Solar fallacies book? Title?

Grinnin

I would like to look at a book that I read many years ago. I am having no luck finding it to request on Interlibrary Loan.

The subject was common errors or fallacies that trip people setting up solar or renewable systems. It was published in the '70s or perhaps '80s I think.

When I search the internet I find many newer books that say solar and renewables don't work. This book was very much in favor of renewables, just focused on clear thinking instead of "going with the gut". This is long before "Renewable energy without all the hot air" which is also very good, but a different focus. The book I read was concerned with DIY and installation. It was written by an engineer who was simply tired of seeing renewable installations compromised by errors.

The specific fallacy that I'm thinking of is about east- and west-facing PV arrays. By pointing half your panels east and half your panels west there is obviously a longer charging day. The book points out that any number of panels will produce more energy by all pointing south as long as south is not shaded. (I don't know if the book addressed the odd situations that COULD suggest a non-south orientation.)

I've used internet searches, WorldCat, and the catalog for the library that had it in the '90s. This was before everything was "green", but I don't know if it was only solar or other renwables. I don't know if it was "fallacies" or just "errors".

I recall thinking that the focus of the book was useful by looking specifically at the fallacies, the book highlighted some areas where thinking about the larger goals works better than minor, distracting goals.

There are some old-timers here. Has anyone read this book?

Thanks.

BB.

Re: Solar fallacies book? Title?

No idea on the book... But facing 1/2 the array east and the other 1/2 west (or some fraction thereof) is what we call around here "virtual tracking".

For lead acid batteries, they do want a lot of hours of charging and with the large drop in pricing of solar panels, you can probably buy a few more panels/build out racking for less cost than a smaller array mounted on a real tracker.

You can use a program like PV Watts to see how many "extra panels" you would need to purchase to over size the virtual tracking array vs an actual tracker.

-Bill

stephendv

Re: Solar fallacies book? Title?

Regarding the east-west arrays, it depends on your goals, your loads, whether it's a grid tie system and what the local grid feeding regulations are. For example if your goal is to generate the greatest number of kWh per year, then facing them all south is better, because you maximise production in summer, when there's the most solar insolation.

Another example, in the UK, there's some sort of soft limit on the maximum power you can feed from the array to the grid, so if you have the roof space and panels are cheap enough then it could pay you to install some of them east and west so that you can stay under the maximum limit, but lengthen the daily production.

And the situation is similar with off-grid installs. IF your loads are constant throughout the year (summer and winter), and you're not in the equatorial region, then you'd want to keep your panels mainly south-ish facing because the worst solar months will be in winter when the sun doesn't move that much east and west.
But if you have larger loads in summer, e.g. a big AC, then it could be better to move the arrays more east and westerly so that you can increase production in summer to meet your loads.

Each case will be different, depending on all those factors so best to model the different scenarios using load calcs and solar calculators like the link Bill posted.