diff --git a/schemas/BaseElements.xsd b/schemas/BaseElements.xsd
index 5fbb29e5..29d5e1a0 100644
--- a/schemas/BaseElements.xsd
+++ b/schemas/BaseElements.xsd
@@ -1721,8 +1721,8 @@
 									</xs:element>
 									<xs:element minOccurs="0" name="CollectorRatedOpticalEfficiency" type="CollectorRatedOpticalEfficiency">
 										<xs:annotation>
-											<xs:documentation>Often referred to as Fr-tau-alpha (FRta), this describes the optical efficiency portion of the overall collector efficiency. In the OG-100
-												SRCC Certified Solar Thermal Collector Directory, this is the y-intercept of the efficiency curve.</xs:documentation>
+											<xs:documentation>[Btu/h-ft^2-F] Often referred to as Fr-tau-alpha (FRta), this describes the optical efficiency portion of the overall collector efficiency. 
+												In the OG-100 SRCC Certified Solar Thermal Collector Directory, this is the y-intercept of the efficiency curve.</xs:documentation>
 										</xs:annotation>
 									</xs:element>
 									<xs:element minOccurs="0" name="CollectorRatedThermalLosses" type="CollectorRatedThermalLosses">