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Solar Import Calculator

Calculate remaining grid imports after solar and the cost they carry.

About Solar Import Calculator

Solar reduces the variable part of a bill but not the standing charge, so bills never fall to zero. The residual import is whatever consumption falls outside generation hours. Standing charges have risen in many markets, which caps the percentage saving solar can deliver however large the array.

Formula

Solar Import

Imports = consumption − solar self-consumed; bill = imports × rate + standing charge

standing charge
Fixed daily connection cost that solar cannot reduce

Worked example

With the default values below, Solar Import Calculator returns Electricity Still Imported of 1,575.0. Change any input above and every figure here is recalculated in your browser.

Inputs used

Annual consumptionminimum 0 kWh
4,500 kWh
Annual solar generationminimum 0 kWh
6,500 kWh
Self-consumption rateaccepts 0–100 %
45 %
Import price per kWhminimum 0
0.25
Daily standing chargeminimum 0
0.5

Results

Electricity Still Imported
1,575.0 kWh
Annual Import Cost
$393.75
Annual Standing Charge
$182.50
Estimated Annual Bill
$576.25
Reduction in Imports Against No Solar
65.00%

Step by step

  1. 1Values used
  2. 2Solar Import
  3. 3Electricity Still Imported= 1,575.0 kWh
  4. 4Annual Import Cost= 393.75
  5. 5Annual Standing Charge= 182.50
  6. 6Estimated Annual Bill= 576.25
  7. 7Reduction in Imports Against No Solar= 65.00

Assumptions and limits

  • The result is derived only from the 5 inputs listed above. Anything not among them is not part of the calculation.
  • In particular, this calculator does not take inflation or tax into account.
  • Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Solar Import calculated?

Imports = consumption − solar self-consumed; bill = imports × rate + standing charge Solar reduces the variable part of a bill but not the standing charge, so bills never fall to zero. The residual import is whatever consumption falls outside generation hours.

Why does Solar Import matter?

Standing charges have risen in many markets, which caps the percentage saving solar can deliver however large the array.

What values do I need to enter?

This calculator takes 5 inputs: Annual consumption, Annual solar generation, Self-consumption rate, Import price per kWh, Daily standing charge. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.

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