Net Metering Calculator
Calculates your monthly electric bill credit when your solar panels overproduce and the cost when they fall short, factoring in net metering rates and fixed fees. Ideal for homeowners evaluating whether net metering makes solar worthwhile.
About this calculator
Net metering lets solar owners sell surplus electricity back to the grid at a set credit rate and buy deficit electricity at the retail rate. Your monthly net bill is: Net Bill ($) = max(0, solarProduction − homeConsumption) × electricityRate × netMeteringRate − max(0, homeConsumption − solarProduction) × electricityRate − monthlyFee. The first term is the credit earned on excess kWh exported; netMeteringRate is often less than 1.0 if your utility pays below retail for exports (e.g., 0.75 means 75 cents per retail dollar). The second term is the cost of importing deficit kWh at full retail price. The fixed monthlyFee represents standing charges that apply regardless of production. A negative result means you owe money; a positive result means you have a net credit.
How to use
Assume monthly solar production = 600 kWh, home consumption = 500 kWh, electricity rate = $0.14/kWh, net metering credit rate = 0.90, and monthly fee = $10. Surplus = 600 − 500 = 100 kWh exported. Credit = 100 × 0.14 × 0.90 = $12.60. Deficit import cost = $0 (no shortfall). Net Bill = $12.60 − $0 − $10 = $2.60 net credit. In a month where consumption exceeds production — say 700 kWh used — the deficit cost = (700 − 600) × $0.14 = $14, and Net Bill = $0 − $14 − $10 = −$24 owed.
Frequently asked questions
What is the difference between full retail net metering and avoided-cost net metering?
Under full retail net metering, every kilowatt-hour you export earns the same rate you pay to import, effectively spinning your meter backward at retail price. Avoided-cost net metering pays you only the utility's wholesale or avoided-cost rate — often 30–50% less than retail. The netMeteringRate field in this calculator captures that difference: enter 1.0 for full retail and a lower decimal (e.g., 0.50) for avoided-cost policies. Many U.S. states have shifted away from full retail NEM, so checking your utility tariff before sizing a system is essential.
How does a monthly connection fee affect net metering savings?
Most utilities charge a fixed monthly fee — sometimes called a customer charge or grid access fee — regardless of how much electricity you consume or produce. This fee directly reduces your net savings and cannot be offset by solar credits in most tariff structures. If your monthly connection fee is $15 and your solar credit is only $12, you will still owe $3 even in a highly productive month. When evaluating solar ROI, always include this fixed cost to avoid overstating payback periods.
When does net metering result in a bill credit that carries over to the next month?
In most net metering programs, any credit that exceeds your monthly charges rolls over as a dollar or kWh credit to the following billing period. This is particularly valuable for grid-tied solar owners in summer months when production peaks, as credits can offset higher winter bills when production is lower. However, many utilities perform an annual true-up, paying out remaining credits at a lower rate or forfeiting them entirely. Check your utility's rollover and true-up policy before assuming year-round credit accumulation.