Sweet Spot Technology: 405W panels hit the optimal balance between residential and commercial applications, offering 20%+ efficiency while remaining cost-effective at $0. 61 per watt, making them ideal for space-constrained installations. Federal Tax Credit Urgency: With the 30% federal tax. Introducing the REC Alpha Pure REC405AA, the latest addition to REC's award-winning line of solar panels. The iconic Twin design of the REC Alpha Pure Series splits the panel into two sections, reducing internal resistance and increasing power and reliability. The following 5 products are among the most relevant options for systems near the 405-watt range, featuring advanced cell technology, durable frames, and flexible mounting for RVs, boats, rooftops. When seeking high-efficiency solar solutions, a 405-watt class panel often balances space, output, and reliability for RVs, homes, shore-power, and remote installations. 5% of their labeled power output. The LG. Power (measured in watts) and efficiency (how well panels convert sunlight to electricity) are some of the most common metrics used to compare solar panel products.