Sales FAQ's

How can I place an order?
The easiest method is purchasing on our website. You can also order by phone Monday-Friday, 8 AM-5 PM MST.
International/Local +1.435.792.4700
Toll-free (877) 727-6433

We also offer ordering by email or fax:


Fax: 435.787.8268

If ordering by email or fax, please include the following information:

  • shipping address
  • billing address (if different from shipping)
  • phone number
  • return fax number
  • e-mail address (helpful if you would like your UPS tracking number sent to you)
  • credit card number, expiration date, and cardholder name

Orders placed by fax will be confirmed by fax or e-mail within 48 hours of receipt.

How soon can you ship?
Our standard lead time to ship is 1-2 business days unless otherwise indicated on the product page. Custom orders generally ship within 1-2 weeks. If you need a rush order, we can work with you. Please call us directly during business hours.
Do you accept international orders?
Yes. We encourage our International customers to order through the distributor in their country. If we do not have representation in your country, you may contact us to order. All tariffs and taxes will still apply.
Do you accept university purchase orders?
Yes. Simply fax the PO to 435.787.8268.
If I order online, how do I know you received my order?
Shortly after you submit your purchase an automatic e-mail confirmation will be sent to you. If this email is not received, please notify us.
How do you calculate shipping costs?
For domestic orders, we use UPS Ground or 3-Day Select, depending on your location (Next Day and 2nd Day Air are also available). For international orders, we use UPS Worldwide Standard, Expedited, and Express.
We provide an e-mail confirmation with a tracking number so you can check the progress of your shipment. We can arrange to use the shipping company of your choice although additional fees may apply.
Actual cost is based on size, weight, package value (we insure for the full amount of the order), and your distance from Logan, UT (84321). The e-store automatically adds shipping charges to orders. Orders placed by fax will be confirmed with shipping costs.
What credit cards do you accept? When I place an order, when will my card be charged?
We accept Visa, MasterCard, Discover, or American Express. Credit cards are charged the day of shipment.
What are your payment terms?
Typically customers choose to pay with a credit card. We will need to have three on-time payments before we can accept purchase order terms for all companies excluding domestic universities. Payment terms on Purchase Orders are Net 30. If you have any questions about your account's terms please contact us at or call us at 435.792.4700.
How do I request a written quote or proforma invoice?
Fill out our Request For Quote form by clicking here or email your request to
What is your return policy?
We will accept returns within 30 days of purchase as long as the product is in new condition. There will be a 10 percent restocking fee for all returns. The PS series spectroradiometers are non-refundable. For more information on returns and warranties please see our terms, or call customer service at 435.792.4700.
How is my personal information used by Apogee?
Apogee Instruments, Inc., has a commitment to your privacy. Please see our Privacy Policy, which has information about our privacy practices for our website.
Do I need to order a sensor to go with my Apogee meter?
No. All Apogee meters (MO, MP, MQ and MU series) either have sensors built into the meter or attached via two meters of cable.

If you order a sensor only (SI, SO, SP, SQ, SU series) you will need to have your own data logger (or, depending on the sensor, a voltmeter) to collect information from the sensor.

How does Apogee get specification information?
At Apogee, our solar radiation sensors have a specification for accuracy (5%), uniformity (3%), and repeatability (1%). The accuracy compares each sensor’s output to an absolute reference standard. Uniformity is how consistent our sensors are compared to each other. Repeatability refers to how a sensor performs against itself. Does the same sensor perform consistently under the same conditions? The numbers in our specifications are based on statistical analysis. Large populations of our sensors are compared to a reference, ISO or NIST traceable where available, and the error is measured. We then calculate the mean and standard deviation of the sample from the reference standard. The specifications listed for accuracy, uniformity and repeatability represent plus or minus two standard deviations from the mean (95% of the population). For more information, click here for a knowledge base article on sensor specifications.
What is photosynthetic radiation and why should it be measured to predict plant growth?
Photosynthesis and plant growth depend on the energy in radiation but only specific wavelengths of radiation cause photosynthesis. We have known since Einstein that one photon excites one electron (the Stark-Einstein Law), which starts photosynthesis. In 1972 a scientist named Keith McCree showed that a meter that counted the number of photons in radiation would more accurately predict photosynthesis than the previously used foot-candle meters. LI-COR (Lincoln, NE) started making meters to measure this radiation and scientists quickly switched to the new measurement system, which is called Photosynthetic Photon Flux (PPF). The energy in a photon is called a quantum so these meters are called quantum meters. A quarter century later, LI-COR has sold thousands of high quality meters, but their least expensive quantum meter with sensor costs $780. The high cost means that they are used only by scientists and large commercial growers. Smaller growers have continued to use foot-candle meters, which measure light for humans. Footcandle meters have errors of up to 45% when used to measure light for photosynthesis.
What are some properties of solar radiation?
Solar radiation is a term used to describe visible and near-visible (ultraviolet and near-infrared) radiation emitted from the sun. The different regions are described by their wavelength range within the broad band range of 200 to 100 000 nm (nanometers).

Terrestrial radiation is a term used to describe infrared radiation emitted from the earth. The components of solar and terrestrial radiation and their wavelength ranges are:

Ultraviolet 250 to 400 nm UV sensor or spectroradiometer
Visible 400 to 700 nm Quantum sensor or spectroradiometer
Near Infrared 700 to 3000 nm  
Infrared 3000 to 100,000 nm Infrared radiometer

Approximately 99 percent of solar, or short-wave, radiation at the earth's surface is contained in the region from 300 to 3000 nm while most of terrestrial, or long-wave, radiation is contained in the region from 3500 to 50 000 nm.

Outside the earth's atmosphere, solar radiation has an intensity of approximately 1370 watts per square meter. This is the value at mean earth-sun distance at the top of the atmosphere and is referred to as the Solar Constant. On the surface of the earth on a clear day, at noon, the direct beam radiation will be approximately 1000 watts per square meter for many locations.

The availability of energy is affected by location (including latitude and elevation), season, and time of day. All of which can be readily determined. However, the biggest factors affecting the available energy are cloud cover and other meteorological conditions, which vary with location and time.

Historically, solar measurements have been taken with horizontal instruments over the complete day. In the Northern US, this results in early summer values 4 to 6 times greater than early winter values. In the South, differences would be 2 to 3 times greater. This is due, in part, to the weather and, to a larger degree, the sun angle and the length of daylight.