What Tariff Should You Be On With Solar, a Battery, a Heat Pump or an EV?

In Brief

If you’ve got solar panels, a battery, a heat pump or an EV, a standard single-rate tariff is rarely the best fit, since it doesn’t reward you for using cheap off-peak electricity or your own generation. Time-of-use tariffs suit homes with a smart battery managing charging automatically, while EV and heat pump specific tariffs offer wider off-peak windows built around exactly this kind of setup.

Once you’ve got solar panels, a battery, a heat pump or an EV at home, the tariff you’re on starts to matter a lot more than it did when you were just heating with gas and charging a phone. A standard variable or fixed tariff charges the same rate whatever time of day you use electricity, which means it doesn’t reward you for shifting your usage to when electricity is cheapest, or for using the power your own roof has already generated.

This guide walks through the main tariff types available in the UK, and which setup each one actually suits, so you’re not paying more than you need to for kit that’s supposed to be saving you money.

 

Why your tariff matters more once you’ve got this kit

A heat pump, a battery, or an EV all use meaningfully more electricity than a typical home did a few years ago. If you’re still on a flat-rate tariff, you’re paying the same price for every unit whether you use it at 3pm or 3am, and you’re missing out on the cheaper off-peak rates that time-of-use tariffs are built around. Pairing solar and battery storage with the right tariff is something we touch on in our guide to what size solar battery you need, since the tariff you’re on affects how much a battery is actually worth to you.

Standard variable and fixed tariffs

This is the default most households are still on, one rate for electricity, whatever time you use it. It’s simple, but it’s the least suited to solar, a battery, a heat pump or an EV, since none of these systems get to show off what they’re capable of if there’s no cheaper off-peak window to shift usage into.

Economy 7

Economy 7 gives you a cheaper rate for seven hours overnight, in exchange for a higher rate the rest of the day. It was originally designed for electric storage heaters, and it can work well for charging a battery or an EV overnight, but the narrow window is less well suited to a heat pump, which typically needs to run for longer, steadier periods rather than in one overnight burst.

EV specific tariffs

Suppliers now offer tariffs built specifically around electric vehicle charging, typically with a longer or cheaper overnight window than Economy 7, sometimes reaching well below 10p per kWh. These pair naturally with a solar and EV charger setup, since you charge from solar during the day when it’s available and top up from the cheap overnight rate when it isn’t. We’ve covered how this works in practice in our guide to solar panels and EV charging.

Heat pump specific tariffs

More recently, suppliers have introduced tariffs designed specifically around heat pump usage patterns, offering multiple lower-rate windows across the day rather than just one narrow overnight slot. These tend to suit heat pump households better than Economy 7, since a heat pump often needs to run intermittently throughout the day rather than in one block.

Agile or time-of-use tariffs

Agile-style tariffs price electricity on a half-hourly basis, following wholesale market prices, which can mean genuinely cheap rates at low-demand times of day, but also higher-than-average rates at peak times. These suit households with a smart battery that can automatically charge when prices are lowest and discharge when they’re highest, since the system does the price-chasing for you rather than you needing to watch rates manually. Without a battery managing this automatically, an Agile-style tariff is harder to make the most of.

The Smart Export Guarantee

The Smart Export Guarantee (SEG) isn’t a usage tariff, it’s a separate payment for any surplus electricity your solar panels export to the grid. Export rates vary by supplier, but it’s worth factoring into the picture alongside whichever usage tariff you choose, since the two work together rather than instead of each other.

Which tariff suits which setup

• Solar only, no battery: a standard tariff is usually fine, since there’s no off-peak charging to plan around, though it’s still worth checking your SEG rate.
• Solar plus battery: an Agile-style, half-hourly tariff tends to make the most of a smart battery that can buy and store electricity automatically when it’s cheapest.
• Solar plus EV, no battery: an EV specific tariff with a cheap overnight window is usually the better fit, so you can top up outside daylight hours without paying peak rates.
• Solar plus heat pump: a heat pump specific tariff, with wider off-peak windows than Economy 7, generally suits how a heat pump actually runs.
• All four together: this is where it’s worth getting proper advice, since the right tariff depends on how your battery, EV charger and heat pump controls talk to each other, if at all.

Frequently Asked Questions

 

Not sure what’s right for your setup?

Every home’s mix of solar, battery, heat pump and EV is different, and the right tariff depends on how they all work together. If you’re considering adding any of this kit, or already have some of it and want to make sure you’re on the right tariff, get in touch for a free, no-obligation chat, or call us on 01747 858 852.