OPENEVSE IS A HOME EV CHARGER THAT CAN RUN ONLY ON YOUR LEFTOVER SOLAR AND NEEDS NO VENDOR ACCOUNT
An open-source car charger that can throttle itself to charge only from the solar you would have exported, and you never need a vendor account.
by OpenEVSE
EnergyHome
Built withESP32
- difficulty
- ●●●●○
- time
- a weekend plus installation
- license
- GPL-3.0
- repo
- repo ACTIVE194 stars
●●●●○ · a weekend plus installation · GPL-3.0 · 194 stars · repo ACTIVE
WHAT YOU’LL NEED
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COMPAREE VERDICT
OpenEVSE is a long-running, actively maintained open-source EV charger. The controller firmware handles the J1772 state machine, monitors temperature through an MCP9808 sensor, and enforces current limits. The ESP32 gateway is what most people actually want: it reads your grid-import or solar-generation power over MQTT or HTTP, then starts, stops and modulates charging to match surplus production. Up to 50 recurring weekly charge rules, session limits by state of charge, range, time or energy, a current shaper to stay inside your supply rating, and RFID per-user logging all run on the device, not in a cloud account. Emoncms, MQTT, Home Assistant and OCPP integrations are optional. The hard part is not the build, it is the wall side. A dedicated 240-volt circuit is regulated work in most countries, and you will need a permit and an electrician unless you already hold the licence yourself. If that barrier does not apply, or you are willing to pay for it, this is a charger you fully control without a vendor account. The one thing most likely to go wrong is assuming eco mode is the default: it is a mode you select after install, and the charger will happily charge at full rate if you skip that step.
IN THE REPO
GOOD TO KNOW
- —Safety firmware is GPL-3.0 and implements SAE J1772 Level 1 and Level 2 with ground-fault, stuck-relay and missing-ground detection.
- —Separate ESP32 gateway firmware adds solar divert (eco mode), timers, RFID authorisation and a local web UI.
- —The project sells a 349-dollar DIY kit and a 659-dollar assembled 48-amp station; both include the boards and sensors.
- —The supply-side wiring is a dedicated 240-volt circuit, which in most jurisdictions requires a permit and a licensed electrician.
- —Hardware design files are in separate repositories (OpenEVSE_PLUS for the controller, ESP32_hardware for the WiFi board); the store also sells pre-assembled boards.
- —Licence permits commercial use.
Parts to buy
3 itemsFrom our check of the build. Exact quantities and part numbers are in the creator’s BOM.
Can I build this?
This build involves mains voltage — for adults comfortable with electrical work only.
Build at your own risk. Projects involve tools, electronics and sometimes mains voltage — follow the creator’s safety notes.
Videos
OpenEVSE build and installed charger
Community build video by James Klafehn, not by the OpenEVSE project; the official documentation (including the web UI and solar divert) is in the ESP32 gateway repository's docs folder.
More builds like this
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Start here
Navigation into the creator’s own docs — we don’t rewrite the guide, we route you to the source.
- 1.Read the OpenEVSE build guide and the hardware files in the OpenEVSE_PLUS repository, then decide whether to buy the kit, the assembled station, or self-source boards.(The v6.5 controller is current; earlier revisions are deprecated.)
- 2.Check your local electrical code for EV charger installation requirements — most jurisdictions require a permit and a licensed electrician for the supply circuit.(The low-voltage assembly is not the hard part; the mains side is.)
- 3.If you plan to use solar divert, confirm your inverter or energy monitor can publish grid-import or solar-generation power over MQTT or HTTP; the solar-divert page in the ESP32 gateway docs explains both.(Eco mode is not automatic — you configure it after install.)
- 4.Order the kit or assembled station from openevse.com, or download the Gerbers and order bare boards from your preferred fab.(The project sells hardware to fund development; buying from them is the easiest path.)
Resources
Documentation, files and community threads for this build — we link straight to the original sources and never rehost the creator’s files.
KNOWN ISSUES
- The supply-side wiring is a dedicated 240 V circuit, which in most places means a permit and an electrician. Do not assume you can install this yourself unless you already hold the licence.
- Eco mode (solar divert) is a setting you enable, not the default behaviour. If you skip configuration, the charger will run at full rate.
- The store sells a 349-dollar kit (no cables), a 589-dollar kit bundle that adds a 48 A J1772 cable and an input cable, and a 659-dollar assembled station. If you are not comfortable wiring and torquing high-current terminals, buy the assembled one.
- The 349-dollar kit does not include the EV cable or the input cable — budget for a J1772 (or NACS/Type 2) cable and an input cable or hardwire materials. The enclosure is included.
- The ESP32 gateway and the safety controller are separate boards with separate firmware. Both must be flashed and working for solar divert to function.
- RFID authorisation needs a PN532 NFC reader module fitted to the gateway, which is not part of the base kit. If you want per-user charge history, order one separately.
Can I charge at full rate even if I do not have solar?
Yes. Eco mode is optional. Without it, the charger behaves like any other Level 2 station and charges at the rate you set in the web UI.
What inverters and energy monitors work with solar divert?
Anything that can publish your live grid-import or solar-generation power over MQTT (the docs use an OpenEnergyMonitor emonPi as the typical example) or POST it as JSON to the charger's /status endpoint over HTTP. If your inverter does not do that natively, a home-automation hub such as Home Assistant can bridge it.
Do I need Home Assistant or another hub?
No. The charge rules and timers run on the ESP32 itself. Home Assistant, Emoncms and OCPP are optional integrations for logging or remote control, not requirements.
What is the difference between the 349-dollar kit and the 659-dollar assembled station?
The 349-dollar kit contains the components to assemble a Level 2 station yourself (controller, WiFi, colour display, meters and enclosure), but not the EV cable or the input cable. The 659-dollar station comes assembled with a 25-foot J1772 cable and a NEMA 14 input cable, adjustable from 6 A to 48 A.
Can I use this in a country that does not use J1772?
Yes. The kit works with SAE J1772, NACS, IEC Type 2 or GB/T single-phase cables, and the firmware includes Mennekes socket-lock control for European Type 2 installs. Check your local rules for EVSE certification.
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Discussion1
FROM THE COMPAREE TEAM
The 349-dollar kit requires assembly; the 659-dollar station is pre-built and tested. Which would you pick, and does solar divert tip the decision for you?
OpenEVSE
OpenEVSE has been developed as an open-source EV charging project since 2011. The AVR controller firmware handles the SAE J1772 safety logic, and a separate ESP32 gateway adds WiFi, a local web interface, solar divert and integrations without requiring a cloud service. The project funds development by selling kits and assembled stations.
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DISCLAIMER
- Comparee is not the author of the projects featured here. All rights to each project belong to its creator — every page links to the original source, and we never host creators’ files.
- Information is provided without warranty and may become outdated as projects evolve. Prices are indicative bands only — always check the creator’s parts list for current costs.
- Building and operating any project is at your own responsibility. Protective equipment, safe workshop practice and compliance with local regulations are the builder’s responsibility.
CompareeTEAM2mo agoedited
Practical notes from our verification: the ESP32 WiFi gateway repository (about 270 stars) is actively maintained separately from the safety-controller firmware, and the hardware design lives in its own OpenEVSE_PLUS repository. The project sells hardware directly, which funds ongoing development — buying from them is the simplest path, and kit bundles come with a build guide. Note that the basic kit does not include the EV charging cable; you add a J1772, NACS, Type 2 or GB/T cable to complete it. The single biggest trap is assuming eco mode is automatic: solar divert is something you configure after install. The mains-side installation is regulated work in most countries; you will need a licensed electrician and a permit for the supply circuit unless you already hold the licence yourself. Correction (4 October 2026): we re-checked this page line by line against the project's own repository, documentation and videos, and fixed errors in earlier versions.