When we started I was the only director who was fully retired, and not for long enough to have the many commitments that most retired people seem to accumulate. So I became the secretary, the only office specifically required by the society rules. My background is technical, with some project management experience. I expected to do most of the work, but that was OK, the main reason why I wanted others round me was for guidance and decision making. We had monthly board meetings.
However it meant that as we tackled each new challenge, I was the one doing all the learning. So if I fell under a bus it would be lost. I didn't, but it leads to problems further down the line as the work load increases. Hydro power is complex - you have to deal with many people, covering many topics. I was involved in most of them, because I had initiated so much. The danger is that with a growing number of emails and small tasks needing quick responses, it becomes easier to deal with them yourself than to spend time finding someone else to do it. But there was a limit to how much I could handle. If you become a bottleneck, the enjoyment fades and it becomes more of a burden.
So it is worth planning ahead, thinking how to cope with a growing workload. It means finding a few reliable people who can spare some time, and spending time with them.
As the tasks multiply, there is too much detail for board meetings. Specialised subgroups can help, reporting back to the board. We had one, to handle the engineering. We also thought about one for marketing, but there was less need for it. There were also individuals who offered help in particular ways, or a board member would know someone suitable. Some were invited to join the board, and as we grew we ended up with 11 directors. This is quite a large number, but they brought valuable skills. One or two contributed little, but most did their best to help where needed. Larger numbers can mean slower decision making, but I don't think that caused any real problems.