Solar power!
Several years ago I had a dream to build a house that contributes to the well being of the planet rather than consumes from it. All too often homes are built with little or no regard for the annual consumption in energy usage. So after much research I decided on a Passive House design and to add renewable energy to provide more power than is consumed. I did not set out to break any records or get certificates to hang on the wall. Rather, I have a deep commitment to do as much as I can towards a goal of reducing fossil fuel consumption. If this inspires others to do the same then we may all have a chance at a better future.
Today the sun was shining brightly all day, well for about four hours of our short winter day...
This in turn produced 14.91 kWhr of clean, renewable electricity from our 40 solar panels that we installed last year.
To view our system production click here.
Specs:
Solar panels: 40 Hanwha 310 watt = 12.4kw
Inverters: 2x Fronius 6kw = 12 kw
Total installed cost: $32,421.10 CAD
Cost per installed watt: $2.62(before rebates)
After rebate cost per installed watt: $2.21
Return on investment: 8 to 12 years
System lifespan >20 years
Expected annual energy use covered: 117% (this includes ALL energy used in the house including heat)
The solar array is a ground mounted system consisting of forty panels rated at 310 watts each. These panels are mounted on a 4" schedule 40 steel pipe rack that I designed and built using old pipe from oil and gas exploration. (This array will also double as a windbreak for a garden which will help fill our 160 square foot root cellar) The 12.4 kw of DC power produced from the array goes though a combiner box/disconnect and then feeds two 6 kw inverters for an AC production of up to 12 kw. On an annual basis this system will provide ~13,500 kwh of clean electricity. This exceeds the energy requirement of the house which uses ~11,500 kwh per year total energy for all loads including heating.
I started to realize that what I created is a plus-energy house
Plus-Energy describes a building that produces on an annual basis more renewable energy than it consumes. This is achieved through reductions in energy usage to lower the energy production requirements. In my case, I chose solar electric power after having a meteorological tower on the site for one year to determine the solar/wind potential. The analysis showed that solar power was more effective at this location.
Plus-Energy differs from Net-Zero or Zero Energy Buildings in the percentage of renewable energy produced compared to consumption. Net-Zero produces 100% of the energy required and Plus-Energy produces more than 100% of energy required.
This home will produce ~117% of the energy needs on an annual basis.
Passive House is an important aspect to consider when designing a Plus-Energy building as the goals of Passive house are to reduce heating and energy consumption to a minimum. As well Passive House produces a building that has superior indoor air quality and increased lifespan due to stricter air tightness standards.
And also a Zero-Emissions home...
Our home uses electric baseboard heaters for the minimal amount of energy needed for heating. I considered a heat pump when building but the installed costs were at the time much higher than the baseboards and the heating loads are so low. There is a geothermal ground loop installed under the septic system which will also provide heat in the future, further lowering the energy bill.
Zero-Carbon too!
Buildings emit carbon in two ways. One way is in the heating/energy requirements and the second way is in the building materials used.
Since the home was designed as a Passive House, the energy requirements for heating are extremely low. Lighting is 100% LED bulbs which use a fraction of the energy of standard bulbs and contain no mercury like in CFL bulbs. Appliances are all low energy rated, although nothing special or expensive.
Our home utilizes a large percentage of beetle-killed wood in the timber-framed structure as well as recycled materials like old bricks from a chimney and natural materials like wood and stone. The insulation in the walls and roof is made from sheep wool that was primarily carding waste and other waste wool. This eliminated the emissions from traditional disposal method of burning the wool as well as eliminated carbon intensive production of insulation such as foam and rock-wool or fiberglass.
Insulation levels
Sub-slab: R-50
Walls: R-80
Roof: R-120
What are the next steps?
Currently the excess power produced is sent to the grid. One goal is to eventually use that excess power to charge an electric car and to store the energy in batteries for use after the sun goes down. This would enable the house to fully utilize solar power 24 hours/day.
As well, the 12.4kw array is half of the planned system. Another 12.4kw is planned for future installation to bring the total up to 24.8kw
One challenge I will face before installing the second half of the system is mainly with obtaining guarantees for long term contracts to sell the excess power. The current agreement annually reassesses the tariff paid and the agreement may be terminated with only 30 days notice. Ideally, micro-generation agreements will have 10 year or longer contracts in place to ensure the future viability of the installation. I am cautiously optimistic of the current Yukon government's promise to "promote energy policies that would position the Territory as a renewable energy leader"
The final step in my mind is to have renewable energy displace 100% of fossil fuel energy. I hope you will help make that final step a reality!
