Featured Solar Products from Run on Sun®

Solar panels are at the heart of every solar power (PV) system. Typically made primarily of silicon, solar panels make use of the photovoltaic effect (not to be confused with the photoelectric effect, the quantum theory of which led to Albert Einstein's only Nobel Prize) to convert the energy from sunlight into DC electricity, much like that produced by a battery. Unlike a battery, however, solar panels can perform indefinitely and most are guaranteed to produce at least 80% of their nameplate power after 20 or 25 years. Indeed, with no moving parts and no chemical process involved, a solar panel purchased today might outlast us all!

The National Renewable Energy Laboratory in Golden Colorado has a tremendous amount of information about How a Solar Panel Works and other renewable energy issues on their website.

Not all Solar Panels are Created Equal!

From a more practical perspective, to qualify for rebates from electrical utilities every solar panel sold in California must be listed on the approved equipment list produced by the California Energy Commission (CEC). Of particular interest on this list is the PTC rating of the different solar panels. The PTC rating is the CEC's estimate of the "real world" power production of a given solar panel. As a result, the PTC rating provides the consumer with a more reliable means to compare the performance of two seemingly identical solar panels.

Here's an example - suppose you wanted to compare an LG 250 Watt solar panel with one offered by our competition, say a Sharp 250 Watt panel. How would they compare? The PTC rating for the LG 250 Watt panel is 226.1 Watts (90.4% of nameplate rating) while the Sharp 250 Watt panel is only rated at 221.2 Watts (88.5% of nameplate). That means that each LG panel is likely to produce 4.9 Watts more power than the corresponding Sharp product. Multiply that difference by the number of panels in your array, and in a typical commercial installation it is like getting multiple panel's worth of power for free!

LG 250 Watt MonoX
solar panel

Our flagship solar panel offering is the MonoX module from consumer electronics giant, LG Electronics. These are very attractive products, with positive power output tolerances and very good module efficiencies. Moreover, these are the first panels in the world certified to be "Carbonfree" meaning that LG's commitment to sustainability is built into every step of the manufacturing process.

These sixty-cell panels match-up nicely with the Enphase M215 microinverters or with more conventional string inverters if shading constraints aren't present. These LG panels allow us to provide high quality, affordable solar power systems for both commercial and residential clients.

LG has an aggressive R&D program and a commitment to innovation that promises to provide outstanding solar products far into the future and the stability to provide a best-in-class warranty that is backed by a company with staying power.

Sanyo HIT Power N Module.

For residential solar power systems with serious space constraints we feature Panasonic/Sanyo solar panels, the best performing solar panels in the marketplace (Sanyo HIT Power N module shown). Sanyo solar panels have some of the highest efficiency values available (that is, what percentage of the Sun's power does the panel convert into electricity). They also consistently out-score the competition when it comes to PTC ratings (as described on the About Solar Panels tab) and they also excel in high temperature performance, as can be seen in this graph:

Unfortunately, the Sanyo panels have pretty much priced themselves out of the market - coming in a full dollar/Watt more than other top-tier panels.

As such, they are only appropriate in situations where maximum output power per square foot is required and money is not an object.

Inverters are sophisticated electronic devices that take the DC power produced by the array of solar panels and converts that into AC power that you can connect to a service panel to power your loads. However, modern inverters must do other things as well. Of greatest importance for grid-tied inverters is the ability to constantly monitor the electrical grid for faults. If the grid fails, the inverter must disconnect itself from the grid and remain off until the grid returns to operation and remains stable for five minutes. This feature - known as anti-islanding - is an important safety feature to protect utility workers from shocks.

Historically, there were two types of inverters: so-called "string" inverters that were used for residential systems, and their larger cousins, central inverters that were used in larger commercial systems. More recently, an addition to the inverter market has been introduced - the "microinverter" - which offers great promise for solar sites that suffer from partial shade during the day.

String Inverters

String inverters are the most common inverter products in the marketplace. A string inverter, as the name suggests, operates by wiring a series of solar panels into a string. One or more strings of identical numbers and types of solar panels are then brought back to the inverter for inversion and monitoring. Modern string inverters are highly reliable and come with a ten-year warranty.

Micro-Inverters

The greatest downfall of string inverters is the problem of partial shading of the array. (No device can solve the problem of total shade - for a solar system to be viable it must be largely unshaded.) Partial shading, say from a specific tree or power poll, can have a disproportionate impact on the performance of a solar power system. When a panel gets shaded, it ceases to produce power and adversely affects the performance of the entire string. If there are multiple strings coming back to the inverter, and just one panel from each string is shaded, the entire array could be effectively shut down.

Enphase Micro-Inverter Array with Shading

Microinverters do away with strings and each solar panel has its own, much smaller inverter mounted beneath it. As a result, every panel in the array operates independently. If one panel is shaded, the unshaded panels adjacent to it continue to operate without interference. An additional benefit of a microinverter system is the ability to monitor in real-time the performance of each individual solar panel.

The illustration here is from an actual system installed by Run on Sun. This is a subset of the entire array and shows a true geographical representation of the array with North at the top of the image. This snapshot was taken at 9:50 in the morning. To the East is a stand of very tall trees. As the sun rises higher in the sky, the shadow line from those trees sweeps across the array. Thus, the panels to the West get full illumination earlier, while panels to the East are still deep in shadow. If this array subset constituted one string, the effective power of the entire string would be negligible. Instead, this subset is producing over 700 Watts - while half the array is still in shade!

Having monitored a number of microinverter installations for over a year, we have found an the actual production from those systems to average 15% more energy than the CSI rebate calculator predicted. You can read about our findings in our blog post: "Microinverters: Are They Worth the Cost?"

Central Inverters

For commercial installations, the most common approach is to use a large, central inverter. These devices are usually free standing and can handle anywhere from 30kW to 1MW or more. Recently some manufacturers, notably Satcon, have taken a page from the microinverter design book and have pushed some of the power control circuitry out of the central inverter and into combiner boxes that harmonize the voltage being delivered back to the central inverter.

Enphase microinverter

Enphase microinverters offer cutting-edge performance, making solar power installations feasible for residential and small to mid-sized commercial installations where shading problems would render conventional string inverters ineffective.

We have installed a significant number of Enphase microinverter systems (more and more over time) and have closely monitored them to see if we could quantify the improvement in energy yield. Our analysis shows that compared to the energy output predicted by the CSI EPBB calculator, our microinverter systems are producing on average 15.6% more energy than predicted.

You can see the real-time performance of one of our Enphase microinverter systems by clicking here.

SMA string inverter

Where site characteristics support them, we feature SMA string inverters, the best selling, most reliable string inverters in the world.  Known as the Sunny Boy, SMA offers a complete line of residential string inverters from 700 to 10,000 Watts.

SMA also offers a line of inverters designed to operate independently of the utility grid, known as Sunny Island inverters, that come in three sizes: 3,300, 4,200 and 5,000 Watts.

Not as well known, but SMA also offers a complete monitoring solution and we have installed a number of systems that use SMA's "webbox" to capture and report performance data from the system. You can see the output from one of those systems here.

The KACO blueplanet product family offers a full range of inverter options. The blueplanet series is perfect for use in solar plants: from single family homes to solar parks in the megawatt range. The blueplanet series is supplemented by an extensive array of accessories for plant monitoring and communication.

KACO blueplanet series inverter

Taking a pioneering role in the field of photovoltaics, KACO has been the first company to initiate CO₂-neutral production of its blueplanet inverter series, and starting in 2011, KACO's blueplanet inverters are now being manufactured here in California. The motivation of the company to produce here is twofold. California remains one of the strongest and most promising markets for photovoltaics and the central location to major national distribution will make this production development strategically beneficial for the solar market of the US.

At Run on Sun, we are excited to offer this innovative product line to our clients who are interested in a solar power system with the lowest possible overall carbon footprint - from manufacturing to sales to distribution to installation and operation.

Power-One Aurora Plus Central Inverter

Central inverters are cost-effective solutions to the problem of converting a great deal of DC power into more useful AC. However, central inverters for large solar power systems also constitute a single point of failure that can cause the entire system to fail. In a commercial or PPA environment, such a failure can be costly. Systems with central inverters require routine maintenance as a way of ensuring the maximum percentage of runtime.

Our choice in this demanding role are the central inverters from Power-One. They combine exceptional performance efficiency (97% according to the CEC) with proven reliability. For large commercial installations, the Power-One product line runs from 50 and 100kW units all the way up to 300kW products.

All solar power systems require a mounting system to support the solar panels. Solar power mounting systems come in a variety of forms depending upon where the array is to be mounted.

Stand-off Roof Mounting Systems

By far the most common mounting system is the stand-off attachment system, such as those manufactured by Unirac. In a stand-off system, a series of metal posts - or stand-offs - are lag bolted into the rafters that support the roof. Those stand-offs are then flashed to make the system water-tight. When done properly, stand-off systems are extremely secure, reliable and provide for excellent system performance since the stand-offs provide clearance from the roof reducing the accumulation of debris and improving airflow which helps cool the array.

Flat-Roof Mounting Systems - Ballasted Arrays

On flat roofs such as what are commonly found on commercial buildings, the multiple attachments used for a stand-off mounting system are disfavored since the possibility of water pooling under the array increases the possibility of leakage. A popular alternative for flat roofs is the ballasted array. In a ballasted array, weight is used to hold the panels in place and resist wind-driven uploads. In earthquake-prone Southern California, ballast alone is not sufficient and some attachments are needed for seismic security.

Ground Mounted Systems

Google Solar Carport

For very large arrays, a ground mounting system is required. These systems typically call for the placement of some type of foundation - concrete feet or piers - and then a lattice work of supports.

One increasingly popular variation on this approach is the solar carport such as this one at Google in Mountain View, California. These free-standing structures both provide shade for parking and generate energy - energy which could be used to recharge Electric Vehicles.

Tracking Systems

The final mounting mechanism are tracking systems - ground mounted arrays that follow the sun. Trackers come in two general classes - single axis and dual axis. In addition, trackers can be either passive or powered.

A single-axis tracker follows the movement of the sun as it tracks from East to West each day. Since the system is always pointed in the direction of the sun, energy yields are improved by as much as 25%. However, since the tilt of the array is fixed (usually at latitude), the North-South orientation is a compromise.

A dual-axis tracker overcomes that compromise by also tracking seasonally for North-South variations in the sun's arc. A properly installed and maintained dual-axis tracker can achieve as much as a 40% improvement in energy yield over a conventional ground mounted array, particularly in more northern latitudes where the seasonal variation is more extreme.

However, those performance improvements come at a price - trackers are more expensive to install and need regular maintenance to keep them operating properly.

UNIRAC - Roof and Ground Mount Systems

For roof and ground mounted systems we use mounting solutions from Unirac, the leading manufacturer of solar power mounting systems in the United States.

Stand-off Roof Mounting Systems

6" Standoff with Flashing

Unirac has a variety of stand-off mounting solutions, and we particularly like their SolarMount Evolution (SME) system for residential pitched roofs. At Run on Sun we start with aluminum standoffs that feature two stainless steel lag bolts. This design is twice as secure as the single-bolt designs used by some of our competitors.

As you can see in the photo at right, we then use an aluminum flashing with a UV-resistant rubber boot to seal around the attachment. This approach provides better weather resistance than simple "L-feet" with sealants.

Using the SME system, rails for mounting the panels snap into specially designed clips that bolt onto the top of the standoffs, as you can see in this blog post about a Run on Sun installation using SME.

Ballasted Systems

RapidRac Array - Note Ballast Blocks

Unirac's ballasted mounting system is known as RapidRac and it is ideal for commercial flat roofs. The RapidRac system consists of interconnected trays that hold concrete ballast blocks to anchor the array to the roof. Fixed tilt arms connect to the trays to support the solar panels at a pitch of 10 degrees. This provides a good trade-off between panel energy yield and array density.

To provide seismic security, a special attachment device, called a RapidFoot, is used to prevent lateral movement of the array in the event of an earthquake. The RapidFoot has its own flashing system designed to prevent leakage, and it also lowers the overall ballast needs of the array.

Ground Mount Systems

For fixed-pitch ground mounted systems, Unirac offers U-LA - it's large array solution. U-LA is a modular system that starts at 3kW and can grow to sizes that are only constrained by the available acreage for the array.

Zomeworks tracking system

For tracking systems we like Zomeworks for their elegantly designed passive tracker.