Solar Facts and Questions

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  1. The sun provides free energy every day. The solar panels convert this energy into Direct Current (DC) electricity which is then sent to the inverter. 
  2. The inverter converts the Direct Current power from the PV array into Alternating Current (AC) electricity for your home.
  3. Sometimes the solar array will produce more energy than you use – when this happens the excess energy will be sent to the utility company and the electric meter will spin backwards.
  4. Solar energy produces high quality energy – this reduces the probability of energy fluctuations that could damage the electrical equipment. 
  5. Thanks to the meter, solar power is provided during non-sun hours and during times when demand exceeds solar production. 
  6. A monitor allows you to see how much energy your system is making with a display or web-based monitor.

What system type best balances my budget>goal>space?

The three limiting factors to every system design are budget, customer goals, and available space. Space for a system on a roof or in a yard is usually pretty hard and fast. Budget and goals are generally more flexible from customer to customer. Consider the following system types to determine which best fits your needs.

Grid-Tied Systems

  • Most budget friendly.
  • Great for maximizing net-metering.
  • Easiest installation.

Battery-Ready Systems

  • Still maximizes effects of net-metering.
  • Helps plan for a switch from net-metering to net-billing.
  • Provides quickest and most economic path to add storage. 
  • Good choice when budget doesn’t allow full storage upfront, but customer is determined to add storage at a later date.

     

Battery Storage Systems

  • Great option to run critical loads for those who lose utility power often.
  • Helps REMC or other net-billing customers manage production push to grid.
  • Allows for self-consumption to keep utility bills lower.

At GAI, we’ve been installing solar in the Midwest for more than a decade. Based on the “interesting” times we’ve had squirming through attics, crawl spaces, and basements, and running wires on top of or behind finished walls, we have experience-based advice we can offer that will make your new home take to a PV solar installation as easily possible. 

Here are some advantages and disadvantages to consider for a ground-mounted array:

Advantages

  • You can select the tilt angle and orientation.
  • You can keep the glass clean.
  • If service is required, it can be done more quickly and cost-effectively on the ground.
  • With the proper hardware, you can adjust the tilt seasonally. 
  • Lowest life-cycle cost (higher production, less maintenance cost).
  • If there are mature trees, the hardware can be moved out of the shadows.

Disadvantages 

  • It will take up space in the yard. 
  • It will be more visible (maybe a disadvantage, maybe not).
  • You may have to do landscape maintenance around it (for new construction, this can be part of your original landscaping – see GAI for suggestions).
  • Higher hardware cost up front. 

Looking strictly at performance and future energy production, ground mounts are our strong recommendation. However, if you can’t go with a ground mount, you’ll want to provide the best roof-mounted solution you can.

Here are some advantages and disadvantages to consider for a roof-mounted array

Advantages 

  • It’s out of the way.
  • It shares the structure of the building, so mounting hardware is less expensive.
  • Usually the best approach for small yards.
  • May be the only option allowed by some neighborhood associations.

Disadvantages

  • Tilt angle and orientation are not negotiable. 
  • Operating temperatures are much higher, also leading to lower energy output. 
  • You must remove them for any service to the roof (re-shingling).
  • Complex roof lines that are beautiful to behold may cast shadows on the array, and make wiring the system more complicated (expensive).
  • Mature trees or other shade obstacles near the house either have to be removed or some loss of energy production can be expected. 
  • Rooftop installations are difficult to clean and service.
  • In locales with squirrel (or other rodent) populations, rooftop panels can provide man-made habitat. 

Roof Layout

  • An optimum roof surface for solar faces south and includes a minimum number of architectural features such as dormers or multiple ridge lines.
  • The ideal south-face will be placed on the site so that it will not be shaded by trees or other structures. At a minimum, the hours between 9:00 AM – 3:00 PM should be unshaded if at all possible to maximize energy production. 
  • A roof pitch between 3-12 and 5-12 will make the most use of the solar resource available during the summer months. Roof pitches steeper than 6-12 start to sacrifice summer production and favor late-season sun angles. Steep roofs are also more difficult to work on in the event that service is required. 
  • Consider having harness tie-off points installed across the roof so all future work can be done safely. 

Roof Structure

  • A roof-top array will add up to 4 pounds per square foot of distributed dead load. The house designer should assure that the load-bearing ability of the roof can accommodate the load of that hardware in addition to the snow load of your region (in most of the Midwest, that is about 20 psf, higher in lake-effect areas). 

Roofing Material 

  • A PV array can be expected to have a 30-year life. If the array is roof-mounted, that longevity should be matched by the roofing.
    • Asphalt
      • Use long-life shingles. If the shingles need to be replaced, the array will have to be removed, then re-installed after re-roofing. 
    • Metal
      • Standing seam or trapezoidal metal roofing is preferred, since it will require no additional roof penetrations to mount the array. The roofer should be aware of the plan to mount an array and verify that they use appropriate fasteners in sufficient quantity to endure high winds. 
      • Corrugated or “exposed fastener” metal roofing is less desirable because it will require roof penetrations for mounting hardware. These penetrations will need to be well sealed. 
      • Decorative metal tile is a speciality surface and will add time and complexity to any rooftop installation. 

Electrical Wiring 

The following will future-proof a house for the addition of battery storage at some point in the future. Additional grounding or other approvals may be required by local code. 

  • Include two load centers
    • One for basic, heavy loads such as A/C, heat pump, pool pumps, jacuzzi, and other loads which are not required in a power outage.
    • One for loads which should run in a power outage (lights, security system, refrigerator, internet hardware, sump pump).
  • Allocate space in each breaker box
    • When wiring the service panels, reserve space for double-pole breakers at the very bottom of the box, one double-pole breaker on each bus bar.
  • Install an empty conduit from the service panel to the attic to accommodate a roof-mounted array.
  • If a ground-mounted array is preferred over a roof-mounted array, install the conduit to a junction box on an exterior wall closest to where the array will be located instead (if possible). This will allow a buried electrical line from a ground-mounted array to be routed to the service panel.
    • This will not be required if the meter base with integral breakers is installed. 

Inverter Mounting 

  • Inverters can be mounted outdoors or indoors. If outdoors, service calls and system checks can be conducted without requiring the homeowners to be present. Brackets generally are designed to be mounted onto studs at 16″ centers. Providing a flat surface near the meter for the mounting (without the contours of siding) would allow for more flexibility in locating an inverter on the wall. 
  • If indoors, allocate wall space near the main service entrance (by the breaker box, typically) to allow inverter mounting near the service panel. Ideally, this wall will be a plywood panel rather than drywall. 
  • Even for inverters mounted outdoors, a wire-way from the meter base or inverter mounting location should be provided. This will allow for inverter communication to a battery unit, which must be installed indoors near the load center.

What is Net-Metering? Check out our 3 minute video below to learn more. 

It is best to reduce your usage even before adding solar. You can do this through some simple and usually affordable efficiency upgrades. 

Heating and Cooling Systems

  • Replace old heating and cooling systems with Energy Star rated units.
  • Use a programmable thermostat.
  • Make sure filters are cleaned. 
  • Have systems inspected on a regular basis.

Insulation

  • Check to make sure there is adequate insulation in the attic and walls of the building.
  • Outlets, fixtures, and switch plates should all be insulated.
  • Windows and doors should be properly caulked and weather-stripped.
  • Install Energy Star windows and doors.
  • Make sure windows are double-paned. 
  • Windows and door frames should be constructed of wood, vinyl, composite, or fiberglass. 
  • Use storm doors for extra insulation. 

Other Air Leakage

  • Make sure fireplace dampers fit tightly. 
  • Kitchen, bath, and laundry exhausts should all seal tightly. 

Shading and Screening 

  • Use awnings and overhangs to shade walls, windows, and doors.
  • Block summer sun and winter winds with landscaping. 
  • Utilize shades and curtains indoors to block sun load.

Water Systems 

  • Check to make sure the water heater is an Energy Star appliance. 
  • Set back the thermostat on the heater when on vacation. 
  • Wrap hot water pipes and the water heater. 
  • Water faucets and shower heads should be leak free.
  • Use low-flow shower heads to save on water consumption. 

Lighting 

  • Switch to LED or CFL bulbs in light fixtures.
  • Turn off all lights when leaving a room. 

Implementing any of the above in addition to solar will cut your bills further!