Solar energy is a renewable energy source which means that it is infinite compared to fossil fuels like propane, oil, coal, etc. The energy generated by the sun is enormous. The sun’s surface is around 1.5 quadrillion acres. It only takes around 50 acres of the sun’s surface to generate the equivalent of Earth’s yearly energy consumption. A solar electric installation once set will generate free energy for many years and a return on the investment in 7 to 8 years.
Why do we use solar panels?
Free and infinite energy
How much energy gets to the Earth's surface?
Energy from the sun is transferred to the Earth’s surface via radiation and just before it gets to us it is diffused in the atmosphere. Depending on the location, the power we can get at noon is around 320 kBTU/hr/sqft (or 1000 W/m2).
Solar panel efficiency
Unfortunately, we are not able to use solar power as a whole. We are limited with solar panel efficiency. Most of the PV modules used have a maximum efficiency of around 20%, which means usable power at noon is around 64 kBTU/hr/sqft (or 200W/m2). That is why standard 60 cell solar modules are around 300 W – 340 W.
What size system do I need for my house?
Solar electric system size is measured in kWp (kilowatt in peak) because their energy output is not the same throughout the year. To estimate your system size you can divide your yearly utility bill by kWh/kWp coefficient.
Values of kWh/kWp coefficient vary based on the location. If you want to find out what is the value for your area check Global Solar Atlas map. Open the map and legend at the bottom right corner to estimate kWh/kWp coefficient value for your house. To achieve maximum performance of your system sign up with us and we will match you with the right professional installer company.
An Example:
For NY State we estimated 1,300 kWh/kWp and annual bill of 5,000 kWh. Your estimated system size will be 5,000 kWh / 1,300 kWh/kWp = 3.85 kWp.
Source: Global Solar Atlas map.
