Grid-tied solar systems use photovoltaic (PV) panels to produce electricity. PV panels have been around for decades and the technology is very simple and reliable. The electricity produced by the solar panels goes to an inverter that converts it to power that you use in your home. When you are producing more electricity than you are using in your home the excess is sent to the utility grid. This excess is measured with your electricity meter, and gives you a credit on your power bill. Utilities require a net metering agreement to do this, and Fortis began offering net metering agreements in September 2009. With this agreement, the electricity you send to the grid is valued the same as the electricity you buy.
Grid-tied systems offer many exciting advantages:
- "make hay while the sun shines": Grid tied solar systems allow us to take full potential of every minute of sunlight by selling excess back to the grid. The credit is used to offset consumption when the sun isn't shining. It no longer matters when we make or use power - day or night, winter or summer.
- simplicity: Because Grid-tied systems don't need batteries it also means you don't need a charge controller and other components.
- efficiency: Without batteries to continuously trickle charge, the efficiency of grid tied systems is increased. The inverter and the wiring are really the only losses between your panels and your meter. Inverters are generally in the 90-95% efficiency range.
- ultra-low maintenance: There are no moving parts, no batteries to maintain and replace, no fluids to change, no levels to check, nothing. The maintenance comes down to rinsing the dust or leaves off of the panels with your garden hose. Or let the rain do it for you.
A safety feature of grid-tied inverters is that they shut down when there is a power outage. This is to protect utility workers servicing the power lines from being electrocuted by solar power feeding the grid. What this means for you is that when the power is down, your house will be dark like everyone elses. If the grid is unreliable in your area this may be an issue. Battery-backup grid-tied systems are available but add considerably to the cost (about $5000) and lose the advantages of simplicity, efficiency, and low maintenance of a normal grid-tied system. For most people the best solution is to outfit yourself with a box of candles and an emergency bottle of wine! A generator may even be a preferable to adding batteries to a grid-tied system if backup power is very important.
Here in the Kootenays we don't get very much sun in the winter months. That's ok with grid-tied systems - we can take full advantage of the long sunny summer days and build credit for the winter months. The amount of sun we receive yearly in this region is actually significantly more than many parts of the world where solar power is commonplace.
Costs and Grants
Livesmart BC provides a grant based on the size of the system that tops out at $1300 for a large system.
Today's Grid-tied products give solar designers a great amount of flexibility. Systems as small as one or two panels are now possible, and may be a great option as an awning or shade. A small system like this may cost as little as $2000 installed.
Larger systems can be sized many different ways. We can size a system to provide as much energy as your home uses in a year, or we can select a system that suits a particular budget amount. It's possible that the amount of shade-free roof space available or aesthetics may be an important part of the decision.
Keep in mind the difference between being 0% independent (100% reliant on the utility) to even just 3% independent is very profound. It's not necessary to aim for 100% independence with your first solar project and, in fact, it may be a good idea to start small. When you produce your own energy you will find you'll develop a more acute awareness of how you use energy. This awareness may motivate your household to adjust some of it's habits to reduce energy use - which is really the most important step of all.
Produce your own energy. Know where your electricity comes from, and know you'll be insulated from whatever happens with the price of utility electricity. Grid-tied solar PV.
More information on photovoltaics and Grid-tied systems is available on our resources page.