PvPowerFormula: Fix comment typo

Signed-off-by: Mathias L. Baumann <mathias.baumann@frequenz.com>

src/frequenz/sdk/timeseries/_formula_engine/_formula_generators/_pv_power_formula.py

@@ -40,7 +40,7 @@ def generate(self) -> FormulaEngine[Power]:
                 "Subscribing to the resampling actor with a non-existing "
                 "component id, so that `0` values are sent from the formula."
             )
-            # If there are no PV inverters, we have to send 0 values as the same
+            # If there are no PV inverters, we have to send 0 values at the same
             # frequency as the other streams.  So we subscribe with a non-existing
             # component id, just to get a `None` message at the resampling interval.
             builder.push_component_metric(