Solar Power and Regenerative Agriculture in Burma

It has been some time since I wrote Solar at Home (Part one), and I thought that I would take this opportunity to go over some solar basics and some industry changes that have happened during the last 30 years of my involvement.

The Unchangeables:

Photons, Not Heat

Some folks think that Photovoltaic panels (PVs) generate electricity using the heat of the sun and the hotter it gets, the more electricity you get. This is not true, indeed, the opposite is true! Electricity is generated when photons, (tiny energy packets of electromagnetic radiation), strike a PV cell. The cooler that cell is, (think, Alaska on a cold morning), the higher the voltage and therefore the more power is produced. So, PV panels in the tropics produce a lot of power, partly due to the clear skies and the long hours of sunshine, but the same number of panels in Alaska would produce more instantaneous power on that cold winter’s morning!

Shade is the Enemy

I think everyone understands that a PV panel in the shade will not produce much energy, but how much shading does it take to reduce the output to zero? Surprisingly little! Logic would suggest that if 50% of the cells were shaded then there would be a 50% loss of power. In fact, there would be about a 95% loss. If even half of the bottom 4 cells are shaded, you can get a 95% loss of power. The reason is that all the cells are connected in Series, (in a long daisy chain), and shaded or partially shaded cells prevent the current from the unshaded cells making its way to the output circuit. So, if a tree has grown to the point where a few leaves are lightly shading your panels, it’s time to get the loppers out and give it a quick trim!

The Changeables:

The Cost of PV

When I bought my first panels in 1990, I could only afford used ones, and when I came to buy new ones in 1999, I was paying $5 or $6 per watt. For a long time, the largest panel available was 60 Watts. Now in Thailand I hear of panels that are 800 Watts and the wholesale cost of all panels can be as low as $0.25 per watt. Clearly, this a game-changing price reduction. Solar has gone mainstream – PV panels are now a commodity – traded like so many bushels of wheat. I still have my old favorites like the Sharps and Kyoceras from twenty years ago, but few people now share my nostalgia! In fact, some of these panels are being removed and replaced by much more efficient ones on the same roof. And actually, I hope that this continues, because a strong used market will be good for lower income families to get their first solar system and who knows, maybe a trade will develop exporting inexpensive used panels to the developing world.

A Battery is a Battery

In the old days, the battery you used in your off-grid cabin would undoubtedly be of the Lead-Acid type, most likely a re-purposed car starting battery, and until recently, that technology still dominated. But now there is a new kid on the battery block – Lithium Ion, and Lithium Iron Phosphate (LifePo4) in particular. This battery technology outperforms Lead Acid in all categories and measures and although it is more expensive, it is well worth it. Are LifePo4 batteries the answer to our prayers for a cost effective, environmentally sound battery? I don’t think so. There are some real-world problems associated the constituent components, such as toxicity in mining and shortage of supply of rare elements, to mention only two. Though not the final answer to the storage battery conundrum, LifePo4 is a big step forward.

I hope that you have enjoyed the potted summary of my 30 years of experience in the PV industry and that the odd technical terms weren’t too much for you.

I am now in Thailand, getting ready to set up my base here and work out how to use my Solar Roots time to best effect in Thailand and the surrounding countries. Thank you for supporting us through good times and bad.

I have include a few photos from my cabin in the mountains of Trinity Country, where I over-wintered for the first (and probably, the last), time in 2020-21.

Best wishes,

Bruce