By Ben Holsen, Holsen Solar & Electrical
The chapter the newsletter didn't write
If you got May's Highline Notes in your mailbox, you saw Cass County Electric's piece walking members through the new time-of-day rate. Good explainer as far as it went — they covered the peak windows, the savings logic, and a handful of behavior-shift tips. If you haven't read it yet, pull it up here and come back — this post builds on it directly.
What it stopped short of is the part that changes the math: pairing solar with a battery. And on top of that, the bonus chapter nobody at the co-op was going to write — what happens when the grid drops.
I wrote a long analysis of the TOD rate itself back on April 11 — that one covers the per-kWh math and how I personally saved $544 a year just by switching my EV charging window. This post picks up where that left off.
Quick refresher on the rate
CCEC's on-peak windows are weekdays only: 6–9 AM and 4–8 PM. That's seven hours a day, roughly 35 hours a week, around 150 hours a month at the higher rate. During the two-year pilot, on-peak ran near 22¢/kWh — close to double the off-peak rate. Saturdays, Sundays, and listed federal holidays stay off-peak all day.
The newsletter's load-shifting advice — run the dishwasher overnight, do laundry on Saturday, set the thermostat back during peak — is real and works. But there's a floor under it. The fridge, the furnace blower, the well pump, the EV charger, the HVAC, the water heater, and a couple dozen always-on loads in a modern house don't negotiate. Some chunk of your weekday kWh is landing in the on-peak window no matter what.
Why solar alone doesn't fully solve it
Here's the timing problem that doesn't get flagged enough. Rooftop solar in eastern North Dakota produces hardest between roughly 10 AM and 3 PM. That window falls almost entirely outside CCEC's on-peak hours.
And here's the part that catches people off guard: on the time-of-day rate, CCEC doesn't buy back excess production. Any kilowatt-hour your panels make that your house isn't using in real time during the day is just gone. No credit, no rollover, no check at the end of the year.
Then 4 PM hits. The sun drops, production falls, and the house wakes up. Kids home, oven on, A/C cycling, evening routines firing. You're now buying CCEC power at the on-peak rate during the exact four hours your panels can't help.
Put those two together and the picture is bleak for a solar-only setup on the TOD rate: midday overproduction is wasted, and the most expensive evening hours are bought from the grid anyway. Solar without storage on this rate isn't the hedge it used to be. A battery is what turns that wasted afternoon production into avoided on-peak power that evening.
What changes when you add a Powerwall
We install Tesla Powerwall 3s on most of our solar projects these days. With a battery in the loop, the timing problem gets engineered out. The panels don't change — what changes is when your house consumes their energy.
A typical sunny weekday looks like this:
- 10 AM – 3 PM — Solar produces hard. The battery absorbs everything your house isn't using in real time — production that would otherwise have no value on the TOD rate.
- 3–4 PM — Production tapers. Battery sits full and waiting.
- 4–8 PM (evening peak) — Battery covers the house. Your CCEC on-peak meter barely moves. You're running on this afternoon's sunshine.
- 8 PM – overnight — Off-peak rates resume. If the battery is depleted, the grid takes over at the cheaper rate.
- 6–9 AM (morning peak) — The battery, recharged from late-evening solar plus a top-off during overnight off-peak, handles coffee, breakfast, water heater, EV preconditioning. Through to mid-morning, when solar takes back over.
You're not changing your behavior. You're changing where the electricity comes from during the two windows it costs the most.
Why we don't oversize the array
Worth saying out loud, because it shapes how we design these systems: CCEC pays members $0.03 per kilowatt-hour for excess production on the standard rate, and nothing at all on the time-of-day rate. So kilowatt-hours flowing back to the grid are either nearly worthless or actually worthless, depending on which rate you're on.
Compare that to the same kilowatt-hour stored in a Powerwall and discharged during the evening peak — it offsets roughly 22¢/kWh of grid power. That's a 7× difference in value between exporting and self-consuming. Every kWh you can store and use yourself is worth seven times what it's worth flowing back to the meter.
The right design under CCEC's current policies isn't a giant array with the meter spinning backwards all summer. It's a right-sized array paired with battery storage — enough panels to cover your daytime loads plus charge the battery, enough battery to carry you through both peak windows. Anything bigger than that is donating kilowatt-hours to the grid for pennies.
If you've gotten quotes elsewhere built on a 12 or 15 kW residential array sized to your annual usage, ask how the math holds up when those summer afternoon kilowatt-hours are valued at three cents. Often it doesn't.
The bonus chapter — when the grid drops, you don't
This is the part CCEC's newsletter was never going to write.
Cass County Electric's day-to-day reliability is genuinely good. Their system averages well under one outage per customer per year, and most clear in under half an hour. I've worked alongside their line crews and they're competent and fast. None of that, though, helps in the events that actually matter — the April ice storm that snaps limbs into distribution lines across half a county, the July thunderstorm that takes a substation offline for 18 hours, the January blizzard that has every available crew on the same emergency at once, or a transformer failure on your own service drop that can take longer to schedule than to fix.
In any of those, a Powerwall on backup mode keeps your house running automatically. Lights, fridge, freezer, internet, well pump, garage door, furnace blower. With a SPAN smart panel in the system — Holsen Solar is a SPAN Authorized Installer for ND, MN, and SD — you can prioritize which circuits stay alive, watch your reserve from the app, and stretch a single Powerwall's charge across multiple days if there's any sun.
A generator does some of this, with caveats: fuel logistics, maintenance, exhaust, noise, and zero useful work the other 364 days a year. A Powerwall is silent, automatic, indoor-rated, and earns its keep daily by cycling against the peak rate.
A recent install in CCEC territory
We commissioned a Powerwall 3 for a Cass County Electric member last month. Their setup: [XX kW] of rooftop solar paired with [XX kWh] of battery storage, with a SPAN smart panel running the show. The battery charges from solar through the midday off-peak window, discharges to cover the 4–8 PM evening peak, and holds a reserve for grid outages. From the Tesla app, the homeowner can watch the on-peak meter sit nearly idle each weekday evening — exactly the result the system was designed for.
[Photo of install + homeowner quote to add before publishing.]
One honest note on tax credits
The federal residential solar tax credit (25D) sunset at the end of 2025. For most CCEC residential members, that means a solar + battery project installed today carries no federal tax credit on the homeowner side. The math still works — it just works on operating savings now (avoided on-peak charges, displaced grid kWh, outage protection) instead of leaning on a 30% rebate.
For commercial members — farms, small businesses, multi-family property owners — the commercial ITC is still intact, and the project economics on solar + storage pencil out very differently. If you're a business owner reading this, the conversation is worth having now, before any further policy changes.
When this conversation is worth having
Solar + storage in CCEC territory makes sense if any of these fit:
- You have an EV (or are getting one) and don't want to charge through the on-peak window
- Your monthly bill is north of $150 and trending up
- You're on a well, work from home, or otherwise need power during an outage
- You're planning a remodel, addition, or new build and want to design the electrical infrastructure once
- You're a commercial member who can still capture the commercial ITC
It's a worse fit if you're a low-usage household on natural gas heat with no EV and no concern about outages. We'll tell you that honestly if your numbers don't support it.
If you want to pull your last 12 months of CCEC usage data and run the numbers together, reach out or call (218) 787-6527. No pressure — just the math.
Ben Holsen is the owner of Holsen Solar & Electrical, a licensed electrical contracting company based in Fargo, ND, specializing in solar installations, battery storage, and electrical work for residential, agricultural, and commercial customers.