Solar Thermal is Hardly Dead

A recent article with the confrontational title "Solar Thermal is Dead" touting Heat Pump Water Heaters (HPWH) coupled to PV systems as replacement to solar water heating (SWH) made a big splash in the solar energy and green building web-o-sphere. This piece was a valid thought experiment about where technology may head but misses a few key points for why solar thermal systems are still a better way to heat domestic water than a HPWH/PV system.  Here are three counterpoints:

1. HPWHs aren't a cure all 

HPWHs move heat from the surrounding environment into a tank of water through the heat pump cycle using mechanical work.  Just as with space heating and cooling, this can be a very energy efficient way to achieve a temperature goal versus traditional HVAC equipment.  There are a couple of problems with HPWHs however.  

Energy efficiency doesn't have to be about reduced quality of life

First of all, the "mechanical work" component of them makes a good bit of noise just as power-vented natgas water heaters (another higher efficiency water heating appliance) have a noticeable fan noise.


Secondly, HPWHs don't work as well if the surrounding air is cold.  Placing it in a cold basement or garage will lead to less than optimal performance that the article's author used to compare this technology to SWH.


Thirdly, the efficiency factor of a HPWH is based on it operating in hybrid (heat pump) mode.  Just as with SWH, HPWHs have a back up element (usually electric resistance heating coils). When a big call for hot water such as to fill a bathtub, might outpace the hybrid mode of the water heater to recover the volume of water required.  In this case, the electric resistance heater kicks in and the water heater becomes no more efficient than a standard tank style electric water heater.

2. The maintenance on a SWH is overstated

and the author underrepresents the maintenance on a PV system.  A trained solar water heater contractor can install a complete pressurized system as a retrofit to a home in less than a day (I've personally seen this over a dozen times). Once system pressure is reached, any solar loop leaks are immediately apparent and are unlikely to spontaneously occur in the future. Circulating pumps are a mechanical item in a SWH system but have little stress applied to them since they have minimal head pressure to overcome. These circulating pumps are also low cost items to replace if they do fail. Solar fluid replacement is a non-issue with a properly sized system since stagnation temperatures would be reach less often.  I'm not sure why the author brought of tracking as this is rapidly becoming a non-issue in both PV and solar thermal as module prices fall; with the fail rate on trackers, it isn't really something to bring up in a negative comment about maintenance on SWH anyways. 

There are companies in business just to do maintenance on PV systems

PV isn't completely free of maintenance either. Inverters are the short pole in a PV system and they are significantly more expensive to replace than any piece of a solar water heater.

3. PV takes up too much real estate

I was going to address the author's underestimate of the installation cost of a PV system. He was called out about this in the comments to the article and admitted that his 1.4kW installation price was dependent on installing a 9kW system along with it.  I think that's a huge if...

SWH array fit between architectural roof facets

In any case, this ties into my final argument for why a PV/HPWH hasn't killed SWH and won't for some time.  PV takes up way too much space to be practical for many homes.  Check out the house above that I was working on last week in Michigan. There were too many roof facets to find a spot on the south face for much more than the 3-panel solar water heating system that we installed. You couldn't fit in enough PV between the dormer below and valleys on each side to offset the energy that the solar water heater would.  For you solar techies out there, good luck on convincing either architects or home buyers that plain expanses of roof are aesthetically pleasing; architectural roof elements aren't going anywhere so solar will have to work around these.

Tale of 2 arrays.  The SWH collectors on the left produce the same amount of energy as the PV on the right.

Conclusion

I'm a big fan of all things solar so I don't want to come off as a PV basher. My point is to highlight that there are appropriate applications for certain technologies but not any one thing is a solution to everything. Eventually PV may fall so low in price and become much more space efficient thus relegating SWH to relic status. This hasn't happened yet. Heating water with the sun will continue to be best done with a solar water heater for many years to come.

Let's keep the intra-solar squabbles to a minimum--we have bigger enemies to address

Energy Factor and water heating technologies

A different sort of green home

According to the US Dept of Energy's website, energy factor (EF) indicates a water heater's overall energy efficiency based on the amount of hot water produced per unit of fuel consumed over a typical day. This rating applies to a variety of water heater equipment: tank-style (storage), tankless/on-demand, and heat pump water heaters (HPWH).


Solar water heating has a very similar rating called the Solar Energy Factor (SEF).  Solar equipment is evaluated for thermal performance efficiency by an organization called the Solar Rating & Certification Corporation (SRCC).  The federal tax incentives for the installation of solar equipment are contingent on the solar water heating equipment having been evaluated by the SRCC.  The SRCC developed the SEF for the purpose of comparing solar water heating systems to a standard 50 gallon residential water heater in an apples-to-apples sort of way. Many natural gas utilities use the industry standard EF rating system to award rebates for high performing water heating equipment.  Since SEF is the solar equivalent of EF for a standard water heater, my view is that solar water heating systems that meet EF ratings for high performance equipment should qualify at a minimum for the existing utility rebate programs.


So how do different water heating technologies measure up with respect to energy efficiency?


Tank storage water heaters

Bradford White 40 gallon gas water heater

Typical residential storage water heaters range in size between 40 and 80 gallons.  This volume of water is heated up to the desired temperature (120 degrees F); the heating element or burner cycles on and off as a thermostat in the top portion of the tank detects adequate heat or not.  This is usually the least expensive water heating technology to install but is also normally the most expensive to operate. Recovery of the heat in the tank during and after use can be slower than with other water heaters which leads to the cold showers in high use situations.


EF rating for gas heated tank water heaters:

• Low efficiency -- < 0.62
• Medium efficiency -- 0.62 to 0.67
• High efficiency -- 0.67 to 0.82

EF rating for electric heated tank water heaters:

• Low efficiency -- <0.90
• High efficiency -- up to 0.95

Keep in mind that EF rating is only with respect to the energy efficiency of the appliance.  The electricity that heats the water in an electric tank model could be coming from sources with varying degrees of efficiency and environmental impact.

Tankless

Tankless water heater (top right) in conjunction with a solar water heater

Also called on-demand water heaters, these units heat water as it flows through the device.  They are capable of reducing water heating costs 10-20% due to the elimination of standby losses (constantly heating a tank of water even when no hot water is needed).  Tankless units come in electric, natural gas, and propane versions for different markets.  Not only are these a bit more energy efficient than tank style water heaters, they are also compact, wall mounted devices to save space in the mechanical room and they can provide almost unlimited amounts of hot water.


The EF rating for gas-fired tankless units ranges between 0.82 and 0.96. 


Heat Pump Water Heaters

From DOE

In a heat pump water heater, electricity is used to move heat from the air around the HPWH into the water tank versus directly heating the water with resistance coils.  Since the heat pump cycle can take a significant amount of time to heat or reheat a tank of water, electric resistance coils are included in HPWHs to augment the recovery of the water heating and thus minimize cold shower scenarios.  HPWHs can be very energy efficient and cost effective when the HPWH is operating in the heat pump mode; they revert to EF ratings of electric water heaters when the resistance coils kick in however.  Like with many things in the sustainable building world, efficient design is only part of the total picture.  How something is used in the real world effects its overall efficiency. 


EF ratings of HPWH in hybrid mode is 2.20 and fall off towards 0.93 in electric mode (average ~1.60).


Solar Water Heaters

In solar water heaters (SWH), the heat from the sun's radiation is transferred to drinking water during the day and stored in a tank of water for use throughout the day and night.  In homes where a 40 gallon tank water heater is appropriate, you'll find a 60 gallon solar storage tank. Because the amount of energy to move the heat from the solar collectors to the drinking water is minimal and the sun's energy is free, the operating costs of SWHs are the lowest of any water heating technology today. They are also the lowest carbon option when the system offsets fuel from gas appliances or electricity from coal-fired plants. SWHs have the highest upfront cost in the water heating space, but federal and state incentives exist to encourage their adoption since they provide a benefit to both the system owner and society as a whole.


Calculating EF from the SEF rating developed at the SRCC is done with the following equation: SEF x (1 - SF) = EF. SEF and SF (Solar Fraction) are calculations from the OG-300 report on each system found at www.solar-rating.org. EF ratings on SWHs range from 0.93 up to over 5.70 depending on the size of the system, location, and back up fuel option.


Summary
The less you pay upfront for a water heater, the more you pay over time.  As fuel prices of all sorts rise in the future, an investment in efficiency today will pay increasing dividends over time.

How to sell a solar water heater in a market with cheap natural gas

With the price of natural gas at a historically low point, selling a solar water heating system in natural gas water heater markets is a tough proposition. While we have to address return on investment as solar professionals, there are many other factors that go into a customer's decision making process about going solar. Solar water heating isn't for everyone so broad brush approaches won't work. The key is to target the right audience with the right message before you spend much time or money. The following is a guide to help you do this.

What to talk about

John Cole Cartoons

People are interested in distributed solar energy for a number of reasons.  Residential solar water heating continues to be an exceptional option in the portfolio of clean energy choices a homeowner has.  Energy cost savings is just one aspect of a clean energy purchase.  Make sure that you are talking about all the other reasons for pursuing solar.  Here are some good ones to start with and expand upon:

• Solar water heating (SWH) is a cost effective way to reduce home energy consumption by over 10%.
• Like electric vehicle purchases, SWH is a visible commitment to clean energy for a much lower sticker price than any car.
• When built into a new home, the net cost of a SWH is on par with the cost of a tankless water heater yet SWH outperforms tankless units in energy savings (EF of 0.82 for tankless vs 1.4 for SWH)
• While low now, the price of natural gas is set to rise with growing demand from electrical generation and transportation as well as with increasing scrutiny of hydraulic fracturing (fracking) practices. A SWH installed today is a hedge against rising fuel prices.
• Talk about the avoided costs & externalities of fossil fuels. Natural gas may be cleaner than coal, but it's hardly clean in comparison to solar water heating.
• Solar water heating creates local jobs--engineering, installation & service, sales & marketing, and distribution.

Tell the story to the right people

You need to maximize the impact of your messaging by positioning them in front of the right audience. The right audience is one that is both receptive and responsive to your point of view. To encourage a conversation and spur interest in SWH, the best approach is a combination of Facebook and blogging. Articles that address your messaging can't be neutral. You have to make a point either with your own blog posts or with comments on articles written by others. Your opinions may alienate some people, but those people are probably not receptive or responsive to clean energy issues in the first place--your target customer is. There are people out there who are concerned, knowledgeable, angry, and ready to act if they find a leader in their community with a solution that resonates with them. Solar is part of the solution and you are that solution provider.  Don't make any assumptions about who a receptive and responsive customer might be; stirring up a conversation about the issues that got you into the solar business in the first place will bring them to you.

Where to tell the story

Web marketing is a hot topic with lots of nuance.  It is an essential part of modern business and is redefining the fields of public relations, promotion, sales, and general marketing.  In the interests of getting you started today, I suggest working with the steps below.  Expand and modify as you get more comfortable and learn more.

1. Find an article that resonates with you and your team.  Get your friends, family or co-workers to suggest an article to post and select one.
2. Post the article to your Facebook business page (make a Facebook business page if you don't have one and encourage people to "Like" it).
3. Make comments on this post that tell your target audience why this article is important to you. 
4. Get all your friends, family, and co-workers to "Like" the article so their network sees it too.
5. Directly ask people to read and comment on your post (via email, phone, twitter, FilterTweeps,  etc).  
6. Repeat every workday.

Once you get comfortable with this daily effort, you can branch out a bit by writing your own blog articles.  Post it to your company website or some other website (Tumblr, Blogger, etc).  Use this as your Facebook link of the day and encourage the comments as suggested above.  Also while Facebook is the current dominant player in social media, explore using other sites like Twitter, LinkedIn, Google+, or any of the other growing number of websites to expand the reach of your effort.

Keep at it

Cheap natural gas makes for a difficult sales process for solar water heating. Difficult but not impossible. Continually remind yourself why you got into this business in the first place and find creative ways to connect with like-minded people. Tell people about your company and its goals.  Keep people continuously aware of your projects to build on successes. Help people connect their daily behavior to greater social trends. Be consistent, be informative, and be real. You'll begin to find that the right people will find you.

Talking solar at the CCGT

I spoke for the second time at the Chicago Center for Green Technology last Tuesday night.  The first time was last September and it went well enough for them to invite me back for another go at it.  My presentation covered solar water heating technologies in a broad way and has been set up to be a continuing education course for AIA architects.  Despite it being Valentine's Day, we had a rather large turn out with over 40 people in the audience.  The CCGT has been seeing strong attendance with all the their courses in this winter session.  I feel the general awareness level of the public is continuing to grow with respect to sustainable building practices and with solar technologies in particular.  The questions from the audience were more technical and specifically focused for projects that people are seriously considering.  I have even had 2 subsequent site evaluations from my talk for solar projects in Chicago from people interested in solar for their particular buildings.

 
I speak all the time about solar water heating and solar technologies in general so feel free to reach out to me about arranging a talk with your group!

The Atlantic's The Most Important Graphs of 2011 (Energy)

From The Atlantic's The Most Important Graphs of 2011

4. ENERGY, ENERGY, ENERGY

Oil Profits v. Oil Prices

"Big oil companies make larger profits when oil and gasoline prices are high.  These revenues come from the pockets of everyday Americans.  The five biggest oil companies - BP, Chevron, ConocoPhillips, ExxonMobil and Shell - have already made $100 billion in profits during the first three quarters of 2011 due to high oil prices. Yet they and other big oil companies have fought tooth and nail this year to retain tax breaks worth $4 billion annually." -- Daniel J. Weiss, senior fellow, Center for American Progress

The Most Disastrous Year Ever

"The National Oceanic and Atmospheric Administration reports that the United States set a record with 12 separate billion dollar weather/climate disasters in 2011.  Total damages were approximately $52 billion.  NOAA Chief Jane Lubchenco noted that "what we are seeing this year is not just an anomalous year, but a harbinger of things to come for at least a subset of those extreme events that we are tallying."  She noted that some of the increase is driven by climate change." -- Dr. Joe Romm, Senior Fellow and Editor of Climate Progress

A Century of Love for Oil and Gas

"Many conservatives have attacked the Obama administration's effort to invest in emerging clean energy technologies, including wind and solar electricity generation. Yet they defend longstanding tax breaks for the mature oil and gas (O&G), and nuclear industries. However, the federal government annually spends an average of thirteen times more money on the oil and gas industry compared to investments in renewable energy." -- Richard Caperton, Director of Clean Energy Investment, Center for American Progress

Our Competitors' Green Investments

"On the two-year anniversary of the American Recovery and Reinvestment Act, we should look back with satisfaction that we have seen the American clean energy industry through a rough period in the global economy. However, the United States risks ceding its gains and falling dangerously behind its competitors without continuing investment.  Many conservatives oppose such investments.   Without it, the United States will see an exodus of firms and capital to countries that  are growing their clean tech industries, particularly China and Germany. U.S. private-sector firms lament a lack of clear and consistent policy on clean energy. This stymies investment and slows job creation." -- Bracken Hendricks, Senior Fellow, Center for American Progress

Where the Green Jobs Are

"The failure of several clean energy companies that received loan guarantees have many conservatives increasing their opposition to such investments.  However, clean energy has been a bright spot in the sluggish economy.  The clean economy sector focused on clean energy--especially wind, solar, fuel cell, smart grid, biofuel, and battery companies--grew far more quickly than the economy as a whole. A Brookings Institution report found major job growth in clean energy between 2003 and 2010: Solar thermal and wind grew by 18.4 percent and 14.9 percent, respectively." -- Kate Gordon, Vice President for Energy Policy, Center for American Progress

Solar isn't a new idea

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.
                  - Thomas Edison

What does Japan's energy troubles teach us about our own?

I came across Mark Pendergrast's new e-book after reading a blog post he did recently for Renewable Energy World.  Japan has very few traditional energy resources at its disposal so it relies on fossil fuels imports and nuclear power to power its economy.  After the Fukushima nuclear disaster caused by the tsunami of March 11, 2011, popular support for nuclear power in Japan fell rather dramatically (as one would expect).  Imported fossil fuels for electricity generation, notoriously expensive anywhere in the world, became it's sole source of energy and put Japan in a tough position to re-grow its economy.

Japan's Tipping Point: Crucial Choices in the Post-Fukushima World

Japan now has a major incentive to adopt energy efficiency measures and install renewable energy systems which is what Mark wanted to explore with his book Japan's Tipping Point.  He does a great job of detailing the sustainability initiatives that have been promoted in different parts of Japan and providing commentary on their efficacy.  Despite major structural reasons to the contrary, the Japanese seem to continue thinking in a pre-Fukushima way.  The conclusion you become forced to consider is that they might not make the leap to the next generation of power infrastructure anytime soon.

I worked for a Japanese company (SANYO) a couple of years ago, based in the US to develop solar energy projects with their solar modules.  At the time, SANYO was the 7th largest manufacturer of solar photovoltaic modules and had the most efficient panel that was commercially available.  I was brought on as the solar leader of a new organization called the US Environmental Solutions Division.  The stated purpose of this division was to bundle various SANYO products with a clean energy focus together as a total solution sale.  It sounded like a great initiative at the time but ended up appearing to be more of a PR exercise to make SANYO branded products more attractive during its acquisition by Panasonic.  While I spearheaded a couple interesting projects like a solar charging station in Portland, OR, there was not much appetite for significant solar market development plans.

OMSI solar electric vehicle charging station for e-bikes and e-cars in Portland, OR

My experience with the Japanese left me with the impression that they will be hard pressed to make the difficult decisions they have to make to move off fossil fuels.  While SANYO was a world leader in solar panel production, they have now slipped out of the top ten.  The leadership seemed to be resting on their laurels for cell efficiency and this has allowed competitors to catch up to them and gobble up market share. Sharp and Kyocera have also lost ground to Chinese and Korean competition.  I saw confusion, indifference, and fear in SANYO with respect to exploring new ways to promote solar products in the US.  In a rather obvious application for solar, they wouldn't consider installing more than a token amount of their own modules on their own new solar wafer and ingot factory opened in Oregon in 2009.  This sort of project challenged their entrenched way of thinking; hype was more important than actually accomplishing something innovative and highlighted how collaboration across internal divisions was extremely difficult.

So what lessons does this teach us in the US?  As I've written before, Americans are cursed with substantial fossil fuel resources under our own soil.  With the Japanese being "blessed" with paltry resources and still unable to take decisive action towards renewable energy, things don't look so great for renewable energy in the US anytime soon.  The Japanese are not alone in their resistance to change with respect to energy.  The US with a population of almost 2.5 times that of Japan has about the same amount of installed solar PV.  US leaders continue to talk about nuclear as the hope for the future despite the obvious safety and economic troubles with it and despite no practical hope for new reactor additions anytime soon.  Wind farms get rejected for aesthetic reasons while coal continues to be our primary fuel source for electricity.

Bike & electronics charging solar canopy (concept)

Regardless, I continue to remain convinced that solar technologies will trump our other current energy options in a rather short period of time.  The cost curves of solar and it's O&M advantages with respect to everything else will win out; the environmental benefits will merely be icing on the cake.  Once we make the decision to go solar, the build out period will be much faster than most people realize.  I don't think the path to our solar future will be clear or easy however.  Some sort of major shock will have to get us all on the same page.  I would have thought Fukushima was that sort of shock for both Japan and the world.  Maybe not.  It's a naive thinker, however, who bets on things staying the same when radical change is the new normal.