Build Your Own RS485 to Wifi Adapter for EPEver Solar Charge Controllers

Posted on 29/12/2017 by Adam

Many EPEver solar charge controllers have an RS485 communication port on them so you can connect a PC or Android device and read it’s statistics or update the settings.

Although EPEver have themselves developed a wifi adapter for the solar charge controllers which support RS485 it has some flaws which makes it less useful than it could have been. Recent versions of the software have prevented the EPEver eBox Wifi-01 from connecting to normal wifi networks entirely although it had been implemented in early firmware versions.

Other commercial RS485 to wifi adapters do exist but typically they tend to cost more than the eBox and draw more current – not ideal for a solar charge controller.

Colin Hickey decided that there must be another option and after much research and a few dead ends found the open source ESPLink software by jeelabs. This allows the popular ESP8266 to easily become a wifi to serial bridge. Now he just needed a serial to RS485 solution which came in the form of the XY-017 TTL to RS485 module which is widely available on eBay.

Colin talks about the journey and his solution for the EPEver solar charge controllers in this series of videos.

DIY RS485 wifi Adaptor Playlist

After dabbling with this design using perfboard, Adam Welch thought it might be an opportunity to take his first plunge into designing a custom PCB and have some boards manufactured to allow easier connection of the components, and to his surprise they seem to have worked quite well!

Colin Hickey is selling completed built and flashed units ready to plug in and connect to your wifi network.  You can buy them soon.

Components required:
RS485 to ESP8266 PCB: (Zipped Gerber File)
ESP8266 ESP-01:
XY-017 RS485 to TTL Module:
RJ45 Network Cable:
Pin Header:

Assembly is very simple – just follow the silkscreen on the PCB and the following colour code for the network cable. (The assumption is you’re re-purposing a standard network cable)

Orange Solid – Vcc (V)
Green Stripe – RS485 B (B)
Green Solid – RS485 A (A)
Brown Solid – Ground (G)
The other four wires may be cut short and isolated.

Flashing the ESP with ESPLink firmware is quite straight forward.  Download ESPLink (I suggest using version 2.2.3) and extract the contents of the tar file to your hard drive (7zip is a good option to untar).  Download the NodeMCU Flasher program and configure it as shown below.








Finally plug in your ESP8266 into your programmer and plug it into your PC.  Choose the correct COM port on the Operation tab and click Flash.

What Others Are Saying

  1. Ed 17/01/2018 at 22:35

    When the completed units are available could you please post a link or otherwise make it known? I am very interested in getting one. I figure by the time I collect all the pieces parts, figure out how to screen a pcb, etc. he will have some for sale. 🙂

  2. Paul 20/01/2018 at 20:05

    Hi Adam,

    Thought you might be interested in this:

    Inspired by yourself and the linked video.

    The bit you might be more interested in is the data logger. Runs on a raspberry PI (or PC). I just send it data in a particular format and it logs it once a minute. Could be panel voltage, outside temperature, anything. Graphs can be generated from the data archives easily.

    • Adam 13/02/2018 at 20:04

      Neat – thanks for posting the link and sorry for the delay in replying. Might have to take a look at that in a bit more detail. Cheers

  3. Dieko 02/04/2018 at 14:21

    Hi Adam,
    thanks for all your efforts and thanks for sharing your project!

    I have a setup with the EPEVER eBox-wifi in station mode in my WLAN talking to my raspberry. It works via socat and the toggio php scripts.

    But: Somehow I lose connection to the eBox device and I have to un- and replug the cable to restart it.

    Before I go for soldering your solution I would be interested to buy your device. How far is the production plan ? 🙂

    Best regards and Happy Easter everybody…

  4. Jim Ryan 04/04/2018 at 22:03

    Aloha from Hawaii! Love this project…

    I just installed a system containing a 175W 24V solar panel, RioRand/Epever Solar Charge Controller RR2210RN and 2x6V deep-cycle golf cart batteries in series. This project would be a great match for my PV system.

    Are you still thinking about selling your PCB or finished product? Are your schematics/code available?

    Also, I am thinking about updating the ESP8266 to an ESP32, and posting PV and battery SOC data to an IoT service via MQTT for remote monitoring. Any ideas here would be helpful.

    Mahalo, Jim

  5. Joe 28/05/2018 at 19:41

    awesome project.
    First of all, i’m new to all of this so not sure what i’m doing. I downloaded the gerber files and went to allpcb to order pcb boards but they need lots of other parameters before even allowing me to upload file. I was wondering if you had all the info for pcb just like yours? This is the info they said i would need along with gerber file.
    Thanks fore your time

    • Adam 12/06/2018 at 20:20

      All the defaults should be fine – 2 layer, 1.6mm thick, green boards, white printing etc. The gerber file will dictate the size of the PCB so for this step just pop in 50mm x 50mm and ten pieces cost the same as one typically. Hope that helps.

      • Joe 14/07/2018 at 04:30

        Thanks. That worked and i have the boards. Now just need to get it working on the “AN” negative ground models. Thanks again for your time.

  6. Pete 28/02/2019 at 04:50

    Hi Adam.

    I built this but facing issues.

    Done all as in guide, but with one exception.

    I have RS 485 to TTL adapter with DI DE RE RO output:

    DI esp8266 TX
    DE+RE to GPIO0
    RO esp8266 RX

    Well, I get nothing on esp8266 serial console.

    Is it so that this will not ever work, or am I missing something?

    I can open the web interface of the esp8266 without any problems, but there is nothing coming out from RS485 line.

    Is the protocol working so that data comes from epever only if requested or is it constant data stream?

    Tried to COM2TCP and SPP app from epever, and nothing, the app fails to connect.

    Looped the esp8266 tx/rx and I am getting serial data, so the esp should be working fine.

    Please help. 🙂

  7. Wayne 18/04/2019 at 13:43

    Hi All, does any still have access ti the gerber file?

  8. Howard Benjamin 18/05/2019 at 09:01

    HI Adam

    I have been using the Epever Tracer A and Tracer AN 4210 regulators for upwards of two years and power my swimming pool motor and some indoor devices as well.

    I also have an MT50 which I use for local monitoring but also have been monitoring on my PC via the WiFi-01 server on a continuous basis up until now but it does not work on my AN model, help!

    After battling with a PC virus I have had to reformat my hard drive and reload my Windows 7 software.

    I have checked the Epever website for the software for my PC but cannot find it now as their website has been updated and I cannot find it among their downloads and do not have a copy.

    Would you be kind enough to direct me as to where I can find the Windows PC software for Windows as Epever have only sent the Android mobile software which does not help.

  9. Toby Johnson 20/05/2019 at 21:56

    Hi Adam
    I very much appreciate your efforts on these controllers. I have 8 small solar units across 60 acres. 50 acres of that has wifi coverage so I want to assign a unique IP to each RS485-WiFi and check on the status of each through Solar Station Monitor. I can do this by changing the polled ip address?

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