If you are a resident of Delhi then you can pay your electricity bills online using BSES web site. There are options for payment via internet banking, credit/debit card and pre-paid cash cards.
You can also pay by phone by resisting your self after filling one form.
For doing online payment open BSES my account detail page http://www.bsesdelhi.com/
and enter your BSES account no(CA no) as shown below.
After entering CA No you can see your current bill details
On account details page you can find different link(yellow highlighted)
You can select payment mode from drop down like credit/debit card, internet banking etc and then you can do transaction by clicking Pay Now link.
You can see you online PDF bill by clicking ?View your Current Bill Details? and your billing history by clicking your Bill History link.