Photovoltaic systems can reduce the CO2 emissions associated with the consumption of electricity in dwellings. One key issue that affects both the economic case for home installation and the integration with the mains electricity grid is the match between the instantaneous production and demand for power. This initial study considers a sample of 10 dwellings which were monitored under the UK Government’s Photovoltaic Domestic Field Trial. A simple PV system model is introduced and used to examine the variations in the balance between the imported and exported electricity of the monitored households. There are cases where a large proportion of the electricity generated by a PV system is be used directly by the household and instead is exported to the mains electricity grid. The possibility of using the model explore the effects of PV system size on the import and export balance, and the benefits of sharing production and consumption between nearby dwellings, is discussed.