This study entailed investigations on the current status of monitoring systems or platforms that provide important operating data usable as reference data in the design stage of photovoltaic (PV) power generation facilities. Thus, insights into the operating characteristics of such facilities were gained. This survey of the literature identified the features, namely, ‘renewable energy cloud platform,’ ‘renewable energy integrated monitoring system (REMS),’ and ‘public data portal’; a quantitative analysis was performed using the obtained dataset. The quantitative analysis confirmed that inaccuracies and data errors occasionally occur in individual monitoring systems. Nevertheless, by using a large amount of high-accuracy long- term data, a clear standard for daily operating hours, which can be the most important data in the design of PV power generation facilities, was devised.