The best solar power meters measure broad ranges of solar radiant flux, have low measurement resolution, are highly accurate, are cosine corrected, and are easy to carry around in just one hand. Therefore, when you buy a new solar power meter, look out its measuring range, resolution, range of accuracy, cosine correction, and portability. But beyond the said features, you should also lookout for the type of sensor, display type & size, and memory function.
Our Top Picks
- Tenmars Handheld Digital Solar Power Meter – Overall Best Solar Power Meter
- TES 1333R Solar Power Meter – Highest Memory Function
- Digital Radiation Measuring Instrument – Highest Measuring Range
- General Tools DBTU1300 Digital Solar BTU Power Meter
- Solarmeter Model 10.0
Solar power meters typically measure solar radiation with two types of sensors: pyranometer and pyrheliometer. In general, the pyrheliometer offers better accuracy when measuring solar irradiation and sunshine duration. But, a pyranometer is more effective at measuring diffuse solar radiation, especially when it is cloudy or foggy. These days, the margin of accuracy between both sensors is very minimal.
Solar power meters often come as small handheld devices. So, in many cases, the display is small. This can be an issue for you when trying to read values off it, especially in the brightly lit conditions offered outdoors.
Radiation from the sun will not always fall directly on the meter. Sometimes the rays reach the meter’s sensor at acute angles. Without cosine correction, the radiant intensity of incident rays that come in at such angles will not be accurate.
Portability is vital with solar power meters. If you are going up the roof with other tools, a portable meter will not burden you.
You will measure the irradiance in various locations over time, and you may want a record of it all. With a solar power meter that has a memory function, this should not be an issue.
Then, of course, you want a solar power meter with a broad measuring range, low resolution, and high accuracy. This way, you are almost sure the sensor can detect small changes in radiant flux and high irradiance levels with near-flawless precision.
Our List of the Best Solar Power Meters
Tenmars Handheld Digital Meter
The Tenmars Handheld Digital Meter comes in at number one on our list. Its portability, display type & size, battery life, and price place it ahead of other solar power meters on the list.
The Tenmars Handheld Digital Meter is one of the lightest and smallest products on this list. It fits quite well in the hands. Only the Digital Radiation Measuring Instrument matches its portability – having about the same size.
Display Type & Size
The Tenmars Handheld Digital Meter display is the largest of any solar power meter on the list. Plus, it is a green LCD screen. So, even in the brightly lit conditions outdoors, you will not have too much trouble reading the screen. No other solar power meter on the list has such a feature.
The Tenmars Handheld Digital Meter uses a 9-volt battery. Only the Digital Radiation Measuring Instrument and the Solarmeter Model 10.0 match this. The other products on this list run on 4 AAA batteries, which, when combined, produce only 6 volts. The 4 AAAs typically last for about 100 hours. But the 9-volt battery of the Tenmars Handheld Digital Meter should last longer.
Compared to the others, the Tenmars Handheld Digital Meter is the least expensive. The next to it is General Tools DBTU1300 Digital Solar BTU Power Meter.
Beyond the above, the Tenmars Handheld Digital Meter has a measuring range of up to 2000 W/m2 and 634 BTU/(ft²-h). Its resolution is 0.1 W/m2 and 0.1 BTU/(ft²-h). Digital Radiation Measuring Instrument only betters this range. Other devices on the list fall within the same measuring range and resolution. The Tenmars Handheld Digital Meter has an accuracy of ±5% or ±10 W/m2 and ±3 BTU/(ft²-h) – any of them is higher in natural sunlight. For temperature-induced errors, the measurement will be accurate within ±0.38 W/m2/℃ and ±0.12 Btu/℃ at 25℃ and above.
The Tenmars Handheld Digital Meter operates in temperatures up to 50 degrees Celsius (122 degrees Fahrenheit).
The Tenmars Handheld Digital Meter uses a pyranometer for sensing. So, it is perfect for when you have to measure diffuse solar radiation too. The Tenmars Handheld Digital Meter is cosine corrected, so it offers angular precision too.
The Tenmars Handheld Digital Meter has a memory function that allows the storage of up to 2000 readings. The only solar power meter on the list with a higher memory capacity is the TES 1333R Solar Power Meter, with a capacity of up to 43,000 readings.
While a memory function of 2ooo readings is decent, it is nowhere near 43,000 readings. So, if you will be doing many insolation assessments, you may want to go for the TES 1333R Solar Power Meter.
- It is inexpensive – comes at the lowest price of any product on this list.
- The display size is the largest of any product on the list. It is a green LCD, so it will not be hard to read in brightly lit conditions.
- Very portable – only the Digital Radiation Measuring Instrument is as small and light as this product.
- Decent memory function – only bettered by the TES 1333R Solar Power Meter.
- It uses a pyranometer for sensing, and this offers more precise measurements for diffuse radiation.
- It runs on a 9-volt battery, so you can expect it to last longer than those using 6 volts.
- Cosine corrected.
- The memory function could be larger to accommodate more readings.
No other solar power meter on this list possesses a memory function that matches what the TES 1333R offers. But apart from its superior memory function, the TES 1333R has a decent measuring range, a decent display, topnotch durability, and is cosine corrected.
Firstly, the TES 1333R can accommodate up to 43,000 readings in its memory. The closest to this capacity is the Tenmars Handheld Digital Meter, with a capacity of 2 thousand readings. Of course, as you can see, the difference is huge.
The measuring range, resolution, and accuracy of the TES 1333R are the same as that of the Tenmars Handheld Digital Meter. Both devices have a range of up to 2000 W/m2 and 634 BTU/(ft²-h) with a resolution of 0.1 W/m2 and 0.1 BTU/(ft²-h). Of course, this falls short of that of the Digital Radiation Measuring Instrument. TES 1333R also has an accuracy range of ±5% or ±10 W/m2 and ±3 BTU/(ft²-h), whichever is higher in natural sunlight. For temperature-induced errors, the measurement will be accurate within ±0.38 W/m2/℃ and ±0.12 Btu/℃ at 25℃ and above.
Display Type & Size
The display is decent – not as large as that of the Tenmars Handheld Digital Meter. However, it is not the smallest on the list and should be easy to read for most people. The TES 1333R uses a 4-digit LCD. Unlike the Tenmars Handheld Digital Meter, this LCD is not green. Nonetheless, you should be able to use it under normal outdoor lighting conditions.
The TES 1333R is made for durability. Its detector is very stable, and the overall structure of the solar power meter is rugged and compact. The TES 1333R is cosine corrected like the General Tools DBTU1300 Digital Solar BTU Power Meter. So, with either product, the precision from measuring the irradiance of angular rays is pretty high.
4 AAA batteries power the TES 1333R. This will not last as long as the batteries of the Tenmars Handheld Digital Meter, the Digital Radiation Measuring Instrument, and the Solarmeter Model 10.0. Nonetheless, you can get up to 100 hours of battery lifespan with those 4 AAA batteries.
The TES 1333R comes with a compact disc containing the software for use on computers. It also comes with an RS232 for connection to a computer.
All in all, the TES 1333R is easy to operate. However, you feel the battery life can be longer, and the screen could be larger.
- It is pretty durable.
- The memory function has a higher capacity than any other device on the list.
- It is cosine corrected, so the irradiance measurement for angular rays is quite accurate.
- Its measuring range and resolution are decent.
- It can be connected to a computer if needed.
- It can make the battery last longer.
- While the screen is okay, it could be larger.
- It is pretty expensive.
Digital Radiation Measuring Instrument
With the Digital Radiation Measuring Instrument, you are getting a device with a high measuring capacity. The Digital Radiation Measuring Instrument has the highest measuring range of any device on the list. But apart from that, it has a decent memory function and rapid sampling time.
With the Digital Radiation Measuring Instrument, you can measure the solar radiant flux of up to 3999 W/m2 and up to 3999Btu/(ft²-h). No other device on this list comes close. However, its range error and temperature change error are pretty much the same as that of the TES 1333R and the Tenmars Handheld Digital Meter (±10W/m²/±3Btu/(ft²-h) or ±5% and ±0.38W/m²/℃ ±0.12Btu/(ft²-h)/℃ deviation at 25°C, respectively).
The Digital Radiation Measuring Instrument has a memory-dedicated push button switch (hold). This switch allows for easy retention and retrieval of data for comparison. Nonetheless, we should state that the memory capacity of the Digital Radiation Measuring Instrument is nowhere near that of the TES 1333R.
Apart from its wide measuring range, the Digital Radiation Measuring Instrument has a rapid sampling time. The sampling rate is about 0.25 times per second.
Like the Tenmars Handheld Digital Meter and the Solarmeter 10.0, it uses a 9-volt battery. However, this battery is not included in the pack.
Display Type & Size
The screen of the Digital Radiation Measuring Instrument is pretty average – not large or too small. It is an LCD that shows up to 4 digits, including the digit after the decimal point.
All in all, the Digital Radiation Measuring Instrument is easy to use – requiring no adjustment to measure sunlight directly. It can operate at temperatures up to 50 degrees Celsius (122 degrees Fahrenheit) and can be stored between -10 and 60 degrees Celsius.
- It has the highest measuring range of any meter on the list.
- The measuring range, resolution, and error ranges are decent – about the same as the other solar power meters on the list.
- Decent memory function.
- Rapid sampling time.
- It is quite portable – about the size of the Tenmars Handheld Digital Meter.
- The screen size is not exceptional.
- The battery is not included in the pack.
General Tools DBTU1300
The General Tools DBTU1300 is basically like the TES 1333R, except it is less expensive and has a lower memory capacity.
The General Tools DBTU1300 has a measuring range of up to 2000 W/m2 or 634 BTU/(ft²-h) and a resolution of 0.1 0 W/m2 and 0.1 BTU/(ft²-h). Its measurement accuracy is ±10W/m²/±3Btu/(ft²-h) or ±5% – the higher value of the two. Both of these values are the same as that of the TES 1333R.
Display Type & Size
The screen size of the General Tools DBTU1300 and the TES 1333R are the same. Both are LCD screens with support for up to 4 digits.
Like the Tenmars Handheld Digital Meter, the General Tools DBTU1300 operates between 0 and 50 degrees Celsius. It is pretty lightweight, weighing just about 5.6 ounces.
Like the TES 1333R, the General Tools DBTU1300 runs on 4 AAAs, which offers up to 100 hours of running time. While this is decent, it is less than the 9-volts battery of the Tenmars Handheld Digital Meter, the Digital Radiation Measuring Instrument, and the Solarmeter 10.0 offer.
While the TES 1333R has a memory capacity that supports up to 43,000 readings, the General Tools DBTU1300 only has space for 99. But on the bright side, the General Tools DBTU1300 goes for less than half the price of the TES 1333R.
The General Tools DBTU1300 works within a spectral range of 400-1100 nanometers. It has a sampling rate of 4 per second, and it is cosine corrected.
- It is relatively inexpensive – compared to the TES 1333R.
- Lightweight and portable.
- Cosine corrected.
- The measuring range, resolution, and error ranges are decent.
- Low memory capacity.
Solarmeter Model 10.0
Like the Tenmars Handheld Meter and the Digital Radiation Measuring Instrument, it uses a 9-volt battery. Unlike the Digital Radiation Measuring Instrument, the Solarmeter 10.0 comes with a battery.
A standard 9V battery will last approximately 2 years – so this is an advantage of the 4 AAAs used by the other solar power meters. The battery operates properly from 9V down to 6.5V. But below that voltage, the numbers on the LCD will begin to fade, indicating the need for battery replacement.
Display Type & Size
The screen of the Solarmeter 10.0 is about the same size as the other meters, except the Tenmars Handheld Meter. The screen is a 3.5 digit LCD – pretty much like every other solar power meter on the list.
The measuring range of the Solarmeter 10.0 reaches up to 1999 W/m2, and it has a resolution of 1 W/m2. While the measuring range is about the same as the vast majority of products on this list, it falls short of the Digital Radiation Measuring Instrument. Its resolution is pretty high, which means it would not pick any changes in irradiance readings below 1 W/m2. One drawback with this product is that it does not show readings in BTU/(ft²-h).
The spectral range of the Solarmeter 10.0 is the same as that of the General Tools DBTU1300 – 400 to 1100 nanometers. However, its operational temperature falls below that of the Digital Radiation Measuring Instrument and the Tenmars Handheld Meter.
The Solarmeter uses a silicon photodiode detector, which is located in its sensor window. The sensor window, on the other hand, is located at the top of the product. Whenever you want to use the meter, all you have to do is point the sensor window to the source of the UV rays, and you get your results.
The calibration of the Solarmeter 10.0 is traceable to the World Radiometric Reference.
- Since it uses a 9-volt battery, you can expect it to run for quite a while.
- WRR-traceable calibration.
- The screen size is decent – only smaller than the Tenmars Handheld Meter.
- The measuring range is decent – about the same as every other meter on the list, except the Digital Radiation Measuring Instrument.
- The resolution is relatively high. This makes it harder to detect smaller changes in solar radiant flux.
- It is a bit expensive.
- It does not support readings in BTU/(ft²-h).
Buyer’s Guide for Solar Power Meters
What Is Digital Solar Power Meter?
A digital solar power meter is used to measure the sun’s irradiance at a specific location. It is typically used during the pre-construction stage of solar systems. However, you may also use it in the post-construction stage.
A solar power meter is used in the pre-construction stage to ascertain how much UV light reaches a surface (irradiance). In turn, irradiance helps in projecting how much power the PV cells of a solar panel system can generate from the sun in that specific area.
In the post-construction stage, a solar power meter may be installed beside PV panels. At such a point, it becomes a diagnostic tool – used to verify if the solar panels are working correctly.
Apart from the description above, a digital solar power meter may also refer to a device used to measure the energy production from a solar power system. This type may also be called a PV meter, and unlike the meter described above, this type of meter measures how much of the electricity the PV cells produce gets inside your house.
Apart from helping you monitor how much energy your solar energy system, this type of solar power meter is vital if you want to get a Solar Renewable Energy Certificate (SREC).
You could get an SREC worth over $300 for every 1000 kWh of solar energy your solar power system produces. But to prove your energy consumption and how much power your PV modules have produced, you need a PV power meter.
Features to Look Out For in a Solar Power Meter
There are 3 main types of solar radiation detectors: net radiometers, pyranometers, and pyrheliometers. Of these 3, pyranometers are the most common in solar power meters, followed by pyrheliometers.
In the past, pyrheliometers were largely reserved for weather and climate studies. But these days, they are also used in solar energy systems. Pyrheliometers have lower zero offsets and directional errors than pyranometers. So, they are generally more accurate than pyranometers.
However, these days, pyranometers have lower zero offsets and directional errors. So, the difference in their precision is minimal.
Besides the difference in precision, pyrheliometers are effective for measuring radiant influx from direct UV beams. Pyranometers, on the other hand, are best for diffuse beams of UV. Keep this in mind when choosing your solar power meter.
Radiant flux is a function of the angle between the incident UV ray and the normal surface. When UV light falls directly above a solar power meter, the angle would not matter. In such a case, the normal and the incident UV ray angle is zero, and the cosine of zero is 1.
However, when UV light falls on a solar power meter at an angle, the angle will matter. Therefore, cosine correction must be in place. Else the readings will not be accurate.
So, when choosing a meter, ensure it is cosine corrected.
Measuring Range, Resolution, and Accuracy
When choosing solar power meters, the measuring range is vital. The higher the range, the higher the amount of solar radiant flux you can measure in the meter at a go.
Apart from that, the units of measurement are also vital. While some products allow measurement in two units [W/m2 BTU/(ft²-h)], some allow measurements in just one unit. It is better to opt for those that give the option of multiple units.
The resolution is another important feature to check in a solar power meter. The lower the resolution, the better the meter will detect small changes in solar radiation flux.
Then, accuracy is also vital. The accuracy of solar meters is usually expressed as their margin of error. With lower values comes higher chances of getting repeatable results for the normal error and the temperature error.
This may not be very important to everyone. But if you want to collect solar radiant flux data from a wide range of locations and compare them, a product with a memory function would be perfect. With such, you can store, retrieve, monitor, and compare your data readily.
You will not have to worry about portability in many cases since solar meters are typically small and handy. Nonetheless, it would help if you went for the most portable yet functional product you can get. This will make climbing the roof and getting off easy for you.
Solar meters would typically not consume so much power. So, the battery can last quite along. Nonetheless, some batteries last longer than others. Generally, products that use 4 AAA (about 6 volts) last for 100 hours, but those that use the 9-volt battery last longer.
We went with Tenmars Handheld as our best solar power meter. It offers a longer battery lifespan, portability, a big screen, a broad measuring range, a fair price, decent precision, and decent memory function. In other words, it offers many of the best features of solar meters. Nonetheless, if you want a product with a higher measuring range, you may consider Digital Radiation Measuring Instrument. Then if you want one with an even more impressive memory function, try out the TES 1333R.
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