Solar terms, in plain English.
159 solar, battery, EV charging and electrical terms explained simply — from kW vs. kWh and net metering to the 120% rule, Xcel Solar*Rewards and the 2026 federal tax credit changes. Written for Minnesota homeowners, farms and businesses.
Reviewed by John Ihle, MN Master Electrician (AM005101) · NABCEP-credentialed · Last updated October 2026
Every solar, battery, EV and electrical word you’ll hear during a Minnesota project — 159 terms in 10 groups, each explained in plain English with a link to our deeper guide where one exists. Search below, jump to a topic, or link straight to any term. Don’t see a term? Just ask us.
Solar basics · Money & savings · Panels & equipment · Inverters · Batteries & backup · EV charging · Roof & mounting · Permits, utility & safety · Commercial & tax · Minnesota programs
Solar basics
Capacity factor
How much a system actually produces compared with running at full rated power 24/7. A Twin Cities system making 1,150–1,300 kWh per kW each year has a capacity factor of roughly 13–15% — normal for solar, since nights, weather and sun angle all count.
Grid
The big network of power lines, substations and transformers that brings electricity from the power company to your home. Most Minnesota solar homes stay connected to it, sending extra power out by day and pulling power back at night.
Grid-tied solar system
A solar system connected to the utility grid, with no battery required. It powers your home first, sends any surplus to the grid for net metering credit, and draws from the grid when the sun is down. It’s the most common and lowest-cost setup in Minnesota.
Irradiance
How much sunlight power is hitting a surface right now, measured in watts per square meter. Bright midday sun on a clear day is near 1,000 W/m²; clouds, haze and low winter sun reduce it. Irradiance is what drives a panel’s moment-to-moment output.
Kilowatt (kW)
What is a kilowatt? It’s 1,000 watts — a measure of how much power something makes or uses at one moment, like the speed on a car’s speedometer. Solar systems are sized in kW; a typical Twin Cities home system is somewhere around 7–10 kW.
Kilowatt-hour (kWh)
What is a kWh? It’s energy used over time — one kilowatt running for one hour. Think miles driven, not speed. Your Xcel bill charges per kWh, and a solar production estimate is stated in kWh per year. The average Minnesota home uses roughly 9,000–10,000 kWh a year.
kW vs. kWh
kW is power (how fast), kWh is energy (how much). A 10 kW solar system is its size; the 12,000–12,900 kWh it might make in a Twin Cities year is its output. Batteries use both: kWh is how much they store, kW is how fast they can deliver it.
Off-grid solar
A system with no utility connection at all — just solar, batteries and usually a backup generator. Common for remote cabins and land where running power lines is expensive. Off-grid systems must be sized for Minnesota’s short December days. See off-grid solar.
Offset
How much of your yearly electric use your solar covers. 100% offset means your panels make about as much as you use over a year. Xcel’s Solar*Rewards program caps sizing at 120% of usage. See solar offset explained.
Peak sun hours
The day’s sunlight squeezed into equivalent hours of full-strength sun (1,000 W/m²). Five hours of weaker light might equal three peak sun hours. Minnesota gets more usable sun than many people expect — see peak sun hours in Minnesota.
Photovoltaic (PV)
The science word for turning sunlight into electricity. “Photo” means light and “voltaic” means electricity. When you see “PV” on a quote or permit, think “solar panels that make electricity” — as opposed to solar hot-water systems, which heat water instead.
Production
How much electricity your panels actually make, usually counted in kWh per year. In the Twin Cities, a well-placed system typically makes about 1,150–1,300 kWh per kW of panels annually. It’s the number every savings estimate is built on.
Production estimate
A forecast of your system’s yearly kWh, built from your roof direction, tilt, shading and local weather data (often NREL’s PVWatts model). Compare estimates between quotes — an inflated one makes savings look better than they’ll be. See solar production estimates.
Shading
Shade from trees, chimneys, vents or neighboring buildings that lowers panel output. Even partial shade matters, which is why we run a shade analysis and often recommend microinverters or optimizers on shaded Minnesota roofs. Tree trimming can sometimes raise production a lot.
Snow shedding
How fast snow slides off your panels after a storm. Smooth glass, dark panels warming in the sun and steeper tilts all help. Panels often clear within a few sunny days — and we don’t recommend climbing on the roof to rake them. See snow on solar panels.
Solar array
The whole group of panels working together — on your roof, on the ground, or on a carport. “Array” is just a fancy word for the full set. A home can have more than one array, such as a south roof face plus a garage roof.
Solar azimuth
The compass direction your panels face, measured in degrees: 180° is due south, 90° east, 270° west. In Minnesota, south is best; east- and west-facing roofs typically produce about 10–20% less but still work well. See best roof direction for solar.
Solar panel (solar module)
A flat, framed board of solar cells that turns sunlight into electricity. No moving parts, no noise. Installers often say “module” instead of “panel.” A group of them wired together makes up your solar system. See solar panels in Minnesota.
System size (kW-DC)
The total rated power of all your panels added together — for example, 24 panels × 420 W = 10.08 kW-DC. “DC” means the panels’ rating before the inverter converts it to household AC. Use it to compare quotes on a cost-per-watt basis.
Tilt angle
How steeply your panels are angled from flat. Most pitched Minnesota roofs are close enough to ideal that we mount panels flush. Ground mounts can be set steeper to shed snow faster and catch low winter sun.
Watt (W)
A small unit of power. 1,000 watts make 1 kilowatt. A modern residential solar panel makes around 400–440 watts in full sun under lab test conditions. Quotes often list system size in watts or kilowatts so you can compare price per watt.
Money & savings
ARUER (average retail utility energy rate)
The rate Xcel uses to credit surplus solar energy under Minnesota net metering for systems up to 40 kW. It’s close to the retail energy price, not a deep wholesale haircut. Credits roll forward, and Xcel pays out by check when the balance passes a threshold.
Avoided cost rate
A lower, wholesale-style rate some Minnesota co-ops and municipal utilities may use to pay for year-end surplus solar energy. It’s why net metering value varies by utility — check your co-op’s tariff. See co-op net metering in Minnesota.
Basic service (fixed) charge
The flat monthly fee your utility bills just for being connected — for Xcel Minnesota residential, about $6 plus small surcharges. Solar can’t erase it, so even a 100%-offset home still gets a small monthly bill. See your Xcel bill with solar.
Cash purchase
Paying for your system outright, with no loan. It’s usually the lowest total cost and fastest payback. iSolar’s residential schedule is a 5% deposit, then the balance in stages tied to permit, install, inspection and PTO. See paying cash for solar.
Cost per watt ($/W)
System price divided by its size in watts — the fairest way to compare quotes of different sizes, like price per ounce at the store. National price trackers put Minnesota residential solar around $3.00–$3.25/W before incentives. See solar cost per watt in Minnesota.
Dealer fee
A charge, often hidden inside the system price, that a lender collects to “buy down” a super-low advertised loan rate. Always ask for the cash price next to the loan price to spot it. See predatory solar financing.
Demand charge
An extra fee on many business bills based on the single highest burst of power (measured over a short interval) used in the month, not total kWh. Solar alone may not trim it; batteries and smart controls can. See commercial demand charges.
Levelized cost of energy (LCOE)
The total lifetime cost of a solar system divided by all the kWh it will produce — your effective price per kWh. If your solar LCOE is lower than what Xcel charges you per kWh, the system saves money over its life. It’s a common way to compare energy options.
Load shifting
Moving energy use to cheaper hours — running the dishwasher, EV charging or laundry overnight, or letting a battery cover the evening peak. On time-of-use rates, load shifting can save real money even without adding more panels.
Net metering
What is net metering? When your panels make more than you’re using, the extra flows to the grid and your utility credits you; at night you draw that credit back. Xcel Minnesota nets monthly for systems up to 40 kW. See net metering in Minnesota.
Payback period
How long until your energy savings add up to what you paid. For Minnesota cash purchases, payback commonly runs about 10–16 years depending on usage, roof and rates. Panels typically last 25–30+ years. Try our solar payback calculator.
Power purchase agreement (PPA)
A deal where a third party owns the system on your property and sells you the power it makes at a set price per kWh. Solar PPAs are mainly used by businesses, nonprofits and public entities. See commercial solar PPAs.
Prepaid lease
A solar lease paid largely up front instead of monthly. In Minnesota, residential third-party ownership mostly takes the form of leases and prepaid leases. You use the power but don’t own the equipment, so read buyout, transfer and removal terms carefully.
Residential Clean Energy Credit (Section 25D)
The 30% federal tax credit homeowners used to get for buying solar and batteries. The One Big Beautiful Bill Act ended it for systems placed in service after December 31, 2025, so there’s no federal credit for homeowner-owned systems installed now. See the 2026 federal solar tax credit.
Return on investment (ROI)
Your lifetime savings compared with what the system cost, often shown as a yearly percentage. ROI depends on your electric rate, how much of the system you pay up front, incentives like Solar*Rewards, and how long you stay in the home. See is solar worth it in Minnesota.
Solar lease
What is a solar lease? A company owns the panels on your roof and you pay a monthly fee to use them. Because the lessor owns the system, it can still claim the commercial §48E credit. iSolar is ownership-first; read the trade-offs at solar leases in Minnesota.
Solar loan
Borrowing to buy your system and paying it back monthly — so you own it. Compare APR, term and whether a dealer fee is hidden in the price. Local credit unions such as Affinity Plus and lenders like CEE offer options; see solar financing.
Third-party ownership (TPO)
Any arrangement — lease, prepaid lease or PPA — where someone other than the property owner owns the solar system. TPO owners can use business tax credits, but you give up ownership value. Compare at solar lease vs. buy.
Time-of-use rates (TOU)
Electric pricing that changes by hour. Xcel’s optional Minnesota TOU plan (rolling out with smart meters) has a cheap overnight period and a pricier 6–9 p.m. evening peak. Batteries get more valuable on TOU. See Xcel time-of-use rates and solar.
Panels & equipment
Bifacial solar panels
Panels that collect light on both the front and the back. On a ground mount, sunlight reflecting off snow or light-colored ground hits the back and adds energy. Less benefit on a flush roof mount. See bifacial panels and snow.
Degradation
The slow loss of panel output with age. Quality panels typically lose about 0.25–0.5% a year, so they still produce most of their original power after 25–30 years. See how long solar panels last.
Hail rating
Most certified panels are tested to survive 25 mm (1-inch) ice balls hitting at about 23 m/s under IEC 61215. Larger hail can still crack glass, so check your homeowner’s policy. See solar panels and hail damage.
Half-cut cells
Solar cells sliced in half so each carries less current. That lowers resistance losses and heat, and lets half the panel keep working if the other half is shaded — helpful with snow patches and chimney shadows. Most modern residential panels use them.
Monocrystalline
Panels made from single-crystal silicon — the most common, most efficient type sold today and what we install. They’re usually all-black, which looks clean on a roof and helps snow slide off as the dark surface warms.
Panel warranty (product vs. performance)
Panels usually carry two warranties: a product warranty covering defects, and a performance warranty promising a minimum output after 25–30 years. Labor and roof leaks are separate. See solar warranties explained.
Polycrystalline (monocrystalline vs. polycrystalline)
Panels made from many silicon fragments melted together, with a bluish, speckled look. They were cheaper but less efficient than monocrystalline, and have largely disappeared from the residential market. If a quote lists poly panels today, ask why.
Production guarantee
A promise that a system will make at least a set number of kWh, with payment if it falls short. Read the fine print: many guarantees have exclusions or cover only part of the shortfall. A realistic production estimate matters more than a guarantee.
Snow load rating
How much weight a panel can hold from snow, in pascals (Pa). Most certified panels are tested to around 5,400 Pa on the front — plenty for Minnesota winters when the racking and roof are designed for local snow loads.
Solar panel efficiency
The share of sunlight hitting a panel that becomes electricity. Higher efficiency means more watts from the same roof area — useful on small or chopped-up roofs. It doesn’t mean a panel produces more per watt you pay for.
Solar panel wattage
A panel’s rated power output in full sun under standard lab conditions, such as 410 W. Higher-wattage panels mean fewer panels for the same system size. Real-world output is usually a bit below the label.
Solar shingles
Roofing shingles with solar cells built in, replacing regular shingles on part of the roof. They look sleek but typically cost more per watt and are harder to service than standard panels. See solar shingles vs. solar panels.
Spec sheet (datasheet)
The one- or two-page list of facts about a panel, inverter or battery — power, efficiency, size, temperature coefficient and warranty. A good quote names exact models. See how to read a solar panel spec sheet.
Temperature coefficient
How much a panel’s output changes as it heats up or cools down, shown as a percent per degree Celsius. Panels lose a little power when hot and gain a little when cold — one reason bright, cold Minnesota spring days can be excellent production days.
Tier-1
A ranking of large, financially strong panel makers based on bankability. It reflects company size and financing history, not necessarily the quality of a specific panel, so always check the exact model’s spec sheet and warranty.
Inverters
DC and AC
DC (direct current) is the power panels and batteries make; AC (alternating current) is what your house and the grid use. The inverter converts DC to AC. You’ll see both on a quote: kW-DC for panel size, kW-AC for inverter output.
Enphase system upgrade
Updating an older Enphase system — new-generation microinverters, gateway or combiner — to restore monitoring, add battery readiness or replace failing units. We inspect first and quote the work. See Enphase system upgrades.
Hybrid inverter
One inverter that manages solar, batteries and the grid together, and can often run a generator too. Popular for whole-home backup and off-grid builds; Sol-Ark and EG4 are common brands. See our hybrid inverter guide.
Inverter replacement
Swapping a failed or aging inverter, often a string inverter out of warranty. Many owners switch to Enphase microinverters at the same time for panel-level monitoring. See replacing a solar inverter with Enphase.
Microinverter
What is a microinverter? A small inverter under each panel, so every panel works on its own. Shade on one doesn’t slow the others, and you get panel-level monitoring. Enphase is iSolar’s residential default, and we install string-plus-optimizer systems too.
Monitoring gateway
The small device that collects data from your inverters and sends it to an app over Wi-Fi or cellular. If your app shows “offline,” the gateway connection is usually the culprit. See fixing offline solar monitoring.
MPPT (maximum power point tracking)
What is MPPT? It’s the smart circuit inside an inverter or charge controller that constantly adjusts voltage and current to pull the most power from your panels as sunlight and temperature change. More MPPT inputs help when panels face different directions.
Power optimizer
A small DC device on each panel, paired with a string inverter (SolarEdge is the best-known example). It tunes each panel’s output to reduce shade losses and enables panel-level monitoring and rapid shutdown, while one central inverter does the DC-to-AC conversion.
Solar inverter
What is a solar inverter? It’s the device that converts your panels’ DC power into AC power your home can use, and it shuts down safely if the grid goes out. It’s the brain of the system and usually the part replaced first over a system’s life.
String inverter
One central inverter that handles a whole “string” of panels wired in series. Cost-effective for large, unshaded arrays, but without optimizers, shade on one panel can drag down the string. See microinverters vs. string inverters.
Batteries & backup
AC-coupled vs. DC-coupled
Two ways to connect a battery. AC-coupled batteries have their own inverter and are easy to add to existing solar. DC-coupled batteries share a hybrid inverter with the panels, which can be more efficient in new installs.
Adding a battery to existing solar
Retrofitting storage onto a system you already own. The right approach depends on your inverter, panel capacity and backup goals. We check compatibility before quoting. See adding a battery to existing solar.
Automatic transfer switch (ATS)
A switch that disconnects your home from the grid during an outage and connects it to backup power, then switches back when the grid returns. It protects line workers and your equipment. Batteries and standby generators both rely on one.
Battery (energy storage)
A unit that stores electricity for later — extra solar from the day, or grid power — so you can use it at night or during an outage. Like a giant rechargeable phone battery for your home. See battery backup.
Battery backup
Using a battery to keep lights, fridge, furnace fan, sump pump and Wi-Fi running when the grid goes down. Under Xcel’s monthly net metering, backup is the main value of a home battery unless you’re on time-of-use rates.
Battery installation code
Fire and building codes limit where and how home batteries are installed — size limits, spacing, garage protection and indoor locations. Inspectors check this on every permit. See indoor battery code.
Critical loads panel
A separate subpanel holding only the circuits you want backed up. The battery or generator feeds this panel during an outage, so a modest battery isn’t overwhelmed by loads like the dryer or central AC.
Depth of discharge (DoD)
How much of a battery’s capacity is used before recharging, as a percent. Running a battery to 90% depth of discharge uses 90% of its stored energy. Deeper cycles can shorten life on some chemistries, so manufacturers set limits and warranties around it.
LiFePO4 (lithium iron phosphate, LFP)
A lithium battery chemistry used in most home batteries today. Lithium iron phosphate batteries are more thermally stable than many other lithium types and handle thousands of charge cycles, which makes them a strong fit for garages and basements.
Peak shaving
Using a battery to cap how much power you draw from the grid at your busiest moment. It mainly helps businesses lower demand charges, and can help homes on time-of-use rates avoid the evening peak.
Power rating (continuous vs. surge)
How many kW a battery can deliver at once. Continuous rating covers steady loads; surge rating covers the brief spike motors need to start, like a well pump or AC compressor. A big kWh battery with a low kW rating can still trip on startup.
Round-trip efficiency
The share of energy you get back out of a battery compared with what you put in. The rest is lost as heat in charging and converting. Higher round-trip efficiency means less wasted solar when you store energy for later.
Self-consumption
Using more of your own solar power yourself — storing daytime sun in a battery to use in the evening instead of buying from the grid. It matters more where exported power earns less than retail, such as on time-of-use plans or some co-ops.
Standby generator
A permanently installed generator running on natural gas or propane that starts automatically during an outage. It handles long, cloudy Minnesota outages that drain a battery. See standby generators and generator vs. battery.
Usable capacity (kWh)
How much stored energy a battery can actually deliver, in kWh — often a bit less than its total rated capacity. Size by what you need to run and for how long. Try our battery sizing tool.
Whole-home vs. essential backup
Essential backup powers selected circuits — fridge, furnace, lights, sump pump. Whole-home backup runs everything, which needs more battery capacity and power. See how big a battery you need.
EV charging
Bidirectional charging (V2H / V2G)
Technology that lets an EV send power back out — to your home during an outage (vehicle-to-home) or to the grid (vehicle-to-grid). It needs a compatible car, charger and transfer equipment, and utility approval for grid export.
Charger amperage (circuit size)
How much current a Level 2 charger draws. Electrical code treats EV charging as a continuous load, so the circuit must be rated 125% of the charger’s draw — a 48-amp charger needs a 60-amp circuit. Panel space often decides the size.
EV charger (EVSE)
The wall unit that safely delivers power to an electric car — technically called EVSE (electric vehicle supply equipment). The actual charger is inside the car. See home EV charger installation.
EV load management
Smart controls that slow or pause EV charging when the rest of the house is using lots of power. It can let you add a charger without a costly service upgrade. Check your panel first with our panel capacity check.
J1772
The standard plug most non-Tesla electric cars have used for Level 1 and Level 2 charging in North America. Adapters let J1772 and NACS cars use each other’s chargers.
Level 2 EV charger
A 240-volt home charger on a dedicated circuit, like a dryer outlet. It adds range many times faster than Level 1 and fully charges most EVs overnight. Our electricians install hardwired and plug-in models. See which EV charger is best.
NACS (North American Charging Standard)
The charging plug developed by Tesla that many carmakers are now adopting. New home chargers come in NACS or J1772 versions, and adapters work both ways — pick based on the cars you’ll own over the next decade.
Section 30C (EV charger credit)
The federal Alternative Fuel Vehicle Refueling Property Credit for chargers. It ended for property placed in service after June 30, 2026. Check current utility rebates instead — see Minnesota EV charger rebates.
Solar EV charging
Using your solar production to cover the electricity your EV uses. With net metering, daytime solar credits offset overnight charging, so you don’t need to charge only when the sun is out. See solar EV charging.
Roof & mounting
Agrivoltaics
Using the same land for solar and farming — grazing sheep, growing shade-tolerant crops or pollinator habitat under raised panels. It’s gaining interest on Minnesota farms. See agrivoltaics in Minnesota.
Ballasted solar
A mounting system held down by concrete blocks instead of roof penetrations or deep footings. Common on flat commercial roofs where the structure can carry the extra weight. See flat-roof commercial solar.
Critter guard
Mesh installed around the edge of a rooftop array to keep squirrels and birds from nesting underneath and chewing wires. See critter guard and squirrels under solar panels.
Detach & reset
Carefully removing solar panels so a roof can be replaced or repaired, then reinstalling and recommissioning them. Best avoided by reroofing before going solar. See detach and reset service.
Dual-axis tracker
A ground mount that follows the sun both daily and seasonally for the most energy per panel. It’s a premium choice for open land; compare its higher cost against simply adding more fixed panels.
Earth-anchored (helical) mount
A ground mount held by helical screw piles twisted into the soil — strong hold-down with minimal digging and no concrete cure time. Works well in many soils and on sites hard to reach with concrete trucks.
East-west array
Panels facing east and west instead of south. Each panel makes somewhat less, but output spreads into morning and evening hours — which can suit time-of-use rates and flat commercial roofs.
Fire setbacks (roof pathways)
Clear spaces left at ridges and roof edges so firefighters can reach and vent the roof. Minnesota fire code sets these pathways, and they limit how many panels fit on a small roof face. See is my roof good for solar.
Fixed-tilt mount
A ground mount set at one good angle year-round. Simple, sturdy and the most affordable option — the right pick for most Minnesota ground arrays.
Flashing
Waterproof metal or composite covers around each roof attachment that shed water like shingles do. Good flashing is how a solar install stays leak-free for decades.
Ground mount solar
Panels on a frame in your yard or field instead of the roof — easy to angle and face ideally, simple to clear of snow, and no roof penetrations. See ground mount vs. roof mount.
Ice-and-water shield
A self-sealing waterproof membrane under the shingles. iSolar adds it under rooftop arrays — more protection than minimum code requires, which matters with Minnesota ice dams. See ice dams and solar panels.
Pile-driven mount
A ground mount whose steel posts are driven deep into the soil, below the frost line. Fast to install and built to resist Minnesota frost heave in suitable soils.
Poured footing
Concrete piers poured below the frost line to anchor a ground mount. The most traditional, very strong base for heavy arrays or tough soils, though it takes longer to install.
Single-axis tracker
A ground mount that slowly turns east to west each day to follow the sun, producing more energy than a fixed array. More moving parts mean more maintenance, and Minnesota snow and wind must be planned for.
Snow guards
Brackets or bars on the roof below an array that break up snow sliding off the panels, protecting gutters, decks, cars and people below. See snow guards.
Solar carport
A canopy structure with solar panels on top that shades or covers parking. It makes power from space you already use and works well for businesses and large lots. See solar carports and ground mounts.
Solar racking
The aluminum rails, clamps and attachments that hold panels to a roof or ground frame. Racking must be engineered for Minnesota snow and wind loads, and correctly flashed where it meets the roof.
Trenching & directional boring
Two ways to run wire underground from a ground mount or detached garage to your house. Trenching digs an open ditch; directional boring drills beneath lawns, driveways and sidewalks with minimal surface damage.
Permits, utility & safety
120% rule
The NEC busbar rule (705.12 in the 2023 edition) for connecting solar through a breaker. Main breaker plus solar breaker can’t exceed 120% of the busbar rating — a 200A panel with a 200A main allows up to a 40A solar breaker.
Anti-islanding
A required inverter safety feature that shuts grid-tied solar off when the grid goes down, so it can’t energize lines a utility worker is repairing. That’s why solar alone doesn’t power your home in an outage. See solar in a power outage.
Backfeed breaker
The breaker in your main panel that connects solar into your home’s wiring, sending power “backward” into the panel. Its size and position are governed by the 120% rule.
Bidirectional meter
What is a bidirectional meter? A utility meter that measures power in both directions — what you buy and what your solar sends back — which makes net metering work. See Xcel solar meters explained.
Busbar
The metal bars inside your electrical panel that breakers clip onto. The busbar rating (such as 200 amps) limits how much current the panel can safely carry from all sources, including solar.
Hosting capacity
How much solar a local power line (feeder) can accept before upgrades are needed. Where hosting capacity is low, interconnection can take longer or require studies. See Xcel solar capacity.
Inspection
A city or state inspector’s check after installation that the electrical and structural work matches code and the approved plans. Passing inspection comes before the utility grants permission to operate.
Interconnection
The utility’s process for approving a solar or battery system to connect to its grid. It’s often the longest wait in a project, especially where the local feeder is near its hosting limit.
Interconnection agreement
The contract between you and your utility setting the terms for connecting your system — equipment, safety requirements and how exported energy is credited. Your installer usually prepares and submits it with the application.
Line-side tap (supply-side connection)
Connecting solar between the meter and the main breaker instead of through a panel breaker. It’s a common fix when a panel can’t take a backfeed breaker under the 120% rule, and often avoids a full panel upgrade.
Main panel (breaker box)
The gray box where your home’s power is split into circuits. Its amp rating and open spaces determine whether solar, a battery or an EV charger can connect easily. Check yours with our panel capacity check.
Main panel upgrade (service upgrade)
Replacing your panel or increasing your electrical service (for example, 100 to 200 amps) so it can safely carry solar, batteries, an EV charger or heat pump. 100-amp homes often need one or a line-side tap. See panel upgrades for solar.
Master electrician
The highest Minnesota electrician license, allowed to plan, supervise and take responsibility for electrical work. iSolar’s master electrician is John Ihle (MN AM005101), and iSolar holds contractor license EA761814. See our team.
Monitoring
An app or web portal that shows how much energy your system makes — often panel by panel. It helps you and your installer spot problems quickly instead of finding out on your utility bill.
NABCEP
What is NABCEP? The North American Board of Certified Energy Practitioners offers the best-known solar installer certifications, earned through training, field experience and exams. It signals tested knowledge; iSolar’s master electrician, John Ihle, holds a NABCEP credential.
NEC (National Electrical Code)
The national electrical safety rulebook that Minnesota adopts by statute. Minnesota adopted the 2026 NEC for electrical permits filed on or after August 17, 2026, so section numbers may differ from the 2023 edition.
Permission to Operate (PTO)
What is PTO in solar? It’s the utility’s final go-ahead to turn your system on, issued after inspection and any meter work. Running a grid-tied system before PTO isn’t allowed.
Permit
Official permission from your city or the state to do electrical and building work. It ensures the install is safe and code-compliant. We pull permits for you. See solar permits and interconnection in Minnesota.
Production meter
A second meter that records everything your solar system produces. Xcel uses it to pay Solar*Rewards incentives on actual kWh made, separate from what you import or export.
Rapid shutdown
An NEC rule (690.12 in the 2023 edition) requiring rooftop solar to quickly drop to safe voltage when shut off, protecting firefighters. Microinverters and optimizers meet it at the panel; string systems need added devices.
Smart panel
An upgraded breaker panel you control from an app — choosing which circuits run on backup power, shedding big loads automatically and tracking energy use circuit by circuit.
SolarInsure 30-year warranty
The 30-year, insurer-backed warranty iSolar puts on installs, covering parts, labor, roof penetrations and monitoring through a third-party provider. It’s transferable if you sell your home. See SolarInsure.
Structural review (PE stamp)
An engineer’s check that your roof framing can carry the panels plus Minnesota snow loads, sealed with a Professional Engineer’s stamp when the city requires it. Older or altered roofs sometimes need reinforcement.
Surge protection device (SPD)
A device in your panel that diverts voltage spikes from lightning or utility switching away from electronics, inverters and battery equipment. Whole-home surge protection is an inexpensive add-on during solar or panel work. See electrical services.
Commercial & tax
Beginning of construction (BOC)
The IRS test for when a project officially starts, met by significant physical work or qualifying spending. It matters because §48E deadlines and FEOC rules depend on when construction began. Projects that started by July 4, 2026 have a longer window.
Bonus depreciation
A rule letting businesses deduct a large share of an asset’s cost in the first year. 100% bonus depreciation was restored for property acquired after January 19, 2025. It can sharply improve commercial solar cash flow — confirm with your CPA.
C-PACE
Commercial Property Assessed Clean Energy financing: long-term funding for energy upgrades repaid through a property tax assessment that stays with the building. It can cover solar with little or no money down. See C-PACE financing in Minnesota.
Commercial solar loan
Equipment or term financing that lets a business own its solar system while keeping the tax credit and depreciation benefits. See commercial solar loans and commercial solar ROI.
Domestic content bonus
An extra credit for commercial projects that use enough U.S.-made steel, iron and manufactured products. For projects beginning construction in 2026, the manufactured-products threshold is 50%. Documentation from suppliers is essential.
Energy community bonus
An additional credit for projects located in areas the Treasury designates as energy communities, such as places with closed coal plants or fossil-fuel employment. Eligibility is set by census tract maps, so verify your site’s address with your tax advisor.
FEOC (foreign entity of concern)
Rules that limit how much of a project’s equipment can come from certain foreign-controlled suppliers for it to qualify for §48E. Treasury Notice 2026-15 set a 40% material-assistance threshold for 2026 construction starts, rising 5 points a year.
Investment tax credit (ITC)
A federal tax credit worth a percentage of a solar project’s cost. For businesses, farms and nonprofits it now lives under §48E (30% base). The homeowner version (§25D) ended for systems placed in service after 2025. Talk to your tax advisor.
MACRS depreciation
The tax system businesses use to write off equipment over time. P.L. 119-21 changed solar’s MACRS class for projects beginning construction after 2024 (see IRS Form 4562 instructions), so have your CPA confirm the schedule for your project.
Placed in service
When a system is installed, complete and ready to operate for its intended use — not when you sign or pay. Tax credit deadlines and depreciation start dates turn on this date.
Production tax credit (PTC, §45Y)
A federal credit paid per kWh produced over time, instead of a one-time percentage of cost. The current version is §45Y; qualifying projects generally choose either it or §48E, not both. Most small commercial solar projects use §48E — ask your tax advisor.
Section 48E (Clean Electricity Investment Credit)
The commercial solar credit: a 30% base credit for qualifying projects. Projects beginning construction after July 4, 2026 must be placed in service by December 31, 2027. See the §48E 2027 deadline and commercial solar 2027.
USDA REAP
The USDA Rural Energy for America Program offers grants and loan guarantees for solar and efficiency projects at farms and rural small businesses. Funding rounds are competitive, so we never promise an award. See the USDA REAP grant.
Minnesota programs
40 kW net metering limit
Minnesota’s net metering rules give the most favorable treatment — monthly netting credited near retail — to systems up to 40 kW. Larger systems fall under different rules and size caps. See net metering changes in Minnesota.
Community solar garden
A shared solar array you subscribe to instead of putting panels on your own roof; you get credits on your utility bill for your share. Subscriptions are open to renters and homeowners with shaded roofs. See community solar vs. rooftop solar.
Income-Qualified Solar*Rewards
Xcel’s program paying $3.00 per watt up front for qualifying households (for example, enrolled in Energy Assistance, SNAP or Medical Assistance) who own and live in the home. iSolar is taking 2027 sign-ups through December 31, 2026. See Income-Qualified Solar*Rewards.
Minnesota HOA solar law
Under Minn. Stat. 500.216, most Minnesota homeowners associations can’t ban rooftop solar, though they can set reasonable restrictions on placement and appearance. See solar and HOAs in Minnesota.
Minnesota solar sales tax exemption
Solar energy systems are exempt from Minnesota sales tax under Minn. Stat. 297A.67, subd. 29, which lowers the installed cost. See Minnesota solar tax exemptions.
Minnesota storage rebate
A state rebate of $250 per kWh up to $7,000 for home batteries outside Xcel territory. Funds were running low as of August 2026, so check availability before counting on it. See Minnesota solar incentives.
Renewable energy credit (REC / SREC)
What is an SREC? A certificate representing 1 MWh of solar electricity that some states let owners sell. Minnesota has no SREC market for Xcel residential solar; Solar*Rewards participants transfer their system’s RECs to Xcel as part of the incentive agreement.
Solar co-op (group buy)
Neighbors joining together to get vetted installer bids and group pricing. iSolar has been selected three times as a Solar United Neighbors co-op installer and twice for Switch Together. See iSolar and Solar United Neighbors.
Solar property tax exemption
In Minnesota, the value solar adds to your property is exempt from property tax under Minn. Stat. 272.02, subd. 24, so going solar shouldn’t raise your tax bill. See do solar panels increase property taxes.
Value of solar (VOS)
A method Minnesota studied for valuing what rooftop solar is worth to the grid and society — avoided fuel, capacity and environmental costs — as an alternative to net metering. See the Minnesota value of solar study.
Xcel battery incentive
Xcel’s incentive for qualifying home batteries — about $175 per kWh up to $5,000, or $370 per kWh for income-qualified customers. Terms change, so we confirm current amounts in your quote.
Xcel Solar*Rewards
Xcel Energy’s Minnesota production incentive, currently $0.05 per kWh produced for 10 years, for systems up to 40 kW sized at or below 120% of usage. Capacity is limited each year, so we confirm availability at quote. See Xcel Solar*Rewards.
Still have a question?
We’ll explain anything in plain terms — no jargon, no pressure. Call a licensed Minnesota electrician, not a call center.