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Idaho Solar Calculator

Enter your utility and monthly bill — get system size, Idaho state tax deduction, federal ITC, net metering savings, and 25-year projections for Boise, Meridian, and beyond.

Your Idaho solar inputs
$
kW
Idaho solar estimate
20 × 400W panels (8 kW system)
Recommended size for your bill: 8.9 kW
Monthly usage1,000 kWh/mo
Annual production (ID 4.7 PSH)10,979 kWh/yr
Annual savings (net metering)$1,098/yr
Gross system cost$22,800
Federal ITC (30%)-$6,840
ID state tax deduction (est.)-$1,160
Net cost after incentives$14,800
Payback period13.5 yrs
25-year savings$27,448
Idaho's state tax deduction: 40% of the first $20,000 in year 1, then 20% per year in years 2-4. This estimate assumes Idaho's ~5.8% state income tax rate applied to deductible amounts.
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How to Use This Calculator

Enter your bill and select your Idaho utility

Idaho has three major electric utilities: Idaho Power serves the Boise metro and southern Idaho with some of the lowest rates in the US ($0.10/kWh); Avista Utilities serves northern Idaho and Coeur d'Alene at $0.09/kWh; Rocky Mountain Power serves eastern Idaho including Idaho Falls and Pocatello. Idaho's low rates — driven by abundant hydroelectric power — are the primary challenge for solar ROI, but the state's tax deduction and net metering partially offset this.

Understand the Idaho state tax deduction

Idaho offers a unique solar equipment tax deduction (not a credit): homeowners can deduct 40% of the first $20,000 of system cost in year 1, then 20% per year in years 2-4. This totals 100% of the first $20,000 deducted over four years. At Idaho's ~5.8% state income tax rate, this translates to roughly $1,160 in actual tax savings on a $20,000 deductible base. It is a deduction from taxable income, not a direct credit — consult your tax advisor for your specific situation.

Idaho's low rates challenge ROI — but sun helps

At $0.09-0.10/kWh, Idaho has electricity rates well below the US average of $0.17/kWh. This means each kWh of solar saves less money than in high-rate states. However, Idaho's 4.7 PSH solar resource is solid, and rates have been rising 4-6% annually, improving future-year economics. Think of Idaho solar as a hedge against utility rate increases rather than a quick payback play.

The Formula

Monthly kWh = Monthly Bill ÷ Electricity Rate Annual Production = System kW × 1000 × 4.7 PSH × 365 × 0.80 efficiency ÷ 1000 Annual Savings = Annual Production × Retail Rate (net metering at 1:1) Gross Cost = System kW × 1000 × $2.85/W ITC Credit = Gross Cost × 30% ID Deduction Tax Saving = min(Gross Cost, $20,000) × (40% yr1 + 20%×3 yrs2-4) × 5.8% Net Cost = Gross Cost − ITC Credit − ID Deduction Tax Saving Payback = Net Cost ÷ Annual Savings

Idaho uses 4.7 peak sun hours — Boise averages 4.9 PSH, Idaho Falls gets 4.6, Coeur d'Alene gets 4.2. The $2.85/W installed cost reflects Idaho's slightly higher installation costs due to smaller market volume. Net metering at retail rates (required under Idaho law for Idaho Power and Avista) means all solar production saves at full retail value.

Example

Mike — Boise Idaho Power customer

Mike pays $100/month to Idaho Power at $0.10/kWh. He wants an 8 kW system on his south-facing Boise roof.

Monthly bill$100 (Idaho Power, $0.10/kWh)
System8 kW, south-facing
LocationBoise, ID (4.9 PSH)

Result

Annual production~10,987 kWh/yr
Annual savings (net metering)~$1,099/yr
Gross system cost~$22,800
Federal ITC (30%)-$6,840
ID state deduction (est.)-$1,160
Net cost after incentives~$14,800
Payback period~13.5 years
25-year savings~$27,475

Idaho's low electricity rates push payback to 13-15 years, but the 25-year savings still substantially exceed the net cost. Mike's system will generate well over his investment in savings over its lifetime. Idaho Power rates have been rising 5%+ annually — each year of delay extends payback while the future savings picture improves.

FAQ

Idaho allows homeowners to deduct the cost of a solar energy system from state taxable income. The deduction is structured as: 40% of the first $20,000 in year 1, then 20% per year in years 2, 3, and 4 — totaling 100% of the first $20,000 deducted over four years. This is a state income tax deduction, not a credit. At Idaho's state income tax rate (~5.8%), a $20,000 deductible base saves approximately $1,160 in actual state taxes over four years. Systems costing more than $20,000 still only get the deduction on the first $20,000. Consult a tax professional for your specific situation.
Solar is financially viable in Idaho, but payback periods run 13-16 years versus 8-12 years in high-rate states. The key factors favoring Idaho solar: (1) Idaho Power rates have been rising 4-6% annually; (2) Net metering credits all solar at retail rate; (3) Idaho's 4.7 PSH solar resource is solid; (4) The 30% federal ITC reduces net cost significantly; (5) Solar adds home value without increasing property taxes. Think of Idaho solar as a long-term hedge against utility rate increases rather than a quick-return investment. The 25-year savings still substantially exceed the net cost.
Idaho Power and Avista are required to offer net metering to residential solar customers. Excess solar exported to the grid earns credits at the full retail rate. Credits accumulate monthly and roll over. At the end of the annual billing period (April 1 for Idaho Power), any remaining credits may be paid out at the monthly system average cost — typically 3-5 cents/kWh lower than retail. This means oversizing your system significantly beyond your annual consumption results in lower-value credits at year-end. Size your system to match your annual usage for best economics.
Idaho does not have a statewide property tax exemption specifically for solar systems. Solar installations may or may not increase your assessed property value depending on county assessment practices. Idaho property tax rates are moderate (approximately 0.7% of assessed value). The lack of a property tax exemption is a minor negative compared to the federal ITC and state deduction available. Check with your county assessor if property tax impact is a concern.
Boise is Idaho's best solar city, with 4.9 PSH — ranking it among the top solar markets in the Pacific Northwest. Twin Falls gets 5.0 PSH, making it the highest solar resource area in the state. Pocatello (4.8 PSH), Nampa (4.9 PSH), and Meridian (4.9 PSH) all have strong solar resources. Coeur d'Alene in northern Idaho gets about 4.2 PSH — still viable but with lower production per kW. All Idaho cities qualify for the same federal ITC and state tax deduction regardless of location.

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