First Solar stands out as the best long-term solar stock amid industry challenges and rivals' struggles.

First Solar outperforms Enphase Energy and SolarEdge Technologies as the top solar stock for retirement investors due to its strong financial health, consistent profitability, and stable cash flow. Despite regulatory challenges and tariffs impacting the U.S. solar industry, First Solar maintains a robust balance sheet with $9.54 billion in equity and growing operating cash flow. It also benefits from a large contracted backlog and a domestic manufacturing footprint that shields it from supply chain risks. Meanwhile, Enphase faces declining cash flow and tariff pressures, and SolarEdge struggles with losses and a weak balance sheet, making First Solar the most durable choice for long-term solar investment.