Rule of thumb: Shares earn Dividends, Savings earn Interest.

Shares are used for the Sacco initial capitalisation, fixed assets and excess will be invested (The returns of this investments are the Dividends).
Savings are used to issue out loans and the interest charged on loans is used as working capital, some may be retained and the rest paid out to savers (As interest on savings).

Some SACCO have high shareholding therefore making it possible to loan out members with the excess capital.

Some SACCO's tend to be high on liquidity than others meaning they may be having cash sitting without borrowers and this is put into projects like buying land, encouraging some form of asset finance like car loans etc.. some of this projects net over the 12% revenue of the typical development loans. *Check and learn your SACCO's products.

A SACCO that is trying to grow it's shareholding, will most likely allocate a higher % of returns on shares (dividends) than returns on savings (interest).

As a member it is important to note that: Savings determine borrowing power. The maximum amount you can borrow is determined by savings. But the shares sit and earn dividends. Depending on the SACCO, you may use shares as security for a loan.
I would advise all who have over 500k in shares and deposits in a SACCO to always try to attend the AGM and read the financial reports.