Solar Energy for a Colder Future
If you are installing a photovoltaic system as part of new construction, 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 and additional space for batteries.
Pre-wire the building to accommodate 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.
Ensure that none of the vents through the roof are located on the south-facing roof. This way solar panels can be mounted unobstructed.
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!
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. LI-Ion batteries have the smallest footprint and do not require venting.
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!