Mark Sandeen, Chair
Sustainable Lexington Committee
Q: I’m planning to install solar power at home and I was wondering if I could use the solar power system to run my home during a power outage.
A: One of the wonderful things about solar power is how well it works with the utility grid. When your solar energy system produces more power than your home currently needs, you can pump that power out to the grid and your utility will give you a credit for the value of that electricity. When your home demands more energy than the solar energy system is generating, you can draw power from the grid to make up the difference.
Unfortunately when the utility power is out, your solar energy system still needs another energy source to act as a backup – a place to send electricity when the system is producing more power than you need and a place to pull extra power from when a cloud passes overhead. Your utility doesn’t want you to do that during a power outage. because it endangers line workers trying to restore power. So all solar installations must disconnect from the grid during a power outage.
One common backup strategy is to add batteries to your solar installation. Unfortunately the price of batteries hasn’t fallen as fast as the price of solar panels. That means a battery backup can easily add 30 – 40% to your overall cost of installation.
Another idea is to combine solar with a backup generator. This makes a lot of sense for buildings – like our schools and municipal buildings – that already have a backup generator installed. Properly designed backup generators disconnect from the grid during a power outage – operating like an island – and supplying all their own power. A well-designed solar energy system can easily integrate with your backup generator, letting the solar panels carry the load when the sun is strong and the backup generator picking up the slack during evening hours. The NY Times has an excellent article about a school that survived Hurricane Sandy by doing just that. http://bit.ly/solarbackup
Q: We’ve all been told that one of the first things we should do to lower our emissions is to replace our incandescent light bulbs. LED lights sound great, but have the costs come down enough to make them a viable alternative?
A: Yes, the price of LED bulbs has been dropping rapidly. LED light bulbs are the longest-lasting and most efficient mass-produced light sources to date. And now, they’re also among the most affordable, with some costing less than $10 per bulb.
They are a much better product than compact fluorescents. They turn on instantly. They are dimmable. They last 25 times longer than an incandescent bulb and 3 times longer than a CFL. They are more durable and contain no mercury. And best of all, they look great, providing warm natural light.
And LED bulbs save a lot of energy — from manufacture to disposal, an LED bulb uses 5 times less energy than an incandescent bulb and about 30% less energy than a CFL.
Plus LEDs can do things no incandescent or compact fluorescent bulb has ever done before. Some LED lights can be controlled over the internet or with your smartphone, allowing you to turn lights on and off remotely. You can set up presets like Home, Away, Night with schedules controlling light bulb groups and dimming levels, all with one touch. No more crawling behind the couch to plug in that timer before you leave on vacation.
Send your sustainability questions to questions@sustainablelexington.org. We look forward to hearing from you.
