TL;DR: A $1,299 3 Panel kit (1,200W AC) offsets roughly $365/year off your RMP bill in Utah, paying for itself in under four years. Plug-in shines because it shaves the upper tier of RMP’s residential rate — and because Utah’s electric rates keep going up, every year you wait is more savings missed.

A bank of residential electricity meters

The headline numbers

Option	Price	Annual savings	Payback	10-year savings
3 Panel kit (1,200W)	$1,299	~$365	~3.6 years	~$3,650
3 Panel kit + roof install	$1,899	~$365	~5.2 years	~$3,650

Adding the roof install doesn’t change annual production. The longer payback is just the upfront cost of having our crew put the kit on your roof.

Numbers assume a south-facing or west-facing install with minimal shading, an average Utah household consumption around 700–900 kWh/month, and Rocky Mountain Power’s current Schedule 1 rates. Your specific numbers will move with your roof angle, your shade, and your usage habits.

How RMP actually charges you

This is the piece most ROI calculators get wrong. Rocky Mountain Power’s Schedule 1 (residential) is tiered and seasonal, you don’t pay one flat rate per kWh. Here’s the published rate for 2026:

Period	First 400 kWh	All additional kWh
Summer (Jun–Sep)	9.32¢/kWh base	12.01¢/kWh base
Winter (Oct–May)	8.25¢/kWh base	10.63¢/kWh base

On top of those base rates, RMP layers about +26% in surcharges (EBA, REC, DSM, EVIP, WBA, lifeline). After surcharges your effective rates land around:

Period	First 400 kWh	All additional kWh
Summer	~11.7¢	~15.1¢
Winter	~10.4¢	~13.4¢

You also pay a $12/month customer charge that solar can’t reduce. That fee buys you the connection — solar reduces what you pay for the energy on top of it.

Why tier 2 is where plug-in solar wins

Most Utah households burn through that first 400 kWh quickly, usually by the second week of the month — and spend the rest of the billing cycle in tier 2. That’s true year-round but especially in summer when AC pulls hard.

Plug-in solar produces during the day. Daytime is when AC, refrigerators, computers, dryers, and most household loads are running. So the kWh your kit produces are almost always offsetting tier 2 kWh, the expensive ones.

This is the leverage. A 1,200W kit producing ~2,600 kWh/year doesn’t save you “average rate × 2,600” — it saves you “tier 2 rate × 2,600,” because every kWh it produces is one fewer kWh in the highest pricing bucket. At ~14¢/kWh effective tier 2 (averaging summer and winter), that’s ~$365/year.

Key insight: Plug-in solar isn’t shaving your average rate. It’s shaving your highest rate. The math is better than a flat-rate calculation suggests.

The rate increase factor

RMP filed a 30.5% residential rate increase proposal in 2024. After regulatory pushback they lowered it, but increases have been cleared in successive rounds, Utah residential rates have moved up steadily for several years and there’s no reason to expect that trend to stop. New gas plants, transmission upgrades, and load growth from data centers all push the same direction.

What this means for your kit’s ROI:

Today’s payback assumes today’s rates.
Tomorrow’s payback is shorter, because the same kWh of offset is worth more dollars next year.
A kit you buy today locks in your generation cost at zero for the life of the hardware.

If you assume even 4% annual rate increases (conservative), the 3 Panel kit’s lifetime savings over 10 years climb from ~$3,650 to ~$4,400. Over 20 years (well within microinverter lifetime), it’s closer to $11,000.

Why a small rooftop add-on is so expensive by comparison

Adding 1,200W to an existing rooftop solar system isn’t 1,200/8,000 of a $20,000 install. It’s not linear. The fixed costs hit hard:

Engineer-stamped diagrams (~$300–600)
Building permit + electrical permit (~$200–400)
RMP interconnection application + smart inverter compliance (~70-day timeline)
Truck roll, ladder day, breaker work — labor doesn’t scale down to small jobs
Rapid shutdown compliance per NEC 690.12 — expensive electronics for code

Real quotes for adding 1 kW to an existing array typically come back $3,600 and up. The panels themselves aren’t the expensive part — the process is the same whether you’re adding 1 kW or 10 kW.

Plug-in solar skips every line item in that list. You’re paying for the hardware, not for the regulatory overhead around it.

The honest caveats

This isn’t fine print buried at the bottom, it’s the real picture:

You don’t get paid for export. HB 340 is offset-only. If your kit produces more than your house is using at that moment, the extra goes to the grid for free. With a 1,200W kit and any normal household load, this rarely happens during daylight hours, but it caps your upside.
Annual production depends on orientation. A south-facing, unshaded install in Salt Lake produces ~30% more than a north-facing one. We tilt and orient for best yield, but your roof or yard sets the ceiling.
The federal solar tax credit was killed in July 2025. No 30% credit. The kits stand or fall on their unsubsidized economics.
No state RESTC for residential solar after January 2024. Utah’s residential credit expired.
The EcoFlow STREAM microinverter carries a 10-year manufacturer warranty. Panels typically carry 25-year power-output warranties. Read the small print before you assume “warranty” means “free replacement” — most are pro-rated and exclude shipping.

Is plug-in solar the right purchase for you?

Plug-in solar makes sense if:

You spend more than ~$80/month on RMP electricity (you’ll be in tier 2 most months)
You have a south, southwest, or southeast exposure with sun for at least half the day
You’d rather buy something once than finance something for 20 years
You want to start small without committing to rooftop solar’s full cost

It probably doesn’t make sense if:

Your monthly bill is below ~$50 (limited tier 2 exposure, slower payback)
You have heavy shading and no clear sun exposure
You’re moving in less than 2–3 years

For most Northern Utah homeowners, the math is straightforward: a $1,299 kit replaces about $3,650 of grid power over a decade. The break-even is well under four years. After that, every kWh is yours.