Solar energy is the other add-on you may consider. PV produces its electricity during the daylight hours and is at its peak on sunny summer days. If your energy consumption matches this scenario then you are onto a winner however, for most people the peak energy usage is the early morning and evening.
If you are lucky enough to have a stream or river alongside the site, small or micro hydroelectricity systems are worth considering, as they will produce electricity all day, all year round. Bear in mind that permission to install one may be required from the water authority.
Exporting excess electricity to the grid is possible in NI and in ROI however the price paid is very small. Instead you can use the excess power to heat water via an immersion however, but solar thermal panels are much more efficient at this task. Electricity is a form of energy that is difficult to store and losses can be high when attempting to do so, even with a battery.
The payback period for PV has been dropping rapidly due to economies of scale and advances in technology but the game changer will be low cost battery storage. Batteries store electricity until you need it but also offers the possibility of fast charging your electric car. Electric Vehicle (EV) chargers are mandatory to install on all new builds – the good news is, grants are available. However, efficiency (e.g. depth of discharge) and also product longevity are limiting the uptake as well, considering batteries contain chemicals that may not be straightforward to recycle.