Do you plan to use all the 30kw when it's sunny enough to max our, or sell it back to the grid?
Also, do you have an idea what a 30kw setup would produce on say a winter's day with a bit of sun and bit of cloud?
I have three phase so can sell / feed back 11.8kw without argument with UK power network / grid. I will be requesting an extra 10kw, so about 20kw, if the local network can take it. I will also have 30kw battery storage. But I am planning on having 3 separate 8kw single phase inverters (max 24kw) so I will be over loading them, and a switch over 6kw power system at 12v.
The feed in will be an unbalanced 3 phase system, otherwise I would have to change my inverter idea, from single phase inverters to a separate 3 phase inverter. I already have an 8kw inverter, thus thinking about keeping it.
As for your question, on a winters cloudy part sun day, with a 30kw panel system, I would be likely to get 3 to 7% of that per hour for about 6 hours, so that will go straight to the battery storage.
Edit - forgot to add
Future proofing the home, I was going to install three electric car charging points, one at 16kw, one at 7kw, and a standard 3 pin plug 64amp rcbo, so I can tailor any electric car charging based upon how well the solar panels are generating.