I Buy Power for a 200-Person Office. Here’s What I Learned About Batteries vs. Generators.

What This FAQ Covers

I'm the office administrator for a mid-sized company. I manage all our facility orders—about $150,000 annually across 15 vendors. When my boss said we needed backup power for our new server room, I thought it was a simple comparison. It wasn't. Here are the questions I wish someone had answered for me upfront.

1. Can I just use household battery backup for my office?

Short answer? No. Longer answer? Absolutely not.

I tried this. It's tempting to think you can just buy a few household battery backup units from the electronics store. A $300 unit looks like it plugs into a wall. Simple. But that's a simplification fallacy.

The 'just plug it in' advice ignores runtime, load capacity, and duty cycle. A household unit is designed to keep a single computer running for 15-30 minutes. We needed to power a server rack, network switches, and a security system for hours. Not even close to enough.

2. What's the difference between 'high capacity batteries' and 'stationary energy storage'?

I know, the terms sound interchangeable. They are not.

• High capacity batteries is a broad term. It can refer to a single large cell (think a rechargeable cell for a forklift) or a bank of batteries.
• Stationary energy storage is a specific system. It's designed to sit in one place, connected to a building's electrical infrastructure. It's not portable. It often includes inverters, cooling, and management software.

The surprise wasn't the price difference between the two. It was the installation cost. A stationary system needs a licensed electrician, permits, and sometimes a concrete pad. That cost us an extra $1,200 we hadn't budgeted for.

3. A battery power station sounds portable and easy. Why not use that?

We looked at this. A medium-sized battery power station (like those for camping or job sites) costs $800-$1,500. It seemed like a no-brainer. We could move it around! Flexible!

But here is the deal-breaker for an office: silent integration. A portable unit doesn't talk to your building's electrical panel. You have to run extension cords from it to the critical equipment. This is a mess. A tripping hazard. Not to code. Plus, you have to recharge it manually. So if the outage lasts longer than 4 hours, you're in the dark. Literally.

It's not a solution. It's a band-aid. Period.

4. What about a cheap start stop car battery for a DIY system?

I actually saw a tutorial for this. Do not do this.

A cheap start stop car battery is designed for a car. It provides a high burst of current to start an engine, then gets recharged by the alternator. It is not designed for deep cycling. If you drain a car battery below 50% charge a few times, it will be dead. Done.

Proper stationary energy storage uses deep-cycle batteries. They are built to be discharged to 20% or even 10% capacity repeatedly. The upfront cost is higher. But replacing a dead car battery system after 6 months is more expensive. Saved you a costly mistake.

5. So, is battery storage better than a generator?

This is the question I spent the most time on. The answer is: It depends on what you need to protect.

Here's my rule now:

• Battery storage is for bridge power. It covers the gap between an outage and the generator starting. It's also good for 'power conditioning'—filtering out surges and dips that can fry electronics. This is critical for servers.
• Generators are for long-term power. If the grid is down for 8 hours or 2 days, a generator (fueled by natural gas or diesel) will keep the lights on. Batteries (at this scale) run out.

We ended up with a hybrid approach: a small stationary battery system for the servers (about 30 minutes of runtime) and a Kohler standby generator for the whole office. The battery handles the glitches. The generator handles the storms. It's not the cheapest option upfront, but it's the most reliable.

6. How much did all this actually cost?

Ballpark numbers based on our 2024 installation:

• Stationary battery system (10 kWh): $6,000 - $8,000 (installed, including permits)
• Kohler 20kW standby generator (installed): $5,500 - $7,500 (including gas line and pad)
• Total project: About $14,000.

Is that a lot? Yes. Did it prevent a single day of downtime that would have cost us $20,000 in lost productivity? Absolutely. 5 minutes of planning beats 5 days of crisis.

That's the bottom line: Do the homework first. Don't just compare unit prices. Compare outcomes.