You’ve got three choices when it comes to installing a solar electric system. You can install a grid connected system, which is by far your cheapest and easiest option. Or you can install a grid-connected system with a battery bank. Or you can go off-grid entirely, by installing a stand-alone system.

When consulting on this matter, I suggest that clients start simple with a grid-connected system. Use the grid as your battery bank and suffer through power outages like the rest of us. Or install a battery bank for backup, and invite your neighbors to stay with you when grid power crashes.

Using the grid as a battery bank obviously poses potential problems. Most notably, it is going to cost you some money. In new construction, for example, you’ll have to pay to run electrical lines to your home and to install a meter or two. (When I was building my home, the local utility wanted about $2,000 to run an electrical line to my house from the buried electrical line near the road 150 feet away from the house and to install a meter.)

In new and existing homes, you will also very likely be required to install a safety switch (an AC disconnect) so firefighters can shut your solar system off in case of a fire or so that utility company employees can shut off your system if they’re working on the lines in the neighborhood. (They don’t want electricity flowing onto the grid from your system while they’re working on nearby lines for fear of electrocution. What some building code officials don’t seem to realize or accept is that modern inverters automatically terminate the flow of electricity from solar electric homes when they sense a drop in line voltage in the grid.)

If you are installing a system on an existing home, be sure to contact the local utility company and inform them of your plans. You’ll need to work out an arrangement with the company: either a single-meter net metering deal or amore cumbersome two-meter system, where they pay you for the electricity they buy from you at a discounted rate.

Despite these problems, grid-connected systems have some serious advantages. They eliminate costly batteries. A single battery bank may contain one to two dozen batteries costing $200 to $300 each. The battery bank needs a home, too, that is, some safe place where batteries can be kept warm but not hot. That’s because the lead acid batteries typically used in solar electric systems function optimally at around 70°F (21°C).

Many people house their batteries in sheds or in garages, often inside a sealed battery box. The battery room or battery box needs to be vented to the outside so that hydrogen gas produced when batteries are charging can be safely vented outdoors. (Hydrogen is explosive at certain concentrations.) Building a battery box and a place to keep it costs money. And don’t forget that your battery bank needs to be wired into your solar electric system, which also requires a bit of money. In addition, batteries require periodic maintenance that is going to take some time on your part (battery maintenance is discussed below).

Optimistically, lead acid batteries only last five to ten years, according to Weiss, depending on how you take care of them, and how heavily you draw on them. Replacing batteries costs money.