PV array <5 kWp + single inverter = grid connected PV system: Are multiple inverter alternatives economic?

Compared with a single, central inverter, multiple inverter photovoltaic (PV) systems are considered to produce higher system energy yields by reducing mismatch losses within dc strings. This paper considers, from an economic viewpoint, whether multiple inverter systems can ever be justified for PV systems <5 kWp, under the conditions that presently exist in the UK. The UK scenario being one of very high labour costs combined with both relatively low radiation levels and feed in tariffs. Analysis of a 7.2 kWp test façade configured with string and central inverters indicates that the mismatch reductions that can be achieved do not compensate for the additional capital cost of a multiple inverter installation. In addition, unless the mean time to failure of inverters approaches that of the 25 year lifetime of the dc side of the PV system, the economics of small scale grid connected PV in the UK will remain difficult, even when the cost of the PV component falls.