$f_{\text{o}\text{r}\text{i}\text{e}\text{n}\text{t}\text{a}\text{t}\text{i}\text{o}\text{n}}=110\%$ and collector efficiency is ${}_c=30\%,$ using the relatic $,$ calculate the collector size

$A_c=\frac{s_f{Q}_{hw}}{{}_c{H}_{\text{s}\text{o}\text{l}\text{a}\text{r}}{f}_{\text{o}\text{r}\text{i}\text{e}\text{n}\text{t}\text{a}\text{t}\text{i}\text{o}\text{n}}}$

he effective area of this solar panel in $2\mathrm{.}1($c$)$ is $0\mathrm{.}8\frac{m^2}{?}$ piece, estimate the ces of solar panel that should be installed to collect this heat demand.

If this family with $4$ members plans to install a solar water heater which is for bath and the hot$-$water temperature required for bath is $50C,$ while the a ge temperature of cold water is $23C,$ estimate the heat that should be pro solar water heater to satisfy the family's demand for bath.