shading, making it advantageous in partly cloudy or shaded conditions.
Recommendations
- Mono-crystalline (130W and 160W): Ideal for sunny areas with minimal shading.
- Poly-crystalline (140W): Better suited for partly cloudy or shaded environments.
Overall, each panel type can meet power needs under varying conditions, but selection should account for expected weather and shading.