Off-grid solar: winter design, batteries and autonomy
Sources checked
Off-grid PV has no distribution-grid connection. Panels, storage and often a generator must supply all required electricity. Design for the worst season in which the property is used, rather than comparing annual generation with annual demand.
Begin with the loads and the difficult month
List daily energy use, simultaneous power and starting currents. Include controller and inverter consumption, conversion losses and a reserve for poor weather. Define the number of days of autonomy and which loads can be reduced.
In the source's south-facing scenarios, December daily generation is roughly a quarter of the summer level. A pleasant summer demonstration does not establish year-round operation. Cold-charging limits must also be addressed for lithium storage.
Choose the complete electrical system
The battery voltage, controller, inverter, cables and protection must be designed together. A 12 V, 24 V or 48 V label is a system choice rather than a measure of energy capacity. Have the complete arrangement designed and installed for the intended loads.
Off-grid can suit a cabin or remote technical site without a connection. For a home able to connect, it is generally more demanding and costly than retaining the grid. A grid-parallel installation set to zero export is still not an off-grid system.