The Sunny Boy 5 kW inverter from SMA has the reputation in the industry as being the most reliable inverter for residential solar systems of all time. This inverter can be loaded with up to 6.66 kW of panels. SMA is a German company founded in 1981 that produces arguably the best quality and reliable inverters for both residential and industrial applications. Their inverters are produced in Germany. They have a 10 year warranty and if you are willing to pay that little bit extra and are looking for a European product then SMA may be the best inverter for you.