Hey - quick one, we just released a free tariff calculator for users with PV + battery storage:
https://www.wonderwatt.com/solar-battery-tariff-calculator/
Basically estimates your average usage over the year, takes into account your PV capacity + battery and works out best import + export tariff combos.
Feedback welcome, thank you.
Just tried your calculator. Confirmed that Flux is the best tariff for me - 13.5kWh battery, 3.96kWp PV - no EV. The projected earnings are very accurate to what I have experienced.
Feedback:
Allow Annual known kWh usage
Put error messages next to the errored boxes
Allow seasonal tariff shifts.
Oddly if I have no EV/smart charger and no Heatpump the FLux is the cheapest
but if I tick heatpump (and no other changes) Flux becomes more expensive....
Looks like there is some maths errors going on though as the numbers are all over the place.
Feedback
Just filled it in and EDF was cheapest being £200 cheaper than IOG with EV, heat pump, solar and battery. Problem is that we have paid about £300 (including standing charge) for the last two years with no real changes but it was showing £1200 minimum so I don’t know what is going on there?
wrighar Thanks for the feedback, all useful.
You can now (deploying as we speak. so give it 10 mins or so) give your use as a yearly figure, and error messages show next to the box that needs fixing. The heat pump tick adds a heat pump's use (3,500 kWh a year by default, or your own figure), mostly on winter evenings, which is why Flux, with its 4 to 7pm peak, gets dearer: it's working as intended, but the page now tells you.
Seasonal switching is a good idea and we're looking at it.
SimonClarke Thanks for reporting, you found a bug.
If you entered your known daily use, we added the EV and heat pump on top of it, counting them twice. That's fixed shortly, so now a known figure includes them unless you untick the box, and you can enter a yearly total too.
It should come out much closer to what you actually pay. And bear in mind the results don't include standing charges.
Wonder Watt I will give it another go in a while
Just ran it again. Much nearer but still high as with standing charge near enough double last year. Obviously the lower export rate will affect it
SimonClarke Thanks for retesting!
This is very interesting. It shows me that Agile and Cosy come out about the same for the year and both are beaten by Flux (because of the export rate). But what my analysis shows is that Cosy is better for the November to February period and Agile for March to October. Could the tool be enhanced to show the best time to switch between 2 tariffs for summer/winter? There is quite a difference when you have solar.
Windy Miller Yep, been mentioned earlier too, good suggestion, we’ll add that in over the next day or two.
Wonder Watt I can report success with your new calculator. Results were v close to real world outturn.
I'm also very interested in WonderBatt and look forward to a beta invitation :-)
Configuration:-
GE 3.6 Gen 3 Inverter, 9.5 kWh battery
GE Premium with Axle 'event management'
HA used for inbound data monitoring and reporting, no other automated tariff automation.
Octopus Flux.
MerseyRider Your luck day https://app.wonderwatt.com/wb/PZEQVZK4
Anyone considering joining Wonder Watt / Wonder Batt can use this code. If you subscribe both you and I get a month of free subscription
Wonder Watt Thanks for making that change.
Did you select October to March as Winter being 6 months long or based on expected solar generation in the respective months? I have found March to be a good solar month with lots of sun and cold temperatures improving the panel efficiency so have counted the Winter months as October to February.
Also I guess the whole analysis is based on historic rates? How have you allowed for the increases that are predicted? For example the analysis uses the current Cosy rates which are going up later in the week. And I know for sure that Agile rates are increasing far more than most of the other tariffs.
This is a really good analysis tool. I've tried several and wrote my own as I wasn't happy with their analysis but this one comes a lot closer to what I predict. Wonder Watt does seem to understand how to get the best from one's system.
Windy Miller Did you select October to March as Winter being 6 months long or based on expected solar generation in the respective months?
Purely related to solar forecasts during those months yeah.
The analysis actually does use current rates.