If you live in a sunny climate, solar power can greatly reduce your electric bills and even eliminate them altogether. But before you put up a solar array, there are some key issues that need to be addressed.

For example:

• Your roof must be strong enough–and have space–to support the weight of the panels.
• You must have a way to route the wiring from the roof to your house and then back again to a junction box that links the panels together.
• Your roof should not face due west–and thus receive no direct sunlight after about 1 PM in the summer, when the sun is at its highest point–because you need as much direct sunlight as possible to enjoy maximum efficiency.
• You need to be able to obtain a building permit for the solar array and connect it safely and legally with your local utility company. (If this proves impossible, you can always go off-grid and power your house with batteries that store electricity generated by the panels.)

Your roof must be able to support at least 50 pounds per square foot of additional weight–including the panels and any snow that sticks to them. That means a two-square-foot panel requires a roof capable of supporting 1,000 pounds. If you live in an older home or one with inadequate framing, consult a structural engineer before going solar.

You’ll need enough space on your roof to accommodate the panels, and your local zoning laws may specify how much space you’re entitled to use (typically 30% of a roof’s total area or about 600 square feet). You might also have problems with neighbors whose chimneys or skylights would be shaded by the panels. There is often a way to work around such issues–it may involve moving the panels, changing their angle slightly or adding more panels–so you’re not necessarily S.O.L. if things don’t look perfect at first glance.

The wiring from your roof to a junction box in your basement must be routed through a wall and insulated to prevent leakage of electricity or fire hazards. You will also need a permit to make this connection legally.

You mustn’t orient the panels in such a way that they will receive direct sunlight only during midday hours in summer, when the sun is at its highest point. The most efficient position for the solar array is directly south–in relation to your house, not in relation to true south. If you’re building a new house or making major renovations and want to take advantage of solar power right away, you can plan the position of the panels on paper before construction begins. Although that’s possible with an existing home too, it’s harder to achieve–you may need to build a small addition or even just paint the roof a lighter color to reflect more sunlight.

You should not plan to go off-grid unless you are willing to deal with major power outages and don’t mind paying significant installation costs. The main drawback of an off-the-grid system is that it’s expensive, especially if you want one big enough to run your entire home. You’ll need to purchase batteries that store energy produced by the solar panels, as well as an inverter to change the direct current–which powers lights and appliances directly from the battery–to alternating current used by standard household gadgets.