Photovoltaic Roof Design
Designing and specifying a commercial photovoltaic system involves a number of additional steps compared to designing a basic roof system. We use standard roof design techniques and integrates the photovoltaic system with the roof design. Solar PV systems can generate power for up to 30-years, so roof service life is an important design consideration.
Ideally, you want a sustainable roof system with a service life to match the solar PV system. Existing roofs have a limited performance life and must be upgraded or replaced, otherwise at some point in the future, the PV system must be disassembled, the roof replaced, and the solar PV system reinstalled.
If the existing roof is in good condition, we have developed a patent pending roof system that integrates high performance elastomeric coatings with thin film photovoltaic systems. The key advantage is the roof system can be re-coated in the future, balancing the roof service life with the PV modules. In new construction or with a complete re-roof, you want to design a 30-year roof system to match the long 25-30 year performance life of the photovoltaics..
The up front cost of solar can be addressed with a number of funding methods, so financial options play a key role in developing a successful solar PV system. You have many options to consider and we help you the owner to determine what options makes economical sense for your project.
Phase I - Preliminary Roof Information for Photovoltaics
- Roof type and number of existing roofs
- Age of roof and current condition
- Perimeter details
- Core cuts
- Photos of roof with major roof details and site conditions
- Moisture survey may be required
- Roof plan with all roof top details (drains, curbs, pipes etc)
- Goggle satellite photo of building and surrounding buildings
- Building site location
- Building solar orientation
- Identify shadow obstacles
- Identify solar access (Solar Isolation)
- Ceiling space and wall structure access for wiring system
Phase II - Preliminary Power Analysis Data
- Utility Bills (highest bill per quarter min.) for the past two years.
- Usage pattern with Peak, Part-Peak and Off-Peak usage, summer and winter
- Demand charges
- Current and future electric rate schedule, factor in tiered rates and time-of-use utility pricing and annual rate inflation
- Inventory list of major appliances and other high ampere drawing equipment (seasonal/non-seasonal)
- Locate and inventory existing electrical services (photos)
Phase III - Information Processing and Preliminary Design
- Electrical load analysis, determine building power requirements (Total Peak KW)
- Module type
- Array sizing Calculate array size requirements (KW)
- Array layout (module size based on roof area and equipment locations)
- Wiring system design (voltage drop , safety building code, NEC code and environment)
- Combiner locations
- Controller specifications (size ) (battery back up system only)
- Inverter Specifications (size)
- Utility-Interactive System design (size)
- Budget, financing and cost analysis
Phase IV - Bid Documents & Bid Process
Provide installation contractor(s) with following information
- Approved Roof Plan and roof system specifications
- Approved Array Plan and specifications
- Approved Wiring Plan and specifications
- Approved Controller Plan and specifications
- Approved Inverter Plan and specifications
- Utility-Interactive System design
- Contract documents
- Document review
- Place RFQ
- Pre-Bid Meeting
-
Phase V – Project Bid and Contractor Review
- Review contractor bids and bid submittal documents
- System cost
- Operating cost
- Operating Profits
- Operating Losses
- Net power savings
- Lifecycle power savings
- Tax credits
- Capital depreciation
- Rebates
- Return on investment (ROI)
- Equity/property value increases
- Property resell value
- System payback period.
- REC (green tag) income
- PBI’s (performance based incentives)
Phase VI – Project Financing
- Coordinate the preparation of application documents with owner and contractor for tax credits, performance based incentives, REC’s with the utilities and with state, regional public agencies.
- Work with capital leasing, tax exempt leasing or power purchase providers if these funding options are used.
Phase VII - Construction
- Coordination with installation contractor
- Periodic site visits to review conformance with project and construction documents.
- Prepare progress reports for owner
- Review change orders
- Assist contractor with commissioning process of solar photovoltaic system
- Final inspection with roofing and solar system manufacturers