“Guerilla” Solar Installations Discovered, Need To Be Controlled, Says Philippine Power Distributor

The Manila Electric Company (Meralco), the Philippines’ largest private electricity distributor, has raised concerns over the rapid growth of unregistered rooftop solar installations, commonly referred to as “guerrilla solar.” These systems operate without formal approval or oversight, posing significant challenges to grid management and safety. Meralco is urging government agencies to tighten technical standards and enforce stricter certification and accreditation requirements for solar equipment and installers to better regulate this expanding segment of distributed generation. Meralco estimates that while over 20,000 rooftop solar systems are officially registered with a combined capacity of around 170 megawatts, an additional 370 megawatts exist in the commercial sector alone without formal registration. Independent research indicates that roughly one-third of solar rooftops in Meralco’s service area fall into this unpermitted category. The primary technical concern relates to the use of inverters lacking internationally recognised safety features, such as anti-islanding protection, which is critical to prevent electricity from feeding back into the grid during outages and endangering utility workers. The proliferation of these unregulated systems stems largely from the high cost and complexity of formal solar installation processes in the Philippines. Retail electricity prices are among the highest in Southeast Asia, making solar an attractive alternative. However, official installations often involve significant compliance costs and lengthy permitting procedures, pushing some consumers and contractors to seek cheaper, informal routes. Although many guerrilla solar setups use standard photovoltaic panels and inverters, their connection to the grid without proper metering and approval leads to issues such as inaccurate energy accounting and potential violations of service agreements. From a grid perspective, the widespread presence of unregistered solar installations complicates load forecasting and voltage control. Distribution networks are designed based on predictable demand and generation patterns, but invisible rooftop generation can cause voltage fluctuations, harmonic distortions, and reverse power flows. These effects can accelerate equipment wear and increase the risk of outages. Moreover, safety risks arise when lineworkers cannot be certain that circuits are fully de-energised during maintenance due to undetected backfeeding from these installations. Meralco’s stance highlights the need for a balanced approach that supports solar adoption while ensuring grid reliability and safety. The company backs legislative amendments aimed at streamlining net metering and improving regulatory frameworks. The scale of the guerrilla solar phenomenon also points to underlying policy and regulatory shortcomings, such as cumbersome approval processes and inconsistent local rules, which must be addressed to integrate distributed solar more effectively into the Philippines’ power system.