Solar FAQs
What is solar electric/photovoltaic (PV) power?
Solar electric or photovoltaic (PV) power is a term used to describe the process of converting sunlight into electricity using solar cells. These cells are constructed from semiconductor materials and are grouped together to form a solar module. Modules are typically enclosed in a glass to protect them from the elements and mounted in a frame to provide strength and a means of attachment. Most home systems consist of 10-30 modules connected together to form the solar PV system.
How do solar cells work?
Solar cells are (semiconductor) solid-state devices (no mechanical action) in which photons (or packets of light) collide with atoms transforming the resulting energy into electrons. These electrons flow into wires that connect all the individual cells in a module and all the modules in a system.
What happens to electricity flowing from the solar PV system?
The electric current that flows from the solar PV system passes through an inverter which converts the direct current (DC) to alternating current (AC); the type of electrical energy used in the home.
What is a complete solar (PV) system?
A Solar PV system typically consists of solar panels, an inverter (to convert electric power from DC to CA), wiring (to collect the electricity from each of the panels and feed it to the inverter and meter), mechanical support structure (to hold and attach the panels) and an electric utility meter (to measure the performance of the system).
How flexible is the solar PV system sizing?
Solar power offers modularity at any scale which makes it ideal for on-site locations. As systems are increased in size, they will require additional inverters and wiring to cope with the electrical load. Systems can be sized to power small single family homes or scaled to industrial applications.
What maintenance is required for a solar PV system?
There are no moving parts on a typical solar system and so very little maintenance is required. The solar modules require cleaning every few months to ensure that dust is not blocking sunlight from reaching the panel. This can be achieved by rinsing the panels with water; a good rainfall achieves the same goal. Some commercial solar PV systems have tracking systems which enable the solar panels to follow the path of the sun throughout the day (to improve performance). These types of systems need additional, regular mechanical maintenance.
How long do solar PV panels last?
The average solar panel will last approximately 30 years and many manufacturer warranties last for up to 20-25 years.
What happens on days when the sun is not shining?
The number of daylight and sunlight hours in a day impacts the performance of a solar PV system. On days when it is overcast or raining, electricity will need to be purchased from the local utility. When your installer is designing your system, he/she will take into consideration historic annual climate/sunlight information (that is available from a number of government and private sources) for your region. The system should be balanced such that credits accumulated (with the utility) during the summer months will offset the cost of electricity purchased from the utility in the winter months.
What is Net-Metering?
Under net metering, a residential consumer receives credit for the excess electricity that is generated by the solar system (during midday in the summer months when the sun is strongest) and which is fed into the local utility grid. These credits can be utilized by the consumer in the evening when the solar PV system is not generating electricity, or during the winter months, when weather often reduces the performance of the system.
What sized solar PV system do I need?
The size of the system depends on individual household energy usage, and whether you want to completely replace the local utility with a solar PV system. Here is a quick way of assessing your system size:
- Total up your kilowatt (kWh) usage for a year (see your utility bill). For a small single family home the number would be approximately 4,000 kWh (annual usage)
- Divide by the number of days in the year (365): 4,000/365 = 10.95 kWh (average daily usage)
- Divide by the number of daily average sun hours for your location (5.5 in sunny locations): 10.95/5.5 = 2 kW (system requirement)
- At $9.00 per watt installed the raw cost of the system would be $18,000 assuming no rebates or other incentives
How long does it take to install a system?
It will typically take 1-3 days to fully prepare a site and install the system.
Where should the solar PV system be placed?
Ideally, the solar panels should be mounted on a roof, building or piece of land, where the panels have maximum amount of unobstructed sunlight. This is typically on a tilted, south facing surface where the solar panel is perpendicular to sunlight.
Does temperature affect solar PV panels?
Yes - solar panels work more efficiently in cooler weather although they are designed to withstand the harshest summer conditions. High (altitude) desert regions are optimal.
How efficient are solar panels?
Commercially available solar panels are approximately 8-15% efficient at converting sunlight to electricity.