This guide is specific to Flow Power. Please refere to the Amber Electric & LocalVolts guide for principles specific to the wholesale market.
Flow Power base their own pricing on the wholesale market that can change every 5 minutes. Electricity is the cheapest to buy during the day, increases a lot during the demand period (usually 4-9pm), then decreases during the night (but stays higher than during the day), and then sometimes there is a morning shoulder peak, then it drops down during the day again. Prices are cheapest during the day simply because of the large amount of renewables (solar and wind) being generated at the time. It is simply supply & demand that drives the pricing.
When these buy prices go up and down, the price that Flow Power pays for your electricity also go up and down, even though you are on a set buy price (usually around 34c/kWh).
Flow Power works on a system they term PEA (Price Efficiency Adjustment) which can result in significant savings if their rules are followed. If you consume your power when it is the cheapest for Flow Power to purchase it wholesale (i.e., usually during the day), then this is looked at as favourable by Flow Power and they can alter your PEA so that your usual 34c/kWh price is reduced. Conversely, if you purchase during expensive wholesale periods, then Flow Power will penalise you, in that they will not give you a discount. The discount is calculated over the entire month, and you will only realise your PEA discount (if you get one) on your bill, and it applies to the whole month. Your energy consumption (and export) behaviour are compared to everyone else using Flow Power. The idea behind Energy Manager for Flow Power is that it watches the wholesale market and will ensure that if you have to charge your battery from the grid, it will do so when the AEMO/wholesale price is at the lowest for the day. It will also export, if enabled, during the peak period, where you can profit from either a 35 or 45c/kWh feed-in (location dependent).
Sometimes the wholesale prices are negative, especially exports. If this is the case, then Energy Manager will curtail, or stop, exports so that you don't get penalised by Flow Power (it is not yet known whether negative export impacts your PEA, but it is assumed it does). Note, Energy Manager is designed to stop drawing from the grid for any price if it is during a demand period.
Energy Manager will always aim to have your battery fully charged by 4pm, which is usually when the demand period starts.
If you're on a demand tariff, then you don't want to ever pull electricity from the grid during this time (this varies, but generally 4-9pm daily).
If your solar array has the capacity, it should be possible to fully charge your battery from the sun during the summer, and mostly charge it during the other seasons. However, if you aren't going to be able to obtain a full battery by 4pm, it is generally more economical to automatically charge your battery to 100% so that you use the cheaper day-time pricing to store electricity in your battery to use when the buy pricing is higher later on.
If your solar array size and battery capacity is such that you can't normally fully charge your battery, then Energy Manager will charge it up for you automatically. If your solar array size and battery are sized so that they can easily be charged purely by the sun, then Energy Manager won't charge your battery for you - unless the solar forecast predicts that there is not enough solar generation remaining to do it yourself (e.g., bad weather), then it will charge it up ready for later use.
There are two methods to charge your battery:
a. From the electricity generated from your solar array
b. From importing from the grid
Energy Manager aims to work out what the best method is for you. If your system is capable of generating and storing enough electricity to charge your battery without help, it will not take from the grid. When it does have to take from the grid, it ensures that it is taken during the periods that are least likely to negatively impact your PEA.
Ideally you should only discharge your battery under two circumstances:
a. During the Happy Hour (or peak period) - it is better to get paid either 35 or 45c/kWh (location dependent) for two hours and import from the grid during a cheap time, than to use your power yourself.
b. After the sun has gone down (or you're generating less than you are using, and it is cheaper to use your stored power than take from the grid).
If the sell/export/fit price is negative, then you may be penalised to export excess solar energy. Energy Manager monitors the wholesale rates and will send a configuration command to your inverter to stop your exports.
Energy Manager will import power from the grid under the following circumstances:
a. You have no power left in your battery (or the reserve has been met)
b. It is advantageous to purchase from the grid during cheap periods than use the power stored in your battery. The stored energy should be kept for later when you might be penalised for importing during a high demand period.
Exports are limited to the following situations:
a. It is currently peak period/happy hour and you will get a good sell price for your exported power. This is generally a forced export.
b. The wholesale sell price is positive AND your battery is full. A forced export will not happen, but Energy Manager may allow your excess to be exported (but not if the wholesale price is negative).