## 5 Discussion and Conclusions  
There are many studies in the literature where the authors argue that profitability cannot improve with increasing liquidity [22; 23; 24; 25; 26; 27; 35]. In general, companies are either highly liquid or profitable. It is difficult to find a strategy that would achieve high profitability and liquidity. Purchasing groups allow reducing costs, and cooperation and trust enable companies to operate within the purchasing group to improve safety. The analysis showed that in GPOs there is a statistically significant relationship (\(p\) = 0.0033 **) with average strength (\(r\) = 0.45) between financial liquidity and profitability. Higher financial liquidity is a factor contributing to higher profitability--Although, as already mentioned, it is not a strong relationship. Such a relationship is undoubtedly a novelty in the field of research on financial liquidity and profitability. It is particularly important for industries that are developing in the market. It allows building financial security, and at the same time generating profits, which will certainly build a strong competitive position in the market in the future. Based on the previous results (Table 2) and the following research implication, it can be stated that the Hypothesis 1 is confirmed. The research has shown that in the case of commercial enterprises operating in the sector related to renewable energy, functioning within the industry GPO allows high profitability and financial liquidity. There is a dependency that the liquidity increases with the growth in profitability. Until now, the authors in their research indicated that liquidity in units as profitability increases or vice versa. \begin{table}
\begin{tabular}{c c c c c c c c c c c c} \hline \hline  & & \multicolumn{8}{c}{**Group**} \\ \cline{2-13}
**Financial** & \multicolumn{4}{c}{**GPO**} & \multicolumn{4}{c}{**Independent Enterprises**} \\
**Variables** & \multicolumn{4}{c}{**(\(N\) = 25)**} & \multicolumn{4}{c}{**(\(p\)**} \\ \cline{2-13}
**[mln PLN]** & **Mean** & **Me** & **Std. Dev.** & **Min** & **Max** & **Mean** & **Me** & **Std. Dev.** & **Min** & **Max** & \\ \hline Net revenues from sales & 57.0 & 32.7 & 64.5 & 5.3 & 331.8 & 18.9 & 12.9 & 28.4 & 2.2 & 148.7 & 0.0000 *** \\ Operating expenses & 52.4 & 26.9 & 61.7 & 5.1 & 313.3 & 17.4 & 11.7 & 27.0 & 1.3 & 140.3 & 0.0001 *** \\ \hline \hline \end{tabular} \(p\) value was calculated using the Mann-Whitney test. *** denotes statistical significance of difference between groups (respectively at level \(p\) \(<\) 0.05; \(p\) \(<\) 0.01 and \(p\) \(<\) 0.001); Source: author’s calculations and studies.  
\end{table} 
Table 5: Net revenues from sales and operating expenses for the analysed enterprises (2016–2019). This is due to the specificity of industry purchasing groups. Industry purchasing groups take advantage of the economies of scale, which significantly reduces costs. In addition, the introduction of the central warehouse in GPO allows obtaining benefits not only for the central unit, but also for all participants of a given group. The central warehouse allows companies operating in GPO to place an order quickly and replenish the missing range at a better price compared to the prices offered by producers. Stock replenishment from the GPP warehouse has a positive effect on profitability. This is confirmed by the profitability results of the enterprises analysed, where significantly higher results are obtained by enterprises operating in industry purchasing groups. Working together in GPOs also means getting beneficial trade credits that allow one to take advantage of additional discounts. The discounts obtained mean an increase in cash, which allows improving financial security. The cooperation enables participants of purchasing groups to use the finances of a central unit or another company in the event of problems. These transactions can be referred to as mutual transactions. One cannot disagree with the authors who claim that the financial security of GPOs is based on trust within the group [27; 55; 57].