Solar a Mortal Threat to Utilities

It appears that the public is waking up to the obvious threat that solar is to the status quo energy providers.  We live in an age of accelerating change and disruption.  I wrote last year about how solar will continue to expand rapidly into the general market regardless of what the utilities do to discourage it.  What today's Wall Street Journal piece means to me is that the national dialog will start to become even more rancorous with respect to clean energy issues.

David & Goliath -- Distributed Generation vs Traditional Utilities

Unfortunately, there is some truth to the fact that solar is currently only feasible for the wealthy and that federal tax credits could be seen as a transfer payment from average tax payers who can't afford solar to wealthy ones who can. The consequence of this dialog will be the elimination of federal and state incentives for distributed generation systems. Solar already has unsubsidized grid parity in many markets so growth their will continue to drive down the global costs for installing solar.  Companies like Solar City & Sun Run will have to re-model their current business plans, and I doubt they will weather the storm very well since their profitability is so tied to the current incentives.  New installation company concepts will emerge though and I think more traditional contractors will finally get into the game.

http://greenzu.com/solar-energy-political-cartoon

Utilities may go further and try to ban the connection of solar systems to the grid. Standalone solar with back up systems will be ready for the market by the time this happens though. Essentially this will be the last arrow in the utility's quiver to stop the rising tide of distributed solar. At that point, we'll probably cross the tipping point where they don't have enough rate payers to maintain affordable rates. Then things get really ugly.

While I am advocate for progress and technological innovation, crippled utilities will be a major issue for an already crippled political system to address. Add this difficult situation to the already huge list of complex issues that we don't seem to be able to effectively address (national debt, climate change, social security insolvency, resource depletion, population growth). The brinksmanship games we are playing will take on an entirely new dimension when we start to have daily brown outs and extended power outages.

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!

Why propane users need to investigate solar

Propane is a dominant heating fuel in rural parts of the US. Propane users typically purchase a large volume of fuel all at one time. It would not be unusual for them to have to write a check for $1250 1-2 times per year.  What this means is that like with a solar water heating system, they are pre-paying for the fuel they use to heat their home and domestic water.  Unlike with natgas and electricity customers, it's not great a leap for propane consumers to understand how a solar water heating system would benefit them in the long run since they can't spread payments out over time.  Additionally, propane customers tend to come from agricultural communities were communities tend to have a longer view of financial prudence.

To give a little flavor of the economics, I modeled a 2 panel, 70 gallon tank system pitched at 30 degrees facing due south in Des Moines, IA.  Using a solar water heater with propane back up tank, the homeowner would save about $450/year in water heating costs (using $2.50 per gallon for propane).  Switching to an electric back up tank with the same solar system, would save this homeowner about $500/year.  Either system would reduce the home's greenhouse gas emissions by about 1.3 tons of CO2.  Even with only the federal tax credit, this system would have a 10-year payback or 6.5% rate of return.  If propane prices go up to $3.50, the payback is cut to just over 7 years.  If your state has any additional incentives, you'll see paybacks as low as 5 years. 

A couple of good resources for propane related information would be Build With Propane and this propane supply outlook paper.

Save now and save later with solar. With a solar system, you fix your energy costs today and hedge against rising prices tomorrow.

Ways to use solar water heating in a home

I love to talk and write about solar technologies.  My goal has always been to encourage all things solar because I think awareness of one type of solar system will benefit all the others.  Solar PV is the darling of the clean energy world--for good reason.  It produces versatile energy in a clean, quiet, safe, and predictable way.  The major downsides are its current cost and efficiency.  While these problems will be overcome with time, solar water heating is ready today.  It's still fun for me to see a home making 130 degree F water just from the sun on a cold March afternoon in Chicago. While my primary focus is on solar domestic water heating, I wanted to expand on some other ways a solar water heating systems could be used in a normal US home.

Solar Domestic Water Heating
The most simple way to harness the power of the sun in a home (after daylighting and applying passive solar design principles) is to heat up domestic (drinking) water with a solar water heating system.  This technology is well-established and easily adaptable to almost any home or building with a hot water demand.  Solar domestic water heaters are sized to reduce the water heating bill of any home in the US by 60-80%.  A typical home would need about 2 solar panels (50 - 80 sq. ft.) and about an 80 gallon storage tank.  Any solar system of this type will have some sort of back up water heating component to ensure that the residents have a steady supply of hot water despite the solar conditions of a particular day.

Solar Space Heating
If a homeowner is looking to squeeze a little more heat out of a solar water heating system and try to contribute some of this free energy to heating the home, there are a couple of ways to accomplish this. Not to be confused with a solar air heater, I'm still talking about an automatic system that heats up a liquid for use in the house.

Option 1:
Homes with an existing forced air furnace could install a solar water heating system sized to heat nearly 100% of the domestic water heating demand plus make a contribution to space heating (~25% or so).  A system of this sort would have about 5-6 solar collectors (150 - 240 sq. ft.) and about 200 gallons of storage tank volume.  This solar system would operate just as in the diagram above but have a second heat exchanger for transmitting solar heat into the return of the forced air furnace.  The second solar heat exchanger would pre-heat the air returning to the furnace so that it has less of a temperature rise to meet the desired room temperature.

Water-to-Air heat exchanger that would go in the air return side of a forced air furnace

Option 2:
Solar water heating systems could also deliver space heat through the use of a fan convector. A comparably sized system to #1 but without integrating the space heating delivery system to the furnace.  The homeowner could install a system which would automatically divert solar heated fluid through a fan convector(s) strategically placed in the home.  In this scenario, heat from the fan convector would warm the space as it becomes available from the solar system.  This contribution would help keep the thermostat from activating the primary space heating system as often.  A good application for this option might be for a vacation home that needs to be kept warm enough to prevent the pipes from freezing when not being occupied.

Myson fan convector unit on the left. Probably VELUX roof windows above.

Option 3:
Some homes have a hydronic heating system where medium temperature (140 degrees F) water circulates between a water heating unit and various zones throughout a house.  This heating system lends itself to a nice merger with a solar water heater.  As the hydronic fluid returns from a zone in the house depleted of heat, a heat exchanger from the solar storage tank could add heat to the fluid before it reaches the traditional heater.  This is one of the most efficient ways to deliver heat from a solar heated fluid to a living space.  These solar systems could be sized to be rather large (8-10+ collectors) depending on the space heating goals the home may have.

Tubes under the floor deliver heat to the room in a hydronic heating system

For any of these options, this style of heating system isn't usually the best primary space heater for a home since the winter months (when you want heat) typically correlate to shorter days and thus less solar energy to be harvested. Like with a solar domestic water heater, however, a solar space heating system will reduce the number of BTUs the traditional heater will have to deliver to the house even during the winter months.

Solar High Mass Systems
In this variety of space heating using solar energy, a solar water heating system heats up a large mass (many, many tons) of sand under a home which then slowly releases the heat over the winter months.  Owners of these systems begin to direct the solar heat to the sand mass which extracts the heat through a matrix of tubes embedded in the sand.  Many homes in cold climates are accomplishing 75%+ of their space heating needs through this style of solar water heating system.  Not all that complicated or that expensive, Solar High Mass systems will require a bit more homeowner involvement to make them work effectively with their lifestyle.  This also would need to be designed into a new home from the start since so much sand or other high mass material would need to be under the living space.  The Artha Sustainable Living Center is a great resource for more information on these systems.

Solar Assisted Ground Source Heat Pumps
A ground source heat pump (GSHP), aka geothermal, is a device that heats and cools a building by moving heat to and from the living space to a series of pipes in the ground.  Additionally, a GSHP can contribute to the domestic water heating needs of a home as well.  These systems function in a very similar way that a kitchen refrigerator does except the ground is the heat sink in the cooling cycle versus ambient air as with the refrigerator.

Imagine an array of 3-5 solar collectors on the south facing roof to integrate with the GSHP

A rather new implementation of a GSHP adds an array of solar water heating panels to the mix.  This Solar Assisted GSHP offers a few advantages over a standard GSHP:

1. The solar collectors can add heat to the ground all summer to allow the GSHP to be more effective at space heating in the winter.
2. Solar panels can pre-heat domestic water in the summer so that the heat pump may not need to function at all to provide domestic hot water when the weather is temperate.
3. Added heat can come from the solar collectors in the winter to augment the space heating cycle.
4. During the spring and fall, the heating load may be low enough that the solar collectors could provide enough space heat so that the heat pump would not need to operate.

GSHPs slowly deplete the ground heat immediately surrounding the bore wells over the life of the system.  For this reason, many green building codes don't classify this technology as "sustainable" or "renewable."  Coupling a solar array to the GSHP is a way to make this excellent technology truly sustainable.

The solution to our energy problems rises in the east every morning.

Free Hot Water with Every New Home!

Image courtesy VELUX America

In a recent NY Times article covering issues surrounding the ongoing housing slump, an interesting sales tactic caught my eye.  One builder outside Chicago is offering a credit at a local GM dealership with the purchase of a new home and he's not the only one.  While this promotion appears to be working to generate some sales, I have an even better idea for home builders.

In a market where new homes are competing against plummeting existing home prices driven by foreclosures, builders must differentiate their product on things other than price.  New homes must offer features that you can't find in older ones if they have any hope of being attractive.  One thing that almost no existing house has is an integrated solar water heating system.  A new home builder looking to stand out and make an impact in the minds of buyers should offer "Free Hot Water with Every New Home!"  Unlike with a free car, a free solar water heating system would reduce the homeowners' monthly power bills, reduce their carbon footprint, appreciate in value as fuel costs rise and make a leadership statement that appeals to 94% of us.  On top of that, local renewable energy creates good, local green collar jobs.

Solar water heating works everywhere in the US with almost immediate payback on invested dollars when financed as part of a standard home mortgage.  In an economic downturn, the best way out is to commit money to long term infrastructure enhancements.  In the past, this has meant roads, dams, bridges, etc that provide value for many years after the upfront costs were recovered.  Now we can add renewable energy to that mix.   Let's commit to making this sound investment today so that we can reap the benefits for decades to come.