The Best Solar Panels Have the Best Value

(*Calculator at bottom)

Want to know how to choose the best solar panels? It’s not too difficult: simply find out which ones give you the most electricity for the cheapest price. Let’s call this ‘solar value’. The lowest price per kwh can help you find the best solar panels.

Well, how do you figure out which panels give you the most electricity? Do I need to know which panels are the ‘most efficient’? Nope – actually you don’t. Efficiency is not the same as output. Efficiency is output per area. If you’re strictly looking for the solar panels with the best value, then you only need to care about the output. Let your installer worry about the area.

How to Calculate Solar Output Like the Pro’s

So, you’ve got a few quotes from solar installers and want to know which solar power system will give you more energy / output / electricity. Let me teach you how to calculate solar output like the pro’s. This way you can double-check their quotes to know you’re getting a good deal.

Get your quotes ready
Visit the CSI online calculator
Plug in the data
Calculate!

Step 1: Grab your solar quotes and look for the specific solar module name and how many solar modules will be installed. Make sure you know the exact panel. Circle the panels and how many. Ex. 20 x SunPower SPR-200-BLK-U.

Then find the exact solar inverter in the estimate. This might be SMA SunnyBoy, Xantrax, Fronius, or Enphase. Circle this too. Ex. SMA SB4000US (240V).

How Many Solar Panels Do I Need?

Step 1: Determine your solar array size in kW and enter it into the calculator below.

Step 2: Decide which solar panels you want to use, and enter the DC Watt rating of the specific solar panel model you want to use into the calculator below.

Example: Suntech STP210-18/Ub-1 are rated at 210 DC Watts. Sunpower 230-WHT are rated 230 DC Watts.

Calculate Which Size Solar Panels You Need

Should I use Sanyo 200’s or Suntech 270’s? SunPower 210’s or Canadian Solar 240’s? Which size solar panel you use depends mainly on how much roof space you have available and how much electricity you plan to use (with solar power). Below are 6 steps to calculate which size solar panels you need for your building.

Step 1: Know Your Electricity Usage

Gather your old electricity bills for the past 12 months. Contact your utility company if you don’t have them and your electricity provider should gladly send you a printout with your past electricity usage. You’re looking for 2 things: (1) your monthly kW/h usage, and (2) your monthly cost.

Step 2: Know your Roof Direction

Grab a compass (maybe your car navigation, or check Google Maps) and figure out which way is South. Go outside, look at your roof and see how much roof space is facing South, Southwest, East and West. The more South the better, but West is actually okay.

How to Calculate Solar Size and Cost Video

Watch this short tutorial on how to use the SRoeCo Solar website and calculators.

Calculators

How to Calculate Solar Cost

Step 1: Look at your past electricity bills to average out your annual electricity usage. Look for the “kWh” and figure out your average yearly usage.
Step 2: Choose the calculator for your electricity provider (Utility).Non-CA or FL Residents:
1. First calculate solar system size
2. Then calculate solar cost
California Resident:
Florida Resident:
- Florida Solar Calculator
- Gainesville Regional Utilities (GRU)
Step 3: Enter “Your kWh/year” and calculate!

How to Design Your Own Solar System

Step 1: Calculate your Solar Array Size.
Step 2: Determine the Number of Panels you’ll need.
Step 3: Choose the Inverter Size!
Step 4: Figure out the array String-Size!

Disclaimer: Our solar calculators estimate the solar cost and size of a solar project. These should only be used as rough estimates, and may be incomplete. A solar installer would be able to provide you with a more accurate estimate.