In most cases, for typical residential PV systems, a Web portal (the website provided for a system to document its production) is provided free from the inverter or MLPE manufacturer, but the hardware that enables data monitoring often needs to be purchased. (Fronius and SolarEdge are two manufacturers providing Web portals and inverter-integrated hardware for a completely free monitoring solution.) Companies that specialize in leasing residential PV systems, such as SolarCity and Sungevity, include their own branded monitoring as part of the packaged PV system. More complex and highly customizable Web portals likely have a yearly subscription fee—especially for larger PV systems with a lot of data, and those using portals hosted by third-party providers unaffiliated with the inverter manufacturer.
Hardware for basic monitoring of a residential system shouldn’t cost more than a few hundred dollars. There are myriad low-cost and high-quality inverter-provided monitoring solutions available. If monitoring is a key consideration for a system, it can be a driving factor in equipment selection, because Web portals vary greatly in their layout and user-friendliness. Taking time to look through the publicly available portals (see Resources) can help you decide which manufacturer provides the best solution for your system.