Grid-tied or off-grid: which is right for your site?

The short answer: if your site has a healthy mains connection and your goal is cutting bills, a grid-tied system with battery storage is usually the right call: the grid acts as your backup, and you get paid for what you export. If your site has no mains connection, a connection quote that makes your eyes water, or a supply too weak to run the loads you actually have, a true off-grid system is the better engineering answer. The two are different disciplines, and we'd rather tell you which one you need than sell you the one we happen to do.

Full disclosure so you know where this guide comes from: Xtant Energy only builds off-grid systems. For grid-tied work we refer people to our partner KMM Energy Solutions, and they send off-grid projects to us. Neither of us has any reason to push you the wrong way.

When grid-tied is the right answer

You already have a mains supply that comfortably covers your peak loads. Your aim is lower bills, a better carbon position, and some resilience with a battery. In that world the grid is a free backup generator and a buyer for your surplus: Smart Export Guarantee tariffs were paying around 12p to 16p per kWh on the better open deals as of July 2026. Grid-tied systems are also simpler and cheaper per kilowatt because they don't need to survive on their own: the design can lean on the grid for cloudy weeks and winter evenings.

When off-grid is the right answer

There's no mains connection at all, or getting one means a Distribution Network Operator quote for a new connection across fields. In our quoting experience those connection quotes typically land between £10,000 and £30,000, and sometimes far higher depending on distance and capacity, with a lead time measured in months. That's money that buys you a standing charge and a bill forever. Put the same money into an off-grid system instead and it buys you generation you own outright, which is why the DNO quote often part-funds the decision all by itself. Or there's a supply, but it's a long rural spur that browns out when the milking parlour starts, can't take a heat pump or EV charger, and fails in every storm. Or you're running a diesel generator as the primary supply, in which case the fuel bill alone often pays for the whole system: we've quoted dairy farms spending £66,000 to £80,000 a year on red diesel where solar and storage pays back in under two years. The full breakdown is in our guide to cutting diesel generator dependence.

Off-grid design is a different job: batteries sized for days of autonomy rather than hours, panels sized for December rather than June, a generator integrated for the darkest fortnight, and every load on the site accounted for, because there's no grid to catch a mistake. That's the discipline we specialise in.

The questions that decide it

• Is there a mains connection at the site today, and what would a new or upgraded one cost? Get the DNO figure before anything else, it often decides the whole question.
• What are your real peak loads, and can the existing supply carry them? A weak supply plus big plans often points off-grid or hybrid.
• Are you burning diesel as a primary supply? Count the annual fuel spend, that's your budget.
• How much does an outage cost you? Livestock, refrigeration and water systems change the resilience maths.
• Do you want export income, or independence? You can't fully have both: export needs the grid.

Money and funding differences

Both routes get 0% VAT on residential installation until 31 March 2027, and both qualify for capital allowances on business installs. The differences: export payments (SEG) only exist with a grid connection, and off-grid systems dodge standing charges and unit rates entirely, which matters more every year. And for sites without a connection, the avoided DNO connection charge, typically £10,000 to £30,000 and sometimes far more, is effectively a discount on the off-grid system: it's money you were going to spend either way. For the full, verified picture matched to your situation, use our Grant Checker.

Written by Mark Street, director of Xtant Energy. Facts checked against official sources 30 July 2026: SEG rates via Ofgem-licensed supplier tariffs, VAT treatment per HMRC VAT Notice 708/6. General information, not financial advice.