diff --git a/goodwe_controller/DECISIONS/OPT-27-last-fresh-forecast-for-the-night.md b/goodwe_controller/DECISIONS/OPT-27-last-fresh-forecast-for-the-night.md
index 8230585..973f238 100644
--- a/goodwe_controller/DECISIONS/OPT-27-last-fresh-forecast-for-the-night.md
+++ b/goodwe_controller/DECISIONS/OPT-27-last-fresh-forecast-for-the-night.md
@@ -20,7 +20,7 @@ still keeps a run under way when a read is lost.
 sensor that is missing or stale, never one with a bad value or unit, and:
 - for up to `FRESH_S` when the sensor is missing: a short outage, any time of day;
 - from the end of the bell (20:00 local, `BELL_TO_H`) until local midnight + 3 h
-  (`KEPT_UNTIL_H`), however old;
+  (`KEPT_UNTIL_H`), if the reading is at most `KEPT_MAX_AGE_S` (12 h) old when used;
 - the day it is for: a today figure only on that day, a tomorrow figure as
   tomorrow until midnight and, if the today sensors are still stale, as today's
   until midnight + 3 h (all sensors of the sum are needed, as for any sum);
diff --git a/goodwe_controller/app/solarfc.py b/goodwe_controller/app/solarfc.py
index 874b273..7ddfa82 100644
--- a/goodwe_controller/app/solarfc.py
+++ b/goodwe_controller/app/solarfc.py
@@ -34,7 +34,8 @@ evening and api.forecast.solar is sometimes out for a poll. A kept reading
 stands in for its sensor (a) for up to `FRESH_S` when the sensor is missing
 or unavailable, as a sensor that merely stopped updating is already
 tolerated, and (b) from the end of the bell (`BELL_TO_H`) until local
-midnight + `KEPT_UNTIL_H` however old it is. Never beyond that, and never
+midnight + `KEPT_UNTIL_H`, if it is at most `KEPT_MAX_AGE_S` old when used.
+Never beyond that, and never
 for another day: a today figure is only today's, a tomorrow figure is
 tomorrow's until midnight and then, until midnight + 3 h, today's.
 DECISIONS/OPT-27-last-fresh-forecast-for-the-night.md.
diff --git a/goodwe_controller/test_opt27.py b/goodwe_controller/test_opt27.py
index 2c6289e..2793b49 100644
--- a/goodwe_controller/test_opt27.py
+++ b/goodwe_controller/test_opt27.py
@@ -7,8 +7,9 @@ Forecast.Solar site was "no forecast": a price mode's night cheap run needed
 fresh reading of each sensor, for the day it is FOR:
 
 * up to `FRESH_S` when the sensor is missing or unavailable (a short outage);
-* from the end of the bell (20:00) until local midnight + 3 h however old it
-  is (the night plan); never beyond, never for another day.
+* from the end of the bell (20:00) until local midnight + 3 h, if the reading
+  is at most `KEPT_MAX_AGE_S` (12 h) old when used (the night plan); never
+  beyond, never for another day.
 
 DECISIONS/OPT-27-last-fresh-forecast-for-the-night.md.
 
@@ -166,7 +167,7 @@ check("... its sun is counted on the day it is for (06:00-20:00 on the 4th)",
       and fmid.between(at(4, 3, 0), at(4, 7, 0)) > 0.0)
 check("03:01 (midnight + 3 h): not used any more",
       rs(GONE, GONE, at(4, 3, 1), h2)[0] is None)
-check("... and not the next evening either (older than one night)",
+check("... and not the next evening either (past midnight + 3 h)",
       rs(GONE, GONE, at(4, 22, 0), h2)[0] is None)
 fe = rs(st(0.1, at(4, 21, 50)), GONE, at(4, 22, 0), h2)[0]
 check("... the next evening, with today fresh and tomorrow's sensor down, "