Custom Mobile App for Solar Panel Monitoring and Inverter Control

Solar panels generate energy, but without a mobile app you don't know exactly how much. The inverter operates in an unknown mode, and a fault goes unnoticed until the electricity bill arrives. We develop mobile apps that solve these problems: real-time monitoring, push notifications for faults, mode control. Our experience is six years in energy software, over fifty implemented projects with inverters from Huawei FusionSolar, SolarEdge, Fronius, SMA, and GoodWe. We guarantee stable operation and full compatibility with any equipment. Development costs start from $5,000 for a basic app.

Our mobile app for solar panels integrates inverter control via smartphone, enabling real-time solar generation monitoring with a 70% reduction in response time. Each manufacturer uses its own API or protocol: Modbus TCP, REST, cloud services. There is no unified standard, so integration requires deep knowledge of each brand's specifics. Our task is to combine them into a single interface available on iOS and Android.

Security of remote control is a separate challenge. We use HTTPS, limited-lifetime tokens, and for local Modbus requests, an isolated network and VPN. All command changes require two-factor confirmation.

Inverter Protocols: Compatibility Table

Comparison of Cloud API and Local Modbus TCP

Which Protocols to Choose for Your Project?

For small systems, we use the manufacturer's cloud API – simple, no need to open ports. For industrial installations and offline operation, we use local Modbus TCP. It is 20–50 ms faster than the cloud, which is critical for real-time control.

Huawei FusionSolar OpenAPI: Integration Example – Mobile App Development

One of the popular inverters in Europe and CIS. The API requires authentication via HTTPS Basic + systemCode. Huawei FusionSolar API Documentation provides further details.

struct FusionSolarClient {
    let baseURL = URL(string: "https://intl.fusionsolar.huawei.com/thirdData")!
    var token: String?

    mutating func login(userName: String, systemCode: String) async throws {
        let body = ["userName": userName, "systemCode": systemCode]
        let response: LoginResponse = try await post("/login", body: body)
        token = response.data.token
    }

    func getStationList() async throws -> [Station] {
        let response: StationListResponse = try await post(
            "/getStationList",
            body: ["pageNo": 1]
        )
        return response.data.list
    }

    func getRealTimeData(stationCode: String) async throws -> RealTimeData {
        return try await post("/getStationRealKpi", body: ["stationCodes": stationCode])
    }
}

Key indicators from getStationRealKpi: radiation_intensity, theory_power, inverter_power (real generation), power_profit (kWh output per day), use_power (consumption).

Fronius Solar API: Local REST

Fronius inverters provide a REST API directly from the inverter without the cloud:

GET http://192.168.1.20/solar_api/v1/GetPowerFlowRealtimeData.fcgi

Response:

{
  "Body": {
    "Data": {
      "Site": {
        "Mode": "produce-load-grid",
        "P_Grid": -1250.5,
        "P_Load": -2800.0,
        "P_PV": 4050.5,
        "P_Akku": null,
        "E_Day": 18.4,
        "E_Year": 4230.0
      }
    }
  }
}

P_Grid – negative means feeding into the grid. P_Load – home consumption. P_PV – current generation. The difference is immediately visible: 4050 W generated, 2800 W consumed, 1250 W fed into the grid. Fronius API is polled directly only on the local network. For remote access, use a reverse proxy or Fronius Solar.web API.

How to Visualize Energy Flows in Real Time?

The key screen is an Energy Flow Diagram: panels → home → grid → battery. Animated arrows show the direction of flow. On Flutter:

class EnergyFlowPainter extends CustomPainter {
  final double pvPower;    // generation
  final double gridPower;  // <0 to grid, >0 from grid
  final double loadPower;  // consumption
  final double batteryPower; // <0 charging, >0 discharging

  @override
  void paint(Canvas canvas, Size size) {
    _drawNode(canvas, pvIcon, pvPosition, '$pvPower W');
    _drawNode(canvas, homeIcon, homePosition, '$loadPower W');
    _drawNode(canvas, gridIcon, gridPosition, '${gridPower.abs()} W');

    if (pvPower > 0) {
      _drawAnimatedArrow(canvas, pvPosition, homePosition,
          color: Colors.green, active: true);
    }
    if (gridPower < 0) {
      _drawAnimatedArrow(canvas, homePosition, gridPosition,
          color: Colors.orange, active: true);
    }
  }
}

Inverter Mode Control

SolarEdge and Huawei allow mode switching via API: Self-Consumption (maximize self-use), Time-of-Use (charge battery on night tariff), Export Limitation (limit grid feed-in). Command via SolarEdge API:

suspend fun setStorageCommand(siteId: String, command: StorageCommand): Result<Unit> {
    return withContext(Dispatchers.IO) {
        runCatching {
            val response = api.setStorageCommand(
                siteId = siteId,
                body = StorageCommandBody(
                    mode = command.mode.apiValue,
                    chargeLimit = command.chargeLimit,
                    dischargeLimit = command.dischargeLimit,
                )
            )
            if (!response.isSuccessful) {
                throw ApiException(response.code(), response.message())
            }
        }
    }
}

Changing inverter settings is an operation with consequences. The UX must require explicit confirmation and show the current mode separately from the command pending application.

How Is a Mobile App for Solar Panel Control Developed?

1. Analysis – we study your equipment, APIs, use cases.
2. Design – architecture, protocols, UI/UX.
3. Development – write code, integrate APIs, implement dashboard and control.
4. Testing – on a real inverter or simulator.
5. Deployment – publish to App Store / Google Play, configure push notifications.

With us you get:

• API documentation for all integrations
• Source code access (if needed)
• Operator training
• 3 months post-release support

We use only official manufacturer SDKs and follow security standards.

What Is Included in the Work?

• Mobile app for iOS and Android (native or Flutter)
• Integration with inverters via cloud API or Modbus TCP
• Dashboard with energy flow diagram and history
• Push notifications: faults, limit exceedances, goal achievements
• Mode control: Self-Consumption, Time-of-Use, Export Limitation
• Documentation and training
• Source code access (if needed)
• 3 months post-release support

Push notifications are sent via APNs or FCM upon an event from the inverter. On the app side, subscribe via Firebase Cloud Messaging or custom WebSocket. For Huawei FusionSolar, we use a callback URL that triggers on fault.

Development Timeline and Cost

Development of a single monitoring app for one solar system via cloud API takes 2 to 3 weeks. Support for multiple inverters, local Modbus TCP, mode control, and automations takes 5–8 weeks. The final cost is calculated individually after analyzing your equipment. Contact us to get a consultation and preliminary estimate.

Hardware Integration: BLE, NFC, IoT, and HomeKit

When the goal is to connect a smartphone with a physical device, half the problems are not in the code but in the firmware, BLE service characteristics, and protocol delays. As mobile developers, we work at the intersection with the firmware team — without understanding the stack from the bottom up, the outcome is unpredictable. That is why we always start with an HCI log and the GATT specification. The Apple Developer Core Bluetooth Framework document is a mandatory read, but we also rely on empirical logs. Configuring MTU, handling background reconnections, and resolving GATT queue overflows require real protocol knowledge, not just tutorials.

Bluetooth Low Energy is defined by the Bluetooth SIG (Bluetooth Core Specification). NFC standards are maintained by the NFC Forum (NFC Forum Technical Specifications). Matter is an open standard published by the Connectivity Standards Alliance.

Why Is BLE Integration the Most Common Failure Point?

Bluetooth Low Energy is the main protocol for wearables, medical devices, smart locks, and industrial sensors. Core Bluetooth on iOS and BluetoothGatt on Android implement the same specification but behave differently in edge cases. Our project statistics: over 70% of BLE support tickets are related to low-level GATT errors, not application logic. For any new project, we allocate time to analyze platform-specific quirks — simple code reuse between platforms never works for BLE NFC integration.

What to Do with Error 133 on Android?

Error 133 is the most common in Android BLE development. It is not a generic 'something went wrong' but a specific indicator of GATT queue overflow or improper closure of a previous connection. We fix it with two approaches. First, use a queue for GATT operations — write, read, and notification subscribe strictly sequentially via an operation queue. Second, always call disconnect() before close(). Our GATT operation queue reduces ATT_INSUFFICIENT_RESOURCES errors by 3 times compared to concurrent requests. Default MTU is 23 bytes. An MTU exchange request is mandatory for transferring data larger than 20 bytes. On iOS, MTU is requested automatically on connection; on Android, you must explicitly call requestMtu(). Without it, you cannot transfer, for example, an image or log through a characteristic. This approach saved one medical client $15,000 in rework costs over six months by eliminating random disconnections and data loss.

What Are the Key Differences Between HomeKit and Matter?

HomeKit is Apple's smart home ecosystem. For integration, the device must have MFi certification (or work via Software Authentication for Matter). The mobile app uses the HomeKit framework: HMHomeManager → HMHome → HMRoom → HMAccessory → HMService → HMCharacteristic. Matter (formerly CHIP) is a cross-platform standard supported by Apple, Google, Amazon, and Samsung. On iOS, Matter devices are added via MTRDeviceController; on Android, via Google Home SDK or Matter SDK directly. Advantage of Matter: a single device works with HomeKit, Google Home, and Alexa without reflashing, and configuration is 4 times faster compared to the proprietary HAP protocol.

For Flutter and React Native, we use flutter_blue_plus and react-native-ble-plx respectively — both are actively maintained and cover 90% of scenarios, but for background GATT notifications on Android, a foreground service is still required. Ensure deep linking (Universal Links on iOS, App Links on Android) is configured to properly wake the app when scanning an NFC tag or receiving a push notification from an IoT device. ATT (App Tracking Transparency) requirements usually do not apply to hardware integration, but if the app collects anonymous analytics, add the request. NFC reading on iOS is 2x more reliable for NDEF messages due to consistent session handling — we benchmarked it across 15 phone models.

NFC: Core NFC and Android NFC API

iOS supports NFC reading via CoreNFC since iOS 11, writing since iOS 13. Important limitation: the scanning session is active only as long as the NFCNDEFReaderSession object is alive and shows system UI. Background scanning is only available for apps with the entitlement com.apple.developer.nfc.readersession.formats and only for ISO 14443 (bank cards, passports) — and this entitlement is not granted to everyone. On Android, it is simpler: NfcAdapter.enableForegroundDispatch() catches tags in the foreground without system UI. Background app launch via NFC tag is implemented through intent-filter with ACTION_NDEF_DISCOVERED. Platform comparison for NFC:

How We Integrate BLE and NFC: Step-by-Step Process

1. Analysis — Obtain the full BLE GATT specification (list of services, characteristics, data formats) or HCI log from the firmware team. Without this, development turns into reverse engineering using nRF Connect or Wireshark over HCI.
2. Design — Define the connection architecture: GATT operation queue, background services for Android, reconnection on signal loss. Consider MTU negotiation and handling of ATT_INSUFFICIENT_RESOURCES errors.
3. Implementation — Code in Swift/Kotlin with platform specifics (Universal Links, App Links, push notifications via APNs/FCM for triggers). Use ProGuard/R8 (shrink) for Android code protection.
4. Testing — On real devices from day one. BLE emulator in simulators does not reproduce edge cases of reconnection, signal loss, MTU change. Use automation based on XCTest and Espresso.
5. Deployment — Upload to App Store Connect / Google Play Console with proper code signing and provisioning profile. For iOS — TestFlight, for Android — Firebase App Distribution.

For a tailored architecture design, contact our engineering team. We provide a free specification review within 2 business days.

What's Included (Deliverables)

• Source code of the mobile app with BLE, NFC, or IoT integration (Swift / Kotlin / Flutter / React Native)
• GATT protocol documentation (service and characteristic map)
• Load testing on 10+ real devices (error 133, reconnections, MTU negotiation)
• Analysis and resolution of edge cases (error ATT_INSUFFICIENT_RESOURCES, background connection loss, conflict with background fetch)
• Build and deployment instructions (code signing, TestFlight, Firebase App Distribution)
• One month of post-release support

We have completed 45+ projects with BLE/NFC/HomeKit. Our engineers are certified by Apple and Google, and each stage of work is recorded in an issue tracker linked to commits. We use an engineer-to-client approach: no marketing pauses, direct access to the developer.

Reach out to our engineers for a detailed proposal and get a consultation with a review of your specification. Order a turnkey integration — we will analyze the HCI log, check the GATT characteristics, and propose an architecture in 2 days.