Compare the payback period, not only the charging rate
A lower home electricity rate does not by itself make a private EV charger the lower-cost choice.
The decision includes the charger, wiring, possible service or capacity work, fixed charges, communications, maintenance, repair, and removal when the residence horizon ends.
Continuing to use public charging has its own recurring burdens: energy, membership or parking charges, detours, and added waiting time.
This calculator places both alternatives on one monthly cash-flow timeline, discounts them to present value, and reports the sustained crossover and usage needed to recover the installation.
Decisions this calculator supports
- Which alternative has the lower life-cycle cost over the expected Korean residence horizon
- How much monthly vehicle energy and driving are needed to recover a written installation quote
- Whether a different public rate or a shorter stay reverses the result
- Which quote, consent, supply, tariff, and support evidence is still missing before a contract
Scope and boundaries
The tool is designed for an owner or prospective owner of a private EV who is considering a dedicated charger at a detached or multi-family residence in Korea.
It is not the communal apartment charger model: mandatory parking-space ratios, resident cost allocation, operator revenue, and shared-capacity governance require a different analysis.
A favorable cost result also does not establish electrical feasibility, safety, KEPCO supply capacity, site rights, program eligibility, or permission to perform work.
Included home EV charger comparison items and separate checks| Area | Included in the model | Confirm separately |
|---|
| Costs | Equipment, work, capacity, fixed, energy, maintenance, removal, and residual value | Unquoted civil work, restoration conditions, and tax-invoice scope |
| Usage | Driving, efficiency, home share, loss, and public detour or waiting | Charger output, vehicle acceptance rate, winter performance, and outage plans |
| Authority | Evidence gaps shown as warnings | Qualified work, owner consent, KEPCO contract, and support-program selection |
Five steps for evidence-matched inputs
- Set the residence horizon and real driving first.
Use the period until a plausible move or sale, not the charger warranty alone.
Derive monthly driving from six to twelve months of odometer or trip-log evidence and use season-aware real-world efficiency rather than a best-case display value.
- Keep unavoidable public charging in the model.
Road trips and outside schedules normally prevent a private charger from serving every kilowatt-hour.
The model applies charging loss to the home share at the meter and prices the remaining vehicle-side energy at the public rate.
- Put both rates on the same billing basis.
For home charging, confirm whether the installation changes a residential bill, creates a separate EV contract, or adds a fixed charge.
For public charging, reflect the membership status and slow-versus-fast mix actually used, then align tax and fund inclusions in the effective KRW/kWh figures.
- Split a site-survey quote into real scopes.
Enter equipment, electrical work, service or capacity work, and design, filing, inspection, civil, or restoration items separately.
Confirm cable length, panel changes, grounding, protection, trenching, waterproofing, networking, and parking-surface restoration instead of relying on an online charger price.
- Carry recurring and exit costs to the last month.
Add basic and communication charges, annual inspection and repair reserves, and removal or restoration at the move date.
Use only support that has been confirmed for this site and a defensible resale or transfer value; otherwise enter zero.
Reading the synthetic baseline
The starting values demonstrate the calculation and are not market averages, quotes, or recommendations.
They assume 1,200 km of monthly driving, 5.5 km/kWh real efficiency, an 85% home share, 10% home-charging loss, and a 60-month residence horizon.
Gross installation is KRW 3,000,000 with no confirmed support, the public rate is KRW 347/kWh, and public-only use involves six monthly sessions with 35 minutes of added travel and waiting per session.
Key results from the 60-month synthetic baseline| Result | Calculated value | Interpretation |
|---|
| Monthly vehicle-side energy | 218.2 kWh | Driving divided by real-world efficiency |
| Monthly home metered energy | 204.0 kWh | The home share including 10% loss |
| Remaining monthly public energy | 32.7 kWh | The 15% road-trip and outside-use remainder |
| Home present-value TCO | KRW 8,692,158 | Installation, operation, and terminal cash flows |
| Public present-value TCO | KRW 8,571,406 | Energy, access cash cost, and time value |
| 60-month result | Public is KRW 120,752 lower | Terminal removal prevents a sustained crossover |
| Usage needed for recovery | 223.1 kWh · 1,227.1 km/month | The boundary with all other assumptions held constant |
The same baseline favors home installation when the public rate is 20% higher.
Extending the horizon to 120 months makes home installation about KRW 3.25 million lower and produces a sustained crossover at month 58.
That contrast is why the public-rate and 24, 60, and 120-month horizon tables matter more than one headline result.
Calculation method
Monthly energy
Vehicle-side energy equals monthly distance divided by real-world km/kWh.
Home metered energy equals vehicle energy multiplied by the home share and by one plus the entered loss rate.
Remaining public energy equals vehicle energy multiplied by one minus the home share.
Present value
The model escalates monthly home and public costs at the user-entered annual rates and discounts each monthly cash flow.
Home installation includes net upfront cost at month zero and removal less capped residual value in the final month.
Confirmed support and residual value are each capped at gross installation cost to prevent impossible negative capital cost.
Sustained crossover
The reported month is not merely the first temporary point when cumulative home present value becomes lower.
Because removal can reverse the comparison at the end, the calculator requires home installation to remain lower through the final month.
A temporary crossing followed by reversal is shown as not reached within the residence horizon.
Required usage
The calculator holds other assumptions constant and searches for the monthly vehicle energy that makes the installation recover by the horizon.
It multiplies that energy by entered efficiency to report the corresponding monthly distance.
No boundary is reported when the home share is zero or home operation cannot displace a cheaper public unit cost.
Korean tariff, support, and electrical-work checks
KEPCO publishes EV charging electricity with a basic charge and time-of-use energy charges, so this implementation does not hard-code a single official rate.
Billing structures can change, including the time-of-use reform effective April 16, 2026, and the effective rate depends on the contract and charging schedule.
The 2026 public-charging support notice on the Korean zero-emission vehicle portal describes communal facilities such as apartment complexes, workplaces, and large parking sites.
The calculator therefore applies zero support to a private-home scenario unless the user confirms the applicable program, selection, and payable amount.
The September 1, 2026 legal snapshot is Electrical Construction Business Act ID 000285 and MST 271253, its Enforcement Decree ID 004686 and MST 282331, and Environment-Friendly Automobile Act ID 009758 and MST 283991.
Economic recovery is not authorization to build
Article 3 of the current Electrical Construction Business Act generally requires electrical work to be contracted and performed by a registered electrical construction business, subject to limited minor-work exceptions in the Enforcement Decree.
Some residence-related minor work in Article 5 of the Decree still carries technician and technical conditions, so a user should not classify a typical EV charger installation as exempt on their own.
Confirm supply capacity, contract type, circuit protection, grounding, cable route, inspection, and qualified-work scope with KEPCO and a registered contractor before signing.
- Check the current basic and time-of-use figures in the KEPCO EV charging tariff table.
- Check eligible facility types and application status in the Korean zero-emission vehicle public-charging support notice.
- Recheck the current act and decree in the Korean National Law Information Center before contracting for work.
- The present-value structure follows general life-cycle costing principles described in NIST Handbook 135e2025, while every discount and escalation rate remains a user assumption.
Scenarios that commonly change the answer
Long stay and high usage
More months spread the capital cost and more displaced public energy can favor installation.
A high separate basic charge, large repair reserve, or low achievable home share can still prevent recovery.
A likely move
A short horizon requires rapid recovery and brings removal and restoration forward.
Do not assume the next resident will pay for the charger without written owner consent and a supportable transfer value.
Poor public access
Repeated detours and queues can materially raise the life-cycle burden of public charging.
Count only time caused by the charging trip, and compare a zero-time-value case to avoid overstating convenience.
Large capacity work
Service, metering, panel, or supply upgrades can cost more than the charger hardware.
Obtain a site survey and a separate capacity-work line instead of entering a retail product price as the entire installation.
Frequently asked questions
Should I simply add charging to the residential progressive tariff?
Not without confirming the metering and contract structure.
Ask KEPCO and the contractor whether the design changes the residential bill or establishes a separate charging contract, then derive an effective incremental rate from recent bills.
Can I enter support as soon as a program is announced?
A program announcement does not mean a private residence, applicant, and proposed charger are eligible.
Confirm facility type, applicant role, selection, owner contribution, payment conditions, and payable amount before turning on the support-confirmed check.
Does time value automatically exaggerate the case for home charging?
Time value is a user planning assumption rather than a cash bill, and the breakdown keeps it visible with public access costs.
Run one case at zero and another at your defensible opportunity cost; the gap shows how much of the decision depends on convenience.
Does no crossover mean I should never install?
No.
The result describes the economic boundary for the entered costs and period; it does not decide the nonfinancial value of arriving home to a ready charger, resilience, or a planned change in driving.
It does reveal the present-value premium you would be choosing to pay for those benefits.
Can the calculator cover more than one EV?
You may combine vehicle-side monthly energy when both vehicles use the same installation and contract.
Calculate distance divided by efficiency for each vehicle before summing, and obtain a separate engineering check for simultaneous charging, demand, and circuit capacity.
Turn the result into a quote-ready next step
First check whether the result survives the 24, 60, and 120-month horizon table and a conservative zero-time-value run.
Then prepare site photos and cable distance, request at least two written quotes with identical scope, and confirm owner consent and KEPCO supply and tariff basis in parallel.
Before contracting, document the charger model, warranty, call-out fees, offline operation after network service ends, removal responsibility, restoration standard, and cancellation terms if expected support is not awarded.
Final evidence checklist
- A written quote separating equipment, wiring, capacity work, civil work, and restoration
- Rights-holder consent for the site, cable route, future removal, and restoration
- KEPCO supply capacity and contract basis plus registered-contractor or qualified-technician scope
- Effective KRW/kWh figures reconciled to recent home bills and public charging receipts
- Program eligibility, selection, and payable amount evidence for any support entered
The planning basis is September 1, 2026, and tariffs and programs can change.
This information tool does not replace electrical design, safety inspection, legal or tax advice, a support application, or provider selection.