Stacklet is an awesome site to get these types of things from. You do need a subscription to download these though. The above link is one for Xen. I am unsure if they have anything that supports OpenVZ though, you may want to look around.
Alternatively, you can also make your own template. Get a container setup the way you want to, and in your control panel, there is a button called something like "Create Template". This will allow you to do create your own.
Do you have an existing hardware node with vzkernel, and want the ability to deploy OpenVZ containers with Ubuntu 12.04 through your SolusVM control panel?
Or are you wanting to set up a fresh server for KVM or other virtualization with Ubu 12.04.3 as your host OS, with SolusVM as your control panel?
I ask because the two are worlds apart and require specific procedures based on your expected end result. I don't want to give out incorrect information.
Remember that SolusVM is simply a control panel interfacing with whichever virtualization architecture installed and running on the hardware node.
I've never heard of Stacklet until this evening -- probably due to specializing in OpenVZ specifically, but I've gone through a couple of pages and some of the verbiage is throwing me off a little.
...templates are available for Xen, KVM, VMWare, SolusVM Xen PV and XenServer/XCP for both x86 and x86_64 architectures.
There is no mention whatsoever of having any OpenVZ OS templates. I see a lot of SolusVM as it associates with Xen, but I can't find a single reference to them having any preconfigured OS templates which will work under vzkernel.
You also have the option of downloading community-provided templates and EOL templates. All you'd have to do is wget them into /vz/template/cache and let SolusVM know it's there, and you'll be good to go ...and it won't cost you $10 per month.
For non-*vz configurations, these tutorials may help.