Are there any solutions other than flashing Gapps, to have Google accounts on CyanogenMod? I've flashed CyanogenMod, nightly, and it is working perfectly. When I flash Gapps, then battery is drained fast, and the device is getting overheated. So, are there any solutions other than flashing Gapps, to have Google accounts on CyanogenMod?

P.S. I extracted the Gapps.zip, there was a folder named "apps" there, none of which could be installed. I tested installation using "adb", and got error related to certificate. I think by having ONLY Google Play Store, other apps can be installed, if I'm wrong, then please tell me what else is needed.

Thanks in advance
You might wish to take a look at the NOGAPPS project at XDA. It's not yet complete, but most parts seem to be in a working order already. NOGAPPS basically is an OpenSource replacement of most Google apps (including Playstore), often mapping to free alternatives (e.g. OpenStreetMap for maps).

Side-effect: More privacy, less tracking :) But keep in mind that some components are still in Beta (Maps, Playstore) or completely missing (still under development; Login Services, Services Framework), so it's not yet a full replacement of GApps. Still it might be sufficient for many cases.