One of the best ways to size a solar electric system is to look at your utility power bill. On the NorthWestern Energy bill in the upper left hand corner there is a graph that tells you how much energy your home consumes on an annual basis. This information and quick view of your site (orientation and shading) enable the SBS Solar team to design a system with your needs in mind.
SBS Solar is super excited to show you the latest Habitat for Humanity of Ravalli Co home in Stevensville, Montana. This is an all-electric home with new energy star appliances, LED lighting and a very well insulated envelope.
With a $17,000 grant from NorthWestern Energy, SBS Solar was able to install a 30 module, 7.5kWh array with a grid tie inverter and an air source heat pump. We installed this system in December and made the final tie into the grid and installed a net meter on January 2nd.
As of this writing 5 months later, the system has made more power than what the home used thru the building process. We utilized electric, milk house, resistant type heaters to keep our workers warm and set the drywall mud. We eventually installed an air source heat pump in March, after the coldest period of winter.
Now that the family has moved in we will see how well all the systems preform and the actual electric usage. Depending on this power usage, we will see if they are actually netting the big Zero at the end of the year.
It was a lot of fun, and a honor, being part of the design and building of what is possibly the first net zero home in Western Montana.
This six module system was a bit different for the SBS crew. The owners have lived in this beautiful off-grid home perched on a knoll in the timbered Ninemile Valley for some time. For 13 years they have been happy with a solar/battery/generator system as it supplied all of the electrical needs. They had the opportunity to bring in grid power last year and shared the line extension cost with a neighbor.
This summer they suffered a lightning strike making landfall on two Ponderosa pines some 40 feet from the solar array. The surge of electricity blew the bypass diodes on the modules and the controller on the propane generator. Fortunately, it did not affect the batteries, the inverter or charge controller.
Since we now had grid power to the site and we were replacing equipment anyhow, the owners decided they wanted a grid tied, battery based inverter installed. This gives them the best of all power worlds in that they have batteries for emergency power and can also sell back excess power they do not need. Remember, standard off grid battery based systems receive a huge variation of power between summer and winter. In winter our light levels are low to where we can easily use all the power our solar arrays generate. Unlike summer when most off grid systems completely charge the batteries by early in the day and the solar modules are effectively turned off for the balance of the day. Not so when we include a grid connected inverter in the system. With this addition we can keep the modules operating at full generation and send this power back through the electric meter, creating credits for later use.
This in effect, gives us the benefit of annual storage of our solar power, something that solar enthusiasts have dreamed about, especially those who live in the Northwest where we have huge variations of insolation through the year.
We used the most advanced charge controller on the market (the Xantrex XW MPPT 80 600) capable of converting up to 550 volts DC from the array to battery bank voltages allowing us to use large strings of up to 12 modules in series. This was a huge benefit on this system allowing us to achieve less then 2% loss running four strings of 10 gauge wire on a 250′ home run instead of 12 strings of 4 gauge with a standard 150 volt max controller with a dramatic cost difference.
This is a great article… thought provoking with good information… suggesting that perhaps Solar Thermal is dead, unless you’re a laundromat or a college campus.
Now that PV rates have some down substantially, combined with various state and utility incentives, as well as federal tax credits, the article suggests it cheaper to heat w/ Solar PV rather than with Thermal.
We’ll followup to this post in a week or two with the numbers from Missoula and Montana so see if this actually makes sense in our area, or not.
Until then, enjoy the article… and let us know what you think in the comments below.
Our Energy Intern/Office Manager, Nick Bowman, recently gave this short talk for one of his classes at UM. We thought it made for an interesting blog post which has some talking points about renewable energy you might not have heard or might find interesting or useful:
Montana, with its huge potential for renewable energy, could do more to use its resources to help strengthen the economy.
Montana is currently ranked 22nd in the nation for the amount of renewable energy produced, yet has enough available resources to become 3rd in the nation if properly developed and invested.
Montana potential for wind is due to its topography. High mountains combined with spacious plains are perfect for developing wind farms. Wind Energy alone has enough power to produce 370 times the amount of electricity used by the state. Here is a great potential for economic growth.
In places where buildings are a barrier, as they decrease the amount of wind which can be harvested, we could use solar power to create renewable energy gains. We need to increase the monetary incentives for solar installation, particularly in light of the cancelation of energy grants by Northwestern Energy.
Montana is also one of 13 states which can produce energy from geothermal hot spots. The technology of geothermal is constantly improving and needs to be developed in order for this technology to be effective without compromising the environment.
Yet with all this in mind Montanas still spend 4.7 billion dollars to produce fossil fuels every year.
Increased implementation of green energy is only possible through the contribution of the average American who wants to better this great nation. Political activism, alternative energy advocacy and service are among the few ways which people can contribute to helping renewable energy succeed in this struggling economy. I would recommend that, if nothing else, each and every person reminds their representatives that they support sustainable energy.
Let’s make a difference.
(What follows is quite possible the best Solar PV testimonial we could ever ask for. With pictures! We hope you agree.)
401 South Orange St, Unit C
Missoula MT 59801
Dear SBS Solar:
I’m writing to share my great experience with your company and my 100% solar-powered home. In the fall of 2011, SBS installed a 24 panel, 6 kW, grid-tied solar PV system at my home in central Missoula. Because my house had additions, I don’t have one flat surface for the panels, so SBS hired subcontractors to design and install a covered back porch structure for the panels. I started producing all of my own power in the early spring and now in the summer am producing 50% morepower than I need. I will receive a credit for this extra power and it will mitigatethe power use in December or January when I might be producing as little as 30%of own my power.
I recently installed more efficient appliances, and thus I will probably producemore power than I use this year. This surplus of power led me to decide to lease a 100% electric car, which will be 100% solar-powered car for at least 6 or 8 monthsout of the year.
I felt compelled to act because we can’t afford to ignore the signs of climate change or the role we play in it. I feel a moral obligation to reduce my carbon footprint, to protect biodiversity and protect the planet for future generations. Can you imagine the reduction of coal and oil consumption we could achieve if every family in Western Montana had a solar-powered home and solar-powered electric car? Maybe mega-loads, tar sands mining, and Otter Creek coal mining would all become unnecessary. The technology is available and ready for this now inWestern Montana.
The cost breakdown for my solar system:
COSTS INCLUDING STRUCTURE:
Materials and installation for PV system: $28,570
New back porch structure:$8,640
Engineering of structure:$1,643
City building permit for structure:$285
Relocation of power/gas lines for structure:$3,605
Electric panel relocation:$620
Northwestern Energy Grant ($6,000)
Federal Tax Credit($11,208)
State Tax Credit($500)
NET Total including structure:$25,655
COSTS EXCLUDING STRUCTURE:
Materials and installation for PV system: $28,570
Northwestern Energy Grant ($6,000)
State Tax Credit($500)
Federal Tax Credit($8,625)
NET Total excluding structure:$13,625
So essentially, the solar system had a net cost of less than $14,000 for 100% annual power.
The system will eventually pay itself off and then the power I use in my home and the “fuel” I use for my car will be free. While this is certainly a meaningful reward, for me the bigger reward is knowing that my decision to choose an alternative to coal and oil is a concrete physical step toward a safer planet for future generations. As Terry Tempest Williams has said: “The eyes of the future are looking back at us and they are praying for us to see beyond our own time. They are kneeling with hands clasped that we might act with restraint, that we might leave room for the life that is destined to come.”
Thank you for the important work you are doing.
(contact info withheld to maintain customer privacy. Please contact SBS Solar directly for more information)
(click above to view video on our new YouTube channel)
We have finished our ballasted roof project from earlier this summer.
(This is continuation of Ballasted Part I.)
Before getting too far along, we realized we needed to replace the building paper with Colbond Enkadrain mat that allows the roof to drain under the entire racking system. Roofer Stan Howard specked this product, and this is the proper way to do any ballasted system. In this picture, the guys are using a table saw to cut this stuff – funny – sometimes you need to pull a MacGyver move on the job.
In this scenario we made sure to request information from UNI-Rac on how to attach the Enphase M-215 microinverters to the Unirac G10 rapidrac ballasted racking and attached them as specified to the brackets. From now on we will use WEEBs to bond the Enphase microinverters to our racking saving a lot of 6 gauge copper bonding wire.
Overall our team liked the rapidrac system and it went together surprisingly quickly. Hopefully we will have a chance to install it on a future job before the river rock ballast is put down. Learning Moment: having to manage existing rock is a large portion of the job.
This system is (4) separate arrays of 9 modules combined on the roof producing up to 8.4 amps at 240 volts AC each for a total of 8.1 kW AC. The system size is 8.64 kw – (36) 240 watt modules. The owner will need to install his internet service before we are able to monitor the system online. The system has already passed inspection and the Net Meter Agreement is signed and in the line up for having it installed. It should be activated when the net meter is installed so they can use the electricity produced from the array while they are finishing construction on the home.
What follows is a great Q&A with a recent install for Bert Lindler and Kristi DuBois:
1. Why did you decide to install solar panels?
When we first bought our home, we realized that the south-facing roof offered an opportunity for solar photovoltaic panels and solar hot water. We want to minimize our environmental impact and installing solar panels is one of the easiest ways to do so.
Kristi feels strongly that every south-facing roof is wasted space that should be generating electricity. Industrial forms of “green” energy like commercial wind and solar farms impact a lot of habitat for wildlife, or in the case of solar farms, replace the habitat completely with solar panels. Rooftop solar units have no effect on natural habitat, so they are a much greener way to meet our energy needs than industrial energy facilities.
We were considering refinancing our home to take advantage of low-interest rates at about the time we were reminded of the subsidies available for installing solar photovoltaic panels. Once we had the roof evaluated for solar power potential and had received a bid for the installation (along with an estimate of the subsidies), we knew we wanted panels.
2. Did you encounter any challenges during the installation process?
The first challenge for us was approval from the homeowners association for our installation. Our installer prepared drawings showing the appearance of the eight panels mounted on our roof. We took to the drawings to our immediate neighbors and discussed our plans. All but one of the neighbors were supportive and the remaining neighbor said that while he didn’t want to look at solar panels on our roof, he understood why we wished to install them and would respect whatever decision the homeowners association reached. The association’s architectural review board approved our request.
The next challenge was a couple of tall non-native trees growing in our yard. We were considering having them removed anyway, but did so promptly after we learned that they would shade the panels. We still have some shading in winter from our aspen trees, but the effects on our power production are minimal. We left the trunk of one of the trees standing as a wildlife snag.
3. How long will it take for your system to pay for itself?
If the price of electricity stays in the range of 10 cents per kilowatt-hour and our photovoltaic system produces 2,289 kilowatt-hours of electricity each year as estimated, the system should pay for our cost of installation in 15 years (the system has a 25-year warranty). If the price of electricity goes up, the recovery period may be much shorter. If the price of electricity goes down, we may never recover the cost of installation.
Our cost was much less than the system’s total cost of $12,629. We received a subsidy of $6,000 from Northwestern Energy for our 2-kilowatt installation and federal (almost S2,000) and state income tax refunds ($1,000).
Our system includes microinverters that convert the DC electricity produced at each panel to AC electricity we can use in our home or return to the grid for use by other Northwestern Energy customers. The microinverters reduce the risk that more than one panel will be affected by shading and are provide real-time monitoring of the power being produced by each panel.
Our account is credited if we produce more electricity than we use (only likely during the summer). This arrangement allows us to receive full benefit of all the power we produce without requiring us to buy a bank of batteries to store power.
We do expect that our home will be easier to sell and may command a higher price because of the panels.
4. How do you see your solar panels contributing/fitting into the larger Missoula effort against climate change?
Our purchase reflects our personal values, greatly influenced by subsidies offered by the power company and federal and state governments. Even though Missoula’s solar energy potential is not as high as in areas with more sun, our community could reduce our environmental impact if more of us took advantage of the subsidies that turn roofs into power plants.
What sort of lessons has the process of installing your own solar panels taught you?
Snow melts quickly off our south-facing roof. We had expected the snow to melt just as quickly off the panels. It doesn’t. The panels, mounted an inch or so above the roof, have cold air beneath them.
We use a pole-mounted plastic snow rake to clear snow from the panels and onto our deck. The deck never used to get shoveled, but it does now.
In general, we were extremely lucky. The cost of solar panels has dropped dramatically in recent years and the cost is still dropping. The installer handled the $6,000 reimbursement from Northwestern Energy so we didn’t have to pay that cost up front. The remaining up-front costs weren’t a problem because we refinanced our home loan when interest rates were at record lows.
The panels were installed on schedule at the agreed-upon cost. Within a week after our panels were operating, Northwestern Energy installed the special meter that gives us credit for the electricity we produce.
During December, our solar panels produced just 18 percent of the electricity we used, but as the days became longer, the panels produced 30 percent of the electricity we used during January and 43 percent during February.
We enjoy having the panels and we’re happy to see them producing more electricity as the days keep getting longer.
Bert Lindler and Kristi DuBois