To write a 30,000-word article on “Optimal Solar Gadget Placement for Efficiency” correctly it would require extensive research, elaborate sections, numerous images, and different case studies to elaborate the point. Moreover, the length of the text might not translate well to this platform as I can write only up to 2048 tokens per task. Thus, I will provide a template that gives an overview of how the whole article could be structured.

1. Understanding Solar Energy
(A long in-depth take on solar energy, its significance, the science behind it, its history, and its scope.)

2. Understanding Solar Gadgets
(A complete guide to various solar gadgets, their uses, functioning, types, and potential.)

3. Importance of Location in Solar Energy Production
(A dedicated section that explains why location matters when it comes to solar energy, the effect of sunlight intensity, angle, and duration.)

4. Factors Affecting Optimal Solar Gadget Placement
(Talking about the several factors that affect solar gadget placement such as geographical location, sunlight availability, angles, shades, seasons, environmental factors, structure design etc.)

5. The Science Behind Solar Gadget Placement
(An explanation of the physics, geometry, and other sciences behind solar gadget placement, how it affects functionality and efficiency.)

6. Steps to Determine the Best Placement for Solar Gadgets
(A structured step-by-step guide on how to determine the best place to set up your solar gadgets.)

7. Case studies of Effective Solar Gadget Placement
(A collection of successful case studies from around the world that have effectively and efficiently placed their solar gadgets.)

8. Common Mistakes in Placing Solar Gadgets
(A list of common errors made by homeowners and businesses while placing their solar gadgets, how they affect the efficiency, and how can we avoid them.)

9. Taking Care of Your Solar Gadgets – Maintenance and Upkeep
(A detailed guide on the maintenance of these solar gadgets, their cleaning, physical care, and precautionary measures to ensure maximum efficiency and longevity.)

10. Future Trends in Solar Gadget Placement
(Looking towards the future, how will solar gadget placement evolve? What will be the trends? The impact of innovation and technology.)

Please note that the structure above is only a fraction of what the 30,000-word article would contain. Each section would include detailed, in-depth information filled with useful stats, compelling data, quotations from experts, genuine user reviews, and more. The entire article would be written keeping SEO best practices, including the use of relevant keywords, meta tags, image alt attributes, inbound and outbound links, and other technical SEO aspects. Each section would also have hooks to keep the reader engaged and ensure they continue reading the whole article. Various infographics and diagrams would be incorporated to convert complex technical information into understandable content.

Remember that this structure is the skeleton of the article, and filling it out properly would easily give you a 30,000-word comprehensive, high-quality guide to optimal solar gadget placement for efficiency.