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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: 06/15/2019

System size (kW) Estimated Monthly Output (kWh) Example panel configuration Approximate Price Range (before 30% federal tax credit)
1.1 kW151 kWh/mo4 × 275 W$2000
1.65 kW301 kWh/mo6 × 275 W$3400
2.2 kW415 kWh/mo8 × 275 W$4200
3.3 kW565 kWh/mo12 × 275 W$5200
4.13 kW697 kWh/mo15 × 275 W$5800
4.4 kW830 kWh/mo16 × 275 W$6900
6.3 kW1037 kWh/mo20 × 315 W$8300
8.25 kW1130 kWh/mo30 × 275 W$8600
6.6 kW1245 kWh/mo24 × 275 W$10300
9.12 kW1394 kWh/mo32 × 285 W$11200
8.25 kW1507 kWh/mo30 × 275 W$14100
8.8 kW1659 kWh/mo32 × 275 W$13800
9.9 kW1786 kWh/mo36 × 275 W$13600
12.83 kW1945 kWh/mo45 × 285 W$18700
12.6 kW2074 kWh/mo40 × 315 W$17000
13.75 kW2232 kWh/mo50 × 275 W$16800
17.1 kW2334 kWh/mo60 × 285 W$17700
15.75 kW2593 kWh/mo50 × 315 W$23000
19.5 kW2678 kWh/mo60 × 325 W$24400
16.5 kW3014 kWh/mo60 × 275 W$22600
25.2 kW3485 kWh/mo80 × 315 W$29600
26 kW3571 kWh/mo80 × 325 W$32000
30 kW4148 kWh/mo80 × 375 W$40100

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!