# Heltec MeshSolar

> Solar-powered nRF52840 + SX1262 LoRa dev board with integrated BMS supporting 1-4 cell lithium batteries, MPPT solar charging, and USB PD3.0. Designed for Meshtastic solar nodes.

## Quick Facts

- **Brand:** Heltec
- **Board Type:** dev-board
- **Price:** ~$54.95
- **Product Readiness:** developer
- **CPU:** nRF52840
- **CPU Architecture:** ARM Cortex-M4
- **CPU Cores:** 1
- **RAM:** 256KB SRAM
- **Flash:** 1MB
- **Power:** Solar MPPT (18-25V), USB PD3.0, DC (18-25V)
- **Operating Voltage:** 3.3V
- **Operating Temp:** -40°C to 85°C
- **Dimensions:** 43 x 97 x 11 mm (BMS), 30 x 20 x 3.2 mm (MCU)
- **Weight:** 35g
- **Battery:** External (1-4 cells)
- **Antenna:** 2x IPEX 1.0

## Connectivity

- **Bluetooth:** BLE 5.0, Bluetooth Mesh
- **Lora:** SX1262 (863-928 MHz)

## Open Source

- **Firmware:** Yes
- **Schematics:** No
- **PCB Layout:** No

## Compatible Firmware

meshtastic, arduino, zephyr

## Use Cases

- lora-mesh-networking
- off-grid-communication
- environmental-monitoring
- remote-sensor-nodes

## Components

- **nRF52840** (mcu): Nordic Semiconductor nRF52840 ARM Cortex-M4 MCU with Bluetooth 5 and 1MB flash — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fdocs.nordicsemi.com%2Fbundle%2Fps_nrf52840%2Fpage%2Fkeyfeatures_html5.html&ref=openhardware.directory&product=heltec-meshsolar&source=md-export)
- **SX1262** (radio): Semtech SX1262 LoRa transceiver supporting 863-928 MHz with +22 dBm output — [Datasheet](https://openhardware.directory/r?to=https%3A%2F%2Fwww.semtech.com%2Fproducts%2Fwireless-rf%2Flora-connect%2Fsx1262&ref=openhardware.directory&product=heltec-meshsolar&source=md-export)

## Description

## Overview

The Heltec MeshSolar is a modular development board combining an nRF52840 MCU with an SX1262 LoRa transceiver, designed specifically for solar-powered Meshtastic mesh nodes. It features an integrated battery management system (BMS) supporting 1-4 cell lithium-ion, lithium polymer, or LiFePO4 batteries.

## Key Features

- **nRF52840 MCU** with Bluetooth 5, BLE, and Bluetooth Mesh support
- **SX1262 LoRa transceiver** with 21±1 dBm TX power and up to 10 km range
- **Integrated BMS** with MPPT solar charging (18-25V), USB PD3.0, and external DC input
- **Multi-chemistry support** — Li-ion, Li-Po, and LiFePO4 batteries (1-4 cells)
- **Protection circuits** — overcharge (4.3V), overcurrent (2A), undervoltage (2.5V), cell balancing (4.2V/100mA)
- **M.2 PCIe modular design** — MCU module connects to the BMS board via M.2 connector
- **Dual IPEX antenna connectors** for LoRa and BLE antennas

## Interfaces

- 3x SPI, 2x I2C, 2x UART, 4x PWM, QSPI, I2S, PDM, QDEC
- USB Type-C expansion port
- XT30 solar/battery input connector
- PH2.0-8P battery cell interface
- MX1.25-9P screen expansion
- MX1.25-8P GPS/GNSS connector

## Specifications

| Spec | Value |
|------|-------|
| MCU | nRF52840 |
| Memory | 1MB ROM, 256KB SRAM |
| LoRa Chip | SX1262 |
| LoRa Bands | 863-870 MHz, 902-928 MHz |
| TX Power | 21±1 dBm |
| Range | Up to 10 km |
| Input Voltage | 18-24V |
| Charge Current | ≤1.5A |
| BMS Board Size | 43 x 97 x 11 mm |
| MCU Module Size | 30 x 20 x 3.2 mm |
| Weight | 35g |
| Operating Temp | -40°C to 85°C |

## Where to Buy

- [OpenELab](https://openhardware.directory/r?to=https%3A%2F%2Fopenelab.io%2Fproducts%2Fheltec-meshsolar-dev-board&ref=openhardware.directory&product=heltec-meshsolar&source=md-export) — $54.95

## Resources

- [product](https://openhardware.directory/r?to=https%3A%2F%2Fheltec.org%2Fproject%2Fmeshsolar%2F&ref=openhardware.directory&product=heltec-meshsolar&source=md-export)

## Tags

`meshtastic`, `solar`, `lora`, `nrf52840`, `sx1262`, `bms`, `mppt`

## Images

![Heltec MeshSolar](https://nbg1.your-objectstorage.com/openhardware-directory/entities/heltec-meshsolar/b4d88a7e2656.png)
![Heltec MeshSolar](https://nbg1.your-objectstorage.com/openhardware-directory/entities/heltec-meshsolar/6e956bfd2a4f.png)
![Heltec MeshSolar](https://nbg1.your-objectstorage.com/openhardware-directory/entities/heltec-meshsolar/8a2cb81e26a0.png)
![Heltec MeshSolar](https://nbg1.your-objectstorage.com/openhardware-directory/entities/heltec-meshsolar/78a1957b57b5.png)
![Heltec MeshSolar](https://nbg1.your-objectstorage.com/openhardware-directory/entities/heltec-meshsolar/050e3fd83b47.png)
![Heltec MeshSolar](https://nbg1.your-objectstorage.com/openhardware-directory/entities/heltec-meshsolar/771ec82417dd.png)
![Heltec MeshSolar](https://nbg1.your-objectstorage.com/openhardware-directory/entities/heltec-meshsolar/719b99043bf7.png)
![Heltec MeshSolar](https://nbg1.your-objectstorage.com/openhardware-directory/entities/heltec-meshsolar/292b72e589e9.png)

> **Battery Powered:** Li-ion / LiFePO4

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