So Good does not agree with the view that a south-facing roof is always more suitable for a solar photovoltaic system than an east-west facing roof. Photovoltaic power generation is not only about producing as much electricity as possible, but also about meeting a constant demand for electricity. A PV system installed on an east-west facing roof will only generate around 80% of its annual electricity compared to a south facing roof. However, the power generated by a solar power system installed on an east-west facing roof can be spread over the whole day, as the system still receives a lot of sunlight in the morning and evening.   Many homeowners whose homes do not have a roof on which to install a PV system solutions will often consider investing in a plug-in solar system. These can be installed either on the balcony or in the garden. However, occupants may be disappointed if they expect them to power household appliances such as coffee machines.   "These panels are particularly well suited to covering the base load of a home," White explains, "where the electricity is used directly, for example, for a telephone, an internet router or an alarm clock radio."   More of the electricity demand will be supplied by the grid. For example, a coffee machine requires around 2,000 W to boil water for heating. According to So Good, this cannot be achieved with balcony photovoltaic modules alone.