Diagnosis
The SolarCell Remote uses Bluetooth for most functions (so you don't need line-of-sight) but uses an infrared (IR) blaster for power commands. Lag or the need to point it means the Bluetooth connection is weak or has interference.
How to Fix It
First, re-pair the remote to the TV. Take the batteries out of the remote (yes, even the solar one has a small backup battery inside). Unplug the TV from the wall for 60 seconds. Plug the TV back in. While the TV is booting, hold the 'Back' and 'Play/Pause' buttons on the remote together for about 5-10 seconds until you see a pairing prompt on the TV screen. This resets the Bluetooth link. Also, make sure nothing is blocking the small IR receiver on the TV's bottom bezel.
If That Didn't Work
The remote might be low on power. Even though it's solar, it needs some light. Leave it face-up under a bright room light or near a window for a few hours. If that doesn't help, the internal rechargeable battery might be failing. You can order a replacement CR2032 coin cell battery and swap it out by prying open the back cover.
Heads Up
Common sources of Bluetooth interference are USB 3.0 devices (like hard drives plugged into the TV), wireless speakers, or even a dense Wi-Fi network. Try turning off or moving other wireless devices near the TV to see if the remote responsiveness improves.