How to use Solar Panels and Battery efficiently

Shrewd_Person

March 2025 I was sold Solar Panels and Battery based on Octopus Flux product information.

Octopus information shows a graph where the Night Import rate is less than Day Export rate and explanation recommends users to fully charge batteries at Night Rate and use Solar to keep batteries 100% charged until Peak Rates to discharge batteries whilst exporting any surplus Solar at Day Rate.

This sounds perfect. However, the actual Import / Export Night, Day and Peak rates of Octopus Flux do not adhere to this as the Day Export Rate is less than the Night Import Rate.

Therefore Octopus gave and is stil giving mis information as Exporting Solar during the day wittles away profit from charging / dicharging the batteries.

However, there must be a way to optimise the rates that are available with either Octopus or other utility companies.

First part of my plan is to charge the batteries at Night Rate up to a variable % based on usage prior to Solar output being greater than load consumption and based on expected weather to achieve 100%.charge as at start of Peak Rate.

Second part of my plan is to discharge the batteries at Peak Rate down to a variable % based on expected usage prior to Peak Rate finishing.

So to conclude, I would appreciate discussions covering either or both points of mis-information and how to best use available rates. 

debitcardmayhem

Who sold you the panels, Octopus flux hasn’t been having rates like that for quite a while, since before 1 apr 24 AFAIK, and where is the mis-information showing what you claim?

QrizB

MSE_Reader said:

March 2025 I was sold Solar Panels and Battery based on Octopus Flux product information.

Sold by whom, exactly?

What equipment (panels, inverter, battery) do you have?

MSE_Reader said:

However, the actual Import / Export Night, Day and Peak rates of Octopus Flux do not adhere to this as the Day Export Rate is less than the Night Import Rate.

Octopuss's tariffs are all published on their website:

https://octopus.energy/tariffs

They are revised every so often.

There's a significant business risk in committing capital outlay when future returns are uncertain. See for example WeWork.

MSE_Reader said:

However, there must be a way to optimise the rates that are available with either Octopus or other utility companies.

Grid-tied solar with battery storage can definitely reduce your energy bills of you choose a suitable tariff. I've been paying  an average of about 9p/kWh for import in recent months, for example.

This is mostly discussed on the "Green and Ethical" forum, but does occasionally come up here too.

amanda1024

Note that the different price points in Octopus Flux are not tied and so which is higher/lower varies. In terms of what this means for getting most value:
- your suggestion of charging to a variable amount in the overnight cheap rate is sensible, although calculating the variable amount is potentially challenging - you could look at each day’s weather forecast to adjust this daily, but I’ve tended to go for a very low % over the summer but now the nights are drawing in and weather’s getting worse I’m up to 50%, and by December will probably be 100% (my battery is quite small)
- I haven’t tended to forcefully discharge in the evening peak (except during saving sessions to get the bonus) because in the summer the battery is usually full by then so excess solar is being exported anyway, and in the winter I’ll end up discharging most of the battery over the evening when most of my usage is - probably this means I’m slightly not making the most of the battery over the summer - but I’m not sure of the impact of extra charging cycles on the lifespan of the battery