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Solar meters can indicate pyranometers, which are used to measure solar radiation flux density (W/m2), or any devices used to measure the kWh production from a photovoltaic (PV) system.

What are solar power meters?

A solar power meter is a device that can measure solar power or sunlight in units of W/m2, either through windows to verify their efficiency or when installing solar power devices.

Solar meters accumulate PV yield production and local energy consumption to monitor and analyze PV plant performance. 

It often comes with a monitoring function to alert plant owners of PV plant performance issues, letting them quickly resolve problems and maximize return on investment. 

When solar panels generate more electricity than needed, energy is sent to the grid in exchange for credits. Then, at night or on gloomy days, when solar panels are underproducing, energy can be retrieved from the grid and used to offset that energy’s costs.

Plant data is transferred to a monitoring platform that produces a concise presentation of PV yields, monetary savings, and plant performance.

A solar power meter device is most commonly used for a variety of applications where overall energy, efficiency, and placement of solar systems need to be calculated, for example:

  • Solar power research
  • Identifying high-performance opportunities
  • Physics or optical laboratories
  • Solar radiation measurement
  • Agricultural applications
  • Meteorological applications

How does a solar energy meter work?

Traditional electricity meters can only measure the electricity that flows one way. That is, from the grid into the house. Solar meters, however, are bi-directional, which means they can also measure the electricity that the home exports to the grid.

Solar energy systems usually reach highest electricity production during the afternoon. This is when many people aren’t home or lights aren’t used. In contrast, home electricity use is typically higher in the mornings and evenings. Solar energy meters help to account for these ups and downs in day-to-day electricity production and usage.

With the solar meter, excess electricity is fed into the electric utility’s grid when it produces more than needed. When this happens, the meter runs in reverse. 

This “back-and-forth” between the system and the grid ensures that the excess production will still be used and there will not be any shortages. With solar meters, the excess electricity produced covers the times when there isn’t enough produced. 

When the solar power system produces more electricity than used for a month, the utility bill will receive credits based on the net number of kilowatt-hours given back to the grid. If the solar power system generates less electricity than used in a given month, there is a need to buy electricity from the utility to make up the difference. In these instances, users would pay for the electricity they use, minus any excess electricity the solar panels generate.

How To Measure Solar Energy and Power?

The energy output is signified by the amount of solar radiation that reaches the absorbent surface. 

The amount of solar radiation on the earth’s surface can be instrumentally measured, and precise measurements are essential for providing background solar data for solar energy conversion applications.

There are two few types of instruments to measure solar radiation:

  • Pyrheliometer 

It is used to measure direct beam radiation at normal incidence. There are different types of pyrheliometers. 

According to Duffie and Beckman (2013), the Abbot silver disc pyrheliometer and Angstrom compensation pyrheliometer are necessary primary standard instruments.

Eppley normal incidence pyrheliometer (NIP) is a standard instrument used for practical measurements in the US, and Kipp and Zonen actinometer is widely used in Europe. Both of these instruments are calibrated against the primary standard methods.

Based on their design, the above-listed devices measure the beam radiation sun and the small part of the sky around the sun. 

Based on the studies involving several pyrheliometer designs, the contribution of the circumsolar sky to the beam is almost insignificant on a sunny day with clear skies.

However, a gloomy day redistributes the radiation so that contribution of the circumsolar sky to the measurement may become more significant.

  • Pyranometer 

It is used to measure total hemispherical radiation. If shadowed, a pyranometer measures diffuse radiation. Most solar source data come from pyranometers. The total irradiance (W/m2) measured on a horizontal surface by a pyranometer is shown as follows:

I tot = I beam cosθ+ I diffuse 

where θ is the zenith angle (i.e., the angle between the incident ray and the normal to the horizontal instrument plane.

Examples of pyranometers are Eppley 180o or Eppley black-and-white pyranometers in the US and Moll-Gorczynski pyranometers in Europe. 

There are pyranometers with thermocouple indicators and with photovoltaic detectors. The sensors ideally should be independent of the wavelength of the solar spectrum and angle of incidence. 

Pyranometers are also used to measure solar radiation on inclined surfaces, which is vital for determining information to collectors. Calibration of pyranometers depends on the inclination angle, so experimental data are required to interpret the measurements.

How to read a solar meter?

There is an alternate between positive and negative numbers on display. The positive number is the amount of electricity that has been imported from the grid, which is seen on a regular electricity meter without solar.

The negative number is the amount of electricity that has been exported from the solar system to the grid. This is the amount of electricity solar has generated, which is beyond what the house needed to use at the time. 

In this case, the positive value is less than the negative value, so this property has exported more electricity than they’ve imported, leaving the property owner with refunds from the power company.

The benefit of the solar meter

The most apparent benefit of the solar meter is to consumers. If people install the solar meter in their home, they can reduce the amount of money they spend each year on energy. 

Consumers can even make money if more energy is produced than consumed. The utility company pays for that excess energy at the retail rate.

Here are a few other benefits of solar meter:

  • The system is easy and reasonable. It allows people to get real value for the energy they produce without the need to install another meter or any expensive battery storage system.
  • It allows homeowners and businesses to generate energy, which drives some pressure off the grid, mainly during peak consumption periods.
  • Each home can possibly power two or three other homes. If enough homes in a neighbourhood use renewable energy and solar meters, the neighbourhood could become self-reliant.
  • It inspires consumers to play an active role in alternative energy production, which protects the environment and helps preserve natural energy resources.
  • Homes that use solar meters tend to be more aware of, and therefore more conscientious about their energy consumption.

Solar power meter price

The price of a solar meter depends on the model, brand, usage, or application. 

  • The solar meter price in the US ranges from $6.90 to $1599.00
  • The solar meter price in the UK ranges from £11.95 to £1200.00
  • The solar meter price in Malaysia ranges from RM78 to RM1810.
  • The solar meter price in India ranges from Rs 7500 to Rs 24 500

Conclusion

A solar power meter is a device that can measure solar power in units. It is bi-directional, which means it can also measure the electricity that the home exports to the grid.

If solar meters are installed in homes, it can help reduce the amount of money spent on electricity. The utility company even pays consumers for excess energy if more energy is produced than consumed. 

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