How solar panels and Agile interact
Solar panels reduce your daytime grid consumption. Octopus Agile provides cheap overnight electricity for the hours solar cannot cover. The two work on opposite ends of the clock, which is why they complement each other so well.
During daylight hours, your panels generate electricity that powers your home directly. Every unit you self-consume from solar is a unit you do not need to buy from the grid. On a sunny summer day, a 3.5kWp system generates 12-18 kWh, which more than covers the average UK household's daytime consumption of 4-6 kWh. The Agile daytime rate on those days becomes largely irrelevant because you are not buying any grid electricity.
In the evening, solar generation drops to zero. Your consumption continues. This is when Agile provides its most direct value. Between 7pm and midnight, Agile prices are typically 8-20p/kWh. Between midnight and 6am, they regularly drop to 2-5p/kWh. Solar owners without a battery rely entirely on these cheap overnight rates to cover their evening and overnight consumption at minimum cost.
Together, a solar and Agile combination can reduce net electricity spend by 60-80% compared to a standard variable tariff. A household spending £1,100 per year on electricity before solar installation could bring that figure down to £200-440 with panels and Agile, without any battery storage at all.
The best-case scenario: sunny day and cheap overnight
On a clear summer day in the UK, the solar and Agile combination fires on all cylinders. Here is what that looks like in practice for a typical three-bedroom home with a 3.5kWp system.
From 7am to 8pm, the panels generate 15-20 kWh. The household uses approximately 5-7 kWh during this period. The remaining 8-13 kWh is either exported to the grid via the Smart Export Guarantee or, if a battery is present, stored for later use. No grid electricity is purchased between 7am and 8pm.
From 8pm to midnight, consumption is roughly 2-3 kWh. Agile prices during this period on a summer evening typically run 8-15p/kWh. Cost: approximately £0.20-0.45.
From midnight to 6am, consumption is around 1-2 kWh for standby loads, overnight appliances, and any scheduled tasks you have set to run in the cheap window. Agile prices in this window regularly come in at 2-4p/kWh. Cost: approximately £0.04-0.08.
Total net daily grid import cost on a summer sunny day: £0.24-0.53. Over a full month of good summer weather, your grid electricity bill might be £8-16. Annual electricity costs drop below £200 for households who manage their consumption well and check live Agile prices to time their overnight usage.
The challenge: Agile daytime prices on cloudy days
Solar and Agile is not a set-and-forget combination on every day. On cloudy days or in winter, solar generation drops substantially, and you will be buying more grid electricity during daytime hours when Agile prices are at their daily peak.
On a grey January day, a 3.5kWp UK system might generate only 2-4 kWh total. Your household may consume 10-14 kWh across the full day. That leaves 8-12 kWh to purchase from the grid. If the bulk of that import happens during the daytime window, you will be paying 10-20p/kWh on Agile. This is still considerably cheaper than the 26.11p Ofgem price cap, but it is worth being aware that cloud cover genuinely affects your Agile economics.
The practical response: shift consumption to overnight wherever possible. Run your dishwasher, washing machine, and tumble dryer between midnight and 6am. Charge devices overnight. Heat your hot water immersion cylinder on the cheap overnight window. This consumption shifting means you draw the grid electricity you need at 2-4p rather than 10-20p, and your solar generation covers most of the remaining daytime loads even on partly cloudy days.
Winter daytime Agile prices of 10-18p/kWh are still 8-16p cheaper than the cap. Over 1,500 kWh of winter daytime grid import, that saving is worth £120-240 per year compared to a standard tariff. The combination still wins, even in winter.
When to self-consume versus when to export
Solar owners on Agile face a daily decision: use your solar-generated electricity in your home or export it to the grid via the Smart Export Guarantee.
The answer is almost always to self-consume first. Exporting earns you 4-20p/kWh via the SEG depending on your supplier, with Octopus Outgoing currently paying approximately 15-20p. But every unit you self-consume avoids buying grid electricity that would otherwise cost you the Agile rate, which ranges from 2-40p/kWh depending on time of day.
During normal daytime operation when Agile prices are 8-18p/kWh, self-consuming solar is worth 8-18p in avoided cost compared to exporting at 15-20p. The gap is narrow, which is why smart diverters (covered in our solar diverter guide) that direct surplus solar into your hot water cylinder are worth considering. Heating water with surplus solar instead of exporting it at 15p and buying gas at 5.5p/kWh provides better overall value.
The export-first calculation only flips in very specific circumstances: if your Agile import price is very low that day (below 5p), and your SEG export rate is above 15p. In that narrow window, selling back to the grid earns more than the cost of the electricity you would be buying. Outside that scenario, self-consumption wins.
How solar diverters complement the setup
A solar diverter is a device that monitors your solar generation and home consumption in real time. When solar generation exceeds home consumption, instead of letting that surplus flow out to the grid at SEG rates, the diverter redirects it to your immersion heater and heats your hot water for free.
The value of this is clearest when you compare the alternatives. Exporting 1 kWh earns 4-15p. Using that 1 kWh to heat water replaces gas heating at 5.5p/kWh or electric resistance heating at 26p/kWh. The effective value of the self-consumed unit is 5-26p, compared to the 4-15p you would earn from export. Self-consumption in the immersion heater almost always beats export.
The main solar diverter products in the UK are the myenergi Eddi (approximately £350-450 installed), the Solic 200 (approximately £200-300 installed), and the iBoost+ (approximately £280-380 installed). All three work with standard immersion heaters in vented and unvented hot water cylinders. If you have a combi boiler with no cylinder, a diverter cannot be used.
Combined with Octopus Agile overnight rates, a solar diverter gives you year-round hot water with minimal or zero energy cost. In summer, the diverter heats your water from solar surplus. In winter when solar is limited, you schedule your immersion heater to run on the cheap Agile overnight window at 2-4p/kWh. Your total water heating cost across the year approaches zero.
Is Agile better than Flux for your household?
Most solar owners considering a smart tariff face the Agile vs Flux question at some point. The answer depends on three variables: how much you export, how much you import overnight, and whether you have a battery.
Octopus Flux offers a cheap overnight import window at 8-10p/kWh (midnight to 6am), a good midday export rate at 15-20p/kWh, and a standard rate of roughly 24-26p/kWh at all other times. It is designed for battery owners who can charge overnight and export during the midday solar peak. The structure is simple and predictable.
Agile's overnight rates typically average 3-6p/kWh, which is 2-5p cheaper than Flux's fixed overnight window. Over 2,000 kWh of overnight import per year, Agile saves £40-100 more than Flux on imports alone. The export side is roughly comparable: both offer around 15-20p/kWh via SEG mechanisms.
For households with 3-4kWp solar, average UK consumption, and a battery, Agile generally produces a better outcome due to lower overnight import costs. For households with large solar arrays exporting 3,000+ kWh per year, Flux's predictable midday export rate may be preferable. Check today's Agile prices to understand the typical overnight rate in your region and compare it against Flux's current overnight import rate before switching.