Probably yes, if you mean your home uses 400 kWh each month? (If so, nice work, you are conserving energy and saving money compared to the average house.) But the amount of solar energy you get depends a lot on where you live. Further north or south in the world (e.g. Anchorage Alaska) you receive less and less light from the sun. It will be hard to get through the winter. Also, your specific location matters -- are you in the shadow of a big tree or an apartment building? Where I live in Toronto, Canada, our solar installers would sell you about 5 kW of solar panels, if you had enough roof space. You'd be short in the winter and you'd have to buy some power from the electric utility. But you'd have more than you need and sell some back in summer. You don't mention how much money you have, or how much rooftop or sunny lawn space. :) Solar energy systems are actually expensive, like totally redoing your kitchen or finishing your basement nicely. Where I live you'd be looking at spending about $40,000 to power your entire house (400 kWh/month) with solar energy. If you actually want to cut your connection to power company it would be more; you'd need batteries too.