3kW solar systems: what to know

Can a 3kW solar system power a home?

A 3kW solar system can technically power a home but only a very small or energy-efficient one. (In other words, don’t expect a 3kW solar system to power an average American home’s lights, electronics and appliances.) Most solar energy companies will tell you that 3 kW of power isn't enough to cover all your electricity use, but adding a 3kW solar system to your roof or backyard can still help you lower your utility bills.

“For residential solar, our installs usually start around 4 kilowatts and go up from there,” explained Mailin Plagge, a solar consultant with Apollo Energy. “Three kilowatts is not a ton of power, but could still save you money.”

How much energy can a 3kW system produce?

To check the solar potential in your exact location, we recommend using a trusted digital resource, such as the Global Solar Atlas or the National Renewable Energy Laboratory's (NREL) PVWatts Calculator.

The amount of power a 3kW solar system can produce depends on several factors unique to your installation. Beyond equipment variables, like your solar panels’ efficiency, the total amount of potential solar power for your 3kW system will depend primarily on site-specific details, such as the orientation of your solar panels, the shade on your property and (most importantly) the number of peak sunlight hours per day.

Wherever you are in the United States, your location should receive anywhere from around 3 1/2 to six peak sun hours per day. While your system’s production will vary with the seasons, in general, southern locales closer to the equator produce greater annual solar power yields.

For example, according to the Global Solar Atlas, a 3kW system could potentially produce roughly 12 kilowatt-hours (kWh) of solar power per day (about 4,300 kWh per year) near Minneapolis and St. Paul, Minnesota. Down south in sunny Albuquerque, New Mexico, however, a 3kW system could produce nearly 16 kWh daily (about 5,700 kWh per year).

» LEARN: How do solar panels work?

How much does a 3kW solar system cost?

A solar panel system with 3 kW of capacity typically costs around $9,000 — or roughly $6,300 after applying the federal investment tax credit, which can recoup up to 30% of your total upfront costs. However, as with production rates, the cost of a 3kW system is going to depend on many individual factors, including your location and whether you qualify for other solar incentives, programs or rebates.

A 3kW system is relatively inexpensive compared with other solar investments. However, considering that a large portion of a solar energy installation’s costs can be traced back to permitting, transportation, labor and other overhead costs, the price of a 3kW solar energy system may not be significantly lower than for an installation with a slightly larger capacity.

» MORE: How much do solar panels cost?

3kW solar system prices by state

If you want a more specific idea of what a 3kW solar panel system might cost you, check out the chart below to see the average cost in your state. (You may need to scroll to see the full table.)

How much can you save on your power bill with a 3kW solar power system?

While your solar savings go the furthest in locations with plenty of sun and high electricity rates, nearly everyone who installs a 3kW solar system will be able to reduce their utility bills somewhat. The question is — how much?

Taking an average from our examples in Minnesota and New Mexico above, let's say your 3-kilowatt solar energy system produces 14 kWh of power per day. Over 30 days, your system would produce about 420 kWh of electricity per month. That’s 420 kWh you don’t have to pay your utility company for.

Based on the national average electricity rate of around 14 cents per kilowatt-hour, a 3kW solar energy system could save you an average of about $60 per month on energy bills. That’s over $700 per year.

How long does it take for a 3kW solar system to pay for itself?

Based on our estimated savings of $700 per year, a 3kW solar panel system that costs you $9,000 upfront would take roughly 12.8 years to pay for itself. However, if you were to apply the federal tax credit of 30% and lower your upfront costs to $6,300, the same solar array could pay for itself in about nine years.

Given that top-tier solar panels often last 25 years, most 3kW solar systems have the capacity to pay for themselves once and even twice over in long-term energy savings.

» MORE: Are solar panels worth it?

How many solar panels do you need for a 3kW system?

The number of solar panels you need for a 3kW system depends on the wattage of your solar panels, but you’ll likely need eight to 10 panels if you go with the kinds of panels normally used for residential applications.

To calculate how many panels you need to create a system with a given capacity, divide the total wattage of your system by the wattage of your panels. (Your solar panels should all have the same wattage capacity to ensure safe and consistent power production.) Because 3 kilowatts is 3,000 watts, simply divide 3,000 by your panel capacity to determine how many panels you need.

In theory, you could design a 3kW system with any wattage of solar panel, but there are practical factors (like space needs and wiring) for you to consider. For instance, even though 100-watt panels may be cheaper than 300-watt panels, a system made of 300-watt panels would only require a third of the installation space.

» MORE: How many solar panels do I need for my house?

How much roof space do you need for a 3kW system?

You’ll probably need around 180 square feet of usable space for a 3kW solar panel system.

Exact panel sizes vary by wattage and manufacturer, but on average, a standard solar panel occupies roughly 18 square feet of roof space. In our experience, 400-watt panels tend to be a bit larger (about 21 square feet), and 500-watt panels are around 28 square feet each.

To calculate how much roof space you need, simply multiply the square footage of each solar panel by the number of panels necessary to create 3 kW of capacity.

Today, most of the high-quality solar panels installed on homes fall somewhere between 300 watts and 450 watts of capacity. Therefore, you are likely to need between 168 and 180 square feet of roof space to accommodate a 3kW system.

Although parts of your roof space will not be ideal for solar (i.e., the ideal spot must receive direct sunlight), most homes have at least 150 square feet of usable roof space to spare.

» MORE: Solar panel size and weight: a guide

Is a 3-kilowatt solar energy system right for you?

If you’re trying to find the best solar panels for your home, a 3-kilowatt solar energy system might not be the answer. Although a 3kW system could save you a significant amount of money on your energy bills, a larger-capacity installation is more likely to cover your home’s electricity needs for even more potential savings.

That said, a 3kW system may be right for you if:

• You're reluctant to invest the money needed for a larger system
• You're designing an off-grid system with smaller energy needs
• You have a small (or very energy-efficient) home