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Top-tier medium & high voltage designs for solar and energy storage systems

Leveraging its over 25 years of utility engineering experience, Castillo Engineering has honed its deep technical expertise in the design and engineering of medium & voltage interconnections from distributed solar power systems to the utility grid. Castillo Engineering is licensed in all 50 U.S. states and Puerto Rico and has been able to consistently deliver safe and high-quality interconnection designs that are fully compliant with national, state and local codes as well as each electrical company’s unique requirements.

Schedule a meeting with one of our solar and storage experts

Our Medium & High Voltage Construction Plans (IFCs) Include:

All Castillo Engineering Design to Permit packages include:

1. Interconnection design
2. Substation design (if applicable)
3. Single line diagram
4. Equipment specifications
5. Short circuit study

6. Coordination studies

7. Arc flash study

8. Relay settings

9. Surge arrestor specifications


Castillo Engineering’s long-standing utility relationships across the country combined with 25+ years of medium & high voltage interconnection design experience containing the most current utility regulations have resulted in the firm’s 99 % first time permit approval rating record. By ensuring that utility interconnections are approved as efficiently as possible, EPCs and developers can move forward with more projects in less time, resulting in greater returns on investments.

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