What Else Can Solar System Do?

Given the number of installations we are performing to meet customer demand, it is easy to forget some of the powerful opportunities solar has for many of our customers. Solar is inherently modular, which leads us to think that every system is a slight variation on the same technology, values and long term impacts.

It is refreshing and very exciting when we can demonstrate through effective collaborations and a listen first approach that the integration of solar systems into our built landscape has immediate and latent effects that far exceed the obvious and measurable benefits of clean power, on site power, emission free power and water free power.

A project example illustrates this point clearly.

Several years ago, LighthouseSolar won a commission and ultimately an IREC design award to design and install solar classrooms at 15 middle and high schools in Austin, TX. We collaborated with Austin Energy, Austin Independent School District, and a curriculum developer to deploy a solar classroom at each location for the student and teacher communities to use.

To inform our design approach, we asked the question: What would it look like to have Stonehenge meet the IPhone? We are guided by the fundamental principles that solar is also technology of mythic proportions and eternal time scales, yet we live in a world enabled and pressurized by technologies of instant and distributed connectivity.

For this, our solar classroom needed to serve both real design guidelines.

First, the solar classroom is monumental in aspect. Not that it is so big that is can’t intimately hold the attention of a small class of students, rather it is informed by systems scaled beyond our local experience. The movement of the sun is an experience shared by everyone on earth and while each location on earth has a slightly different experience it is worth remembering that a Greek geographer, Anaximander, calculated very closely the circumference of the globe by looking down a well in Egypt. The global is in the local. This sort of expansive curiosity is available upon casual but pointed interest in a solar system. Our classroom makes this more apparent due to the design elements. The structural supports align with the altitude of the sun at the summer solstice. The depth of the room is defined by the lowest sun angle at the winter solstice. Sun angles are also reflected within the tapered angle of the bench foundations that ring the classroom. The student can feel the shape of the solar ecliptic through their feet.

This brings us back to the power and breadth of the connectivity that the iPhone generation is growing into. The expansive question occurs to us: What will the generation look like and be capable of having experienced the sense of the sun coupled with the tools that hand held computers offer? It is more exciting in what is possible than what is quantifiable.

The solar classroom is also equipped with tools of the modern era. Electronic teaching tools, QR Codes, skype conferencing, weather data monitoring and solar production monitoring set up the ability to run experiments, track results and test hypotheses. These are also tools of sharing, global connectivity all in the context of primary education.

Solar energy is more than a commodity, more than an economic opportunity and more than a switch in the dominant energy paradigm. If culture is where science and imagination meet, then perhaps solar holds a deeper proposition to recast our culture in ways that we are yet to discover.

We continue to ask the simple question: What else can solar do? We invite you to inquire accordingly.

Choosing The Right Inverter for Solar Panels

One of the most important questions to ask when designing a solar array is, “What type of inverter does the system need?” Which inverter will provide maximum production for the best price?

Every grid connected photovoltaic (PV) solar system needs an inverter. It’s the brains and the brawn of the system, the integral piece of equipment that takes the Direct Current (DC), being produced by the solar panels, and inverts it to an Alternating Current (AC) which can then be used to power your appliances and interact with your local electrical grid, AKA, your utility company. The inverter is the workhorse of the system and does a majority of the heavy lifting.

Although there are many companies from all over the world that produce them there are only a few types of inverters including central inverters, string inverters and micro inverters. Since central inverters share many similarities with string inverters and are more often used in commercial and utility scale projects, we’ll focus on the two types that comprise a majority of residential solar systems, string inverters and the module level power electronics known as micro inverters.

Simply put, string inverters allow panels to work together as a unit while micro inverters allow the panels to work independently. Let’s look at them in more detail.

Micro Inverters

A micro inverter is exactly what it sounds like, a tiny inverter. They are small enough to attach one to each and every solar panel in the array, allowing them to operate independently from one another, converting the electrical current from DC to AC right at the panel itself. Micro inverters allow the panels of a system to work optimally under less than perfect conditions.

If you look at a satellite image of your neighborhood, you’ll see that roof tops come in all shapes and sizes. Some are big and simple while others resemble MC Escher lithographs, with multiple arrays of varying size pointed in different directions.

In situations like the latter, a micro inverter would be the best option. The presence of large objects that will cast shadows such as chimneys, tree limbs or even your neighbor’s house might also benefit from installing micro inverters. Remember, as the Sun moves across the sky, shadows will move across your solar array. Also, a shadow that exists in December may not be present in July. Any situation where, at any given time, a panel will be shaded while other panels are receiving direct sunlight would be a perfect situation for a micro inverter.

Imagine that your roof is comprised of many small arrays, multiple hips and valleys all aimed in different directions. Right in the middle is a chimney casting a shadow that moves across the plane throughout the day. When one section is getting direct sunlight, another is just receiving a glancing blow. When one panel is stuck in the shade of the chimney the panel next to it is getting kissed by the Sun. This scenario is easily solved by installing micro inverters to each and every panel. With micro-inverters, if one panel is basking in direct sunlight it’s not in danger of being slowed by another panel in the array that is hiding in the shade.

String Inverters

Now picture one big, open space to place an array of solar panels. This could be a large section of roof or even an open field on your property where you could place a ground mount. All of the solar panels in the array can be placed side by side and there are no objects such as trees, chimneys or satellite dishes that might cause shade. All of the panels will be under the same conditions. This would be a perfect environment to employ a string inverter.

String inverters come in different sizes and wattages. In a string inverter system, all of the panels send their DC current to a single inverter which will invert the entire load to AC. They are efficient with fewer moving parts and fewer possible points of failure than their micro counterparts. They can be used individually or in different combinations to match the size of any system. The panels can be configured onto two to three separate strings per inverter allowing for a certain amount of flexibility as well as increased efficiency. String inverters also come with two distinct advantages.

First, rather than being placed on the roof, the hottest and least accessible part of the house, the string inverter will be placed right next to the utility meter. It will be in the shade, which will boost efficiency, and will be easily accessible for any possible service. The second advantage is a lower price tag. Generally, a string inverter is a less expensive option than micro inverters, and saving money, along with reducing your carbon footprint and championing the environment, is one of the primary benefits of making the move to solar.

Optimizers

A hybrid alternative would be to use an optimizer. Optimizers can be used in conjunction with a string inverter and are placed on individual panels that might be affected by shade throughout the course of a day. If a part of the array is affected by shade the optimizer will adjust the output of the affected panel, saving the other panels from being slowed down in the process. Then, when that panel comes into full sun, it will readjust the output and re-engage with the other panels at full power. Optimizers can be added to a system even years after the initial installation as shade from growing trees begins to affect the production of the existing panels.

In short, going with the right inverter will allow your system to perform at its peak potential. Beware of salesmen or installers that bid only one type of inverter or even one brand of panel, claiming that their product is “the best” or the “most efficient”. What that usually means is that they only have one option available to them and they are trying to sell that product as the best for all situations. Your home and even your energy usage is unique and there is no one-size-fits-all solution. As always, a little homework goes a long way. Read some reviews, get proposals from several qualified installers and go with the company that will design an efficient and cost-effective solar system around you.

Our Consumption Habits

Invariably, the first 2 questions we receive when introducing solar to folks are the same:

1. How do the panels handle hail? (we are in Texas afterall)

2. What would it cost to run my 2000 square foot house?

The answer to the first is that the panels are warranted against a direct impact of

1” hail and the incidence of damage is miniscule.

To the second question, we reluctantly but accurately have to answer, it depends. This is not a dodge, a sheepish sales tactic or our lack of understanding. It is quite accurate and must follow with an investigation of what the customer’s energy consumption actually is. This is where it gets quite interesting.- sometimes pandora’s box kind of interesting.

To refresh, there are some basic principles that inform this conversation. In the solar industry we are used to talking about power and energy as very distinct phenomena. In common parlance, things get overlapped and often lead to confusion. Think about the difference between an energy drink (like Red Bull, astimulant) and an energy bar (often a source of protein). The terms are confusing. She is a powerful leader, he has good energy… We characterize our experience in these terms very often.

In the context of electricity and specifically as it relates to your home, it is very specific and needs to be kept distinct. Think of a light bulb. A 13 watt LED bulb draws 13 watts of power the instant you turn the switch. And it continues to draw that amount of power as long as the circuit is intact. That’s power: 13 watts. Now run that bulb for an hour- you get 13 watt hours. That’s energy. 13 Wh. When you take a look at your residential bill, you are charged in units defined at kilowatt hours (kwh) That’s a lot of LED bulbs by the way.

As you go around your house you can add up the power you may draw as individual circuits or appliances are turned on. You can just talley them up. There are many that may escape attention (ghost loads), because there is not much going on visibly, yet there is still power being drawn. Your TV likely is drawing power to stay warmed up so that is comes on instantly when you want it. Be thorough to take stock.

And then there is energy and this is the key metric for most residential settings. It is a combination of the power you are drawing and for how long. As you use more power your consumption goes up, but more impactfully, the longer you run those loads, the more your energy consumption goes up.

Now there is no real magic here. Running your whole house for 1 hour is the same energy consumption as running 1/24 of you loads for 1 hour. But the rub, is that no one manages their household this way and better said, it is quite rare for folks to manage their household from an energy perspective that is thorough and time based. We have grown up not really concerned with that or equipped with the right tools to see what the actual effect our habits have on energy consumption.

Like many of you, I grew up with the blanket admonitions to turn lights off, don’t waste energy, all the while I had no real conception of how the walls that surrounded were managing heat, or how efficient the appliances really were. We believe, management does not hinge on guilt, but can thrive when one is equipped with tools to visualize in real time how much power and energy we are using. For this we install Lighgauge Monitoring on all of our solar system and even on building with no solar. You can see, at circuit level, what you are using and where the energy is going.

And this gets us back to our first, or second, question. How much does it cost to run my 2000 sf house with a solar system? While I will unpack other dimensions of this question in a following blogpost, we much first recognize that the house is specific, you habits are specific and the way you manage your habits in your house are even more specific.

So we begin to inquire, analyze and recommend how your habits measure up to your expectations or even to general averages. In the end, we can speak confidently from a set of regional averages and rules of thumb, but that partly misses the point, that our experiences are all our own. Our habits needs to be recognized. The solar system we will design and implement for you is specific, even though it draws on the generous, available power of the sun, your solar system will be an integral part of your experience, which is inherently unique and tailored.