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The Uplift Pupdate
by Tarawatt


Solar Energy Conversion, a Lesson in Photosynthesis

Updated: Sep 19, 2022

A day’s hard work

Watching a solar panel convert sunlight into electronics is exactly like watching the grass grow. In both cases, it’s not obvious what is happening so we won’t spend any time observing it. It’s easy to take for granted both plants and solar panels, which seem to be passive loafers that loll about in the sun. In fact, both are invisibly – and fast and furiously – adapting to minute changes in sunlight to convert it to usable energy. The strategies each uses are remarkably similar, as are the challenges of doing it well.

Like solar cells, plants convert sunlight into energized electrons. They produce less energy in partial or full shade than when in full sun. The photosynthesis in plants cannot respond to changes in light as fast as those changes happen in the real world, however. When sunshine comes up suddenly, a leaf has to gear up its inner workings to make use of it. It dissipates as heat the light it cannot use in those moments of getting up to speed, which can damage the plant. When shade overcomes the leaf, the photosynthesis needs time to ramp down. The moments of mismatch between these internal machinations and available light result in waste of some of that energy as heat.

Our recollection of grade-school lessons on photosynthesis may be dim, but most of us probably recall that a plant with limited or inefficient photosynthesis will not grow or produce. In other words, too much or too little sunlight and the conversion into useful energy that manifests in more leaves or fruit might be poor.

The same is true for solar panels: we can’t use those excited electrons until effective DC-DC conversion of the current to hit the right voltage. That’s when electrons become the power capable of charging a battery or passing through an inverter for use as AC electricity. Inefficient conversion means we lose precious power that our many electric appliances and devices depend upon.

DC conversion, like photosynthesis, can be inefficient. Like plants, solar panels must also be capable of reacting instantaneously to rapid light changes. Inductors and capacitors collect current, releasing it when the voltage becomes high enough to hit its target set point. Current beyond what the capacitor can hold will dissipate as heat. Most power optimizers conditioning DC current don’t have a heat loss problem because the capacitors are large enough to boost the voltage to the right level. But this creates a different inefficiency: an economic one.

Capacitors are necessary but expensive components in DC power conversion. For a while, the solar industry used electrolytic capacitors. Those ultimately proved to be short-lived and unreliable. The better option, ceramic capacitors, become pricier and harder to get with increasing size. Moreover, oversizing the capacitor is a practice for extending the capacitor lifespan, but one that also increases the cost.

Tiny capacitors like those used in cell phones are cheap and readily available. Breaking up the current into lesser bursts of excited electrons that can be boosted with more numerous – but much smaller – capacitors, is one way to decrease the cost of DC conversion. Doing so, however, brings us back to the same timing challenge that plant photosynthesis faces: the smaller capacitor must release the electrons at a faster rate or be forced to waste the pent up energy as heat.

Fortunately, cell phones have made super-fast microprocessors as cheap and readily available as those tiny capacitors. The Uplift power converter combines a super-fast microprocessor with tiny capacitors, solving the “photosynthesis problem” in solar systems while making the conversion and optimization less expensive. Our power optimizers spread the voltage boost across the cell strings within the solar panel. By handling lesser current, we can use smaller capacitors. With a microprocessor that samples each capacitor in microsecond time intervals, releasing the current at the moment it hits the target busbar voltage, we can right-size our capacitors for that voltage without the consequence of heat waste or damage. Our power management thereby achieves conversion efficiency with economic efficiency.

I’m a big fan of grass. I want it to be long, green, and lush because I run on it (and sometimes eat it). So I want photosynthesis to work as well as it can. My owners want solar panels to produce as much usable power as possible, because they want to see solar panels become the least expensive and easiest way to access the electricity we all need. Fortunately for plants, some smart people have figured out a way to make photosynthesis more efficient.* Even better for the solar industry, Uplift is making available to solar panel and system providers the most efficient DC energy conversion possible.

*To learn more about genetic scientists improving plant photosynthesis, see The Economist, “Light and shade” (Aug. 27, 2022).

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