eFriends

This function block reads the electricity prices of the Austrian supplier eFriends. Unlike a pure exchange price source, eFriends provides two price series: the consumption price and the feed-in price. Only with both is it possible to judge when feeding a battery into the grid actually pays off.

• Consumption price (called cons in the interface): what you pay when drawing electricity from the grid. It applies to consumption and to charging the battery from the grid.
• Feed-in price (called gen in the interface, from generation): what you receive when delivering electricity into the grid. It applies to feeding in and to selling from the battery.

The consumption price is always above the feed-in price; the difference is made up of grid fees, levies and the supplier's margin. Both are delivered by the interface in Euro per megawatt hour excluding VAT and converted by the block into cent per kilowatt hour — plus the VAT and surcharges configured below.

Both prices are output separately and passed on separately to the Block storage optimizer. There it is the interplay of both prices that decides whether to charge, consume or feed in.

Prices apply per billing interval. Depending on the tariff an interval is 15 or 60 minutes long; the block detects this itself and reports it on the output Interval duration. Today and the following day are always requested. eFriends publishes the prices for the following day from 17:00 only — until then the output Prices next day available stays at 0, which is not an error. From 17:00 the block retries every 15 minutes until the prices are available.

Before 17:00 the interface already returns the intervals of the following day, but fills them with zeros. A whole day at exactly zero is not a market result but a placeholder, so the block discards it. Without this check the Storage optimizer would plan against a fictitious day and empty the battery in the evening.

The price series read last is stored. After a restart of the controller or after transferring a project it is therefore available again immediately, even when there is currently no connection to the cloud. Prices before the start of the current day are discarded in the process. All addresses are written once in full after the start — otherwise they would stay empty until the next change, as normally only changes are transmitted.

In addition to the prices the block can read the live values of a local eFriends Cube or eFriends Watch+: three-phase grid meter, grid and community flows and — if present — generation power, inverter and battery state of charge. This request runs on the local network and is completely independent of the price request: if the Cube fails the prices remain valid and vice versa. That is why the error outputs are separate.

The price series is also made available internally and can be picked up by the Block storage optimizer function block without any wiring.

On its outputs the block only ever reports the price of the current interval. The course of the feed-in price over the next 24 hours is shown by the Block storage optimizer control element in its schedule, hour by hour next to the planned setpoint and the state of charge. The block no longer creates its own address per hour. With diagnostics switched on it outputs both price series of the complete following day as a message.

The block may exist only once in the project. Several instances would request the same prices repeatedly.

Setup:

• Create a key in the eFriends app under Settings → API Manager. Enter it in the parameter Cloud access key.
• Enter the name of your own tariff in the parameter Tariff name, for example Der bessere Flex Tarif. The name must match the contract tariff exactly.
• If the local live values are to be read as well: enter the IP address of the Cube or Watch+ and create a second key in the API Manager for the parameter Cube access key. If the IP address is left empty, only the price request is carried out.

Notes:

• The interface delivers prices excluding VAT, whereas the eFriends app shows them including VAT. Use the VAT and surcharge parameters to bring the values up to the price actually billed.
• The price request needs a secured connection and works with the SSL version of the runtime only. The local Cube request also works without it.
• The prices of individual friends cannot be retrieved through the interface. Consumption and feed-in price are already the prices effective for your own metering point.
• The outputs only ever carry the price of the current interval. The course of the feed-in price over the next 24 hours is shown by the Block storage optimizer control element.