diff --git a/tariff/solcast.go b/tariff/solcast.go
index a96143734..7042b7ee0 100644
--- a/tariff/solcast.go
+++ b/tariff/solcast.go
@@ -76,7 +76,7 @@ func (t *Solcast) run(interval time.Duration, done chan error) {
 		var res solcast.Forecasts
 
 		if err := backoff.Retry(func() error {
-			uri := fmt.Sprintf("https://api.solcast.com.au/rooftop_sites/%s/forecasts?period=PT60M&format=json", t.site)
+			uri := fmt.Sprintf("https://api.solcast.com.au/rooftop_sites/%s/forecasts?period=PT30M&format=json", t.site)
 			return backoffPermanentError(t.GetJSON(uri, &res))
 		}, bo()); err != nil {
 			once.Do(func() { done <- err })
@@ -91,7 +91,7 @@ func (t *Solcast) run(interval time.Duration, done chan error) {
 
 	NEXT:
 		for _, r := range res.Forecasts {
-			start := now.With(r.PeriodEnd.Add(-r.Period.Duration())).BeginningOfHour().Local()
+			start := now.With(r.PeriodEnd).BeginningOfHour().Local()
 			rr := api.Rate{
 				Start: start,
 				End:   start.Add(time.Hour),