Combination solar PV and solar thermal panels for swimming pools

Q:  Are you aware of solar panel company called FaFco they make a combination solar panel PV / Thermal….. The thermal output is about 10,000 BTU per 10 FT. SQ. These are making an impact in the swimming pool industry. Have you looked at these FAFCO .?

A: I have not heard of this panel, but it does not overcome the biggest issue with solar thermal panels which is that you cannot store the heat generated on a sunny day and use it on a cloudy day. With solar PV you can effectively store the energy because of net metering. However, using them to heat pool water is a better idea than using them to heat a house. I would have to check the economics compared to just installing solar PV and using it to power a heat-pump hot-water heater for the pool.

Q&A From High-School Students after seeing my webinar for homework:

Out of all of the jobs you have had, which has been your favorite, and why?My career was in biotechnology, not energy. We produced a new product that combined stem cells from the patient with a tube made from plastic nanofibers to replace the trachea or esophagus of a patient with something awful like throat cancer. My favorite moment was being in the operating room, dressed in surgical scrubs, with the first patient in the US, a baby girl, who was born without a trachea.
I’m aware of when you got this idea, but when you were getting your two degrees did you know that you wanted to enter into the environmental realm?No, not at all. My career in biotechnology combined science and business so it built on both of my degrees.
What made you first begin to capture data and really invest your time into making these changes in your home, as well as your lifestyle?Two things. First my kids were interested in it and second, I had to take time off work to recuperate from a nasty road accident. That was what gave me the time to do the research.
How feasible of an option is solar given that our area of the country doesn’t get as much sun as areas like Arizona or New Mexico? Is it more difficult to have more solar panels installed onto houses without flat roofs?Solar panels work in MA, many homes have them. It is sunnier in AZ but the subsidies from the state government are better in MA. Houses with south facing sloped roofs generate about 10% more electricity per square foot than a flat roof. Sloped roofs that face east or west generate about the same electricity per square foot as a flat roof.
Are there severe detriments to your solar panels because of the snow/New England weather?No, the snow just melts off within a few days.
You mentioned in the video that you bought a Tesla earlier in 2020, and that the cost per mile dropped to only 2 cents per mile. What might be a more cost-friendly option to teens and/or people who are looking to cut down on their carbon footprint related to transportation that can’t afford the up front cost of a Tesla?Leasing a car is a good option if you do not have the up-front cash.
Do you think the reason why people don’t change to a more environmentally friendly lifestyle is because it is too much money economically?This used to be the case, but today it is more that people do not know they can save money by cutting their carbon footprint, which is why I frequently do webinars to educate people that you can. The webinars are very effective – 72% of webinar attendees say they intend to install at least one of the fab four within a year.
What was the biggest hardship that you and your team had to overcome during your process to produce a zero carbon home?We have big windows in our house that look out over a large grassy area that attracts deer and even coyotes. My whole family was concerned that low-E triple glazed windows would look green and hence distort our wonderful views. I ordered sample panels of several different types of low E glass in double and triple-glazed glass and set them up on our deck so that everyone could see them before we bought them. The first round of samples all arrived broken so it was a very long and involved process before we decided on the final windows. We chose ones that were very clear and transparent on the ground floor and ones that were slightly tinted green on the upper floor. Now they are installed no-one thinks they have even the slightest green tint – but convincing everyone took a lot of work!
What is the hardest part/most difficult change to transitioning to a zero carbon footprint?Installing the windows was a very long process. By contrast the heat pumps, insulation and solar panels were fairly quick.
What are some ideas you have for ways to convince people that being carbon neutral is an economically advantageous decision as opposed to more expensive than they are willing to pay when there is such a strong narrative out there that it is incredibly expensive?I do the webinar for free 2-3 times a month and give the book away free to all attendees.
These savings seem incredible to me, so I’m wondering why this knowledge isn’t more widespread. I have never seen advertisements for any of these things.I honestly think I am the first person to do both the financial analysis and the energy savings analysis with such a scientific approach. I wrote the book precisely because there was no guide book. I would have been very happy to use someone else’s guidebook, but there was none.
How long would it take to accomplish a zero carbon home/footprint (timeline to implement the fab four start to finish)?It took about 2.5 years from start to finish. But this was because I was doing everything for the first time. With homeowners who I advise on how to save money by cutting their carbon footprint it takes about a year.
Do zero carbon homes require lots of maintenance to keep the solar panels and other components performing well?No.
Do you in any way feel that, by your neighbors seeing what you’ve done for your home and how much money it is saving you each year, that they may follow in your footsteps?I am encouraging them to do so!
Why are geothermal pumps more costly than air pumps?It is mostly the cost of drilling the wells. The heat pump itself is about the same cost as an air-sourced heat pump.
What made you study finance but shift gears in your focus of your studies to environmental science and applications like these?I spent 25 year in biotechnology. It was only after the road accident that I focused on cutting our carbon footprint.
What is it like seeing your work referenced on a national stage?It is always nice to get recognition like that, but I honestly feel better when a homeowner tells me about how much money they are saving because of installing one or more of the fab four.
What are your thoughts on windmills for people who have large fields in towns like dover and sherborn.I looked into a wind turbine at our home. But with trees around it is not viable.
What do the Rs represent in the grade of insulation? Are you able to get an insulation that is higher quality than R50?R comes from resistance, as in resistance to heat flowing. You can always get more R value by increasing the thickness of the insulation. However, more than R50 is probably not worth it. 
What would you say to someone if they still don’t want to switch to the fab four? How could you convince them further?I have found that wanting to save money is almost universal. If even that does not get people interested I find the health aspects like reducing the risk of asthma for a family member is often a good way to spark interest.
Does the fab four also work for schools and other community buildings are does it have to be modified?Yes. The fab four recipe is rooted in the laws of physics and those are the same everywhere. The subsidies are a little different for commercial properties, schools and homes but the basic recipe is the same.
Our winters can get bitterly cold, sometimes below zero for long periods of time. Can your heat pumps support a large home in this scenario?No. In my experience heat pumps cannot keep a house at 70F when the temperature outside is below about 20F which happens on about 20 days a year in New England. This is why I always recommend that you keep your old furnace as a back-up heating system.
Do you think Britain is better at cutting down carbon emissions than the US?Britain has done a very good job of closing coal-fired power stations and building offshore wind farms. The US is usually ahead of Europe in all things technological (how many European internet companies can you name?), but in this area, especially wind farms, Europe is far ahead of the US.
My house is Surrounded by lots of trees and doesn’t receive much sunlight. Are there any alternatives to solar that are just as beneficial.You can get your electricity from a community solar installation. There are several companies offering this in MA. Their electricity is 100% solar, usually from large arrays in rural areas. They sell you the electricity, usually at 10% off the utility rate and one offers 12.5% off.
There seems to be a focus on heating, what is the contrast with cooling? Is the fab 4 solution still the best?In MA, winter heating costs far more (and has a far higher carbon footprint) than summer cooling. This is why I focus on heating.  In the winter you want to keep the heat in. In the summer you want to keep the heat out. The answer is the same in both cases – insulation, draft-sealing and triple-glazed windows.
Living in a house that doesn’t seem very sustainable and is far from zero carbon, what is the best place to start moving toward a zero carbon home? Even with bringing awareness to the idea/ the first stepsAlmost always the best place to start is with insulation and draft sealing. MassSave will pay for almost all of it. Go to their website and book a no-cost, virtual audit.
I would like to know more about the benefits of a carbon neutral home when you are only a few years away from selling it. My parents like the idea of solar panels but say its too late to get them.According to Zillow, houses with solar panels sell for about 4% more than comparable houses without solar panels. Academic studies show that houses with heat pumps sell for between 4-7% more than comparable houses without heat pumps. These price increases often exceed the cost of adding the solar panels and heat pumps. Hence, adding them is a good way to position your house for selling it and you will probably get more money out of the sale than you invested in the fab four.
How can I save money and cut down on my carbon footprint while living in a dorm while going to college? What techniques can I use while living in a dorm. (obviously I won’t be able to install solar panels or triple glass windows ect.)In a dorm room there are still things you can do: block drafts under doors and around windows; make your own “fit from the inside” triple glazed windows (I have done this) using a simple wood frame and the stretchy plastic film you can buy at any hardware store, and advocate for solar panels. The recipe for the windows is in the book, “Special COVID-19 Edition of Zero Carbon Home” which you can download for free from my website or it that does not work send me an email to and I will email you the pdf file.
Is there a way to use the fab four if you live in a smaller residence like an apartment or a condo since it might be harder to use solar panels?Yes. Focus on insulation, draft sealing and window inserts. Also see if your condo association is interested in putting solar panels on the roof.
Do you think it’s going to take people a long time to realize that going zero is one of the best things for the environment and actually try to do so? Or do you think there will be a rapid response with the new generations?I am trying my hardest to make it happen fast!
How do you recommend we spread word of the fab four?Talk to your parents over dinner. Say things like, “Did you know you can save a lot of money on heating bills by cutting your carbon footprint? We studied it in class today. Someone in Dover, you won’t believe this, his name is Mr. Green, he has cut his house’s carbon footprint to zero and he pays nothing for heating or electricity. He does webinars on it. Can we watch the next one together?” Sign up for the free webinar on my website, all attendees get a free copy of my book Zero Carbon Home too.
Can you elaborate on the ways tax breaks and subsidies contribute to the success of the fab 4?There is a lot here. I cover the subsidies for each of the fab four in the book. But, in short, MassSave will pay for insulation and draft sealing. Solar panels are heavily subsidized by the federal government, the MA government and your utility company. Heat pumps are subsidized by your electric utility and with the 0% interest Heat Loan from Masssave. Triple-glazed windows can also be subsidized with the Heat Loan.
Do you think it is possible for people to have their own windmills instead of solar panels?Yes, but it is far more expensive than solar panels.
How can we as teenagers do this… it’s not always an easy transition for adults/homeownersTalk to your parents over dinner. Say things like, “Did you know you can save a lot of money on heating bills by cutting your carbon footprint? We studied it in class today. Someone in Dover, you won’t believe this, his name is Mr. Green, he has cut his house’s carbon footprint to zero and he pays nothing for heating or electricity. He does webinars on it. Can we watch the next one together?”
How long do solar panels last and do they become less effective over time?The power output is guaranteed by the manufacturer for 25 years and they will probably produce electricity for 40 years. They become about 10% less efficient after 25 years.
What was your role as a strategy consultant?I advised large companies on how to improve their competitiveness. I also worked in South Africa in 94/95 which was when apartheid gave way to democracy and I advise the new government, headed by Nelson Mandela, with its industrial strategy.
What led you to be studying this? When did you realize this was your passion?The scientist in me has always been interested in energy. As a kid, I was fascinated by the potential of making hydrogen and oxygen from water with electricity. So, I have always been passionate about science and spent 25 years in biotechnology. I only got interested in zero carbon stuff when I was doing it on my own house. When I realised that I had cut the carbon footprint of my house to zero, which no-one thought possible, and I was saving so much money on heating and electricity bills that I was making a very good return on my investment, I decided I needed to spread the word and wrote the books.
How many members of our community have gone carbon neutral? What else are you doing to spread this amazing message?My sister, who lives in England, is interested and my sister-in-law, who lives in Needham, has added heat pumps and solar panels. I personaly know of at least 12 people who have cut their carbon footprint by using the fab four after seeing one of my webinars, and if the 72% of webinar attendees who say they will add at least one of the fab four in the next year actually do so, then over 1,300 homes will have done something major to cut their carbon footprint. 
Around how long will it take for you to make back the money spent on the fab four from cheaper heating?About 6 years.
If people only wanted to or could afford to use 1 or 2 components of the Fab Four, would it still be worth it and effective even though they’re not completely zero?Yes. It is not necessary for everyone to get to zero. One homeowner I know cut his carbon footprint 38% with just insulation, draft sealing and home-made triple-glazed windows. He spent $1,000. You do not need to go zero. Do what is right for your family. But do it.
How should we, as non-homeowners, contribute to lowering our carbon emissions?Talk to your parents over dinner. Say things like, “Did you know you can save a lot of money on heating bills by cutting your carbon footprint? We studied it in class today. Someone in Dover, you won’t believe this, his name is Mr. Green, he has cut his house’s carbon footprint to zero and he pays nothing for heating or electricity. He does webinars on it. Can we watch the next one together?”
What is a piece of advice you have for others who want to find innovative / entrepreneurial ways to help the environment?Whether you become a scientist or not, I believe a strong grasp of the fundamentals of science (such as gathering the data, carefully observing the real world, doing experiments and analyzing the results) will give you a strong ability to be both innovative and entrepreneurial. 
Do they offer Triple- Glazed Windows at hardware stores such as Home Depot?Probably not. I got all my triple-glazed windows directly from the manufacturers. 

Green Hydrogen and the Hydrogen Economy. Q: I keep on asking the questions but no one gives me an answer:-The are three grades of hydrogen:
Grey (high levels of CO2), Blue (low levels of CO2) and green (no CO2) 
Based on what I have read so far the Grey and Blue are made from natural gas while the Green is made from breaking down water.
There is also a maximum amount of hydrogen that can be piped though regular old fashioned gas pipes.

My big question is “How much does Blue hydrogen cost above natural gas?”

A: I do not know the answer but you are asking the right question. 
Energy is a total commodity, only the lowest cost player (or fuel) will survive. This is why coal displaced wood for heating homes, then natural gas displaced coal. Natural gas is now displacing oil for both heating and electricity generation. Now solar and wind are starting to displace natural gas for heating (solar PV plus a heat pump is half the cost to heat your home than natural gas) and for transport (solar PV plus a Tesla costs 2c per mile vs. gasoline at 10c per mile). It is game over for fossil fuels. Unfortunately it will take 20 years. But the outcome is now inevitable.

I doubt that even green hydrogen will be low enough cost to be able to compete with renewables and heat pumps for heating or renewables and electric vehicles for transport. 

The only way to make green hydrogen today is to use solar or wind electricity to split water molecules into hydrogen and oxygen. This is fundamentally less efficient (i.e., more expensive) that just using the renewable electricity directly. There may be some niche applications, such as using excess solar electricity (that would otherwise be wasted) during sunny days to make hydrogen and then burning the hydrogen at night to run a power plant. But other than temporary energy storage, I just do not see hydrogen being competitive with solar, heat pumps and EVs.

Q: You mentioned that you  have an EV.  Do you find it performs well when it gets really cold?  Are charging stations easy to find, or do you mostly charge at home?  

Yes we have an EV, I bought a Tesla model S about a year ago. We have three kids and they are all taller than my wife so we needed a car big enough for 5 adults. Also, I wanted 4WD given the winters we have in NE. This made the model S about the only option. We bought the long range 100kWh battery and that gives it a range of about 400 miles. The performance in really cold weather (like this week) has been completely normal except that the mileage goes down. If I drove it today it might only get 250 miles on a full charge. Unless the weather is really cold the range stays at about 400 miles.
It is charged about once a week from home (we had an electrician install a Tesla wall charger which charges much faster than just plugging it into a 110V socket) almost always overnight. When we do long trips (like the 400 miles round trip to NYC and back) we stop and recharge at a Tesla supercharger station which can add about 200 miles of range in about 20 minutes. There are many supercharger stations and the car’s software tells you which ones have spaces free and directs you to them. They are usually just off the highway in a shopping mall or something similar. So road trips are not a worry, in fact taking a break every 3 hours or so is actually quite convenient. 

Q: Will electric vehicle play an important role in zero carbon emission?

A: Yes. According to a study at MIT authored by Prof. Jessica Trancik, the lifetime cost of owning an EV (which means the cost to buy it, plus the cost to repair and maintain it plus the cost of fuel) is now at or below that of owning a gasoline-powered vehicle. Her study assumed that you were paying utility rates for electricity. If you are using cheap solar power from your roof the lifetime cost of an EV is now lower than that of a gasoline-powered vehicle. If you power your EV from your solar panels then your transportation with have a zero-carbon footprint too and emit no pollution.

My wife recently drove in our Tesla to New York City and back in a day, a distance of about 400 miles. The whole trip cost $8. And had a zero-carbon footprint. The Greyhound costs $26, the seats are uncomfortable and it drops you at the Port Authority Bus Terminal.

Q:;Are there solar systems that will provide enough power for our home during a power outage?

A: Yes, but probably not the whole house, probably only the circuits you would power from an emergency generator. Since solar panels must, by law, disconnect from the grid during power outages (to prevent the linemen getting electrocuted by your solar power) you will need to install a re-connect switch at your electrical panel just like that for a back-up generator. This usually needs to be installed with a battery, but when the grid is out and the sun is shining you will be powering the house from the sun. Nice. I intend to do this on my house this year.

More on who owns the claim to having a zero carbon footprint, the owner of the array or the owner of the SREC?

Hi Bob, 
This point is often debated but it does have a bit of a “how many angels can dance on the head of a pin” quality to it. At the end of the day, RECs and SRECs help to fight climate change and I am not about to argue against them.

The generalized version of the debate over who owns the zero carbon claim on a REC is: whoever pays for the carbon footprint reduction is the rightful owner of the claim that they have cut that carbon footprint. This has some logical sense to it, if I pay for a car I own it including the right to brag about how good I look while driving it. The federal government subsidized 30% of the cost of my arrays. The SREC subsidy was for about another 30%. Net metering subsidized more than the remaining 40%. Net metering is the biggest of the subsidies because I am paid 23c/kWh for my electricity when the wholesale price for electricity is about 12c/kWh. I paid very little of the overall cost of my arrays. An economist would argue that since the NPV is positive at a 3% discount rate that I have actually paid nothing for my arrays. The total subsidies exceed the total cost. I agree with the economist. I have not paid anything for my solar panels, I been paid to own my solar panels.

By this logic, the cut in my carbon footprint should be owned 30% by the federal government, 30% by the purchaser of the SRECs (whoever that may be) and about 40% by Eversource because it pays the excess price to me for the net-metering. Logic then, requires that Eversource claims it owns 40% of my carbon footprint reduction, not 100%. And the 40% claim is because of the net-metering subsidy not because I have sold the SREC. Unless Eversource can prove that is has actually bought my SRECs (and not somebody else’s) it has absolutely no basis for claiming that I cannot claim my zero carbon production.

So, logically the argument that Eversource owns 100% of my claim to zero carbon electricity is invalid. At best it has a claim to 40% and not because it bought SRECs.
An exception to this would be if the various parties had contractually agreed to split the bragging rights. Some contracts do explicitly say who has the bragging rights. But mine do not. The federal government could have claimed to have 30% (or 100%) of the bragging rights in return for the tax credit, but I have not made any such agreement with the federal government. Neither have I made any such contractual obligation when selling my SRECs through my aggregator, nor with Eversource in my net-metering contract.

Furthermore, the argument that Eversource owns the bragging rights to my zero carbon electricity is not only logically flawed, it does not pass a basic legal test of ownership. A restaurant does not claim it owns half my meal if it gives me half off the usual price. The fact is that I get to eat the meal no matter who pays for a subsidy in order to buy it for me. By analogy, the owner of the array (not the one who subsidizes it) is the one who has the right to make the claim about cutting the carbon footprint. I am indisputably the owner of my solar panels. I wrote the check to the installer for the full $75,000 purchase price. My solar panels are not owned 30% by the federal government, 30% by the owner of my SRECs and 40% by Eversource. I own my array lock, stock and barrel, including the right to sell it to someone else, and all bragging rights associated with the zero carbon electricity it produces. 

So, in my opinion, the argument that the purchaser of an SREC (in the absence of an explicit agreement to allocate the bragging rights) has the right to claim that it has cut its carbon footprint fails both the logical test and the legal test of ownership. I own my solar panels and I have the sole right to claim that I have produced electricity with a zero-carbon footprint. No one else has any such claim, even those who have subsidized the cost of buying the solar panels. 

Again I look forward to your response Bob. 

If you sell your SREC are you double counting the carbon footprint reduction?

Question: Hi David, I really enjoyed your talk last week on your zero-carbon adventure. I did have a question, which didn’t get answered. I have a friend that works at National Grid and she told me if you sell your solar RECs, which I believe you did, you cannot claim to be carbon free as those rights go with the REC? After your talk, I went back to her and she felt that this was definitely the case and that you would need to buy RECs to offset the ones’ you sold, to make the carbon free claim and you should also tell people you sold your RECs and brought other ones. 
Just wondering your thoughts on this 
Thanks and thanks again for a wonderful talk. I plan to share this with some folks 

Hi Rob, I have occasionally heard this perspective before, and I think that reasonable people can disagree on this one.

I have two concerns with your friend’s perspective. 

The first is that I have not counted either RECs or SRECs in my calculation of my carbon footprint. I am not offsetting any of my carbon footprint with credits such as SRECs. I have actually cut my carbon footprint to zero by using the fab four. It is Eversource (our electric utility company) that is claiming it has cut its carbon footprint when it has not done so. So, I think it is more accurate that I say I have cut my carbon footprint to zero and it is Eversource that has been allowed by the state regulators to claim it has cut its carbon footprint (by buying my SRECs) when it has not done so. But I have genuinely cut my carbon footprint and it is zero. The SRECs have not been counted in any part of my carbon footprint reduction. My carbon footprint is zero because I no longer burn heating oil and I generate all my own electricity, including that to heat my house, using heat pumps, powered with zero-carbon solar panels. 

My second point is that, where I do count the SRECs is in the financial subsidies. I genuinely receive this cash, so I do not think it is right to remove it from the financial forecasts. There are many subsidies involved in going zero, from net metering and zero-interest loans (which are essentially funded through all of us in MA paying the highest price for electricity in the US, other than Hawaii) to federal and state tax credits. SRECs are calculated per kWh I generate. The federal tax credit is calculated based on the price you pay for the solar system you install. Why should one subsidy not count just because it is based on kWh generated rather than on the price of the solar system? In 2018, SRECs were replaced with SMART and so it is only owners of legacy systems that receive them. I do not see why a subsidy should be dismissed for those who installed systems prior to 2018 but should be allowed for those who installed systems after 2018. 

In my opinion, SRECs are just a form of subsidy, paid from a regulated utility to an owner of solar panels, which means they are ultimately paid by all electricity customers because that regulation has been imposed on the utility company by the state. . This is essentially a regressive form of taxation because it takes money from everyone who uses electricity (including poor people) and funnels it to those who can afford to install solar panels which tend to be wealthy people or investors. I think this is rather unfair, but I do not make the laws Rob, I just abide by them.

Please share these thoughts with your friends, I am interested to hear what she says. 

As of November 16th 2020 I have not heard back.

Q: How do you calculate so many cents per PV-generated KW? Once a panel is installed, isn’t the cost per KW zero?

A: In one sense the cost is indeed zero. You do not write checks for the electricity produced by your solar panels so in that sense it is zero. However, a more common definition is the Levelized Cost of Energy (LCOE) which is the upfront cost of the array divided by the amount of kWh it produces over its lifetime. This works out to be about 5c/kWh if you have a sunny roof and about 10c/kWh if your roof is in about half shade.