Solar Lens Effect

Solar lens effect must be taken into account when choosing your MPPT; surges in solar power energy occur regularly.

If you are planning to build a green home you must take into account how certain properties of droplets of water can effect the sun's radiation, increasing its energy temporarily by fifty-percent and perhaps more.

Solar lens effect

Updated on 7th February, 2024.


What is unexpected is that a 100 percent cloudless day, with very low humidity produces lower levels of radiation. Moisture in the air can increase the sun's effect and concentrate the energy received at your photo-voltaic panels by refraction.

Solar Lens Effect

This solar lens effect is especially true as a cloud brushes past the sun, refracting and focusing the light onto your panels.

A PV panel turns photons of sunlight into a usable direct-current, powering your home and office; your factory and farm too, of course. First it must be inverted to AC.

Have you ever noticed that your skin is far more likely to burn should you be tanning on one of those days when there is a thin-haze in the sky?

By refracting the solar energy, moisture in the atmosphere can substantially increase the energy at the PV panels on your roof.

That moisture coming from the ocean, actually carries fine salt crystals too; did you know that rain is about one hundredth of the concentration of sea-water, depending on how close to the ocean you live?

These minerals can also influence the solar lens effect of clouds.

Refracting lens

Solar power energy

This sudden but temporary, surge of the sun's energy has importance in the planning when you are building a solar powered generator; the amperage may exceed the specs of your regulator. Whilst a high quality MPPT is designed to cope with abrupt surges in power, el-cheapo may blow.

Buying cheap is often expensive. If you put in the best equipment the first time, it hurts only once.

When choosing the required items for a solar generator, it's best to assume upfront that, when you discover that Mr Golden Sun offers his energy free of charge, you will want to add more PV (photo-voltaic) panels which of course deliver more amps.

Whilst your original planning may be for lights and computer equipment only, my experience is that it won't be long before you are kicking yourself for designing too small. Having needlessly to upgrade a 20A regulator to a 60 amp was an expensive mistake for me.

Oddly the sixty amp is not much more expensive that the twenty; an upgrade will be costly.

Back to the solar lens effect

On a dry day, my solar panels will deliver about 1050 watts of power at midday. But yesterday, as the cloud above passed over the sun, the energy surged.

Lens effect 1309W

That's a 15% increase. I have seen it yielding a massive 50 percent sometimes but only for a few seconds. It's not your imagination; your skin will burn worse on a slightly cloudy day on the beach.

These measurements incidentally were taken in the early days when we only had enough panels to run computers and lights. Now we have 10kW and it will power every and any appliance; during the day.

Solar power panels 4 x 90W

So I feel comfortable doubling the number of PV panels which will yield around 40 amps for my 48V solar powered generator

40A x ~ 50V = ┬▒ 2000W (or 2kW), roughly the power used by a hot water kettle.

Upgrades of the solar generator

We have done several upgrades since writing this page some years ago. We now have 10kW of panels, yet stay on the grid for rainy days, simply for convenience. I'm not yet that much of a solar nut!

One innervation, after a consideration about shadows on PV panels, was to put 900 watts of panels on a west facing wall. It sounds crazy, receiving direct sunshine for less than half the day, but in fact it's the late afternoon when our need for energy is the greatest; when our solar electric oven is being used.

Yes a 10kW inverter is ample for heating water, cooking and using my power tools; and even the heavy-duty electric lawnmower. Plan to go big from the start and save yourself a lot of money and headaches is my advice.


On the other hand reflection does not have to do with the concentration of power if you have a flat mirror; but simply the redirection of light. You cannot use it to set fire to a piece of paper as you could do with a lens.

But I am thinking of using a concave mirror made of small squares glued onto a disused satellite dish to increase the energy reaching my panels by focusing the light. That is really just an idea that is unlikely to come to fruition. Odd as it may seem, some PVs face away from the sun, the photons directed to them by huge curved polished aluminium sheets.

But here is another example of reflection from our home.

This triple reflection has nothing to do with your proposed solar generator; it is just an exercise in fun, and an appreciation of the beauty of creation.

For just two weeks in the year, once as the great ball of fire moves north, and the other as it retreats south again, we enjoy this triple reflection of the sunshine in our home; it is right around the equinoxes. 

Reflections sunrise

The sun beams land on this window opposite which acts as a mirror.

Reflections mirror

Mirror 1

And then the sunshine is reflected onto the mirror on this sideboard below.

Reflections mirror 2

Mirror 2

From the sideboard mirror the sunshine is reflected a second time, on this occasion onto the glass on the hall-stand.

Today the good wife has made a flower arrangement of poppies she has just rescued from the honey bees that seem to love the pollen, and wear the blooms out with their coming and going.

I wonder if they get a high from snorting it? Within an hour they have ruined the blooms.

In reflection there is no bending of the sunbeams.


Our newsletter is entitled "create a cyan zone" at your home, preserving both yourself and Mother Earth for future generations; and your family too, of course. We promise not to spam you with daily emails promoting various products. You may get an occasional nudge to buy one of my books.

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Reflections mirror 3

Mirror 3

And so the third reflection. Here is the image blown up on the wall; it's beautiful, eh?

This light is lovely to behold, but perhaps even more important is that it can be put to work to power your electronica; and even your lawnmower and oven. See how a day in the life of solar geek Bernard Preston unfolds.

Reflections image poppies

Reflection and refraction are two very different aspects of optics, something we take for granted perhaps; using them every day to brush our hair and in spectacles. And of course in the eyeball itself where the lens effect enables us to see objects clearly.

Is Creation not stunning? Or do you believe it all came about by chance?

Shadows on PV panels

Shadows on PV panels in contrast to the solar lens effect drastically reduces the output.

If the shadow covers one whole panel, the output from a whole string will be zero even if the remainder are in full sun.

Useful links

Bernard Preston

Helen in her Nissan Leaf.

Bernard Preston certainly has something of an inquiring mind; and his wife says he should be on Ritalin. Observing surges in power far beyond the expected output of the PV panels he noticed the solar lens effect.

She is not displeased though as these theoretical musings have had a very practical outcome. Our home is in effect now off the grid, having used only 43kWh of utility power in the last three years; to heat water after protracted misty periods.

Nor is she unhappy that we were able to turn over a blue Leaf in January, 2020; the most beautiful car to drive that we have ever owned.

Good MPPTs like those produced by MicroCare[1] handle these occasional surges but beware of those made in "Ping Pong Ting."

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56 Groenekloof Rd,

Hilton, KZN

South Africa