Actually there is such an instrument. I saw one on Gardening By The Yard on HGTV. It's called the "Sunlight Calculator" and they sell it on their website or you can see it at the manufacturer's website - http://www.thesuncalc.com

Here is a link that might be useful: HGTV Marketplace

How about a wrist watch?? Just set it out there and watch it from dawn until sunset, and ya won't have to buy that expensive gadget!

Oh, but who has the time to sit in one spot all day? And you may need to check dozens of spots throughout the yard. That could take forever!

Besides, I could by several SunCalcs for what my watch costs.

Maybe you could find the pieces in your garage to make a real simple one.
Solar cell, charge controller, 12v hour meter.

One recommendation I heard was to put sheets of paper down in the spots you want to measure and look at them hourly. Anything in the sun when you look at it gets a check mark, then you add them all up later. Takes a day of course, but not really much effort if you are around the house and can set a timer.

I found some kind of sun or moon phase device, on one of my rounds! It is crescent shaped, has a taut wire streched across the ends of the crescent, and some little holes around the circumference of the crescent. Each hole has different phases of the moon cast into it. The thing pivots on its stand.
A neighbor, who fancies herself as a "knower of all things pertaining to the moon" says it came from one of the Arab countries. Makes a nice place for birds to sit!
Anybody have an idea?

The clock has to be an analog type LCD types wont work.

That solar light / clock idea is pretty ingenious. It makes sense since most solar lights work off a rechargable AA battery, like those cheap clocks you can buy for wood working projects and such.

You can get some good solar information from this weather site:

www.wunderground.com

Just punch in your zip code.

Here is a link that might be useful: weather underground site

I bought one called "EasyBloom" from the big orange box online, mostly on a lark as far as I was concerned because my wife wanted it. She's something of a gadget hound. :-)

It measures soil moisture, sunlight, temperature, and humidity then you plug it into your computer and it graphs it. It's also supposed to give recommendations based on your readings and planting zone but I haven't really looked into them. You're also supposed to be able to "diagnose" a plant.

I used it on the north side of our house that gets a little morning sun and a little late afternoon sun. It reported that it the location had moist soil, was partial shade, the average day temperature was 75°, the average night temperature was 68° and it was moderately humid.

For the heck of it, I tested it's diagnostic ability on a fittonia that was floppy because my wife had over watered it. I put it in the pot, took it out 24 hours later, plugged it in and it told me that "Your red nerve plant is too wet" but the sun and temperature was just right.

It actually seems to work pretty well overall. I went to Amazon and read their reviews before I ordered it because it wasn't what I would call cheap. The main gripes were a lack of Mac compatibility at the time and someone thought it would analyze the soil needs, nutrients, ph, etc.

It's kind of neat and would be nice for someone unsure of or just starting in gardening. I have a couple of spots in back where we have all our trees that I'll probably try it once they finish leafing out.

Here are screenshots of some of the readings:

{{gwi:317356}}
{{gwi:317357}}

If they could add a Ph meter to it, they would have a great product but they'd have to redesign it.

I can calulate that in my head by just looking up and the angle of the sun vs. what creates shade. if it an't under no tree or shadow of house or barn it should get sun. How many time have we been out in our yards? Have we ever noticed the sunny spots????

I can just set in a lawn chair and read a hot rod magazine for 20 minutes.
In the morning if the tops of my legs are pink from too much sun, stuff will grow there just fine.

I'm still thinking about getting that EasyBloom. According to this, it will measure fertilizer needs if you get a subscription.

Here is a link that might be useful: EasyBloom Plus Plant Sensor

Hi, I was just reading up on sunlight calculators and am very interested in yours ... are you able to share exactly how you did the things you did? (I'm not technically inclined but I know people who might attempt this if they had instructions) --- do you need a soldering iron?

Thanks!

If you are referring to me. I just connected 2 clip leads to the battery terminals of the solar light and the clock. You may have to open the back (bottom) of the solar light to find the battery. Then connect the clip leads to and analog clock battery terminals plus to plus, neg to neg. Set the clock to 12. Place a board on the ground and lay them on it. I only wanted that data for ones sunny day. If you want more data put them in a plastic box. you could solder wires instead of using clip leads or could even just twist the wires together.

Area 51 Data Loger !

The best and cheapest device is called a solar pathfinder. It is about $100 and just be sure to get the right paper insert for your latitude. Best part of this is it shows sunlight area and shading for the entire horizon of an area over the whole year! Not just one spot on one . You can see company demo video here on YouTube: https://youtu.be/DJc4pGwZh-c