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a$)$ An autonomous drone has a $2$m$2$ solar panel made from $3$rd generation multijunction cell solar PVs$.$ Compute the energy generated over $8$ hours assuming an average sunshine of $500$w$/$m$2.$Compute the required solar panel size for $1$st and $2$nd generation cells. $(8$ marks$)$

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b$)$ A $30$ m$2$ solar PV$$s efficiency is $2\%$ under $0-199$ w$/$m$2$ of sunshine, $4\%$ under $200-399$ w$/$m$2,8\%$ under $400-999$ w$/$m$2,12\%$ under $1000-2000$ w$/$m$.$ In a typical day, the sunshine is $4$ hours of $1500$ w$/$m$2,4$ hours of $1000$ w$/$m$2,4$ hours of $500$ w$/$m$2,4$ hours of $100$ w$/$m$2,$ and $8$ hours of $0$ w$/$m$2.$ Find how much electricity is produced on this day. If all years $365$ days have the same electricity as the above typical day, in how many years does the solar PV cost of $9000$ be paid back, while the electricity price is $34$ p$/$kWh$?(12$ marks$)$