What is the maximum team level in Heroes of the Storm?

Solution 1:

The maximun team level for now is 30,

You can verify this by going to the shop try out a hero and using the second button from top right you can level up your "Team" until reaching the maximun of level 30.

Solution 2:

xerido posted the right answer, but I thought it would also be helpful to have an experience chart. Ahli from reddit has data-mined the team level experience requirements, for anyone interested:

level   xp req for level up     total accumulated xp
1               0                    0
2            2010                 2010
3            2154                 4164
4            2154                 6318
5            2154                 8472
6            2154                10626
7            3303                13929
8            3303                17232
9            3303                20535
10           3303                23838
11           3303                27141
12           4452                31593
13           4452                36045
14           4452                40497
15           4452                44949
16           4452                49401
17           5600                55001
18           5600                60601
19           5600                66201
20           5600                71801
21           9000                80801
22          10000                90801
23          11500               102301
24          13000               115301
25          15000               130301
26          17000               147301
27          19500               166801
28          22000               188801
29          25000               213801
30          28000               241801