Is it a good idea being involved in your advisor's consulting activities as an exploratory activity during your PhD? For how long? I am a first semester PhD student. I am not paid by a grant or scholarship. My advisor has been including me in multiple teams and meetings in consulting jobs he is taking. Most of them are loosely related to my research topic. 

They can help in certain aspects, such as:


Learning how to use some of the models developed at the research group (main advantage);
Giving me more professional experience;
Getting in touch with the needs of businesses;
Eventually having access to an interesting dataset (unlikely);


However, in spite of perhaps being an opportunity to learn some tools with a driver that is some real-world issue or problem, this involvement really worries me in some aspects:


It is not clear if it will advance my thesis. I find it unlikely that it improves my research project;
My advisor said the payment from these consulting jobs may help with financing my participation in conferences. I don't get paid as a consultant and don't know if I will be able to put this in my CV. It is time I don't devote to writing articles. I need to publish more to get funding, and this kind of work probably does not help with that. Of three consulting jobs, only one is for a public institution with a history of funding grants.


I consider this kind of an "exploratory" work, but I don't know for how long it would be OK to do this, when it is not clearly advancing my PhD thesis? Is helping your advisor in consulting work a good idea during your PhD? For how long, first year, second year? I intend to finish mine in four years.
This could be a good thing or a bad thing. If you are being included to advance your education and it doesn't interfere with your degree progress then it is a good thing. 

If you are being exploited to the sole benefit of the advisor - slave labor - then it is a bad thing - very very bad. 

Are you free to decline? If not, then beware. Can you set your own conditions? If not, then beware. 

But, yes, these sorts of things can go on a CV: that you participated in consulting activities. 

In the US, as an early student, you are most likely involved in coursework where such activities might be less intrusive. Elsewhere, or later in the program, you need to focus on your comps and on your research. Then these things become much less likely to have value outweighing their cost to you. 

Keep your eyes open. Don't be led into traps.