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Grid-Tie Calculator: Size Your System for Grid-Tie

This solar panel calculation will give you an approximate system wattage so that you can get an idea of cost and components needed for your system. In order to calculate how large your home power system needs to be, run the Grid-Tie sizing calculator below.

  • Make sure you have the average kWh usage from Step One.
  • Decide what percentage of power you want to generate.
  • Get the daily sun hours for your building location.
  • Calculate your system size.
  • Once you have your system size, write it down. You will need this for Step Four.
    You can also explore some of our pre-designed systems to get a ballpark idea of what your system might cost.
Please work with experienced Wholesale Solar staff to design a system which fits within your budget and can be expanded as needed.

1. What's the most electricity you might use in a month?

Take the average kWh Usage for twelve months that you wrote down from Step One and put this number in the space below.

* This provides a rough estimate of your solar needs. To talk with a Solar Design Technician about your results, please give us a call at 1-800-472-1142.

2. What percentage of your house/business power do you want to generate with solar power?

If you want to produce 100% of your electricity, leave 100.

3. How many Peak Sun Hours do you get per day?

Enter your zip code, and we'll look up the the sun hours in your area.

Or, you can look at the Solar Map to find this number.

This gives you the annual average. If you will use your system during the winter, subtract 1.5 hours from the annual average to account for decreased sunlight during those months. This ensures your system will be properly sized to provide year-round power, even during darker months.

Sun Hours/Day
Minimum System Size:
Approximate Solar Panel Wattage:

Approximate Number of Solar Panels Needed:

* For 20 Astronergy 270-watt solar panels to produce 5,400 watts..... 5,400 divided by 270(watts per panel) = number of solar panels needed.
NOTE: These figures are approximate and do not take into account the variable efficiency ratings of solar panels. Please work with experienced Wholesale Solar staff to design a system which fits within your budget and can be expanded as needed.

I have my mininum system size.
Go to Step Four
Let us design your system

To get a ballpark idea of what your system might cost:

Click the button on the right to view our Grid-Tie ballpark cost table.

Last updated: 02/16/2019

System size (kW) Estimated Monthly Output (kWh) Example panel configuration Approximate Price Range (before 30% federal tax credit)
1.12 kW151 kWh/mo4 × 280 W$2000
1.68 kW272 kWh/mo6 × 280 W$3200
2.8 kW429 kWh/mo10 × 280 W$4400
3.36 kW545 kWh/mo12 × 280 W$4900
4.2 kW681 kWh/mo15 × 280 W$5900
5.6 kW857 kWh/mo20 × 280 W$6900
6.2 kW997 kWh/mo20 × 310 W$8800
6.72 kW1090 kWh/mo24 × 280 W$8500
9.3 kW1286 kWh/mo30 × 310 W$11000
8.4 kW1361 kWh/mo30 × 280 W$11300
8.96 kW1513 kWh/mo32 × 280 W$13800
10.08 kW1635 kWh/mo36 × 280 W$14600
11.2 kW1815 kWh/mo40 × 280 W$14000
11.2 kW1891 kWh/mo40 × 280 W$16800
15.5 kW2143 kWh/mo50 × 310 W$21900
14 kW2269 kWh/mo50 × 280 W$17700
15.5 kW2492 kWh/mo50 × 310 W$22700
20.1 kW2724 kWh/mo60 × 335 W$24200
21.6 kW2991 kWh/mo60 × 360 W$28700
20.16 kW3025 kWh/mo72 × 280 W$23400
24.8 kW3428 kWh/mo80 × 310 W$29100
26.8 kW3632 kWh/mo80 × 335 W$31200
28.8 kW3988 kWh/mo80 × 360 W$37300

These figures are based on complete solar power systems that Wholesale Solar sells. Prices are approximate. Prices do not include freight, tax, or installation.

Why are smaller systems sometimes more expensive than larger ones? Because higher-efficiency panels cost more. For example, to get a 10 kW system, you can either use 35 285W panels or 39 260W panels. Even though you need more 260W panels (they are less efficient), economies of scale actually make them more affordable. So when would you want to use higher-efficieny panels? Only when you're limited on roof/ground space and need to squeeze the most power out of every available square foot. In other words, more efficient panels cost more but can generate more power per square area. If you're not limited by space, we suggest you go with the best price per watt instead.

Click the button on the right to check out our pre-designed systems that closely match your current calculated energy needs.

Take your calculated numbers and explore the Grid-Tied Systems.
Or give us a call at 1-800-472-1142. We are here to help!