To help you get started, ROOFCORP has answered some of the most frequently asked questions regarding PV systems and other issues our clients encounter when they decide to go solar.
What is Solar PV?
Unlike a solar hot-water system that uses the sun’s energy to heat water, solar electric or photovoltaic technology uses the sun’s energy to make electricity. Electricity is produced directly from the electrons freed when sunlight interacts with the silicon in a solar panel. The electrons are collected to form a direct current (DC) of electricity.
A complete solar PV system usually consists of one or more panels connected to an inverter that changes the direct current to alternating current (AC) to power your electrical devices. Batteries sometimes provide back-up power in case of utility power outages.
How do I know how what size system I will need?
The size depends on a how much energy (in kilowatt-hours or kW-h) is needed, the system’s location, orientation and tilt as well as the available space and available funds. The first rule in sizing a PV system is to reduce consumption. Less consumption means a smaller and less costly system. Secondly, DON’T oversize your system. And finally, call for a consultation.
Solar PV systems range in size from 50 to 400 square feet. A system composed of high-efficiency cells will produce 1kW per hour for every 100 square feet.
What is a “net-metering grid-tie” PV system?
Net metering is the principle reason solar electricity has become economically viable. In California and other states, solar-power system owners may connect directly into the wires of their utility. This allows them to spin their meter backwards when their system generates more power than gets consumed. Thus system owners can “sell’ electricity back to the utility. Without “net metering,” you would be forced to “sell back” the energy at a lower or wholesale rate and buy it back at a much higher retail rate.
What is payback?
Payback is immediate. If you finance your solar-energy system, your monthly payments would typically cost less than the electric bill it replaces. A solar-energy system also adds value to your property, reduces your monthly expenses and protects you from rising energy costs. If you pay cash for your system, at today’s rates, you will typically recover all your investments within the next six to 10 years. As rates go higher, it could easily take less than five years to fully recoup your investment.
Aren’t solar panels and systems obsolete by the time they are installed?
Many people don’t install solar power just to save money on electricity. The average five- to 10-year payoff is a little daunting. Panel technology is improving, though the dramatic gains we hear about are still several years away. Still, investing the $500 to $1,000 paid each month to the utility company into a hard asset is a better use of money. And finally, it seems right for our area and time. The California rebates are decreasing substantially next year and the federal tax refund may or may not be around forever. Also, utility rates have been rising at a rate of more than 6% annually for the past decade with nothing but higher rate increases predicted for the future. In a nutshell, it’s time to go solar.
How do I know if my site will work for a PV system?
Solar designers look for sites that provide an optimal southern orientation, good exposure to the sun and an adequate amount of structural support and space for solar panels to be placed. The best location is on a south-facing roof, although an east-or west-facing roof might also work. Flat roofs are good with a variety of solar panels. If the space or sun exposure is limited, a system with a higher efficiency rating requires less room.
Can my Homeowners Association (HOA) place restrictions on the installation of a PV system?
No. In most states, legislation prevents homeowner associations from blocking improvements that save energy.
Can PV systems produce power on cloudy days?
Yes. Although a PV system may receive 80% to 90% less sunlight on a cloudy day, the panels can still generate electricity.
Do PV systems work well in the cold?
Yes. In fact, photovoltaic systems generate more power when the temperature is lower. Yet PV modules do generate less energy in winter than summer because of fewer daylight hours and the lower angles of the sun.
Are PV systems safe?
Solar panels are a quiet, non-polluting source of energy. Still, PV systems do generate electricity and should be treated with care and maintained with the assistance of a solar professional.
Is the “tilt” of my solar array important?
The optimum elevation angle for your solar system depends on your latitude. In general, the optimum tilt angle is equal to you latitude to ensure the maximum amount of sunlight over the course of a year. Even better would be to manually change the elevation of your solar collectors over the course of a year to follow the sun’s elevation in the sky.
Will my system have batteries?
Connected PV systems don’t need batteries but if the system is “off-grid” then batteries are essential for the storage of electricity so you can use electrical equipment when there is no sunlight.
What happens during a power outage?
With a grid-connected PV system, the inverter will automatically disconnect itself from the utility grid during a power outage. This prevents back feeding the grid and putting engineers working to restore power in danger. A grid-connected PV system with battery backup it will automatically switch to backup power. Both systems will automatically hook back up to the grid once power is restored.
What does the term TOU rate mean?
TOU is time-of-use rates. Each day is broken into four areas: Off-peak (base rate), morning part-peak, peak and afternoon part-peak. TOU charges can account for a large percentage of a utility bill and the assumptions used in these estimates may not be accurate for your particular situation. Solar energy can reduce average cost of electricity by taking advantage of time-of-use rates. Electric rates are usually higher during peak daytime periods. This is when solar energy systems produce peak output and can “spin your meter backwards.”
Does PV add to the resale value of my home?
PV “system resale value” for your home is based upon research published in the Appraisal Journal, which concluded that “the increase in appraisal value for a home is about 20 times the annual reduction in operating costs due to energy efficiency measures.”
How much will a system cost?
That answer depends not on the size of your home but rather what your average electricity bills are and how much you would like to offset. That dictates the system size and cost.
How long will my solar-energy system last?
Most solar panels come with a 25-year power output guarantee from the manufacturer and are expected to last at least twice that long. After 25 years, a solar panel produces at least 80% of their original power output.
How will the weather affect my solar electric system?
Solar electric systems are designed to withstand all weather conditions. Lightning, wind up to 80 miles per hour and extreme temperatures are all things your solar system can handle, although these conditions will temporarily reduce its energy production.
In business since 1985, ROOFCORP can work with your organization or business to help you determine if a photovoltaic roofing system is the right for you. We have the knowledge to tailor a system that meets your specific needs and recoups your investment. To learn more, contact us today.