"Power surges" and lightning are two different issues. Lighting is almost always a covered peril under a homeowners policy covering a single family home. The issue in the event of lightning is whether your polcy provides replacement cost coverage, as opposed to "actual cash value", i.e. the depreciated value of your equipment. A "power surge" is when your power goes off and a surge subsequently enters your home when the power comes back on. This event is often not covered at all, even under the broadest of homeowners policies - or at best is subject to a low limit as Nicksgem10s referenced.
The best best is to specifically schedule your equipment on your policy. In most cases equipment specifically scheduled on a property "floater" or "rider" is provided "all risk" coverage and payout is based upon the "stated value" of the property as indicated in the floater. Also, specifically scheduled equipment is usually covered anywhere in the world , whereas property only generally covered under a Homeowners policy will be subject to a minimal coverage limit if it away from home.
I would certainly encourage that everyone review this issue with their agent to ensure proper coverage.
You know, I don't recall hearing of anyone on this forum that has lost an entire system to lighting or power surge. Has anyone had it happen?