If you would like use a 400W panel that has a system originally made with more compact panels, Check out how you can reconfigure for what you already have… That will help you have an understanding of the cost of going solar close to you, we have analyzed SunPower price https://solarpanelinstallationcalifornia.car.blog/2024/06/15/steps-to-do-when-installing-a-solar-energy-system/