Solar Southwest Florida

We sprung forward last night for Daylight Saving Time, and naturally many people want to change the clocks on their Pentair SunTouch Solar Pool Heating Controllers. It’s actually quite simple, and I’ll show you how here.

Here are the steps to change the time on your Pentair SunTouch for spring Daylight Saving Time:

1. Press Menu 5 times
2. Press the right arrow
3. Press the up arrow
4. Press the right arrow 2 times
5. Press the left arrow to return to the main screen

In the fall, do the same thing, except in step 3 you will press the down arrow. If you need to adjust the minutes because the clock has drifted off a little, in step 4 you can use the up and down arrows between the two right arrow presses.

Here is a video showing the above process:

Here is another video on general time setting:

If you are an FPL Netmetering customer with a solar electric system, you may have received an email recently describing changes to the program. All of these changes apply only to new Netmetering customers, and no action is needed for existing customers.

The only significant change that applies to non-government entities is that a manual disconnect switch is no longer needed for new Tier 2 and Tier 3 interconnected systems (systems with a gross power rating exceeding 10kW).

Specifically, the email addressed these following changes:

• Eliminating the requirement for a manual visual load break disconnect switch on U.L. 1741 listed inverter based renewable energy systems. It is still required on non-inverter based systems.
• Adding text to recognize the insurance limits that apply to governments in Florida.
• Changing the agreements so that you can type in the information, print, have it signed, and return.
• A witness signature is no longer required.

If you have any questions regarding the changes to the FPL Netmetering program, let me know!

It’s not uncommon for people to mishear or misunderstand our company name as Fasco, Fastco, Falco, or something else. Even people that know us well might wonder why we are called Fafco Solar.

I had the distinct pleasure of spending a substantial amount of time with the busy man behind the name this week. FAFCO is an acronym for Freeman A. Ford COmpany. Freeman (I think it’s safe to say we are on a first name basis) is a visionary in the solar thermal industry, having revolutionized/started the solar pool heating industry in addition to a variety of other solar thermal technologies. He is what my father-in-law, who I similarly respect, calls a “thinker.” Always inquisitive, Freeman brings out the best in people by asking them well-crafted and prescient questions.

My employer is actually Fafco Solar (note capitalization). Fafco Solar is a fictitious name (dba) of Solar Pool Heaters, Inc., a Florida corporation. FAFCO, Inc. Is the California manufacturer of our main product offering. Another visionary, Ward Morrissey, the late father of Fafco Solar’s current owner Dan Morrissey, brought the FAFCO brand to Southwest Florida in the late 1970′s. Later, Dan asked permission to use Freeman’s company acronym in his company’s name. It was both a sign of ultimate respect and a brilliant marketing coup that continues to bring us recognition to this day.

Freeman and I have a bit in common. We are both private pilots. We started businesses from the ground up, enduring hardship and embracing success. We have an insatiable appetite for knowledge and understanding. Having a couple of decades on me in age, he’s clearly and understandably more accomplished in all of these areas, and I look forward to the mentorship that he may not even be aware he is providing.

I’ll take the opportunity to sit next to Mr. Ford any time, be it in a national sales meeting, at a spectacular Las Vegas dining experience, or at a Cirque de Soliel show, all of which I gratefully had the opportunity to experience this week. Our time together is invaluable, and his gracious hospitality is extraordinary.

The FAF in Fafco Solar is Freeman A. Ford.

What are you looking to get out of a solar pool heating system? Do you know how it works? What made you consider a solar pool heating system? Why do you want a solar pool heater? Have you experienced a solar heated pool at a friend or neighbor’s house? What other pool heating sources have you considered? Are you aware of the alternatives? Are you aware of the options? How did you find us, and what prompted you to call me? What are your concerns about buying a solar pool heater?

These are all things you might hear out of a solar company’s sales professional. Notice something? That’s a lot of questions!

I didn’t enjoy my educational experience until my last year of college. For the first 16 years of formal education that I received, I endured daily lectures on what I needed to know. Very few educators asked me what I would like to know! When I finally hit my stride as a Finance student at the University of Florida, my advisors and professors started asking questions. They wanted to know about my career aspirations, what I expected to accomplish as a floor trader at the New York Stock Exchange, and how I would treat my employees as I rose to the top. They identified the education I needed, and they delivered it with a genuine interest in my success and happiness. Fortunately as a result, I changed my tune and never pursued my lifelong interest in becoming a high-flying Wall Street stockbroker. That life was not for me.

A good solar company is an educator that tells you what you want to know, not what they want you to know. Let’s face it – you probably don’t know much about solar pool heating when you start making calls. You need an education.

I insist that our solar advisors learn about you, the customer. They should leave your home understanding how you use your pool and what your expectations are about the performance of the a solar pool heating system. If we fail to understand your needs and desires, the likelihood of you becoming a satisfied customer that refers your friends and neighbors is far lower.

Sure, we can give you a long-winded monologue about the technical details and features of our product, and how our product is so much better than the competition’s. We will probably give you at least an overview of how the system works and for what you should look in a solar pool heater. However, the most important thing is that we understand what you want, and then DELIVER a solution.

Ultimately, you are going to do business withe a solar company that you trust. Gaining your trust comes from understanding you. If a solar company approaches you without a clear interest in solving your problem, they are not the company you should hire. The relationship developed between you and the solar advisor is key to your future happiness.

I’m in Las Vegas learning and sharing with the FAFCO folks, and let’s just say I’m feeling lucky… not just in the Sports Book, but because of the valuable information and face time we will get this week. This is the time of year we all get a good status check and go over trends in the industry. Serious meetings – with a little fun sprinkled in.

Naturally I was reflecting on the plane about the “gamble” of going solar. Is it a safe bet? What is the risk/reward trade off?

If I head down to the Casino and drop $100 on red, there is a 52.63% chance that I’m walking away with nothing and a 47.37% chance I’m heading home with $200 stuffed in my wallet (much less after taxes).

There are lots of solar energy options out there, but the odds on most are extraordinary. For example, a solar pool heater is 100% sure to heat your pool. Every single day of the year, your pool will be warmer than an unheated pool, with no additional cost, providing years of enjoyment. There is essentially no risk. As long as you have a suitable place to put panels, the only question you have to ask is whether you want it or not. It’s not a “gamble.”

Solar electric panels will provide electricity to your home every day, some days more than others, but within a reasonably predictable range over the long run. If you expect the sun to continue to rise for the next 40 or so years, it’s a pretty good bet! Unlike securities investments, and Roulette for that matter, there is virtually no chance that your bet will not pay out.

Does that mean I won’t set foot in the Casino this week? Too late for that! I consider it entertainment – a totally unsecured bet. When I get home, win or lose, I can look up at my solar panels and bask in the glow of the safest bet I’ve ever made.

Unlike the southern tip, the northern end of North Captiva, FL, not accessible by land vehicles, actually has utility electric power available. Just like any mainland homeowner, this one wanted to offset increasing utility bills with solar energy. Working on an island is obviously a challenge, but our amazing crew pulled off this 4.6kW SunPower solar photovoltaic system in two days.

Fafco Solar crew takes a moment to enjoy island time after a North Captiva solar photovoltaic installation.

This system is comprised of fourteen SunPower 327W modules, among the most efficient modules commercially available. Paired with a SunPower branded SMA SB-5000US inverter, this system is expected to cover the majority of this homeowner’s electrical consumption. The system was installed to meet the Florida Building Code’s 170 mph design wind speed requirement, and being in close proximity to the water, required additional safety factors to secure the system against wind uplift. The system performance can be tracked remotely using SunPower’s online monitoring system and via mobile devices.

Net Metering, the concept and laws that allow solar electricity producers to connect to the grid and sell back energy, is under attack in the United States. Florida has been spared from the recent trend of utility companies working publicly to repeal or amend Net Metering laws. Utility companies in other states have taken various public and well-funded measures to repeal Net Metering laws or to make Net Metering less attractive to solar energy customers. For example, Arizona utilities recently succeeded in adding a fixed charged for solar producers based on photovoltaic system size. While it was opposed by the solar industry and the final amount was far less than proposed by the utility lobbyists, it was seen as a victory for the utility industry and a dangerous precedent by the solar industry.

Florida is particularly vulnerable because Net Metering is virtually all we really have to encourage solar electric (PV) installations. Lack of state and sensible utility rebate programs puts Florida way down the list of states in terms of new and existing installed solar electric capacity. As a result, Net Metering opponents likely see Florida as a blip on the radar, choosing to focus their efforts elsewhere. The loss or instability of Net Metering in this state would be devastating to the industry.

Opponents of Net Metering in other states are pushing their agenda under the guise of less regulation, less government, and lowered solar subsidies. This is the same utility electric industry that would not be possible without strong regulation, government protection (monopoly status), and massive fuel subsidies and tax breaks. This is a power struggle (pun intended).

Here are some things you can do to keep up to date on Net Metering in Florida and help preserve your right to produce your own energy at an economically viable rate:

• Follow U.S. Rep. Kathy Castor (D-Tampa/St. Petersburg, FL) and State Rep. Dwight Dudley (D-St. Petersburg) who are pushing for energy policy reforms in Florida.
• Read the Florida Net Metering Rule, Rule 25-6.065, F.A.C.
• Join Net Metering in Florida and watch their video below.

I left my phone in the living room last night, and awoke in panic when I saw my charging cord dangling on my nightstand. Being without my phone makes me feel naked. Alone. Rendered useless.

Okay, maybe it’s not that bad, but I do have a bit of an iPhone addiction.

It got me thinking… Could I do my job without my phone? Could my employees do theirs? What would solar energy sales and contracting look like without our phones?

The phone has long become “not a phone” at this point. Calling people still happens, of course. Of the time I spend “on my phone,” I would guess about 5% is actually spent communicating verbally with someone. Just off the top of my head, I can say that solar contractors use their phones for:

• Taking presales and post installation photographs
• Measuring roof angles
• Recording roof measurements
• Reviewing equipment data sheets
• Studying equipment manuals and troubleshooting guides
• Going over commissioning and post installation checklists
• Checking the weather
• Accessing site service records
• Preparing quotations
• Accessing property ownership data
• Checking status of permits
• Researching building code issues
• Calculating wire and conduit sizes
• Performing site shade analyses
• Estimating system performance using computer models
• Setting up solar energy monitoring systems
• Monitoring system performance
• Mapping prospective solar installation locations
• Administering company website and social media presence
• Writing this blog (I’m doing it now!)

… and probably 100 other things that I’m not thinking about right now.

Our phones have become indispensable, and that is no different for the solar contractor. Hopefully I will remember to plug in my phone tonight. Fortunately, I do not rely on my phone as an alarm clock.

Signing off – battery at 7%.

Solar pool heaters are usually installed as an afterthought, which means we often need to get creative with plumbing. Obstructions created by windows, doors, gutters, electrical equipment, and sometimes the pool equipment itself can present quite a challenge.

I’m always impressed with how our guys can visualize a plumbing run, select the best route, and execute it with a combination of fittings.

It’s funny that after years working with Fafco Solar, I can often identify the installer based on how they built a valve manifold or ran plumbing around a gutter. In this picture I have to admit that I have no idea who did it. It’s just perfect – and any one of our guys could have done it. It follows existing lines and could easily be painted to match the house color. It looks purposeful.

We often end up cutting out a bunch of plumbing at the equipment pad, even if it’s not specifically included in the contract. Cleaning up existing plumbing is just part of a professional solar pool heater installation, and I’m proud to say we have the most professional group of installers out there. Whoever did this, great job!

In my last article I explained that a Hybrid Solar Pool Heater is a combination of a solar pool heater and an auxiliary heater, either an electric heat pump or a gas heater. Hybrid systems can be an excellent choice, bringing together the benefits of each heat source while minimizing the drawbacks of each. In this article I attempt to explain and compare the various pool heating options available to Southwest Florida pool owners.

The three most popular pool heaters that I will describe are solar pool heaters, electric heat pumps, and gas heaters (LP or natural gas). Geothermal heat pumps are also an option, but are very infrequently considered due to the initial cost and complexity.

Solar Pool Heating System

Solar Pool Heaters

Features

• Year-round heating
• Essentially no additional operating costs.
• Very low maintenance.
• Environmentally friendly.
• Affordable initial cost.
• Long lifespan.
• No moving parts.
• Essentially no noise.

Drawbacks

• Performance limited based on the weather.

Conclusion

Naturally I started with the bread-and-butter product of the local solar energy industry, and it’s what we try to steer people into. Solar pool heating offers the luxury of a year-round heated pool with little to no operating and maintenance costs. Solar pool heaters can keep your pool at temperatures about 10ºF above unheated pool temperatures, and up to 15ºF when using a pool cover. Because unheated pools rarely drop below 65 degrees in Southwest Florida, temperatures considered warm enough by most are attainable virtually year-round. In the spring and fall, solar heated pools are luxuriously warm, and in the summer, spa-like temperatures are often reached if heaters are not turned off.

If you demand a particular temperature every day of the year, solar alone may not give you what you want. Believe it or not, people call us wondering why their pool isn’t 85 degrees when it’s 50 degrees and cloudy outside. After a cold spell, it can take a day or two to reach desired temperatures again. Despite these limitations, the trade-off of free heated pool water is a very attractive option. Not many people desire to swim when the ambient temperature is below 65 degrees anyway. Solar pool heating is the most efficient way to heat a pool in terms of total heating performance delivered.

Electric Heat Pump

Electric Heat Pumps

Features

• Affordable initial cost.
• Moderate heating speed.
• Economical heating during good conditions.

Drawbacks

• Moving parts.
• Moderate to high maintenance costs (outside of warranty).
• Moderate service life.
• Noisy.
• Energy hogs, especially in cold weather.
• Poor performance in cold weather.

Conclusion

Heat pumps are similar in cost to solar pool heaters, but have ongoing costs of electricity. Dealers and manufacturers claim “$1/day” heating performance, but the truth is in the small print. This analysis assumes a modest temperature, not warm enough for many pool owners, and exclusions are made for times when weather is cold. Why is this? Heat pumps perform poorly when the outside air temperature drops.

Heat pumps work by taking latent heat in the air and transferring it to the pool water through a heat exchanger. This is done by compressing and evaporating a refrigerant, just like you home’s air conditioning system, except in reverse. You will notice that cool air escapes from the top of the unit – that’s the “cold” coming out of your pool, or conversely the “heat” that is being put into your pool. If the outdoor temperature is high, especially in relation to the pool temperature, heat pumps perform great, costing relatively little to heat up a pool. The problem is, most people want to heat their pool in sub-optimal weather conditions. Similar to solar pool heaters, performance suffers as conditions deteriorate. However, with heat pumps, poor performance means big electric bills.

Nonetheless, there is a good argument for heat pumps if you want to heat your pool sparingly when outdoor conditions are ideal. If you are an infrequent swimmer, willing to plan ahead, and willing to pay for electricity to heat your pool, heat pumps may be an acceptable alternative for you.

Gas Pool Heater

Gas Heaters

Features

• Fast pool heating.
• Reliable pool temperatures year-round in any condition.
• Low initial cost (excluding tank installation and hookup if necessary).

Drawbacks

• Extremely high operating cost (fuel).
• Maintenance, especially if heavily used.
• Limited fuel source (if tank-fed).
• Short lifespan.

Conclusion

Gas heaters are superstars when it comes to heating speed. You can raise the temperature of a pool by multiple degrees per minute in any conditions, limited only by the rating of your heater(s). The initial cost is often lower than a quality heat pump or solar pool heater, but costs for buried tanks can connection can offset those savings. Lifespans (and warranties) of gas heaters are shorter than heat pumps, especially if heavily used.

The major drawback is operating cost. Because gas heaters are less efficient than heat pumps, it takes more energy to develop the same amount of heat. LP and natural gas are very energy dense, but also very expensive. Imagine heating 15,000 one-gallon pots on your gas stove. It takes a LOT of gas to heat water. Heating your pool every day to a set temperature can easily cost hundreds of dollars in sub-optimal conditions.

However, if you are the type of person that doesn’t swim often, doesn’t want to plan ahead to heat your pool, absolutely requires a set temperature year-round, or has money to burn (pun intended), a gas heater might be a good choice for you.

Overall Conclusions

You can quickly see that there are great features and unavoidable drawbacks to each pool heating option. With a little thought, it becomes apparent that a combination hybrid solar pool heating system may be the ultimate option. If you can afford the upfront cost, you can let a solar pool heater take on the heavy lifting, heating your pool year-round to adequate temperatures most of the year, and “topping off” the pool to desirable temperatures when conditions are not quite good enough to meet your needs. In my circumstance, a solar pool heater with a gas backup is the best option. I’m spontaneous and infrequent with my pool use, and willing to bite the bullet and pay for gas when I want to swim in 50 degree weather on a whim (disclaimer – I have an unheated pool because I actually rarely use it, refusing to get in unless it’s 85ºF+ outside). If you are an avid swimmer for exercise, but willing to stay out of the pool when outdoor temperatures plummet, a solar pool heater with heat pump combination may be best for you, providing desirable temperatures most of the year at a reasonable operating cost. If you swim when the weather is nice, don’t want ongoing operations and maintenance costs, and love free super-hot water when available, solar pool heating alone may make the most sense for you.

Some in the industry call a solar pool heating system with a heat pump or gas heater a Hybrid Solar Pool Heater. I prefer to call it a solar pool heater with auxiliary or backup heater. The word ‘hybrid’ is a bit overused in the industry, and can be misleading.

Integrating Solar Pool Heaters with existing heat pumps is common.

Nonetheless, pairing an auxiliary heat source with a solar pool heater can be an ideal solution for some people, especially those who demand particular pool temperatures year-round. If you want your pool a particular temperature all the time, and operating cost is a secondary concern (cost is rarely a complete non-issue), you might consider installing a solar pool heater to reduce the demand on electricity or gas auxiliary heaters. Solar pool heaters can be installed concurrently with, or as an addition to an existing heater.

Solar Pool Heaters can also be connected to existing automation systems. Most people with hybrid solar pool heating systems use auxiliary heaters on an on-demand basis, whether controlled manually or with an automated controller. Automation systems can use what’s called solar priority mode. This allows solar to operate when practical, and backup heaters to operate when solar heating is not feasible, to attain a desired temperature. This often results in the best of both worlds, balancing heating expectations and energy savings. However, solar priority mode can also result in unneeded and wasteful auxiliary heating costs when the pool is not being actively used.

In my next article I will explain the pros and cons of each heating system. While a single heating source may work for you, you may find a hybrid solar pool heating system is best suited for the way you wish to use your pool.

I just received my FPL Solar Rebate check for the solar photovoltaic system I installed at my home. Needless to say, I’m a happy man today. FPL has a highly competitive rebate program that grants funds to about 300 lucky residential customers per year. The maximum rebate amount is currently $20,000 for a 10 kilowatt rated solar energy system, covering about half of the typical cost. The Federal government kicks in another 30%. The bad news is, the rebate funds are exhausted for 2014. The good news – plummeting PV prices have made photovoltaic systems reasonable investments without utility rebates!

My $20,000 FPL Solar Rebate Check!

FPL rates for Bonita Springs, FL residential customers effective January 2, 2014, not including taxes.

Did you notice your latest bill from FPL hit you a bit harder in the pocketbook? Effective January 2, 2014, FPL raised rates for residential customers by about 5%, caused mostly by increased fuel charges. This change, approved by the Public Service Commission, also increased the non-fuel base electricity charge slightly. The fixed customer charge remained the same.

Bills with the higher charges are arriving in mailboxes now. Want to fight back? Fuel and non-fuel consumption is reduced by conserving energy or by producing your own energy with solar energy or other renewable energy sources. The best part about solar energy is that you shave off the most expensive energy first (your consumption above 1,000 kWh per month).

At my home, I’m not concerned much because, while I have the same rates as everyone else, my consumption is almost completely offset by solar energy production.

If you’re tired of ever-increasing energy rates and want to hedge against energy inflation, solar is the way to go!

Master Solar Pool Heating Installer, Jeremy… always smiling… installing a valve manifold.

The 2014 solar pool heating season is in full swing, and our team is working hard to meet an aggressive installation schedule. This is our busiest time of the year – the combination of a high seasonal population in Southwest Florida and cool pools with great outdoor weather makes for a lot of phone calls. If you want solar pool heating for the best part of the swimming season, NOW is the time to get on our schedule.

2014 happens to be Fafco Solar’s 40^th year in business! To celebrate, our company’s owner, Dan, is spending forty Fridays in the field working alongside our installers. This is a great opportunity to see the challenges and successes of our hard working young men as they install systems, just as Dan did years ago. The basic concepts have remained constant, but some of the materials and techniques have improved throughout the years through experience, building code changes, and component availability.

One of the big innovations we have embraced in recent years is the availability of affordable variable speed pumps. These pumps are huge money savers, and work well to balance energy savings with pool heating performance. While electronic pool automation systems have been around for many years, the need to interface with variable speed pumps and solar pool heating systems has become a bit more complex, and we are on the leading edge of the learning curve.

Our goal is to install well-performing and long-lasting solar pool heating systems, and Dan has already brought back a list of observations from his first day in the field that will surely result in further improvements to our installations, solidifying our lead as the most advanced solar pool heating company serving Southwest Florida. This will be our best season yet, and we’re looking forward to a successful 40th year heating pools in Southwest Florida!

Stay tuned for updates and observations from the field at Dan’s blog, http://www.gosolarenergyforlife.com.

My wife will tell you that I was screaming at the TV last night while watching an episode of CSI. I’m one of those guys that points out every little factual mistake in TV dramas. The crack team of CSI agents were trying to determine which home in a neighborhood was using inordinate amounts of energy to identify a drug grow house. They had obtained the “energy” usage of a neighborhood of homes, and identified a home that consumed 5,300 “kilowatts” in one month – a sizable amount of energy supposedly. The problem is, a kilowatt is a measure of power, not energy.

It’s been a couple of years since I discussed the difference and relationship between power and energy, two words that many people use interchangeably, including CSI script writers apparently. Solar power and solar energy are often misused phrases as well, and it’s important to understand the two concepts to evaluate solar energy system performance (note that I called it a solar energy system).

To recap my previous post, energy is power over time. Power measures the instantaneous output (or input). Power is the ability to do something (to do work in terms of Physics). Energy is the amount of power consumed, or work performed, over time. We “consume” or “produce” energy in our homes and businesses, not power.¹

In theory, the CSI team could identify a potential grow house if they were able to see how much power was being consumed. In fact, it might even be easier to use power as an identifier, but they were clearly using energy figures to make their analysis.

Yesterday my 10kW rated solar energy system produced energy in the amount of 31.1 kilowatt-hours, but barely got above 8kW of power production at any time.

How does this relate to solar energy?

What can be confusing is that solar energy systems are often (usually) rated in terms of watts or kilowatts, which are measures of power. When you go to buy a solar electric system, you may be quoted a “5kW System.” That system rating is a measure of power – the ability to create energy. However, what you really care about is how it will affect your electric bill, or how much usable energy the system will supply to offset your utility bill. So why do solar energy contractors sell solar energy systems in terms of power, not energy?

The first answer is that it provides an apples-to-apples comparison point for you to make a purchasing decision. While all solar equipment is not created equally, at least there are standard test conditions on which we can compare component and system ratings. Using energy production as a comparison point can be dangerous because assumptions made by manufacturers and contractors may be biased or have different degrees of conservatism applied. Since there are various models and sources available for energy production data, identical systems could be quoted as producing dramatically different energy values.

The second answer is that solar energy is variable. We have good models that estimate solar energy production, but we can’t predict the weather precisely. We can’t tell you exactly how much energy your system will produce in a day, week, year, or even a lifetime, but we can come close. Predicting precise solar power at any given instant is even more impractical. Nonetheless, we have standardized ways of determining maximum power output that can be duplicated and tested, but we have no definitive, accepted, or regulated way by which we can provide an energy rating. Furthermore, we would have to wait 25+ years to prove out energy production on a given system.

The final answer is that it’s far too dangerous to “promise” an energy production figure unless the promise is grossly underestimated, which puts dealers at a competitive disadvantage. In some states, power production agreements (PPAs) are popular because the system installer is paid for energy produced rather than charging you up front based on a power rating. PPAs typically skew benefits to the seller, but do provide a way for people to get into solar with low or no up front cost. Note: PPAs are not legally available in Florida due to arcane and outdated laws protected by well funded utility lobbyists. Nonetheless, PPAs often provide the power ratings of systems for comparison purposes.

Would you buy one car over another just because it’s the same price, but has double the horsepower? Of course not – fuel efficiency, size, and many other factors come into play. more importantly, how often do you utilize “peak horsepower” anyway? That brings me to my next point…

The rated power of a solar energy system will almost never be seen. Since the power rating of the system is based on standard test conditions of the solar modules, a lot of things have to come together for peak power to be observed. The sun’s angle, irradiance, temperature, haze, cloud cover, time of year, time of day, module soiling, age degradation, shading and other factors all impact solar module performance. In addition, solar modules are often, if not usually, rated well above the inverter output rating. For example, it’s common practice to pair a 250W solar module with a 215W microinverter.² As a result, the theoretical power limit of the system can by substantially lower than the rated power that is given for comparison purposes when proposed to a potential buyer. That’s okay – remember that we are ultimately concerned with energy production, not power output. “Oversizing” the solar modules relative to the inverter typically results in overall greater energy production and cost effectiveness.

Misunderstanding about how power and energy differ is prevalent, and it’s frustrating to solar energy professionals, as proven by my recent outburst at an inanimate object. In many countries you can prepay for energy in “units,” and I have found that people there are much more cognizant of energy use. Knowing how much power your devices and appliances require is only half the battle. Understanding energy, power over time, is critical. The same applies to solar energy systems – the focus should be on energy production, not power output alone. Nonetheless, we are stuck with power ratings to provide meaningful comparisons.
¹ Energy cannot really be produced or consumed (created or destroyed) – it’s just transformed – see the Physics Law of Conservation of Energy.
² For a discussion of why, see Enphase’s “module rightsizing” paper here.