Home > FAQ

FAQ

How much does a typical residential solar system cost?
How long does a solar system take to pay for itself?
Do the solar modules need to mount on the roof?
How long will a solar system last?
What does a typical solar module warranty cover?
What kind of maintenance does a solar system require?
Should I purchase a solar maintenance contract from my Solar Contractor?
Will a solar system provide power during an electrical power outage?How much roof space is needed for a solar electric system?
Will my solar system need to be inspected by the building department?
Can a modern home with stardard mechanical systems and appliances be powered by an off grid solar system?

How much does a typical residential solar system cost?
While system sizes can vary greatly, a typical residential solar system will have a post rebate cost between $15,000 and $40,000.

How long does a solar system take to pay for itself?
This depends on a number of factors including your current cost of electricity, the rate structure of your electrical service, the incentives available to you, and the cost of money on your investment. When paying cash, a typical residential system may see a simple payback in 8-12 years. If you are financing the purchase of your solar system, you may see immediate positive cash flow or you may initially see a slight negative impact on monthly cashflow when factoring the cost of the loan against the initial savings. As electrical rates increase, and with your loan payment staying fixed, you will eventually see positive cashflow, a break even point, and then a positive rate of return. Financed systems typically either see immediate positive cashflow or will attain positive cashflow within three years or so. How much space do I need for a residential solar system installation? Typical residential solar systems range from 3-10kW. Depending on the solar module, each DC kilowatt requires roughly 70 square feet of mounting area. So, for typical residential systems, you will need from 210 to 700 square feet.

Do the solar modules need to mount on the roof?
No. Though the roof is the most common location for mounting solar modules, they can also be mounted on the ground or in other architecturally integrated ways such as on walls or shade structures. Ground mounted systems tend to cost more than roof mounted systems because of the need for trenching, concrete footings and (typically) a steel sub-structure. Ground mounted systems are, however, viable and common.

How long will a solar system last?
The main component of a solar system, the solar modules, are typically warranted for 25 years but have a design life of over 40. There are modules still operating today that were manufactured in the 1970's. The inverters are typically warranted for 10 years. It is not certain how long they may last beyond their warranty period. A conservative set of assumptions when considering the long term financial performance of your system is to figure the performance at 30 years with the replacement of the inverters at year 15. The inverters may represent roughly 10% of the post rebate cost of the system depending on system size, configuration and system installation cost.

What does a typical solar module warranty cover?
Solar Modules are typically warranted to produce up to 80% of their original capacity up to 25 years. Different manufactures warrant the production degradation on different schedules. When comparing solar module warranties, read the warranties to determine which has the better coverage.

What kind of maintenance does a solar system require?
Washing the solar array with water a few times a year is a good idea but not strictly critical.  Most good solar designers have factored the effect of seasonal dust on your projected system output over time. Occasional visual inspection of the array is wise in order to identify any serious soiling of the array such as significant bird droppings or other types of opaque soiling. Checking the integrity of mechanical and electrical connections, checking the electrical characteristics of the system and logging data are other good annual maintenance practices.

Should I purchase a solar maintenance contract from my Solar Contractor?
A maintenance contract with your solar contractor is a good idea to insure the continued optimal performance of your system. In addition to a thorough visual inspection of your system, a solar maintenance contractor can check mechanical connections, perform a re-torque of all electrical connections, take voltage readings of the individual PV strings in your system to confirm proper voltage and performance, and log cumulative data from your inverter(s) to keep and compare performance records for your system.

Will a solar system provide power during an electrical power outage?
Most grid tied solar electric systems do not provide electrical power during electrical power outages. As a requirement of a grid tied inverter's safety listing, it must shut down in the event of grid power loss. Backup power systems can be designed into a grid tied solar system with the addition of a battery bank and a battery powered inverter. This option adds complexity and expense that should be weighed agaist the benefit of having backup power.

How much roof space is needed for a solar electric system?
Depending on which solar module is used, each DC (namplate) kilowatt of PV will require roughly 85 square feet of roof space. So, a 4kW solar system will require roughly 340 square feet (4 x 85' = 340 square feet).

Will my solar system need to be inspected by the building department?
Solar systems that receive government rebates typically require proof of approval from the building jurisdiction. Also, generally all electrical construction requires inspection from the building authority.

Can a modern home with stardard mechanical systems and appliances be powered by an off grid solar system?
Yes. Off grid solar sytems can be designed to power any home with modern systems and appliances. Though special appliances are not required, it is typically prudent to avoid any form of electrical heat such as electical space heating or water heating and to rely on gas for providing energy for heat. Such gas heated systems (as well as electrical heating) can also be assisted by solar thermal collectors.

Residential solar panels for home