Solar Energy for a Colder Future

If you are going to install solar energy as part of building, keep these points in mind:

  • If you are going to install solar panels on your roof, be sure that a large, south-facing roof is designed into the structure. Solar panels take up a lot of space for the amount of energy that they make, so they need a big roof.  A steep roof is best in the Tahoe area - like a 7 in 12 pitch (30 degrees) or steeper, though in lower snow areas the ideal pitch is 6 & 12. You will need about 100 square feet of roof space for every kilowatt of photovoltaic panels you install.
  • Designate appropriate space and locations for the solar equipment. This includes an inverter and disconnect switches for a grid-tied photovoltaic system, additional space for batteries for a stand alone photovoltaic system, and a large water storage tank for solar hot water (in addition to your hot water heater).
  • Pre-wire and/or pre-plumb the building to accomodate the solar system equipment as an integrated part of the building. Ensure that the wire size and conduit size are large enough to accommodate the current that will be going through the wires, or that copper pipe with high-temperature insulation is installed.
  • Ensure that none of the vents through the roof are located on the south-facing roof.  This way solar panels can be mounted unobstructed.
  • Contact us to guide you through the process, and to work with you, your architect, and your contractor so that all your bases are covered.

 

How To: 

Grid-Tied PV

When you are already connected to the utility power grid, or if your connection is nearby, installing photovoltaic panels is easy and a great way to cover your energy costs.  This is how it is done:

Install the panels facing south, tipped up to about 30-40 degrees, in full sun from 9 a.m. to 4 p.m.  These are the times that the sun is the most intense, so it is important to capture the sun when it is coming in strong.  It is not practical to put pv panels in the shade, obviously you can't make solar power without having sun on the panels!  The panels can go on your roof or in your yard, it just depends on your particular site and design ideas.

Run conduit and wire from the panels to the DC disconnect, and then to the inverter, and then to the generation meter, and then to the AC disconnect, and finally into your service panel.  It is important to size the wires, conduit, disconnects, inverter, and service panel properly so the there is not a dangerous situation.  These calculations are best left to a licensed professional who will follow the local codes.

Finally, watch your meter run backwards and enjoy making clean, renewable energy for years to come!



How To: 

Stand-Alone PV (battery based)

Stand-alone pv systems require the solar energy to be stored in batteries, so that you will have power available even when the sun is not out.  Be sure to designate a safe location for your batteries. For lead-acid batteries, which are not sealed, the battery box must be properly vented, insulated from the cold, and away from any living space.  Sealed batteries do not need as much venting, but should not be located in living space.

Decide how much electricity you will need each day, and how many days of reserve that you will need.  This figure will tell you how much solar energy you will need. Your solar panels should be able to charge your batteries fully, so matching tha amount of solar panels to the size of the battery bank is a critical step in the design of any off-grid system.

The components necessary for an off-grid system include pv panels, batteries, a charge controller, an inverter, safety breakers and a system monitor. With these components you can be completely independent and make your own energy every day! 


How To:

Solar Household Water

Heating water for your house using the sun is a great way to save on energy costs. Solar collectors can be mounted on your roof or in your yard.  Install them facing south and tilt them to about 40 degrees. In freezing climates, mix non-toxic glycol into the water that will flow through the collector(s).  Most families just need one collector, usually a 4x8 or 4x10 collector. Take the area of the collector that you will use and multiply that number by 2. This number will be the number of gallons required for the storage tank.  Plumb in a heat exchanger and for each side of the heat exchanger, plumb in a pump that will circulate the hot water.  A differential controller is used to determine when the water in the collector is hot, and when it is, the controller turns on the pumps.  The entire time that the sun is shining on the collector, the pumps will be capturing that energy into the storage tank by circulating the fluid through the system. At the end of the day, you will have a tank-full of hot water - from the sun.

 

How To:

Solar Space Heating

When you need heat, you usually are talking about quite a bit of energy, so this means that if you are going to get that heat from the sun, you will need a lot of collectors:

Take the total area of the collectors that you will be installing and multiply that by two to get the number of gallons that your storage tank must hold.  Usually for space heating, you will need a 500 - 2,000 gallon storage tank! Make sure that you have a designated space for this tank. The design temperatures for solar space heating are a great match for in-floor radiant heating. Your design should include enough tubing to disperse the heat throughout the building. You may also need a boiler if you need heat during extended bad weather.

Tilt the panels to about 50 degrees so that you can capture the winter sun, and minimize overheating during the summer months.

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