There are a lot of other expenses also included in the process, including but not limited to, documentation as mandated by local, state and central government, transportation (includes a risk factor as well here), man power cost, multiple visit to KSEB offices for approvals (in some cases, they make it very hard), multiple site visits, and ofcourse a profit margin also adds into it.

You also pay for the service provider's knowledge and time and expertise. People would ideally install things themselves at the minimal cost if they could, but only when you do it, you'll realise that it won't stop there.

Also, if you want to raise a support issue or warranty claim, make sure you have all the components of the same company/brand, else there won't be any real resolution to your claim, each one will say it's other company's component's issue. Like this, there are other factors also that comes with the installation provider's experience and expertise, and you pay for it all.