diff --git a/.idea/AndroidProjectSystem.xml b/.idea/AndroidProjectSystem.xml
new file mode 100644
index 0000000..4a53bee
--- /dev/null
+++ b/.idea/AndroidProjectSystem.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="AndroidProjectSystem">
+    <option name="providerId" value="com.android.tools.idea.GradleProjectSystem" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/src/main/kotlin/typed/EnergyPriceTimeSeries.kt b/src/main/kotlin/typed/EnergyPriceTimeSeries.kt
new file mode 100644
index 0000000..78ca36b
--- /dev/null
+++ b/src/main/kotlin/typed/EnergyPriceTimeSeries.kt
@@ -0,0 +1,7 @@
+package com.zenmo.timeseries.typed
+
+import java.time.temporal.Temporal
+
+interface EnergyPriceTimeSeries {
+    fun getEurPerKwh(intervalStart: Temporal): Double
+}
diff --git a/src/main/kotlin/typed/UnitlessTimeSeries.kt b/src/main/kotlin/typed/UnitlessTimeSeries.kt
new file mode 100644
index 0000000..0f82457
--- /dev/null
+++ b/src/main/kotlin/typed/UnitlessTimeSeries.kt
@@ -0,0 +1,10 @@
+package com.zenmo.timeseries.typed
+
+import java.time.temporal.Temporal
+
+/**
+ * For duty cycle or power factor
+ */
+interface UnitlessTimeSeries {
+    fun get(intervalStart: Temporal): Double
+}
diff --git a/src/main/kotlin/typed/VolumeTimeSeries.kt b/src/main/kotlin/typed/VolumeTimeSeries.kt
new file mode 100644
index 0000000..5b156b4
--- /dev/null
+++ b/src/main/kotlin/typed/VolumeTimeSeries.kt
@@ -0,0 +1,7 @@
+package com.zenmo.timeseries.typed
+
+import java.time.temporal.Temporal
+
+interface VolumeTimeSeries {
+    fun getM3(intervalStart: Temporal): Double
+}