QUESTION $2$

$2\mathrm{.}1.$ The storage stize $V_{\text{e}\text{r}\text{e}\text{r}\text{g}\text{e}\text{s}\text{e}}$ for domestic hot water is twice the total requiremants of persons $(P)$ with a dally requirement $V_{\text{p}\text{e}\text{r}\text{r}\text{a}\text{n}}$ per person.

Based on the hot water requirement $Q_{persen}$ per person per day, for a four$-$person household with an avarage consumption of $45$ litres or $1\mathrm{.}8$ kWh of hot water per day.

$($a$)$ calculate the storage size $V_{\text{t}\text{a}\text{r}\text{s}\text{a}\text{r}}$ in litres

$($b$)$ the annual hot water requirement $Q_{hw}$ in kWh

$($c$)$ If the amual solar radiation is $H_{\text{s}\text{a}\text{t}\text{e}\text{r}}=1000\frac{kWh}{s^h},$ annual sclar fraction $s_f=0\mathrm{.}9,$ till gains foriwescion $=110\%$ and colector efficiency is $n_c=30\%,$ using the relationship below, calculate the collector size

$A_c=\frac{s_i{Q}_{ne}}{{}_c{H}_{\text{s}\text{o}\text{b}\text{e}\text{r}}{f}_{\text{e}\text{r}\text{i}\text{m}\text{i}\text{t}\text{a}\text{t}\text{i}\text{o}\text{n}}}$

$($d$)$ If the effective area of this solar panel in $2\mathrm{.}1($c$)$ is $0\mathrm{.}8\frac{m^2}{?}$ plece, estimate the number of pieces of solar panel that should be hstalled to collect this heat demand.

$2\mathrm{.}2($a$)$ If this family with $4$ members plans io instal a solar water heater which is mainly usedfor baih and the hot$-$water temperaturerequired for bath is $50C,$ while the annual geverage temperature of cold water is $23C.$ estimate the heat that should be provided by the solar water heater to satisfy the family's demand for bath.