Totally off-grid developments aren’t all that common in the UK – at least, not when it comes to the plots that people want to build on. There are actually relatively few areas that aren’t inhabited to the level that means mains electricity is available, though there are more places without access to the mains gas network, which doesn’t have the same coverage, especially in rural Britain.
However, we still occasionally come across truly off-grid developments. Sometimes they will be off-grid because there’s simply not a mains electric or gas supply in the area, but sometimes it will be because the significant costs involved in infrastructure upgrades simply aren’t feasible within the bounds of the developer’s budget. Compromises must be made – but they should be well-informed ones. That’s where we come in.
Electricity generation for off-grid developments
Where mains connection is technically possible, but complex and expensive, off-grid energy generation is often the better option. We recently worked on such a project – a self-build property situated on a landlocked site, with connection routes only available across agricultural land, which meant that the costs quoted for providing a mains electricity supply were more than £100k and a significant part of the construction budget.
We worked with the client, and their architect, to review the various energy options for the property. Our client’s preference was ideally to install a ground source heat pump for space heating and hot water, but the annual electrical demand made this unviable – the inclusion of the electric-fed heat pump system would have trebled the off-grid solution system size to provide the necessary electricity, and this would have been incredibly expensive. After giving all possible choices due consideration, it was decided that an LPG boiler was the only solution which reduced the electrical demand sufficiently – not ideal, in the context of the client’s initial desire to avoid fuel deliveries, but the best compromise to make with all factors borne in mind.
Working with our client, we established the expected peak and annual electrical demands, considering both summer and winter conditions, and called on an off-grid system specialist to supply the required solution – a battery storage system, powered by a large solar photovoltaic (PV) array and an LPG-fuelled generator, with a complete controls package. While the PV system was sized to provide the majority of the annual electrical demand, the LPG generator was included as it was always expected that an additional means of electricity generation would be required (and it made sense to match the fuel type to the boiler, since that would avoid the need to bring another fuel type to the property).
Balanced decisions based on data
What this case study illustrates is the need to make compromises and choose the best energy solutions on balance, when it comes to specifying for off-grid developments. No solution will be perfect, of course, but it should be as efficient as possible within the constraints of the development’s location and budget, and that can only be achieved by giving all possibilities due attention – and adding a little creative problem-solving into the mix, too.
For example, one of the more unexpected ideas we’ve come across recently relates to the uptake of electric vehicles (EVs) in the UK, which is being driven by the government’s Road to Zero strategy. There’s been talk of utilising an electric vehicle’s battery as a storage system – so when plugging your EV in to your house in the evening, the vehicle might be charged, or the vehicle might power the house’s electrical requirement.
Naturally, all these energy challenges will gradually be lessened, with time and innovation – just look at battery storage systems, which have gone from a nice idea that was not financially feasible, to a more affordable real-life solution, in what is really only a few years. With the combination of this improvement, and better system efficiency (which has reduced the annual energy usage for dwellings), it should become increasingly easier and more sustainable to provide a more flexible way of generating, storing, and using energy.