Price Per Watt: The Most Unintentionally Misleading Metric for Solar Consumers

How much is that doggie in the window?

See something. Find out the price. Buy it or not.

It’s a tale as old as human civilization.

And it is partially responsible for creating the most unintentionally misleading number in residential solar: Price Per Watt.

At this point, almost everyone reading this knows what a solar panel looks like.

So asking, “How much does a solar panel cost?” feels natural–it’s just what we ask when we may wanna buy something we can see.

A solar panel costs a couple hundred bucks.

And if I sent a solar panel to your house, its value to you, by itself, unless you were using it for a table, would be zero.

So “How much does a solar panel cost” is a well-intentioned question which returns no useful information to the person asking it, even when answered truthfully.?

The cost per panel could be a nickel, and that's too much if the value to you is zero.

But those panels do produce power.? And that is valuable.?

So what people are really asking is, “How many DC Kw of solar modules do I need to have installed and activated to produce X amount of power based on where I live and want to place them?”

Simply put, once folks understand, “Oh, I can cover my naked roof and produce power I’m already paying someone else to make, that’s pretty cool”, the natural progression is:

“How much will that cost, and is that a good deal?”

And for the last decade the best possible data point someone could receive to answer those last two questions was a very simple number:

Price per Watt.

Specifically, cash price per DC watt of solar modules installed.

This made a lot of sense last decade.? Why?

Almost everyone was installing the same basic solution: solar panels + string or micro-inverters + no battery.

So a standardized way, using a simple number, to convey the total cost of an installed system made a lot of sense. Price per watt was a great metric for the adoption of solar.

It created a number, that once you knew it existed, made choosing where to buy solar as simple as knowing which gas station to pull into for lowest gas price.

Sure, there were variables that made this metric imperfect–like the quality of the install, the panel quality, the inverter capability, the speed of the install, the cost of monitoring, warranties, registration support for utilities and incentives, etc.

But from a technical perspective, the equipment being offered by everyone provided the same solution for consumers:

An affordable way to turn sunlight into DC power and convert DC power into the AC that powers your house.

And when your house doesn’t need all the power you’re producing?

No problem, the grid uses AC too, so just ship it back to them if you don’t need it for a credit of some sort.

And when the utilities are giving a full retail credit for anything you send back, this is one heckuva setup.

Great deal for you. Not so much for the utilities.

We’ve completed solar projects in twenty-one states and more utility companies than I care to remember, and one national trend is plain as day:

These programs are going away.

So what does this have to do with price per watt??

And how did it become unintentionally misleading?

Simply put, “Solar” is just not the same animal as “Solar + Storage.”

In a solar + storage system, the most important part of the entire setup isn’t even included in the words “solar + storage”, so it’s easy to miss.

The most important part of a solar + storage system is the inverter.?

Ever heard anyone say, “Solar + Inverter + Storage”?? Me either.

And the inverters we used last decade just aren’t capable of optimizing the potential of storage.

Check out these questions–I bet you can guess your answer to all of them:

If you had a choice, and your power went out, would you like to be able to run all of your things or just some of your things?

If the utility company started paying you a lot for the electricity you could send to them from your batteries during certain times when they needed it most, would you like to earn more or less from those programs?

If you produced something valuable daily, would you prefer to lose seven or fifteen percent of it??

If you installed a clean power plant on your property, would you want to be able to use it immediately or only after the months it may take to? gain permission from your utility company?

Would you like to use a less expensive, longer lasting, more environmentally friendly battery chemistry, or would you prefer the option we need to move bc it’s sitting in our warehouse.

The inverter you choose determines the answers to these questions.

There is new hybrid inverter technology born for the solar + storage era. And the foundation for that era will be built this decade.

Because different inverter technology now creates far different outcomes, and value, for the property owner than last decade’s equipment, a simple metric like price per watt simply doesn’t answer the “Is it a good deal?” question like it once did.

So price per watt isn’t intentionally misleading, it’s unintentionally misleading because it’s incomplete.

I don’t think there are people sitting around in dark rooms asking, “How can we force people into inferior technological solutions like AC-Coupled storage so we can maximize our profit?”

People are just busy.

Why learn to do something new when what you already do is more than good enough?

And if you had an entire pre-existing market, your customers already using solar, that have to choose AC-coupled batteries because they went solar before these new inverters existed, why not get excited about creating these technologies? Any battery is better than no battery.

But peak battery is optimal.?

And peak battery happens when we all use inverters containing bidirectional inverter chargers and built-in automatic transfer switches? that make DC-Coupled storage with ample continuous AC output possible and simpler to install.?

There are currently multiple options for bi-directional inverter chargers. And while some of these options are superior to others, all of them are superior to an AC-Coupled battery solution.

So if you are buying or selling an AC-Coupled solution, pause for a moment and learn about what’s possible. You’ll be happy you did for decades.

In summary,? maximizing solar + inverter + storage potential is not captured in Price Per Watt, or at least it won’t be until every competing quote is using the same technology.?

Solar is already too complicated for the most busy consumers to parse the information–even without batteries. That was the beauty of Price Per Watt–when everyone was using the same equipment, at least it was kinda simple.

It’s up to the professionals–the designers, educators, engineers, and contractors to do what makes sense to maximize our nation’s distributed energy future–even if you have to get a little uncomfortable for a minute by learning something new.