Solar Without Storage Is Dead in Arizona — But Peak Shaving Is Just Getting Started

David McCorkle
3 days ago
4 min read

Introduction

If you live in Arizona and use APS as your electric provider, you may have noticed that solar isn’t the slam-dunk investment it once was. For years, rooftop solar panels promised savings and independence. But today, thanks to shifting rate plans, reduced compensation for solar exports, and rising complexity in dealing with solar providers, the financial benefits have eroded.

But here's the good news: while solar-only setups are losing ground, battery-only systems are becoming a smart, flexible alternative for energy savings — especially when paired with APS’s demand-based rate plans. This approach, called peak shaving, offers significant savings without the complexity of solar.

What Is Peak Shaving? (In Simple Terms)

Think of your electricity bill like a water bill — you don’t just pay for how much you use, you also get charged based on your biggest "gulp." With APS’s demand plans, your highest one-hour usage during peak times (usually 4–7pm) can trigger a hefty demand fee.

Peak shaving is when you use a battery to power your home during those expensive peak hours. By avoiding that big "gulp," you keep your demand charge low. You still use the grid the rest of the time — but you avoid getting slammed when electricity is most expensive.

Total Monthly Peak Cost Without Using a Battery:

Demand Fee: 8 kW × $19.585 = $156.68
On-Peak Grid Usage: 420 kWh × $0.14227 = $59.75
Total: $216.43

Now Compare That to Using a Battery Sized at 15 kWh:

In Arizona, you typically only need to exceed 5 kWh/hour during the hottest summer months — June through August — when cooling demand peaks. As temperatures drop in the rest of the year, your peak usage naturally falls below the demand threshold. That means with proper battery management, you could see zero demand charges for nine months out of the year.

New Demand Fee: 3 kW × $19.585 = $58.76
On-Peak Energy Usage from Grid: $17.07
Battery Recharge Energy: 5 kWh × 3 hours/day × 20 weekdays = 300 kWh
Recharge Cost (Off-Peak Rate): 300 kWh × $0.05943 = $17.83
Total: $93.66 for peak periods and battery charging

Savings with Peak Shaving:

Without battery: $216.43 vs With battery: $93.66 → You save $122.77/month

Why Solar-Only Is No Longer a Smart Move (Unless You're Grandfathered In)

Let’s be clear: if you already have a solar system under a grandfathered APS plan, you’re in a different boat. But for everyone else:

APS no longer offers meaningful net metering.
Your peak hours expand from 4pm–7pm to 9am–9pm.
Solar-specific fees and added utility requirements often apply.
Solar providers may go out of business, leaving warranties hard to claim.

In short: solar-only setups are no longer the clear win they once were.

APS Rate Plan Overview (Non-Solar Customers) as of May 2025

1. Fixed Charge Plan

Tier 1 (<600 kWh): $0.12925/kWh
Tier 2 (601–999 kWh): $0.14052/kWh
Tier 3 (1000+ kWh): $0.15418/kWh

2. Time of Use (TOU)

Summer (May–Oct):

Peak (4pm–7pm): $0.34396/kWh
Off-Peak: $0.12345/kWh

Winter (Nov–Apr):

Super Off-Peak (10am–3pm): $0.03495/kWh
Peak (4pm–7pm): $0.32543/kWh
Off-Peak: $0.12351/kWh

3. Time of Use with Demand Charges (Best for Peak Shaving)

Summer:

On-Peak: $0.14227/kWh
Off-Peak: $0.05943/kWh
Demand Fee: $19.585 per kW

Winter:

On-Peak: $0.09932/kWh
Off-Peak: $0.05938/kWh
Super Off-Peak: $0.03495/kWh
Demand Fee: $13.747 per kW

4. EV Overnight Plan

Summer:

Peak: $0.36824/kWh
Off-Peak: $0.12345/kWh
Overnight Off-Peak (11pm–5am): $0.08468/kWh

Winter:

Peak: $0.3480/kWh
Super Off-Peak: $0.03495/kWh
Off-Peak: $0.12351/kWh
Overnight Off-Peak: $0.08468/kWh

Why Battery-Only Peak Shaving Works

You don’t need 24/7 battery power. You only need to cover the 3 peak hours per day and you need to size it as close as possible for as much as you think you need during the summer months. For most Arizona homes, that’s roughly 15 kWh/day.

Using APS’s Time of Use with Demand Charges plan:

You avoid demand spikes
You cut your peak kWh costs
You charge cheaply overnight or midday (winter)

End result: You pay less and keep full control.

Real Example: My APS Bill Before and After Battery Peak Shaving

With two EVs, most of my energy use happens overnight, making off-peak rates crucial. I avoided APS’s demand plan because a single peak-hour EV charge could spike my usage—and my bill. My charger draws 11 kWh in an hour, and with AC and cooking, I could hit 19 kWh, triggering a $372 monthly demand fee.

Battery peak shaving gave me the confidence to switch. Now, my off-peak rate is half what it was, and I’ve cut charging costs dramatically. The battery doesn’t just manage demand—it supercharges my monthly savings. To avoid accidentally charging or even plugging in my vehicle during peak hours, I have disabled the power to the charger during that time window. I also bypass the battery system entirely when charging the EVs to ensure I don’t overload it.

Using a 15 kWh battery and switching my plan has resulted in just about $800 in 6 months — and we haven’t even reached peak usage yet.

Here’s my recent bill reduction:

December: $320 → $204
January: $342 → $189
February: $357 → $244

This is without solar — just smart battery scheduling.

For my home, a 15 kWh battery system cost around $10,000. Depending on installation, I expect to recoup this in as little as 4 years.

Conclusion: Solar Isn’t Dead — But It’s No Longer Alone

In Arizona, solar-only is no longer a guaranteed win. But battery-only peak shaving? That’s a game-changer.

You lower your bills, protect against rate hikes, and avoid solar's long-term complications. All with just a battery.

Want to know if this works for your home?DidYouReboot.com offers personalized APS bill analysis for a low one-time fee.

Coming soon: A breakdown of battery options and the smart controllers that make this possible.