Hawaii Solar Blog

All Watts Are Created Equal, But Not All Systems Are

An article by: Keith Hertz of Haleakala Solar

There is no denying that 1000W = 1kW = 1000W

The same holds true for a typical system size of 6200W = 6200W. So why choose one panel over the other? Haleakala Solar has installed panels from over 20 different panel manufacturers over the last 37 years. With over 12,000 installs you could say we have some experience (more so than any other Hawaiian solar company).

A simple web search of “Top PV Panel Manufacturers” will result in many Top 10 lists. All are relatively different. Some of these lists have repeat offenders but for the most part if you have your eye on a specific panel and you look far enough, chances are you will eventually find it in a Top 10 list somewhere. Once you do, you will have the piece of mind knowing you have selected the right panel… right?

After perusing PV manufacturer site after PV manufacturer site, it becomes apparent that almost every panel manufacturer out there is the #1 panel manufacturer. So what are you to do? Who do you trust? Are more expensive panels better?

Solar PV panels installed for Akaku Maui by Haleakala Solar

Situation Matters

If you have limited space on your roof, consider a panel with higher wattage density. These panels produce more watts in a smaller footprint. You may think this is the way to go with every situation however if cost is an issue, keep in mind higher density panels come with a higher price tag.

Remember, a watt is a watt, so if you need 7500w and have enough space, go for a standard density panel of 250W and use (30) panels. If space is not available consider the same 7500W system using (25) 300W panels. Both systems given the same architecture will produce 7500W. The last scenario might save you an additional 90sqft of roof space but usually cost you a little more because you will be getting the same 7500W but in a smaller footprint.

Panel Manufacturers History Matters

Sure, everyone seems to have a 25 year warranty these days. But what if the manufacturer isn’t around in 10 years? It’s important to choose a panel whose company will be around to service the warranty period. Not all manufacturers have a stellar financial forecast so do some checking and a little predicting.

Some manufacturers have even gone to the extent of offering 3rd Party Insurance good for 25 years just in case they go out business. This insurance gives their customers the peace of mind knowing they will be covered in the unlikely event their panels fail and they are no longer in business. I like these companies.

I subscribe to Homepower Magazine. Every two years they come out with a very comprehensive PV Module Specification spreadsheet. The latest list to come out was in 2012 and it has 53 panel manufacturers with 833 different panels. The list is complete with Model Numbers, Cell Types, STC and PTC ratings, Power Tolerance, Module efficiency, physical size, weight, etc… you get the point. It’s comprehensive.

My background as an Engineer pulls me into these details like a tractor beam. After reviewing the list for over an hour it appears very likely most of these panels would perform very similarly given they were all the same rated wattage. Say I took panels from five different manufacturers with the same rating and placed them on my roof. Would I be able to see a discernable difference in the output wattage in a blind test. The answer is NO. We’ve tried it. We have had eight different panel manufacturers on the same roof plane with the same size micro inverter for over two years. The LG, Sanyo, Samsung, Mitsubishi, Hyaundi, Sharp, SolarWorld and Canadian Solar all look the same when the numbers come in.

If the numbers look the same then how do we as a contractor decide which panel manufacturer to go with? It’s easy. Look at the warranty, salt mist rating and the price. You wouldn’t by a new $30,000 car without a good warranty and service plan so why buy a $30,000 solar system without a good warranty and service plan.

The largest contributing factor to the system efficiency is not the panels. It is the inverter. This is where the bottleneck occurs.

System Design Matters

Over the past 37 years we have come to realize the system design plays the most important roll in performance. By design we mean panel layout and inverter selection or architecture.

You can purchase the most expensive, most efficient panel on the planet but if the system architecture doesn’t share the same efficiencies then you’ve just wasted a whole lot of money.

System Architecture

There are two main system architectures (we have installed thousands of each) the string inverter verses the micro inverter. Once again a quick web search will show you that each technology is superior to the other. We install either depending on the circumstance. Here is a little Pro-Con list we’ve put together.

string inverter vs micro inverter

During the past several years we have moved further away from the string inverter architecture and on to the newer micro-inverter technology. This move is mainly due to system reliability and performance. We run a full service department and warrant our systems, which means we are liable if these systems are under performing.

Since the switch to micro inverters (Enphase), troubleshooting by our Service Department has become very easy and we have fewer and fewer production complaints from customers.

In the past if a customer lost a string inverter, we would receive a call as soon as they realized the sting inverter had failed because that meant the entire system failed. With micro inverters it’s usually Haleakala Solar Service Department informing the customer they need an inverter serviced because the customer didn’t notice the loss in production… at least not an entire catastrophic failure.

We have found upfront costs for the micro inverter architectures to be 5 to 10% more than traditional string inverter architectures. However, the added monitoring capabilities and long term system production have always surpassed the string architecture efficiencies. This then decreases the payback time and increases the return on investment. In recent years the costs associated with micro inverters have come down so this price discrepancy is now becoming smaller and smaller. So… in a nutshell, you either pay a little more upfront for Micro Inverters or get less efficiency in the long term and limited troubleshooting with string inverters.


Each customer is different. Each situation has design criteria that must be met. Very rarely is there a case where one size fits all in construction. My advice to investing in a good solar system is:

  1. Consider the panel placement and determine if higher density panels are required. If not, go with standard panels (1 high density panel watt = 1 standard density panel watt).
  2. Consider a panel manufacturer that will live up to its warranty (some have salt water exclusion clauses you need to be aware of here in Hawaii).
  3. Strongly consider the investment in Micro Inverters given their warranties, waterproof enclosures, system efficiencies and monitoring capabilities.
  4. Choose a solar contractor with a track record… a good track record. According to Forbes magazine 80% of small businesses fail within the first 18 months. The trend is your friend and we’ve already witnessed this struggle with PV Contractors in the Hawaiian Islands (mostly due to utility grid saturation). Your system warranties are only as good as the contractor who installs your system.

In the end, all solar power is good. It’s a never-ending free resource. I think Thomas Edison put it best in 1931. We are like tenant farmers chopping down the fence around our house for fuel when we should be using Nature’s inexhaustible sources of energy — sun, wind and tide. … I’d put my money on the sun and solar energy. What a source of power! I hope we don’t have to wait until oil and coal run out before we tackle that.

Have a Great Sunny Day,

Keith Hertz

The Advantage of Enphase Microinverters

Enphase Microinverter M190

Inverters convert direct current (DC) electricity generated by solar panels into alternating current (AC). The alternating current is then fed into the electrical grid. There are, in general, two types of inverters used in most solar systems, “central” and “micro” inverters.

Microinverters have several advantages over central inverters. Microinverters are connected to each individual solar panel in the system. Central inverters combine all of the power from multiple solar panels in one central location. With microinverters, if one panel is defective or has coverage issues, such as dirt, shading or even slight orientation mismatch, it will not affect the rest of the panels. With central systems, if one panel has issues, it could alter the energy output of other panels, greatly reducing the effectiveness of the entire system.

The development of microinverters has greatly increased the efficiency of solar systems and the company on the leading edge of microinverter technology is Enphase. One of the main reasons Haleakala Solar uses Enphase microinverters is because of it’s reliability, specifically its robustly-engineered hardware, integral for withstanding harsh climates of Hawaii.

Haleakala Solar was recently featured in an article on the Enphase website. Check it out here.

Brief History of Solar and Hawaii Photovoltaic Highlights

Humans have been harnessing the sun’s power since the beginning of time. Due to our limited resources, Hawaii has always been a leader in clean energy and advances in solar power. Here is a brief history of solar energy and photovoltaic highlights in the 50th State.

700 BC – Sunlit Fires
The sun was used to start fires by concentrating sunlight with a magnifying glass.

1767 – First Solar Oven
Swiss physicist Horace de Saussure invented the world’s first solar oven. Today, there are many different types of solar cookers that allow those without access to electricity to prepare their meals.

1839 – Discovery of Photovoltaic Effect
Alexandre Edmond Becquerel, a French physicist who was only 19 years old, found that certain materials produced little amounts of voltage when exposed to light.

1876 – Electricity from Light
Professor William Grylls Adam and his student Richard Evans Day were the first to observe an electrical current when selenium was exposed to light. Although it wasn’t efficient enough to produce energy on its own, it proved the phenomenon can occur naturally and could be reproduced without heat or moving parts.

1883 – First Design of a Photovoltaic Cell
Charles Fritts, an American inventor, made simple plans for solar cells based on selenium wafers.

charles-fritts-1883 First Design of a Photovoltaic Cell

1954-60s – Birth of Photovoltaics
In 1954, David Chapin, Calvin Fuller and Gerald Pearson of Bell Laboratory patented the first solar cell capable of converting enough of the sun’s energy into power to run everyday electrical equipment.

The Hoffman Electronics-Semiconductor Division announced the first commercial photovoltaic product in 1955. It was 2 percent efficient and priced at $25 per cell, or $1,785 per watt (in 1955 dollars).

By 1960, solar efficiency levels had grown to 14 percent. Due to space exploration in the 1960s-70s, PV development increased dramatically.

1976 – Hawaii Enacts Tax Credit for Solar Power
Hawaii’s first tax credit legislation was signed into law to promote the purchase of solar energy systems and reduce the importation of fossil fuels. Although it was designed to be a “limited-time-only” incentive for homeowners and corporations, Hawaii’s solar tax credits have never left.

1977 – Birth of Haleakala Solar
Jim Whitcomb officially started his solar company on Maui, called Haleakala Resources at that time.

1978 – Energy Tax Act (ETA)
The ETA (Pub.L. 95–618, 92 Stat. 3174, enacted November 9, 1978) was passed by Congress as part of the National Energy Act in response to the energy crises of the 1970’s – the Arab Oil Embargo and the taking of U.S. hostages in Iran. The bill included a 40% tax credit for solar space and water heaters, and a $2,000 tax credit for installation, which were phased out in the mid ’80s.

1996 – Hawaii Solar Water Heating Rebate
Since the rebate has gone into effect, over 50,000 systems have been installed, making Hawaii a national leader with an estimated one out of three single-family homes equipped with solar water heating.

2001 – Biggest Hybrid Power System in the World
The world’s largest hybrid power system, combining wind and solar, is installed at Parker Ranch on the Big Island of Hawaii. The grid-tied system is unusual in that its solar energy capacity of 175 kilowatts is actually larger than its wind energy capacity of 50 kilowatts.

2006 – Federal Government Issues Renewable Energy Tax Credit
In addition to the state credit, homeowners are given a 30 percent tax credit from the federal government for solar electric systems. This tax credit is currently slated to run until the end of 2016.

2008 – Hawaii Clean Energy Initiative
The State of Hawaii and the Department of Energy announced the Hawaii Clean Energy Initiative to meet 70 percent of our energy needs through energy efficiency and renewable energy by 2030.

2008 – Solar Approval in Hawaii Legislature
Hawaii focused on bills that contribute to an energy-independent future.
– The approval of House Bill 2502 allows solar energy facilities to be located on less-productive agricultural lands.
– Governor Lingle signed Senate Bill 644 which prohibits the issuing of building permits for new homes without solar water heaters as of 2010. The bill excludes homes located in areas with poor solar energy resources, homes using other renewable energy sources, and homes employing on-demand gas-fired water heaters.
– SB 988 allows the Hawaii Public Utility Commission to establish a rebate for solar photovoltaic electric systems, and HB 2550 encourages net metering for residential and small commercial customers.
– In July 2008, the governor approved three energy bills, including HB 2863, which provides streamlined permitting for new renewable energy facilities of at least 200 megawatts in capacity. HB 2505 creates a full-time renewable energy facilitator to help the state expedite those permits, while a third bill, HB 2261, will provide loans of up to $1.5 million and up to 85% of the cost of renewable energy projects at farms and aquaculture facilities.

2009 – First Photovoltaic Plant with Battery Storage
Dedicated in January 2009, La Ola Solar Farm on Lanai was the first photovoltaic power plant in the world to include battery storage and, at 1.5 megawatt (MW), the largest solar facility in Hawaii at the time.

2009 – Largest Roof-Mount Solar Installation
Installed on the island of Hawaii at Kona Commons Shopping Mall, the 804-kilowatt system generates over 1.1 million kilowatts of electricity, enough to power almost 130 homes and eliminate 959 tons of carbon emissions annually.

2010 – Solar Power Reaches Grid Parity
Hawaii reaches the break even point for solar power, with the average price for electricity at $.25 per kilowatt-hour and the average resident price at $0.28 per kWh.

2011 – Largest PV System in the State
With 5,376 solar panels and the capacity to produce 1.21 MW of electricity, the Kapaa Solar Farm becomes the largest in Hawaii, and the first on the island of Kauai.

2013 – Solar Energy for Underserved Markets
Governor Abercrombie signed SB 1087, which creates the framework for the Green Energy Market Securitization program (GEMS), a financing model that will make solar more accessible for lower-income homeowners, renters, and non-profits. GEMS is targeted to be launched in 2014. You can read more here: http://www.haleakalasolar.com/hawaii-solar/solar-energy-savings-for-hawaii/.

The Scoop on Hawaiian Electric Company’s Solar Changes

According to a news release from Hawaiian Electric Company, Hawaii utilities have the highest percentage of customers with rooftop solar and the most solar watts per customer. Solar installations in the Aloha State have experienced major growth, doubling every year since 2008 and are on track to double or nearly double in 2013. With this continual demand and Hawaii’s renewable energy goal of 40% by 2030 in mind, Hawaiian Electric Company is implementing “changes to make adding solar faster, cheaper and fairer.”

On September 6, Hawaiian Electric Company announced a policy that requires their approval before solar photovoltaic systems can be installed. Hawaiian Electric Company is concerned about solar creating excess electricity that could damage the utility’s power grids, cause power outages, and harm utility workers.

Previously, contractors were able to install solar photovoltaic systems before hooking it up to the grid, so the stalling effects of this policy change has stunted the Hawaii solar industry during its busy season and left solar customers in limbo. Many customers took out loans or made upgrades to their roofs in preparation for a solar photovoltaic system that they now have to wait for.

Since the new policy went into effect, Hawaiian Electric Company agreed to grandfather in 228 customers who had their solar photovoltaic systems installed on or before September 6. Hawaiian Electric Company also changed the threshold that triggers an interconnection study from 75% of the daytime minimum circuit load to 100%, so more small PV systems (10 kW and under) can be added. The utility will be performing studies on “several representative circuits and will apply the results to as many projects as possible on similar circuits.” The first study should be completed by the end of the year, and the last one in the first quarter of 2014.

However, over 1,000 customers are waiting on an interconnection study and/or upgrades to the grid before their net energy metering (NEM) applications are given the green light.

Scott Seu, Vice President, Energy Resources and Operations, for Hawaiian Electric Co. wrote an article in Civil Beat that claimed “more than 80 percent of the circuits on Oahu have room for more solar without dealing with studies.” Yet, Civil Beat’s fact check on this percentage found this statement to be only half-true. Although it may be technically true that 80 percent of HECO’s total circuits can handle more solar without more studies, significantly more than 20 percent of customers who are looking to install solar photovoltaic panels in residential areas could encounter delays and perhaps additional costs.

On October 14, lawmakers called a hearing to discuss Hawaiian Electric Company’s photovoltaic changes. “It was a good start to a discussion about the future of our energy landscape in Hawaii and the viability of our utilities business model,” said Representative Chris Lee, Chair of the House Committee on Energy & Environmental Protection.

There is hope that Hawaii’s solar customers and companies will be given a better resolution. Senator Mike Gabbard, chair of the Senate Committee on Energy and Environment, has “asked Hawaiian Electric Company and the solar industry to report back to the Legislature by November 14 on the progress they’ve made in coming up with a solution.”

Hawaiian Electric Company’s map below shows solar penetration levels for Oahu. Areas highlighted with the darkest shade of blue have already hit the utility’s circuit threshold, which means that residents may have to pay for grid upgrades in order to connect a solar photovoltaic system for their home.

Map of Oahu Solar Saturation Levels

Map of Oahu Solar Saturation Levels

How Solar Photovoltaic (PV) Panels Work

It’s no small wonder that ancient civilizations worshipped the sun. The sun is amazing; providing energy, heat and light. It’s hard to imagine life on Earth without it. In modern times, we have found ways to harness the energy of the sun to create electricity. And not just a little bit of electricity… lots of it.

Solar Photovoltaic Systems In Hawaii

One technology that has developed to turn solar energy into electricity is called Solar Photovoltaics (or solar PV for short). It’s quite a popular way to harness solar energy and you’ve probably seen lots of PV panels popping up in your neighborhood on your neighbor’s homes, local grocery stores, etc. In fact, PV panels have been installed on many homes and businesses all over Hawaii for many years.

It’s a well-known fact that residents of Hawaii want to keep their islands as green, lush, and beautiful as possible, and one very good way to accomplish that is with the use of solar power through solar photovoltaics.

Solar PV Panels Can Now Harness Even More Solar Energy

Recent advancements in PV have greatly improved efficiency and amount of electricity solar panels can produce. Solar PV systems are now able to harness more of the abundant energy coming from the sun. There is so much solar energy coming from the sun. In fact, every hour the sun produces enough energy to power the planet for an entire year. Yes, that’s a lot of energy. So, it’s exciting that the newest break-throughs in PV allow for more gathering of the solar energy… which allows for creating more electricity to power our homes and businesses.

Here’s How It Works

Okay… guaranteed, you will feel like you’re back in your old Biology class in high school, but here we go…
Sunlight consists of tiny packets of energy called photons. These photos burst forth from the sun radiating out into space. The Earth is in prime location to these solar photons which hit the Earth after traveling a mere 93 million miles. It all happens very quickly, in the speed of light. These photons hit the surface of a semi-conductor on a solar panel and then the magic happens.

When you look at a photovoltaic solar panel more closely, you will find that each panel is made up of many individual cells. Each cell has a negative and a positive layer. This co-mingling with negative and positive creates an electric field, or electrons. So, the photons from the sun hit the panel and free some of these electrons in the semi-conductive field. The electrons then create an electric current which is then collected by wires that are connected to the negative and positive sides of the cell. The amount of electricity that is created is multiplied by the number of cells in each panel and the number of panels in each solar array. This creates a lot of electricity. Depending on the number of solar panels in a system, it could power your entire home or business.

From the solar PV panel, this DC (direct current) electricity then passes down to the inverter. The inverter changes the DC power into AC electricity which is needed for ordinary household uses.

For solar PV systems that have a battery backup (for those that want to be completely off the grid), the inverter has the special job of regulating the charge to the battery unit. The battery system is great since then the electricity stored in the batteries can then be used at night or during blackouts.

Advantages Of Using Solar Photovoltaic Energy

There are lots of advantages to using solar PV energy. The first one we have to mention is that it creates clean energy. How is that so? It has no emissions and no moving parts. It creates no pollution. It doesn’t even make any noise pollution. Solar PV doesn’t need any fossil fuels to run, or even water. And, it can be located right where the power is needed – right on the roof – or even out in the boonies. If you’ve dreamed of being completely off-the-grid, Solar PV is the way to do that, in combination with a good battery unit. Solar PV can also be tied into the power grid, allowing you to sell extra electricity that is not used back to the utility companies – a very valuable feature, indeed.

There’s no doubt that Solar Photovoltaic (solar PV) is growing fast and is an important element in our nation’s move toward a clean energy economy.

haleakala solar logo



(808) 400-4181