The cost of a solar system depends on the size of the system that is built. Systems can be built so they are scalable. It is important to know what size the solar panel system is, how much electricity will be produced, and the price per watt. Each solar system will produce different amounts depending on how good the design is, what shading could reduce the systems daily production, and where the solar panels are on the earth. Each geographical region and even location is going to receive different amounts of sun. After all of this is calculated, then you can make an educated decision on what size of solar panel system you need and want based on your energy demands and budget. Also, renewable incentives help offset the end and overall cost of a PV system.