When sourcing solar lights, you must prioritize Luminous Efficacy (lm/W), Battery Capacity (mAh/Wh), and Solar Panel Conversion Efficiency. High-quality units should feature Monocrystalline Silicon panels with a conversion rate of over 21%. For the battery, Lithium Iron Phosphate (LiFePO4) is the industry standard due to its 2,000+ cycle life and thermal stability compared to standard Ternary Lithium batteries. Ensure the IP Rating is at least IP65 for outdoor durability against dust and heavy rain.