Wishlist - What do you need for DIY Solar Energy?

First one is 5W (5V, 1A) from DFRobot and the second one is 2W from Seeedstudio.

To accive the best results try to make your cable lengths as short as possible. If you have to bridge higher distances, consider the Stepdown conversion on the recieving side for less power loss 

What is the rating of the solar cell on top of the box ?

After taking some readings with a 1.5w  solar panel, the rated watts are at the mercy of the load as well as the sun output. Using a solar controller does its best to operate for max power output of the solar cell.

Another interesting observation with the solar panel I tested, it was temperature dependent. For example if output volts were measured in full sun just after the solar cell was brought outside , it measured at maximum.

After sitting in full sun for 15 minutes in a 85 F ambient, the solar cell got really hot to touch and the output volts dropped 5-7%

I like to use the 2 inch square solar cells on my projects to extent battery life or eliminate the need to plug into recharge. they are small enough to fit any where on small designs and if the project requires more you can connect them in series to make an array or panel. a small design that i have used these on powering a sensor to alert when the chicken water is low and needs refilled.

In the category of "small power source for the DIY maker", I think solar walkway lights could be a good start of a project.

I've been thinking of using a basic solar walkway light as the power source for a WiFi IoT temperature sensor.

That should save some build effort and provide me with a half-decent power supply for the sensor. It would probably have to be the bigger type of light with more than just one tiny battery to be able to run the sensor, and it will most likely require a boost converter.

I've seen some solar-light AA batteries that are 3.2v LifePo, which might be suitable.

I've been lazy though, because my sensor is used in the same place as the hummingbird feeder heater, which requires too much power to be feasible via battery, so I just plug it all in

So I guess the other things I would need is "enough motivation" and "no other nearby power source"

Compass and some software to calculate sun elevation during the year - this way you can optimize panel's angle to get maximum power when motorized mount is not possible/too expensive

What do you need?  Crimpers for those cool MC4 connectors.  We all know that cables only come in two sizes:  too short and way too long.

Agreeing with taifur, what would really be nice is low drain power monitoring system that doesn't consume all the power - as shared by beacon_dave with his power bank.
That might be an idea for the next Summer of Green design challenge because Newark has a few IC's that would probably do the trick.

In looking for solar panels for my battery storage system here at work, I was surprised to learn that solar installers would rather do ground mount than rooftop due to the decrease in efficiency caused by the heat of the roof.  One person told me that it can be as much as a 30% reduction.  I never knew.

For a remote IoT device like data logger or environmental monitoring solar power is very effective if you don't like to replace the battery every few days. An efficient solar charger is required for this purpose. As most of the case we use li-ion battery for our IoT project the charge controller must have li-ion charging option. Lipo rider pro from Seeedstudio or Solar Power Manager from Dfrobot  is a good option for hobbyist IoT project. The device should be placed where direct sunlight is available. The cable should be as short as possible. Environment proof cable is required for long lasting and the connection should be sealed and waterproof. 14500 & 18650 are two very common li-ion battery you can try.

I made several solar powered project in last few years. One of them was Urban Noise & Air Pollution Monitoring device using Particle Argon. The primary work of that project is to collect temperature, humidity, air quality, noise level and position data and publish those data to cloud. The data can be visualized from Android apps, web dashboard and can be downloaded as excel sheet for research purpose. The project link is: https://www.hackster.io/taifur/urban-noise-air-pollution-monitoring-d14088

Another project I made was Smart City Environmental Monitoring that was published in the link: https://www.electromaker.io/project/view/smart-city-environmental-monitoring

In that project I used Nordic Thingy:91, a cellular IoT device. The device upload environmental data to AWS IoT Cloud.

Agreed.  I have south facing panels and a string inverter, so for 2/3 of the year I have shadowing from my neighbor's trees (they grow taller each year) and from his chimney in the winter (because of the close proximity of our houses).

But starting about now and into mid-September the sun angle is high enough that there is no shadowing.  On a nice day like today (warm - 72F, sunny, high sun angle), the panels are running full tilt and the inverter is clipping .

Here's the irradiance looking south maybe 15 degrees from vertical with no obstruction: