The Hornets had to come from behind to earn a 1-1 draw after Essaid Belkalem's needless challenge on Lawrie Wilson at the start of the second half conceded a penalty which Yann Kermorgant converted.
But the hosts deservedly got back on terms in the 70th minute when Daniel Pudil converted the rebound after Ben Hamer could only parry a Diego Fabbrini shot.
The Hornets head coach said: "The expectations were different for today's match and things didn't go the way we wanted. But it is a good point considering we went down and it wasn't easy so I take it as a positive thing.
"There are obviously a lot of things that didn't work as I wanted and I know exactly what those things are and we're going to be addressing them tomorrow and working a little bit on that."
With Almen Abdi sidelined through injury and other midfielders rested after being on international duty, Zola decided to change his side's formation from 3-5-2 to 3-4-2-1.
He explained: "I saw it as an opportunity and we've played this system before and we played really well it, so I was trying to see the potential and problems of this team and I saw enough. I know when I can use it and when I don't have to use it as well.
"I've had a lot of indications and although it hasn't been our best game, which everyone agrees with that, but still we could have won. If we had been a little bit more ruthless towards the end we could have won the game because we created enough chances."
Charlton boss Powell was satisfied with the outcome and said: "It's a tough place to come, a decent team and we had the victory in our last game and we wanted to build on it.
"Obviously taking the lead, you want to try and see it out and try and take three points but I think it was a well earned away point.
"It was quite a heated battle at times but of course it was definitely a penalty. They obviously got their equaliser, it was a little bit nip and tuck and they put us under pressure towards the end but our players stood up to it.
"It was a decent point and a decent way to start this quite a tough week for all Championship sides. But for us with two away games, we go away now to Huddersfield and then we've got a local derby next Saturday so a good start to what is quite a hectic week."