SolarTech Inc. and WindPower Ltd. are two key players in the renewable energy sector. Over the past five years, SolarTech has experienced steady growth, with its stock price increasing by 80% and capturing a larger market share in solar panel manufacturing. Conversely, WindPower's performance has been more volatile, reflecting fluctuations in wind energy demand and regulatory restrictions.

Analyze the recent performance of SolarTech Inc. and WindPower Ltd., discussing the factors contributing to their growth and volatility. Evaluate the investment opportunities and risks associated with each company.