How Big and Expensive Is a 6kW Solar System?


How big is a 6kW solar system exactly and what does it cost?

Solar installations can be very small such as 2 kW (kilowatt) installations composed of just 8 panels, or they can be large 25 kW systems with over 100 panels! This large playing field for installation size might make a 6kW solar system look fairly small, but in all actuality it’s very close to the size of a vast majority of residential solar installations.

So what do 6kW mean and, just as importantly, how much does it cost? Read on to find out!

Efficiency First!

Before we jump into what 6kW really means, let’s quickly discuss your home’s efficiency. No matter the size of your solar installation, taking the time to install inexpensive efficiency measures before you begin planning your solar system will help you save even more money going solar.

Consider replacing lighting with extremely efficient and long-lasting LEDs. Nip any vampire loads in the bud. Install weather stripping around doors and windows. Install low-flow faucets and showerheads if your water heater is electric. Not convinced all this is worthwhile? Simply plugging air leaks around your home can decrease your heating and cooling needs by 30%!

All of these measures help ‘prepare’ your home for solar. They save you money by lowering your electricity needs and in turn allow you to install a smaller solar installation. So before going solar, just remember: efficiency first.

Not sure where to begin? Call your local utility to see if they offer any rebates for energy audits, where a technician walks around your house and checks your doors, windows, and basement for air leakage, as well as anything else that can use unnecessary energy. Afterwards, they’ll give you an itemized and prioritized list of efficiency upgrades to help decrease your overall electricity use.

Once you’ve taken some action on efficiency, it’s time to go solar!

How big is a 6kW solar system?

A 6kW installation is just a little larger than the national average of 5.6kW. For a better understanding of what that really means, there are other ways to look at the size of a 6kW solar installation:

What does 6kW actually mean?

Kilowatts is a measure of your solar installation’s output in one single moment in time – a 6kW installation produces 6 kilowatts of electricity under perfect test conditions. In real life, the actual output of a solar installation is much lower, due to temperature differences, clouds, snow, rain, dirt on the solar panels, and inefficiency of the wiring and inverters. When you are estimating your solar production, the National Renewable Energy Lab (NREL) recommends dropping the total output of a solar installation by 14% to account for these losses.

So in the real world, a 6kW installation will actually produce around 5.15 kW – still enough to power 572 LED lightbulbs!

Over the course of 1 hour, a 6kW solar installation will produce 6 kilowatt-hours (or 5.15 kWh in real world situations). How much a 6kW installation produces over the course of a day, month or year depends on the location.

In San Antonio, TX, a 6kW installation will produce about 8,370 kWh a year, according to NREL’s PV Watts online solar calculator. The average household in Texas uses 14,112 kWh a year, so a 6kW installation would cover about 60% of most people’s usage.

In Helena, Montana, a 6kW installation would produce about 8,102 kWh a year – just a little less than in San Antonio. But since homeowners in the state use much less energy than their Texas brethren – an average of just 9,816 kWh a year – a 6kW system actually offsets about 82% of a Montana household’s use.

How many solar panels is that?

Common mid-priced residential solar panels, like Hanwha’s Q Cell panels, produce around 260 watts. A 6kW installation (which you could also call a 6000-watt installation, as 1 kW equals 1000 watts) would then need 24 solar panels.

Obviously, you have options for which solar panels to install. If you want the top of the line, take a look at SolarWorld’s high-efficiency SunModule panels, which produce a very-high 300 watts. At this rate, you’d only need 20 panels to get to 6kW, saving you space on your roof but not necessarily money, as they are more expensive than most.

How much space does that take on my roof?

Residential solar panels are typically about 66” x 38” (roughly 3 feet by 5 feet), so 24 panels take up about 418 square feet – just a bit bigger than a four-square court (you remember that elementary school game, right?)

If you’re wondering if you have enough space to play four-square on your roof, don’t worry. Solar panels don’t need to be in one large group. As long as you’ve got space somewhere on one section of your roof, solar companies can install the panels around chimneys, vents, and satellite dishes and still make your installation produce well and look tidy at the same time.

How expensive is a 6kW solar system?

At the national average cost of $2.93 per watt, a 6kW solar system would cost you around $17,580. With the 30% federal tax credit applied, that total drops to $12,306.

That’s a lot of money, so the real question is whether $12,306 for a 6kW installation is a good deal? Well, let’s do some math and find out!

Going back to our example above, a 6kW installation in San Antonio produces 8,370 kWh in a single year. The solar industry estimates modern solar panels to last about 25 years, in which case the San Antonio installation would produce 207,253 kWh by the end of its life. Solar panels also lose about 0.08% efficiency each year due to their internal parts degrading, so we’ve added that loss into our estimate above.

In Texas, the average utility charges $0.1156 per kWh. Utilities typically raise their rates about 2.5% each year, so purchasing 207,253 kWh over 25 years would cost $37,274. Subtracting your initial investment from the total price you would’ve paid the utility if you never went solar, we find that a San Antonio homeowner can save $24,968 by installing a 6kW solar installation!

Texas’ utility rates are actually lower than the national average, so if you’re thinking about installing solar, chances are high you’ll save as much or more than $24,968 over the life of your installation, though of course it depends on your utility prices, weather, and financing.

We hope you found this brief overview of the size and cost of a 6kW solar system helpful. If we forgot anything, or you have any follow-up questions or comments, don’t hesitate to add them in the comments below.

Image Credit via Flickr under CC License

  • by Ryan Austin
  • |
  • February 27, 2017