Compare price and performance of the Top Brands to find the best 4 kW solar system with up to 30 year warranty. 25 per watt with the latest, most powerful solar panels, module optimizers, or micro-inverters. . Choosing the right 4kW solar panel system for your home or off-grid needs can significantly reduce energy costs and provide reliable power backup. **Images have components which are not included in all packages. Easy Set Up: The integrated EcoFlow Power Hub has a simple plug-and-play design, allowing you to expand and customize your kit faster than any other power solution on the. . To help you decide which solar energy supplier you need, we examined the top competitors and compiled this list of the best off-grid solar system companies. We developed our list of the best solar panel installation companies after first identifying competitors that met basic criteria, then. . Our 4 kW solar systems feature DIY solar kits, which will produce at least 4kW (or 4,000 watts) of power. This translates to approximately 300 to 750 kilowatt-hours (kWh) per month depending on your system choice, location and other factors.