How should you size and design a solar PV system for your site?

1 Assess your site

Assessing the suitability of your site for solar PV is the first step. Take into account the available roof or ground space for the panels, the orientation and tilt of the panels, the local climate and solar irradiance, and any shading or obstructions from nearby buildings, trees, or other objects. Additionally, be aware of the grid connection and interconnection requirements, as well as any local codes and regulations for solar PV installation. To get an estimate of your site’s solar potential and output, try online tools such as Google Project Sunroof or PVWatts.

2 Determine your load

To determine your electrical load, or the amount of electricity you need or want to use from your solar PV system, you can review past utility bills to find your average monthly or annual consumption in kilowatt-hours (kWh). Additionally, identify your peak demand in kilowatts (kW), as well as estimate any future load growth or reduction due to changes in your appliances, lifestyle, or energy efficiency measures. Also, decide how much of your load you want to offset with solar PV, or your target solar fraction — online calculators such as Solar-Estimate and Solar Calculator can help.

4 Optimize your system

Consider the costs and benefits of different system options, such as grid-tied, off-grid, or hybrid systems with or without battery storage, backup generators, or smart meters. Research financial incentives and programs available for solar PV in your area, such as rebates, tax credits, net metering, feed-in tariffs, or green certificates. It's also important to decide on the best financing and ownership model for your system, such as cash purchase, loan, lease, or power purchase agreement. Lastly, make sure to select a reliable installation and maintenance contractor with experience and a good reputation. Online resources such as NREL's Solar Advisor Model or SEIA's Solar Consumer Guide can help you with this step.