Is Zakat obligatory on a sum of 7500 dinars saved in a bank and on which a year has passed, given that there are installments for a solar energy system amounting to 2800 dinars, a decline in business, and household expenses are covered from the same saved amount?

If the wealth reaches the nisab (definition) and a year passes over it before purchasing with debt, zakat (definition) is obligatory on the entire amount. However, if you purchased before the year elapsed, and then the year passed while you have installments, then if you have other wealth exceeding your needs that suffices to repay the debt, you pay zakat on the entire amount. But if you do not have other wealth, it is permissible to deduct the amount of the installments and pay zakat on what remains, if it does not fall below the nisab. The more cautious and absolving for one's responsibility is to pay zakat on the entire amount without deducting the debt.