What you see in the picture above is a Renogy 100 watt solar panel I have. This panel weighs about 15 pounds and is 6.7 square feet in size, about 2/3’s of a square meter, with 1.5 inches in width. Not a small piece of equipment by any stretch of the imagination.
As you are probably well aware, the sun is a huge ongoing energy source. Each and every day rises in the east and sets in the west and provides the energy for life here on earth.
The whole idea of solar panels is to capture this bountiful, renewable, free source of energy and convert it to electricity as opposed to burning a fossil fuel which is inherently a non-renewable. This argument, in of itself, makes sense and is very seductive.
But here is the problem. The sun provides roughly 1000 watts per square meter of earth at peak capacity. This panel you see above though only provides 100 watts of electricity at peak capacity. If this panel was truly 1 square meter large it would provide, at peak, about 150 watts of electricity.
In simple terms, at peak production, the sun provides 1000watts of energy, the solar panel can turn that into 150 watts of electricity. That means the panel is 15% efficient. Remember, this assumes the most favorable conditions in the world. Here in Atlanta, for instance, we are not getting 1000w per square meter, we’re actually getting less than 200w per square meter.
So, now we need to do more calculations to get a true estimate of the electricity my solar panel will provide. 200 watts at 15% efficiency equals 30 watts, but remember my solar panel is only 2/3 the size of a square meter. Thus this panel will provide about 20 watts on an average day. 20 watts times 24 hours in a day equals about 1/2 a kWh/day in electricity production.
Now, if things goes awry and the grid is down that .5 kWh/day will prove to very valuable, don’t get me wrong. But I’d need a lot and I mean, A LOT, more panels to provide the electricity that my family can live on. And remember, we’re just talking electricity here, not total energy.
What heats your hot water? Natural gas? What runs your vehicles? There are many other energy requirements that go well above what electricity will provide. For this exercise, though, I just wanted to focus on the electricity you can expect from a typical solar panel.
The debate I find myself frequently in with those advocates of renewable energy revolves around two things:
- Solar is getting cheaper per watt
- Solar panels will become ever more efficient
The fact that solar panels are getting cheaper per watt I find quite irrelevant. If I need 60 kWh/per day to run my household, paying 50cents a watt or $1/watt is rather meaningless if I can only get .5 kWh/day out of a 7 square foot, 15 pound solar panel because it’s only 15% efficient. Which leads to the second argument of increasing efficiency.
Yes, there are some panels that are providing about 23% efficient right now. But how much do those guys cost? Certainly more than any average person can afford. Will the technology increase enough to allow a 23% efficient panel to be affordable to the masses?
How about a 30% efficient panel though? 35%? Not. Likely. To. Ever. Happen.
So, we’re stuck at a HOPED-FOR max efficiency of say 25% for the masses.
Even if my panel was 25% efficient, my kWh/day production would now provide 3/4 of a kWh/day. A nice improvement, sure, but enough to provide the electricity for the vast majority of homes? Not in the least.
I don’t write this to steer you away from solar. I write it because I find the arguments of solar proponents misleading as can be which hurt the cause. When people find they’ve been deliberately mislead they won’t believe anything going forward. That’s not good. Because solar can fill a huge gap in electricity supply. We’re seeing with the hurricanes of 2017, that when the grid goes down, solar can be a wonderful backup and provide some electricity, for things like running a fridge, turning on lights, keeping cell phones charged.
In dire times, having access to commonly-used gadgets can be a huge relief to a family who is worried how they’re going to get by. So, don’t turn completely away from solar, just remember its limitations and act accordingly,