AWATTAR

This function block reads the exchange electricity prices of the supplier aWATTar. The source is the EPEX Spot exchange; the hourly prices of today and the following day are requested. No access key is required, the interface is freely available.

The prices for the following day become available from about 14:00. Until then the output Prices next day available stays at 0; this is not an error.

The interface delivers the plain exchange price excluding VAT and without grid fees. The VAT and surcharge parameters turn it into the price actually billed. Only with this does the Storage optimizer work with the correct cost as well.

The hourly prices are also made available internally and can be picked up by the storage optimizer without any wiring. As aWATTar knows the consumption price only, the parameter "Fixed feed-in tariff" has to be set there for the feed-in side.

Besides the outputs, 24 hourly values each for today and tomorrow are written to separate addresses. They are created by the automatic address generation and can be used for displays and charts.

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. 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.

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

Inputs
SI	Limit min. %	Limit in percent for computing "Price reached min." (deviation from the median).
SA	Limit max. %	Limit in percent for computing "Price reached max." (deviation from the median).
MM	Limit min/max %	Limit in percent that minimum and maximum must reach at least before "Price reached" is output.
FR	Enable	At 0 the request is stopped. If the input is not connected, the block is enabled.
Outputs
FE	Error	The request has failed three times in a row. The last price series read is retained and continues to be used.
PA	Price now	Price of the current hour in cent per kilowatt hour.
PI	Price minimum	Lowest price in the period still ahead. Hours already past are not taken into account.
PM	Price maximum	Highest price in the period still ahead.
PE	Price median	Median price in the period still ahead.
DR	Price average	Average price in the period still ahead.
AI	Diff. min. %	Deviation of the current price from the median, relative to the distance between median and minimum.
AA	Diff. max. %	Deviation of the current price from the median, relative to the distance between median and maximum.
EI	Price reached min.	The current price is below the limit formed from the inputs.
EA	Price reached max.	The current price is above the limit formed from the inputs.
MI	Cheapest window active	Set to 1 when the current hour lies within the cheapest contiguous window. The length of the window is defined by the parameter "Time minimum cost".
MA	Most expensive window active	Set to 1 when the current hour lies within the most expensive contiguous window. The length of the window is defined by the parameter "Time maximum cost". This allows, for example, a battery to be discharged into the grid exactly when electricity is most expensive.
MO	Prices next day available	1 as soon as the prices for the following day have been read. Before about 14:00 the output is 0; this is not an error.
IZ	Number of intervals	Number of hourly prices read. On the two daylight saving change days there are 23 or 25 per day accordingly.
Additional addresses
	Price [ct] 0:00h … 23:00h	Hourly price in cent per kilowatt hour, including the configured VAT and surcharge. The addresses are created by the automatic address generation, have no terminal on the block and are intended for displays and charts. The block is a ring buffer covering the next 24 hours: from the current hour onwards it holds the current day, before that the following one. At 17:00, 17:00h to 23:00h therefore hold today's prices and 0:00h to 16:00h those of tomorrow. The curve is thus always complete and only shows prices that are still ahead. It is re-sorted on every full hour. Only what is known is output. While the prices for the following day are not yet available, the hours that have already passed stay at 0 — a past price no longer applies and would be misleading. With diagnostics switched on the block additionally outputs the complete following day as a message.
Parameters
	Country	Austria or Germany. The two countries are separate market areas with different prices.
	VAT	Percentage added to the exchange price. The interface delivers net values.
	Surcharge	Fixed amount added to the price, for example for grid fees, levies and the supplier's margin.
	Time minimum cost	Length of the cheapest window in hours. If 2 is entered here because a load needs two hours of operation, the output "Cheapest window active" reports 1 exactly while these two hours are running.
	Time maximum cost	Length of the most expensive window in hours.
	Price request interval	Cycle time of the request. As the prices change only once a day, a short cycle serves no purpose.

AWATTAR

Inputs

Outputs

Additional addresses

Parameters