diff --git a/wlauto/instrumentation/energy_model/__init__.py b/wlauto/instrumentation/energy_model/__init__.py
index 43b5b8b8..6ce94740 100644
--- a/wlauto/instrumentation/energy_model/__init__.py
+++ b/wlauto/instrumentation/energy_model/__init__.py
@@ -11,6 +11,8 @@ from collections import Counter, namedtuple
 try:
     import jinja2
     import pandas as pd
+    import matplotlib
+    matplotlib.use('AGG')
     import matplotlib.pyplot as plt
     import numpy as np
     import_error = None