Options:

• Metal
  • - Construction not particularly environmentally friendly
  • + Lifetime construction
  • $7-10 / sqft
• Composite
  • + Highly resistant, low maintenance
  • $8 / sqft
• Rubber
  • + Durable, low maintenance
  • - Higher installation cost
  • $6 / sqft
• Solar
  • + Generates electricity
  • - High cost, more complicated
  • $22 / sqft
• Green
  • Intensive (> 6 inch depth) or Extensive (1.5-6 inch depth)
  • + Good insulation
  • + Easy to install
  • + Absorbs runoff
  • - Expensive
  • - Heavier, requires extra reinforcement
  • - May require more maintenance and building in roof access
  • $25 / sqft for extensive, $30 / sqft for intensive

Try going with building an extensive green roof, probably needs to be done on a slope for snow. Solar roofs are a nice idea but probably simpler to keep power generation separate. If green roof is not pratical for the area go with Rubber. Use metal fascia and soffit.

Cost: $22,500 = $25 / sqft * 900 sqft

References:

• Ecohome roofing materials
• Tesla solar roof
• Tesla roof pricing
• 6 Green roof myths busted
• Winter maintenance for green roofs