Updates specific fields of an existing solar system design.

Business Context:
Design updates are common throughout the project lifecycle as systems
are refined through engineering review, customer feedback, equipment
availability, and performance optimization.

What Can Be Updated:

Design Specifications:

• System size and performance metrics
• Annual production and offset calculations
• Annual Solar Access (ASA) shading analysis
• Design name and version tracking

Design Status:

• Primary/secondary design designation
• Design source and origin tracking

Update Triggers:

• Engineering Review: Refined calculations and specifications
• Equipment Changes: Updated product availability or selection
• Site Conditions: Revised shading or structural analysis
• Customer Requests: Size or aesthetic modifications
• Utility Requirements: Interconnection size restrictions

Primary Design Changes:

• Setting isPrimary=true promotes design to active status
• Previous primary design automatically becomes secondary
• Primary changes may trigger financing recalculation
• Customer approval may be required for significant changes

Business Rules:

• Designs attached to submitted projects may have update restrictions
• Primary design changes may require customer approval
• Equipment updates may affect procurement and scheduling
• Projects must be in "new" status to allow design updates
• If a project is already "in_progress" or later, create a new design instead

Common Use Cases:

• Design version control and iteration tracking
• Performance optimization and refinement
• Equipment substitution and availability updates
• Customer-requested modifications
• Engineering review and approval workflow