Why Solar?
Back in the good old days (30 years ago), Real Goods approached environmentalism by educating as many people as possible as fast as possible about new renewable energy technologies and the wisdom of simple processes like recycling, composting, natural building, and resource conservation. The abundance of new energy resources and dialogue in the media today has finally opened the eyes of millions of people to the possibilities of FREE renewable energy from the sun. As opposed to wind or hydro power, solar power generates electricity at peak times—when the grid needs it most. This is good news for saving on your electricity rates, and good news for 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 30 years –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 IRR over 25 years in most cases averages around 15-25% — 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.
Within the solar renewable category, the term solar energy may refer to many different types of systems - photovoltaic systems, solar thermal systems, passive solar systems - leading to a fair amount of confusion about exactly what one means when one refers to “solar.” Real Goods Solar designs and builds solar photovoltaic systems - that is, systems that convert solar energy directly into electricity. If you are looking for systems that convert solar energy into heat (for example, to heat your pool or your shower via the sun), or if you are looking for systems that collect solar energy throughout the day and release it as heat during the night (passive solar), you can find out more information by visiting our green lifestyle catalog at www.RealGoods.com.
How Solar Works on Your Home
When people refer to solar electricity, most often they are referring to a “grid-tied” system, which means it is tied in where your home connects to your utility electrical grid. The wonder of these systems is that the electrical “grid” of your existing electric 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 off line. This all happens automatically and silently, so you don’t even have to think about it.
The most common system is mounted directly onto your roof, but if you do not have enough roof space, there are a variety of other ways to install a system utilizing the land or other structures on your property.
Solar panels are made up of crystelline photovoltaic (PV) cells, which convert sunlight into DC (direct current) power. However, your home runs on AC power, so the DC current from the solar panels is sent to an inverter, where it is converted into AC (alternating current) power. AC power travels from the inverter to the electrical panel, or breaker box, as it is commonly referred to. Your home is interconnected with the utility grid, and all electricity flows automatically. On sunny days, you will be feeding the grid. And at nighttime or in winter, you will be pulling from the grid. Depending on the size of your system, you may even have credit at the end of the year!
Powering Your Home
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PHASE 1 : ABSORBThe solar photovoltaic modules absorb the energy from sunlight and generate direct current (DC) power. |
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PHASE 2: CONVERTThe Inverter converts this power into high quality AC electricity for connection to the utility. |
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PHASE 3: PROFITNet-Metering allows your meter to spin backwards and "bank" excess energy for later use. |
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PHASE 4 : ENJOYYou are living independently solar powered by the sun! |
Types of Solar Electric Systems
There are three general types of Solar Electric Systems that you may have seen around the Santa Cruz and Monterey Bay areas: The "grid-tie*", "grid-tie with battery back-up" and "stand-alone" systems. Independent Energy Systems installs all three types for our residential and commercial solar clients, depending on their specific needs.
Grid-Tied Solar Electric Systems
Grid-Tied solar electric systems are the most efficient type of system and the least costly, making them the most common. A standard grid-tied solar system does not have battery backup. The system consists of photovoltaic solar modules and an inverter. The modules, which can be mounted either to an existing roof or on a ground-mounted structure, convert the sun’s energy into direct current (DC) power. The Inverter takes the DC power from the modules and converts it to high quality alternating current (AC) electricity, which is compatible with your home and the utility. The inverter is then tied into your electrical breaker panel allowing you to use the sun’s energy to power your home or business. Grid-tied systems must be connected to the utility to function; therefore they do not operate during a utility power outage. Find out how it works.
Grid-Tied with Battery Back-Up Solar Electric Systems
Grid-Tied with Battery Back-Up solar electric systems differ from straight grid-tie systems in that they have a battery bank and will continue to operate when there is a power outage. They operate in conjunction with the grid just like a grid-tied solar electric system, but if the power goes out your solar electric system will continue to power critical circuits in your home. Battery Back-up solar electric systems are less common due to the higher cost of installation, and the fact that such a system is not as efficient as a straight 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, however instead of tying into the local utility they function independently from the grid. They are used for properties where utility power is not available, 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.
Net Metering
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 PG&E, 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. Independent Energy Systems 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.
For more information on how Net Metering works for solar systems in the Santa Cruz and Monterey Bay areas, please contact us.
