When I first had my solar and battery system installed, I thought the hard part was done. Sixteen 410 W panels, a 5 kW inverter, and an 8.2 kWh GivEnergy battery, all hooked up to Octopus Energy. Job done, right?
Not quite.
It turned out that how I used the system mattered almost as much as what I’d installed. The right tariff and the right settings made a surprisingly big difference to how much I actually saved.
If you’ve got a similar setup, solar panels, a GivEnergy battery, and Octopus as your supplier, here’s what I learned and how you can fine-tune yours for better results.
If you’re thinking about how all this fits into the bigger picture, why so many people chase “energy independence” and what that really means, you might like my other post: Energy Independence with Solar Power: The Vision vs Reality. It explores the promise (and limits) of relying fully on solar at home.
My Starting Point
I began on the Flexible Octopus tariff:
- 27.68 p/kWh for imports
- 59.37 p/day standing charge
- 15 p/kWh export on Outgoing Octopus SEG
Simple, predictable, and fine for getting started. But the “flat rate” structure meant I paid the same price no matter when I used power, day or night. That’s not ideal when you’ve got a battery sitting there ready to store cheap electricity.
Why Tariffs Matter More Than You’d Think
Once you’ve got storage, your home becomes part power station, part time machine. You can literally shift when you buy and sell energy.
Octopus offers a few smart tariffs that reward this kind of setup. Here’s what I found when I started comparing them.
1. Octopus Flux — The Solar Export Specialist
Flux is built for homes with panels and batteries.
It splits the day into three zones:
Import:
- Off-peak (02:00–05:00): import around 17 p/kWh
- Peak (16:00–19:00): import around 39 p/kWh
- Daytime: import around 28 p/kWh
Export:
- Off-peak (02:00-05:00): export around 5 p/kWh
- Peak (16:00-19:00): around 30 p/kWh
- Daytime: export about 10 p/kWh
The trick is simple: charge a little at night, use your solar through the day, and then let the battery discharge, or export, during the evening peak. You’re effectively buying cheap and selling dear without lifting a finger.
The following rates a re specific to my area so be sure to check the rates on the website for an accurate representation.
Flux works well when solar production is strong and you can plan around the 3-hour export window.
2. Octopus Go — The Reliable Saver
Then there’s Octopus Go, which is more straightforward. It’s designed for those who own an electric vehicle.
- 00:30–05:30: import around 8.5 p/kWh
- Daytime: roughly 30 p/kWh
- Export remains at 15 p via the standard Outgoing SEG
When you’re not charging your EV, set your GivEnergy battery to charge fully during that cheap overnight window. The next day, it will power the house through breakfast, school runs, and even the dishwasher before lunch. The math works: the overnight rate is so low that it doesn’t really matter that the export is only 15 p/kWh.
Go’s predictability makes it a preferred option in winter when solar production dips.
(If you’ve got an EV, Intelligent Go can extend that cheap window even longer — bonus.)
3. Octopus Agile — For the Tech-Curious
I tried Agile briefly out of curiosity. Prices change every half hour, every day. Sometimes it’s brilliant, like 2 p/kWh at 2 a.m., and sometimes it’s brutal. You need automation tools such as Home Assistant or GivTCP to make it worthwhile. If that sounds fun to you, go for it. If not, stick to something more stable.
What the Numbers Look Like
Here’s a rough snapshot from my calculations (based on 10 kWh daily use and about 4 kWh export):
| Tariff | Daily Import Cost | Daily Export Credit | Net |
|---|---|---|---|
| Flexible + SEG | £2.77 | £0.60 | £2.17 |
| Flux | £1.92 | £0.98 | £0.94 |
| Go + SEG | £1.50 | £0.60 | £0.90 |
It won’t be identical for everyone, but even at this scale, switching to a smart tariff roughly halved my energy costs.
How I Set Up My GivEnergy System
Once I’d chosen the right tariff, I adjusted the settings in the GivEnergy app:
| Setting | For Flux | For Go |
|---|---|---|
| Charge Window | 02:00–05:00 | 00:30–04:30 |
| Discharge Window | 16:00–19:00 | None (use freely) |
| Target Charge | 80–100% | 100% |
| Grid Charge | Enabled | Enabled |
| Solar Forecast Mode | Optional | Optional |
After that, I mostly left it alone. The system quietly handled the rest, charging when rates were low, discharging when they were high.
A Few Real-World Notes
Not every household runs the same way. If you’re home most of the day using appliances, Flux’s evening export period might not matter much. If you’re out during daylight and draw more power at night, it could be perfect. And if you drive an EV, Go or Intelligent Go is usually the winner.
Tariff rates also shift slightly every few months, so it’s worth checking Octopus’s site before making changes. If you’re not yet a customer, grab £50 credit with my Octopus Referral.
Final Thought
Your solar and battery setup can do more than just lower bills. It can work like a personal energy hedge. The panels generate, the battery arbitrages, and you control the timing.
If you’re on the standard Flexible tariff right now, take an evening to explore Flux or Go. A few minutes tweaking your GivEnergy schedule might save you hundreds of pounds a year.
It’s not about chasing perfection, it’s about letting your system do what it was designed to do: work smart. And if you’re still wondering whether investing in solar is truly worth it, check out my detailed analysis on whether solar is worth it, where I break down the costs, payback, and lessons from our £13k UK system.