HOMER Knowledge Base
HOMER Grid Utility Tariff Component
Does the utility tariff builder allow us to input/import a utility that we have custom created and has the granularity of a time-series data (i.e. hourly price data)? What are the possible formats in which we can import a custom-built tariff? For example, can we have an Excel spreadsheet with hourly price data that we then import into HOMER Grid?
Yes, it is possible to import a price strip into a custom tariff by opening the Library and clicking on "Use the Advanced Tariff Builder".
Then go to the Consumption tab and click "Add Rate". In the new window, click on "Import Timeseries" to import the price strip using a CSV file format.
Then go to the Consumption tab and click "Add Rate". In the new window, click on "Import Timeseries" to import the price strip using a CSV file format.
How exactly does HOMER combine two tariffs that are input using the “Combine 2 Custom Tariffs” option?
When combining two tariffs, HOMER will concatenate all of the rates. HOMER does this by taking all of the Consumption rates from Tariff 1 and adding those to the list of the Consumption rates from Tariff 2, showing a final combined list of Consumption rates. When we calculate the bill in the simulation engine, the cost for each rate is calculated separately, and then the costs are all added together to determine the total bill. So combining the tariffs has the effect of adding the costs together. But no rates are merged -- the rates are all kept unchanged, just all inserted into a single tariff.
For example:
Tariff A:
Consumption rates: Off-peak rate 1; on-peak rate 2
Demand rates: demand rate 3
Fixed rates: fixed rate 4
Tariff B:
Consumption rates: off-peak rate 5
Demand rates: none
fixed rates: fixed rate 6
Combined tariff:
Consumption rates: Off-peak rate 1; on-peak rate 2, off peak rate 5
Demand rates: demand rate 3
fixed rates: fixed rate 4, fixed rate 6
Tariff rates will state “TBD” whenever a rate is defined by a complex formula. For example, a tariff rate that is $0.2/kWh when the load is less than 100 kW but increases to $0.3/kWh when the load is greater than 100kW would state “TBD”. Depending on the complexity of the rate, HOMER may not be able to combine two TBD rates.
When combining two tariffs, HOMER will concatenate all of the rates. HOMER does this by taking all of the Consumption rates from Tariff 1 and adding those to the list of the Consumption rates from Tariff 2, showing a final combined list of Consumption rates. When we calculate the bill in the simulation engine, the cost for each rate is calculated separately, and then the costs are all added together to determine the total bill. So combining the tariffs has the effect of adding the costs together. But no rates are merged -- the rates are all kept unchanged, just all inserted into a single tariff.
For example:
Tariff A:
Consumption rates: Off-peak rate 1; on-peak rate 2
Demand rates: demand rate 3
Fixed rates: fixed rate 4
Tariff B:
Consumption rates: off-peak rate 5
Demand rates: none
fixed rates: fixed rate 6
Combined tariff:
Consumption rates: Off-peak rate 1; on-peak rate 2, off peak rate 5
Demand rates: demand rate 3
fixed rates: fixed rate 4, fixed rate 6
Tariff rates will state “TBD” whenever a rate is defined by a complex formula. For example, a tariff rate that is $0.2/kWh when the load is less than 100 kW but increases to $0.3/kWh when the load is greater than 100kW would state “TBD”. Depending on the complexity of the rate, HOMER may not be able to combine two TBD rates.
Can HOMER Grid perform an optimization such that a battery system is optimized to charge at peak periods of high prices and discharge at off-peak periods of low prices? If this is not one of the default options in HOMER Grid, is there a workaround where this calculation can be performed? Does HOMER Grid have the ability to choose from different dispatch strategies, such as the ones in HOMER Pro?
HOMER Grid has one dispatch strategy, which is to peak shave and perform energy arbitrage (charging/buying when the grid price is low and discharging/selling when the grid price is high). I think this is what you meant in your question, although you stated it the other way around. So yes, HOMER Grid automatically does this when the difference in grid price is great enough. Technically HOMER Grid has one more dispatch strategy you can use, although it is not the default and must be built custom by the user, which is the HOMER Grid MATLAB Link. So there are two dispatch strategies available for HOMER Grid: Peak Shaving and the custom MATLAB Link.
HOMER Pro has more flexibility and has 7 dispatch strategies to choose from. More information on Pro's dispatch strategies can be found in this Knowledgebase article, although I believe we have added one or two dispatch strategies since this was written.
HOMER Grid has one dispatch strategy, which is to peak shave and perform energy arbitrage (charging/buying when the grid price is low and discharging/selling when the grid price is high). I think this is what you meant in your question, although you stated it the other way around. So yes, HOMER Grid automatically does this when the difference in grid price is great enough. Technically HOMER Grid has one more dispatch strategy you can use, although it is not the default and must be built custom by the user, which is the HOMER Grid MATLAB Link. So there are two dispatch strategies available for HOMER Grid: Peak Shaving and the custom MATLAB Link.
HOMER Pro has more flexibility and has 7 dispatch strategies to choose from. More information on Pro's dispatch strategies can be found in this Knowledgebase article, although I believe we have added one or two dispatch strategies since this was written.