Tariff
What an exported kWh is worth
Self consumed generation is worth your full retail rate. Exported generation is worth whatever your rider says, and that number decides how big your array should be.
- Self consumedFull retail
- Sample avoided cost$0.035 / kWh
- Typical retail$0.135 / kWh
- RatioAbout 4 to 1
How it works
Three meters' worth of arithmetic
Your array produces. Your house consumes. Only the difference crosses the meter, and only the part that crosses the meter is exposed to your export rate.
Production
The array generates. On a clear June afternoon a 9 kW system might be producing 7 kW while the house draws 1.2 kW.
Self consumption
That 1.2 kW never reaches the meter. It offsets electricity you would otherwise buy, so it is worth your full all in retail rate.
Export
The remaining 5.8 kW crosses the meter outbound. What it earns depends on your rider, and the range between arrangements is wide.
Evening import
After sunset you import again. Whether the afternoon export offsets it one for one depends on the netting interval.
Worked example
The same array on three arrangements
A 9.24 kW array producing 12,382 kWh a year in a home using 12,000 kWh, with a 42 percent self consumption share. All figures are samples to show the mechanism.
| Arrangement | Self consumed value | Export value | Annual total | Effect on sizing |
|---|---|---|---|---|
| Full retail netting | 5,200 kWh at $0.135 = $702 | 7,182 kWh at $0.135 = $970 | $1,672 | Oversizing to 110 percent is reasonable |
| Netted billing, credit below retail | 5,200 kWh at $0.135 = $702 | 7,182 kWh at $0.085 = $611 | $1,313 | Size to consumption, not above it |
| Avoided cost buyback | 5,200 kWh at $0.135 = $702 | 7,182 kWh at $0.035 = $251 | $953 | Size to self consumption, consider storage |
Sample figures for illustration. The same physical array returns $1,672 or $953 a year depending only on the arrangement it sits under. That is a difference of roughly 43 percent in annual value with no change to a single module. Confirm your current rider with your utility before relying on any number here.
What to do about it
Three responses that actually work
When export is credited well below retail, the answer is not a bigger array. It is a different shape of system.
- Shift consumption into daylightRun the dishwasher, the dryer and the EV charger while the array is producing. Every kilowatt hour moved from evening to afternoon converts export value into retail value.
- Store the surplus instead of exporting itA battery charged on surplus afternoon generation and discharged in the evening turns a 3.5 cent kilowatt hour into a 13.5 cent one, less round trip losses of about 10 percent.
- Aim some capacity westA west facing plane produces less annually but produces more of it late in the day, which lines up with both household evening load and on peak time of use windows.
Questions
Export and tariff questions
Modern bidirectional meters do not spin backwards, they record import and export as separate registers. What happens to the exported register depends entirely on your rider. Under a full retail netting arrangement the exported kilowatt hours offset imported ones. Under a netted billing or time of use arrangement they are credited at a stated rate that is usually lower than retail.
Net metering nets your export against your import, so an exported kilowatt hour is worth the same as one you avoid buying. A buyback or avoided cost arrangement pays a stated rate per exported kilowatt hour, typically a few cents. The difference is large: at a retail rate near 13.5 cents and an avoided cost near 3.5 cents, an exported kilowatt hour can be worth a quarter of what a self consumed one is worth.
Only if export is credited close to retail. Where export is credited at avoided cost, every kilowatt hour above your own consumption earns a fraction of what the first kilowatt hour earned, and the marginal payback on that extra capacity gets long. This is the single most common way a proposal overstates savings.
The period over which import and export are compared. Monthly netting lets a sunny afternoon offset a dark evening within the same month. Instantaneous or hourly netting does not, so your self consumption share matters far more. Ask which interval your rider uses before assuming a savings figure.
Substantially. Under time of use, generation during an on peak window is worth considerably more than the same generation off peak. In this region summer on peak periods commonly fall in the late afternoon and early evening, which is exactly when a west facing array or a battery discharging on schedule earns its keep.
Rider dependent. Some arrangements roll credits forward indefinitely, some settle annually at a lower rate, and some expire. It is a question worth asking before you size an array to produce more than you use.
Model it against your own rider
Bring a recent bill to the site check. We read the rider off it and build the production model against the arrangement you are actually on rather than a generic one.
No pressure appointment. The site check is free and the design is yours to keep.