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Teal Photon


Distinctive features: Appears to have been the first solar cell powered calculator.

Technical details:
Display is 8 digits, LCD with yellow filter.

4-function, %, memory, square root.

Power supply is solar cell, only.

Integrated circuit is an NEC D1831G, here date coded 1979

Size 68 x 127 x 9 mm (2.7 x 5.0 x 0.4").


TEAL Industries Inc., Carson, Calif. 90746.

Made in Japan.

Was announced in April 1978 with a price of US$39.95[1].

The TEAL PHOTON appears to have been the first commercial solar-cell powered calculator, and so one of the first electronic calculators without an on/off switch!!

The liquid crystal display has a yellow filter over it to prevent damaging ultra-violet radiation from reaching the liquid crystal.

Inside Teal Photon
Inside Teal Photon

With the rear cover removed, showing the integrated circuit and the lack of any battery.

One unusual feature is the two red LEDs at the bottom of the circuit board, which cannot be seen when the casing is in place. They appear to be used as clamping diodes to limit the voltage generated be the solar cells.

Here the circuit board has been removed and turned over.
The series array of solar cells is at the top, with the NEC integrated circuit below, in a hole in the circuit board to minimise the thickness of the calculator.
The main area of the circuit board is taken up by an array of contacts for the keyboard buttons.

On the left is the LCD module while above it is a length of rubber with metallised rings around it which provides electrical contacts to it from the circuit board.

Alongside a photograph of the TEAL PHOTON the journal New Scientist, of 20th July 1978 reported[2] "The concerned environmentalist can now calculate the downfall of society without eating into the world's resources in the process. A new calculator that is coming on to the market in the United States does not have an on/off switch - it doesn't need an on/off switch because the power comes from a small panel of solar cells. The cells' output is such that if there is enough light around for the user to see the calculator there is probably enough light to power it".

This report appears to be a little optimistic since the calculator requires bright light to operate.

Click here to see an advertisement for the TEAL PHOTON from August 1978.

Previous calculators with solar cells just used them for recharging the internal batteries. These models included the  Sharp EL-8026 "Sun Man" and the Royal Solar 1.
For other early solar-powered calculators see the Sharp EL-825 and the related models

"TEAL" was the brand name of calculators made by Tokyo Electronic Application Laboratory. Entering the calculator business in the late 1960s the company produced some innovative calculators, including early LCD models. Some Teal calculators were also sold under the names of other companies.
Unfortunately, the company was greatly affected by the calculator price war of the mid 1970s and went out of business in 1978.
However, some calculators, like this one, have a U.S.A. address. TEAL Industries Inc., of Carson, California, U.S.A. was a subsidiary of Tokyo Applications Laboratory, Ltd., and may have continued in busines after the demise of the parent company.

"TEAL" calculators should not be confused with "Tealtronic" calculators, which was the trade name of a British company.

The TEAL TL-2M desktop calculator is also featured on this site.

This model demonstrates all the features of the modern calculator - Solar powered, LCD, very thin. From the first hand-held electronic calculator of 1969 it has taken 9 years to achieve this.
Also see the Sharp EL-825, an early credit-card size solar calculator.


  1. Hawkins, William J., "Whats New in Electronics: Solar calc", Popular Science, April 1978, p98.
  2. "Feedback: Calculating intentions", New Scientist, 20 July 1978, p221.

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© Text & photographs copyright Nigel Tout   2000-2016  except where noted otherwise.