When sourcing solar garden lights, you must prioritize the Photovoltaic (PV) Conversion Efficiency and Battery Capacity. Look for Monocrystalline Silicon panels, which offer efficiency rates of 19-22%, compared to cheaper polycrystalline options. Ensure the battery is Lithium Iron Phosphate (LiFePO4), as it provides over 2,000 charge cycles and better thermal stability than standard Li-ion batteries. Additionally, verify the Luminous Efficacy (measured in lumens per watt) to ensure maximum brightness with minimum energy consumption.