Grid-tied photovoltaic systems – or PV, use solar panels to create electricity. When the sun strikes these panels, they generate direct-current, or DC power. This power then flows to an inverter, which converts the DC power into the alternating current, AC power used in your home.
If you’re running lights, computers, or other electric loads, your solar will power these loads first.
Any extra power your system makes you sell to the grid, generating a credit, which you can use whenever the sun is not out – at night or when it’s raining. At the end of the month, your credit bill will reflect either a positive credit from your solar electric generation or a bill reduced by as much solar electricity as you sold to the grid. Credits can be carried forward for a year.
With grid-tied solar electric, your home uses power just like it does now – no batteries or funny controllers. With a guaranteed environmental AND economic return on investment, solar power is one of the best investments you can make today.
Solar hot water systems work by capturing the thermal energy present in sunlight and turning it into usable energy in your home.
When solar hot water collectors (either flat plate or evacuated tube style) on your roof are warmer than your water tank, a differential temperature controller activates a pump. This pump then circulates a nontoxic antifreeze mix up to the solar collectors on your roof, where the fluid heats up.
This solar-heated fluid is then pumped to a super-insulated storage tank, where it gives off its heat as it passes through a heat exchanger. It is then pumped back to the roof, continuing the cycle as long as the sun is out.
Should there be unexpectedly high solar thermal gain (or should you be away), the system is designed to automatically go into an overheat protection mode called “Steamback.” Once a certain temperature threshold is hit, the solar circulating pump stops circulating fluid and the fluid present in the collectors turns to steam and fills an expansion tank. The copper elements of the solar hot water collectors are not harmed by high heat and will reach high temperatures until the end of the day. After the system has cooled overnight, the differential temperature controller will reset and allow the system to start running normally the following day.
From May to September, all of the hot water a household uses for washing dishes, clothes or taking showers will be provided by the sun, even on cloudy days. In the darker months of winter, the sun will still help out, but a backup unit – such as a boiler or electric element – will run to ensure a steady supply of hot water. Instead of running all summer, a home’s boiler will only fire up as a backup unit to heat the second coil in the upper part of your tank.
Overall a typical system will produce about 80% of a home’s water heating needs.
Just up the road from our Portland showroom is Oceanview at Falmouth, a unique retirement community that makes smart growth a core part of its mission. Solar hot water is a major part of that smart growth.
Since 2007, Oceanview at Falmouth has installed numerous solar hot water systems, including:
360 tube array on Hilltop Lodge
12 flat plates on Falmouth House
Heliocol collectors for their pool
14 collectors instaled on their newest expansion to the Main Lodge
We visited as part of our ongoing Solar Road Tour, taking the opportunity to speak with Oceanview’s Sales & Marketing Manager, Gloria Walker, and resident John Radebaugh, M.D. We learn a little bit about Oceanview’s environmentally-minded vision of growth and how solar hot water is a crucial part of that vision.
Solar Thermal A Clear Environmental and Economic Winner
Chris Wasileski, who works in Seacoast Management’s Development Office, took some extra time to speak with us about the big picture of solar energy in our world.
“We have always been interested in solar energy, from both a social and environmental standpoint, but for it to work as a business there needs to be a solid case on the side of economics,” he says, “This sweet spot is what has lead us to invest in so much solar hot water over the years. We found that solar thermal offers great payback and great potential – there are strong incentives and rebates, which when combined with impressive fuel savings have made these investments clear winners for us.”
After partnering with ReVision on nearly a dozen projects, Chris says his experience “Has been very easy, ReVision is my go-to firm for solar hot water. They are as critical to our business as the plumbers we work with.”
In addition to saving money, solar hot water helps Oceanview achieve a greater vision of raising awareness of fossil energy alternatives and encouraging their adoption. “By having these systems all over our buildings, we’re showing our customers, clients, and staff that we believe in solar energy, and help them to believe in it, too. Since the Carter era, the biggest question mark with solar has been whether it is cost feasible, and I believe we’re showing that it is. We look forward to a renewable energy future for everyone.”
Big thanks to Oceanview for letting us tour the facility, and to Dr. Radebaugh for sharing his story with us. Stay tuned next month for our final leg of the road tour for 2011, which sends us up to Midcoast Maine.
Miss Solar Road Tour Episodes?
We’ve had a lot of fun touring Maine and New Hampshire on our journey. Prior videos on our blog:
Our Solar Road Tour takes us a little further up the coast, where we visit The Highlands in Topsham, a unique retirement community with a strong environmental commitment.
In 2007 The Highlands installed what was Maine’s largest solar hot water system at the time, a 540 evacuated tube system expected to pay for itself in 6 years due to its dramatic reduction in fossil fuel use. The Highlands expanded this year with 24 flat plate solar hot water collectors on their Maine Lodge.
For The Highlands, solar hot water is a win-win: the collectors save their business thousands of dollars a year in fuel costs, while helping to preserve the memorable local environment that appeals to their residents. In this video, we talk to Highlands Sales Consultant, Don Wessels, as he tells us a bit about the system, its value to Highlands, and their commitment to sustainability.
In the second half, we check out a sizzling 48 flat plate solar hot water array on top of Bowdoin’s Thorne Dining Hall… you can see system performance for Thorne (as well as many other campus buildings) online!
Miss Solar Road Tour Episodes?
We’ve had a lot of fun touring Maine and New Hampshire on our journey. Prior videos on our blog:
In this edition of the Solar Road Tour we head to Southern Maine Community College (SMCC) located on a sun-drenched peninsula of Casco Bay, where from the front of the new SEA Center you can see alternative energy technology on display, juxtaposed with a view of oil tankers coming into Portland Harbor in the distance.
We talk to John Brautigam, program director, about SMCC’s dedication to training students how to install the renewable energy technologies of the present and future. A diversion then takes us to Scratch Baking Company where we have the ultimate delight: the solar cupcake.
Farming and gardening is, of course, the original use of solar power, but the Maine Organic Farmers & Gardeners Association (MOFGA) went the next step and installed the 21st century evolution: an 11.7kw solar photovoltaic array. This grid-tied system has no moving parts, no batteries, just fifty-two Solon Blue 225 watt panels tied to two inverters that will convert sunshine into electricity for the next several decades.
This 21st century system marks the latest step in the restoration of a 200 year old barn – a true symbol of old tradition meets new technology! This unique and highly visible project was a great opportunity for some video coverage, and in this 7-minute feature we hear from Vernon LeCount from MOFGA and John Luft from ReVision Energy’s Liberty office about the installation and MOFGA’s long-term ambitions about renewable energy.
MOFGA provides year-round services to organic farmers and gardeners, but they may be best known for their big upcoming event: the Common Ground Fair to be held this September 23-25. The fair is the premiere celebration of rural traditions and sustainable living and attracts over 60,000 people each year.
We’ll be there the whole weekend with staff from all three branches. Be sure to keep an eye out for the new PV system as you approach the south parking lot, and talk to us about any questions you’ve ever had about solar, energy efficiency, and green building.
Thanks again, MOFGA, for making a big commitment to sustainable energy, and to Darryl Czuchra Production Services, who went above and beyond in the creation of this video.
More Photos in Our Commercial Solar Photo Gallery:
Thought you couldn’t build an apartment building in Maine without depending on fossil fuels? Think again! Paul Ledman proves with his new 3-unit dwelling in Portland that exceptional insulation and smart mechanical systems can work to make a home that requires no source of energy other than the sun… even in Maine! Even with tenants!
We’re proud to have this exceptional building in our backyard and thank Paul for taking the time to talk to us about this exciting project.
