Many of the benefits of solar energy are obvious — it provides clean power without burning fossil fuels, electricity-generating costs are pegged to a low, fixed rate (or potentially eliminated) and power from solar panels is generated most efficiently at peak times (when electricity is needed most). But there are other benefits, too. A photovoltaicsystem is also a sound financial investment with very low risk, and increases the value of your home dramatically. It all adds up to good news for your electricity rates, your home equity and a greener economy. It’s a win-win, no matter what moves you.
When you choose solar energy, you:
- Secure your energy independence and own your power! Lock in your electricity rates for 25 years or more — utility company rates have been steadily increasing by about 6.7% a year, with a 30% jump in the last three years alone.
- Make a sound investment. The pre-tax internal rate of return (irr) over 25 years in most cases averages 10-25% — far better and far safer than the stock market, bond market, money markets, and long-term cds.
- Increase your home's value by $20 for every $1 reduction in annual utility bills, according to the national appraisal institute. And, your property tax won’t increase even one cent.
- Become part of the renewable energy solution — the sun provides enough energy in one day to power the entire world for a whole year! It’s free, clean and renewable.
- In the field of renewable energy, the term "solar" can refer to different types of systems — photovoltaic systems, solar thermal systems, passive solar systems — leading to a fair amount of confusion about exactly what is meant when one refers to "solar." real goods solar designs and builds solar electric systems — that is, systems that convert solar energy directly into electricity.
How solar electric systems work:
Phase 1: absorb
Photovoltaic modules (solar panels) are made up of crystalline photovoltaic (pv) cells, which absorb sunlight and convert it into dc (direct current) power.
Phase 2: convert
Your home runs on ac power, so the dc power from the solar panels is sent to an inverter, where it is converted into ac (alternating current) power. The ac power then travels from the inverter to the electrical panel, or breaker box, where it is used to power your home. Excess electricity is fed into the utility grid.
Phase 3: profit
Net metering (available with grid-tied or grid-tied with battery backup systems) allows your meter to spin backwards and "bank" excess energy for later use. Depending on the size of your system, you may even have credit at the end of the year! See the section on net metering below for more details.
Phase 4: enjoy
You are living independently, powered by the sun!
Most systems are mounted directly onto your roof, but if you do not have enough roof space there are a variety of other ways to install them on your land or other structures on your property.
Types of solar electric systems
Grid-tied solar electric systems
When people refer to solar electricity, they are usually referring to a grid-tied system, which is a solar electric system tied in where your home connects to your utility electrical grid. These are the most efficient and least costly systems. They do not have battery backup, but the electrical grid of your existing utility is used like a giant rechargeable battery. The utility will buy power from you at peak and part peak rates during the day when your system is generating, and you will buy power from the utility at low rates during the evening when your pv system is offline. This all happens automatically and silently, so you don’t even have to think about it. Grid-tied systems must be connected to the utility to function; therefore they do not operate during a utility power outage. Grid-tied systems consist of photovoltaic modules and an inverter.
Grid-tied with battery backup solar electric systems
Grid-tied with battery backup solar electric systems operate in conjunction with the grid just like a standard grid-tied system but if the power goes out, this kind of system will continue to power critical circuits in your home. These systems are less common due to the higher installation cost and the fact that they are not as efficient as a standard grid-tied system.
Stand-alone solar electric systems
Stand-alone solar electric systems operate on the same basic principles as grid-tied with battery back-up systems, but instead of tying into the local utility, they function independently from the grid. They are used for properties where utility power is unavailable or very costly. A stand-alone system utilizes a battery bank to store the energy produced by the modules, allowing you to draw electricity even when the modules are not receiving energy from the sun. After being stored in the batteries, the dc power flows to the inverter, where it is converted to ac electricity for use in your home.
On a sunny day, depending on your energy consumption, your solar electric system typically produces more energy than you use. Rather than going to waste, this excess electricity is sent back to the utility via net metering.
Net metering (available only with grid-tied and grid-tied with battery backup solar electric systems) allows your meter to spin backwards so that you may "bank" your energy for later use. You will receive credit for this power at the same rate the utility sells it for. While you will receive a monthly statement from the utility, your actual electric bill will only arrive annually. This bill will reflect the difference between the amount of energy your solar electric system generated for the year and the amount of energy you consumed.
A properly sized solar electric system will generate only as much energy as you need. In order for net metering to be used, a series of steps need to be taken with the utility. Real goods solar will submit the net metering application, coordinate the authorization necessary to connect to the utility, and arrange for the final inspection of the system by the utility.