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How to interpret the various parameters of a photovoltaic monitoring system

This article mainly introduces some commonly used metrics in photovoltaic monitoring systems.

Overview of Solar PV Monitoring System

Please visit Solar pv monitoring system of IAMMETER-cloud to login the demo account of IAMMETER-cloud and understand all functions of solar PV monitoring

It will display different UI if you access to demo link via computer or smart phone.

You will see same UI with IAMMETER web portal if you access to the demo link by computer. You will see same UI with IAMMETER app if you access to the demo link by mobile phone. We recommend you to access via computer so you can see more functions and reports.

1. Yield and Consumption

This graph shows the KPIs of your solar PV system.

Yield and Consumption in Solar PV Monitoring System

  • Yield Energy: If you set any meter/CT as "Inverter" type, the energy measured is "Yield Energy" (kWh). IAMMETER calculates this in a preset billing cycle. For the calculation method, refer to Yield Energy Calculation.

  • Exported Energy: If you set any meter/CT as "Grid" type, the energy exported to the grid is "Exported Energy" (kWh). IAMMETER calculates this in a preset billing cycle. For the calculation method, refer to Exported Energy Calculation.

  • Grid Consumption: If you set any meter/CT as "Grid" type, the energy imported from the grid is "Grid Consumption" (kWh). IAMMETER calculates this in a preset billing cycle. For the calculation method, refer to Grid Consumption Calculation.

  • Direct Self-Use: Direct Self-Use (kWh) = Yield Energy - Exported Energy.

  • Direct Self-Use Rate: Direct Self-Use Rate = Direct Self-Use Energy / Yield Energy.

  • Income: Income = Exported Power Tariff * Exported Energy.

  • Savings: Savings = Imported Power Tariff * Direct Self-Use.

  • Bill: Bill = Imported Power Tariff * Grid Consumption.

2. Power

Inverter Power, Grid Power, Load Power in Solar PV Monitoring System

  • Inverter Power: Output power of the solar inverter, measured by the meter/CT set as "Inverter" type.

  • Feed-in Power: Power exported to the grid when positive; power imported when negative, measured by the meter/CT set as "Grid" type.

  • Load Power: Load Power = Inverter Power - Feed-in Power, calculated automatically by IAMMETER.

3. Current State

Energy Flow Chart in Solar PV Monitoring System

This graph shows the energy flow of your solar PV system. See below for the coding for better understanding.

var r = 0; // 0: no flow, 1: A->B, 2: B->A 
switch (i) {
    case 1: // inverter-feedin
        if (inverter > 0 && feedin > 0) r = 1;
        break;
    case 2: // inverter-load
        if (inverter > 0 && load > 0) r = 1;
        break;
    case 3: // inverter-battery
        if (battery > 0 && (inverter - load) > 0) r = 1;
        break;
    case 4: // load-feedin
        if (inverter >= load) {
            r = 0; // No need to import energy from grid
            break;
        } else {
            if (feedin < 0 && load > 0) r = 2;
        }
        break;
    case 5: // load-battery
        if (battery < 0 && load > 0) r = 2;
        break;
    case 6: // feedin-battery
        if (feedin < 0 && (inverter - load) < battery && battery > 0) r = 1;
        break;
    default:
        break;
}

4. Yield

  • Yield Energy: If you set any meter/CT as "Inverter" type, this is measured as "Yield Energy" (kWh). IAMMETER calculates it in a preset billing cycle. For the calculation method, refer to [Yield Energy Calculation](#Ref 2).

  • Exported Energy: If set as "Grid" type, this is measured as "Exported Energy" (kWh). IAMMETER calculates it in a preset billing cycle. For the calculation method, refer to Exported Energy Calculation.

  • Direct Self-Use: Direct Self-Use (kWh) = Yield Energy - Exported Energy.

IAMMETER calculates Yield Energy, Exported Energy, and Direct Self-Use Energy over selected time periods (Day, Month, Year, or All Year).

Monitor the Hourly, Daily, Monthly Yield Energy in Solar PV System

5. Consumption

  • Grid Consumption: If set as "Grid" type, this is measured as "Grid Consumption" (kWh). IAMMETER calculates this in a preset billing cycle. For the calculation method, refer to Grid Consumption Calculation.

  • Direct Self-Use: Direct Self-Use (kWh) = Yield Energy - Exported Energy.

IAMMETER calculates Grid Consumption and Direct Self-Use Energy over selected time periods (Day, Month, Year, or All Year).

Monitor the Hourly, Daily, Monthly Consumption Energy in Solar PV System

6. Energy Balance

IAMMETER calculates Grid Consumption and Exported Energy over selected time periods (Day, Month, Year, or All Year).

Monitor the Hourly, Daily, Monthly Import/Export Energy in Solar PV System

Reference

Solution: Monitor your solar PV system

Sort and Compare More Than One Solar PV Site in the Solar Analysis

Part 1: Insight into Your Photovoltaic System

Part 2: Optimizing Your Photovoltaic System

Ref 1: Meter/CT Type and Energy, Power, and Power Tariff (Import & Export)

  • Yield Energy (kWh) & Inverter Power (W): Meter/CT type → Inverter
  • Export Energy (kWh), Grid Consumption (kWh), & Feed-in Power (W): Meter/CT type → Grid

Select the Meter Type

Ref 2: How IAMMETER Calculates the Total kWh in a Selected Time Period (Hour, Day, Month, Year)

Total kWh = First kWh data logged in next time period - First kWh data logged in current time period.

Here is a simple example. In the demo account:

  • On the left graph, the Total Yield Energy is 4.9 kWh from 9 am to 10 am.
  • On the right table, the first kWh data logged @ 9:02:05 is 39262.5 kWh, and at 10:02:06 it is 39267.4 kWh.

39267.4 - 39262.5 = 4.9. Therefore, the Total Yield Energy is 4.9 kWh from 9 am to 10 am. The same calculation applies to daily, monthly, or yearly energy totals.

![How to Calculate the Hourly Energy Data in IAMMETER System](https://iammeterglobal.oss-accelerate.aliyuncs.com/img/iammeter

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