diff --git a/docker-compose.yaml b/docker-compose.yaml
index ae1e62c..e2e749a 100644
--- a/docker-compose.yaml
+++ b/docker-compose.yaml
@@ -12,8 +12,20 @@ services:
       - /app/data/power-compare-mcdowall-persistent/.env
     environment:
       - DB_PATH=/data/power_compare.db
+      # Shared with the Kallangur (power-compare) stack's identical setting
+      # via the volume below -- both instances authenticate against the
+      # same iSolarCloud account, and Sungrow's OAuth server only keeps one
+      # active token session per (app, account), so each instance
+      # refreshing its own copy independently was silently invalidating
+      # the other's. Pointing both at the same bind-mounted file makes
+      # them share one session.
+      - ISOLARCLOUD_SHARED_TOKEN_PATH=/shared-oauth/isolarcloud_oauth.json
     volumes:
       # Bind-mount SOURCE, by contrast, is resolved by the real Docker
       # daemon against the actual host filesystem -- a real host path.
       - /Users/davidlawler/docker/power-compare-mcdowall-data/data:/data
+      # Same host path as the power-compare (Kallangur) stack -- this MUST
+      # stay identical across both compose files, since the point is for
+      # both containers to bind-mount the literal same file.
+      - /Users/davidlawler/docker/power-compare-shared-oauth:/shared-oauth
     restart: unless-stopped
diff --git a/docker-compose.yml b/docker-compose.yml
index ae1e62c..e2e749a 100644
--- a/docker-compose.yml
+++ b/docker-compose.yml
@@ -12,8 +12,20 @@ services:
       - /app/data/power-compare-mcdowall-persistent/.env
     environment:
       - DB_PATH=/data/power_compare.db
+      # Shared with the Kallangur (power-compare) stack's identical setting
+      # via the volume below -- both instances authenticate against the
+      # same iSolarCloud account, and Sungrow's OAuth server only keeps one
+      # active token session per (app, account), so each instance
+      # refreshing its own copy independently was silently invalidating
+      # the other's. Pointing both at the same bind-mounted file makes
+      # them share one session.
+      - ISOLARCLOUD_SHARED_TOKEN_PATH=/shared-oauth/isolarcloud_oauth.json
     volumes:
       # Bind-mount SOURCE, by contrast, is resolved by the real Docker
       # daemon against the actual host filesystem -- a real host path.
       - /Users/davidlawler/docker/power-compare-mcdowall-data/data:/data
+      # Same host path as the power-compare (Kallangur) stack -- this MUST
+      # stay identical across both compose files, since the point is for
+      # both containers to bind-mount the literal same file.
+      - /Users/davidlawler/docker/power-compare-shared-oauth:/shared-oauth
     restart: unless-stopped