Rigid panels are ranked mainly as a value yardstick for portable panels, so price per watt carries the most weight. Every panel gets a score from 0 to 100% built from four factors, which maps onto the 5-point rating shown on the site (a 0% score would be 1.5 stars; a perfect score, 5). Each factor is scored against fixed reference points, not against the other products in the list, so adding a new model never moves another model’s rating. Weight and folding don’t count here, since these panels are made to be mounted, not carried.
| Factor | Measures | Weight |
|---|---|---|
| Value | price per rated watt | 45% |
| Tested output | measured watts vs. rated | 15% |
| Durability | junction box rating, warranty | 25% |
| Efficiency | claimed conversion efficiency | 15% |
Reference points by size
| Size | Price per rated watt scoring 0 → 100 |
|---|---|
| Under 150 W | $2.00 → $0.60 |
| 150 W and up | $1.50 → $0.45 |
The factors
Value is the current lowest checked price divided by the rated watts (the front side only, for bifacial panels). Prices are checked by hand and dated on every page; a product with no current price gets the neutral middle score.
Tested output is the highest output independent reviewers measured from the panel in real sun, as a share of its rating: 60% scores zero and 90% full marks, as for portable panels. Manufacturer claims don’t count here.
Durability combines the junction box’s water-resistance rating (IP67 and IP68 score full marks, IP65 most of them) with the length of the product warranty (1 → 10 years). Long output warranties, such as 80% of rated power after 25 years, are listed on each page but not scored, since few buyers of a single panel ever claim one.
Efficiency is the conversion efficiency the maker publishes: 19% scores zero, 25% full marks.
Missing data
If a figure isn’t published, that factor gets the neutral middle score (50) and the product page marks it as estimated. A panel that hasn’t been independently tested gets an output estimated from the tested rigid panels, weighted toward its own brand’s results, worked out as for portable panels.
Ties and discontinued models
Products are ranked by score within each size. Discontinued models stay listed but rank below every current model and can be hidden with the “Hide discontinued” filter.