After deciding to install a solar energy system, choosing the right size for your home can seem challenging. A six-kilowatt system is fairly standard, and will probably cover energy needs for most American households. Planning for a system of this size means understanding how much space it will require and how many kilowatt-hours of electricity it will produce. It’s also important to know how much a six-kilowatt system should cost to ensure you get a fair price.
Most U.S. households consume about 11,000 kilowatt-hours per year, or a little over 900 kilowatt-hours per month. Six-kilowatt systems typically produce 400 to 1,000 kilowatt-hours per month, but the actual energy production of any solar system depends on your location, local weather conditions, and the way in which you position your panels. In San Jose, for instance, a six-kilowatt system will produce around 430 kilowatt-hours in December and about 970 kilowatt-hours in May. An identical system in Detroit, by contrast, will produce a low of around 350 kilowatt-hours in December and reach a high of 812 kilowatt-hours in May. Energy production will decline in winter months as the days grow shorter, then increase again as the days begin getting longer.
To calculate your precise energy needs, look over your energy bills from the past year. Average the monthly kilowatt-hour totals by adding them all together and dividing by 12. If you find your energy needs are higher than average, you might want to invest in a solar system larger than six kilowatts.
If you’re in an off-grid location (or just want to ensure you’ll be able to produce enough electricity to meet all your energy needs year-round), consult a solar professional. Using data about your location and your energy consumption patterns, they’ll help you determine whether a six-kilowatt system is adequate for your home.
The number of panels your six-kilowatt system has depends on the wattage of the panels you’re working with. You might, for instance, use 20 300-watt panels or 30 200-watt panels.
Panels with wattages that don’t divide evenly into 6,000 (the number of watts in a six-kilowatt system) will require you to slightly overshoot your six-kilowatt target. If you plan on using LG’s 295-watt Mono X Plus, for instance, you’d need 21 panels and would end up overshooting your six-kilowatt target by 195 watts (since 295 times 21 equals 6,195). While there’s nothing inherently wrong with doing so, a six-kilowatt system is probably already more than enough for your energy needs, so unless you’re selling energy back to your local electric utility through a net metering arrangement, it’s best to stay as close as possible to your target energy production range.
On average, a six-kilowatt system will require about 450 square feet of space. But the exact amount of space you’ll need depends on the size of the solar panels you use. Every manufacturer produces panels of slightly different sizes, even if they are all of equal wattage.
Mounting will also add space to your solar installation. Some racking clamps, for instance, require you to add up to an inch in space between each module. Other modules require as little as a quarter-inch between them.
At any given wattage, high-efficiency modules will generally take up less space than their standard-efficiency counterparts, so if you’re working with a roof or land area of limited size, high-efficiency panels are probably your best bet.
On average, a six-kilowatt system will probably cost about $12,500 to $15,000 after factoring in tax credits and other financial incentives. But the cost of any system can vary considerably based on your local economy. In sunny Arizona, you might be able to get a six-kilowatt system installed for closer to $11,000, but in New York or Washington, you might have to pay upwards of $17,000.
The installer you choose to work with can also affect the price you pay for your six-kilowatt solar system. Before choosing which installer to work with, be sure to obtain multiple quotes and shop around for the best deals.
The type of solar panels and other equipment you install will also make a difference in the system’s ultimate price tag. High-efficiency solar panels and microinverters, for instance, will cost more than string inverters and panels of standard efficiency.