I have had solar water heating since 1985, which has operated flawlessly for these 35 years, and my PV
battery systems in both my home and also in my office building have been operating 33 years and 27
years respectively. My 20 year old company blends clean energy technologies - high-value energy efficiency,
the entire portfolio of renewables and energy storage for the C&I. government, & infrastructure markets.
And I teach three separate courses on this at The George Washington University (GWU). That said, I am
a strong believer in using solar thermal, waste heat, and geothermal heat pumps in buildings and utilize
PV for the pumping/fan functions. A better optimization than trying to orchestrate PV for everything, and frankly way more efficient and economic. Best to all, Scott
Scott Sklar
President
The Stella Group, Ltd.
706 North Ivy Street, Arlington, VA 22201
VA Phone: 703-522-1195 (3049 direct)
E-mail: solarsklar@aol.com
Website: www.TheStellaGroupLtd.com
The Stella Group, Ltd.. is a strategic technology optimization owner's rep firm for clean energy users and companies, with a focus on system standardization, modularity and web-enabled diagnostics. Scott Sklar is an Adjunct Professor at The George Washington University teaching three unique interdisciplinary sustainable energy courses, and an Affiliated Professor with CATIE, an international graduate university in Costa Rica offering graduate degrees on sustainability. Sklar is the Energy Director at GWU's Environment and Energy Management Institute (EEMI).
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Scott Sklar
President & Adj Professor
The Stella Group, Ltd, GWU EEMI
Arlington, VA
solarsklar@aol.com------------------------------
Original Message:
Sent: Mar 11, 2021 10:41 AM
From: Gail Burrington
Subject: Thermal system
Yes, It is exciting to see the flurry of comments about solar thermal for domestic hot water, perhaps it is not "passe" as much as PV would like to think! Of course, with the cost of PV dropping, the new age of PV powered domestic hot water is upon us, but I prefer to use the electrons first for the battery then engage a diversion controller to dump extra sun into the hot water heater....
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Gail Burrington
proprietor
Burrington's Solar Edge
Windsor Locks CT
solaredge@yahoo.com
Original Message:
Sent: Mar 10, 2021 03:53 PM
From: Rolland Riives
Subject: Thermal system
so Fantastic! some are talking about SHW! Im on FB under "Guilt Free Hot Water" nothing to sell but its what i did and actively promoting. My closed loop system works with a small Dc pump that gets power from a small Photo Voltaic panel,20 volts and it only needs 25 watts and i use a small line Thermostat, my only controller - Item # 4MY93
- Mfr. Model # TRF115-005 from Grainger about $80 which i can adjust seasonally . This makes all my Domestic Hot water and 95% heat for home
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Rolland Riives
President
Guilt Free Hot Water
cambellrives@comcast.net
Original Message:
Sent: Mar 10, 2021 01:19 PM
From: Meg Needle
Subject: Thermal system
Thank you for the UPS tip! I will look into that for pump back up to be certain.
Regarding the tank, it is an 80 gal Rheem Solaraid https://s3.amazonaws.com/WebPartners/ProductDocuments/3031962E-2462-403C-8981-231AF6BD8197.pdf . My understanding is that the electric element is designed to hold the set temperature in the upper 40 gal of the tank and the solar loop heats the bottom 40 gallons. Naturally, the heated water rises so that the full benefit of the solar heating in the lower half of the tank is realized. The solar system consistently provides 100 degree F at the top of the lower half of the tank. Very simple use of thermal convection and no moving parts in the tank.
The solar collector is Apricus evacuated tube array comprised of (30) 1-meter long tubes (approximately 6' wide). This type of collector only has water circulating at the top where copper pipes within each glass tube exchange heat into the water circulating at the top manifold. That loops around the lower part of the DHW tank. The glass tubes are very resilient, offer a rounded surface to optimize collection morning to evening, and stay pretty clean throughout the seasons.
Regarding the hydronic floor heating, that system is completely decoupled from the DHW tank but gets heat through a plate heat exchanger fed by DHW loop. There are two pumps for that system; one for the loop to and from DHW and one on the floor loop. I designed that system, including pex tubing cast into slab on grade, controller, pumps and plate heat exchanger with the help of houseneeds.com Pex Tubing Radiant Floor Heating. PEX Radiant Underfloor In floor HeatI kind of use the floor loop and thermal mass of the slab on grade to store heat during the day when the solar collector is active and then turn down the floor system thermostat at night.
I'm guessing I could install a UPS on the circuit powering all three pumps Two for hydronic floor loops and one for solar collector loop) to achieve system resilience during a power outage.
Thanks again for that suggestion!
Meg
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Meg Needle
Senior Associate
Lord Aeck Sargent - a Katerra Company
Atlanta, Georgia
mneedle@lordaecksargent.com
Original Message:
Sent: Mar 10, 2021 11:56 AM
From: william fitch
Subject: Thermal system
It might be cheaper and better to put a UPS on the pump and controller circuit for the evacs.
https://www.walmart.com/ip/Tripp-Lite-1500VA-UPS-Battery-Backup-AVR-LCD-Line-Interactive-10-Outlets-120V-USB-TEL-Coax-Protection-OMNI1500LCDT/23422694?wmlspartner=wlpa&selectedSellerId=0
The above as an example. A UPS like this will not only protect the pump and controller but will most likely run the system for a couple of hours in a power failure. You also can add extra batteries to extend run time. The typical AC pump and controller does not draw more than 150 watts, and a UPS of that size will handle the spike load as well. Ac motors have better starting torque than PV run motors, especially in the smaller sizes. The cost of this solution will be way less and easier to install than a transition to PV DC powered solution.
It sounds like with a single DHW tank, you are running a "boost" system. The element inside will always maintain the Rheem tank at what ever the tank thermostat is set to, so solar gain only happens above the elements set point, for the most part. I would also guess you have a tempering valve on that tank output for your DHW fixtures.
How may tubes do you have? Can you divert the collector output directly to the floor, bypassing the tank? Adding a Radiant floor can make for some interesting configurations in flow and control.
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william fitch
Owner
www.WeAreSolar.com
fcfcfc@ptd.net
Original Message:
Sent: Mar 10, 2021 09:36 AM
From: Meg Needle
Subject: Thermal system
Hi all -
I have an Apricus evacuated tube solar thermal water heating system. I have not had any problems with the system since installation ~13 years ago except for replacement of the controller last year. I have a Rheem 80 gallon water tank with a closed loop and small electric anode. I also run a hydronic floor heating system in my basement floor slab from the tank via heat exchanger. My array is installed as an awning so it shades a south facing window as well. My only reservation is the pump which does run on AC. I would like to upgrade that to a PV powered pump when/if it ever fails so we have hot water and a warm basement when power goes out.
It is hard to quantify energy savings but I do regularly get 100+ degree F water heated by the array. I too seek to install PV when the timing is right but chose solar thermal because efficiency is much higher and heat seems to me a more direct use of the sun than conversion to electricity. Georgia does not have a robust incentive plan for integrating PV into the power grid so that's kind of a downer.
It may be a non-starter but I have always believed that on-site use of DC power generated by PV is the most efficient utilization. Of course, grid connection and AC inversion makes sense with the electrical infrastructure in place.
Curiously, I see that Walmart is offering a pretty similar solar thermal water heating system! 700 Liter Duda Solar Water Heater Active Split System Single Coil Tank Evacuated Vacuum Tubes Hot SRCC Certified - Walmart.com| Walmart.com | remove preview |
| | 700 Liter Duda Solar Water Heater Active Split System Single Coil Tank Evacuated Vacuum Tubes Hot SRCC Certified - Walmart.com | | Free shipping with no order minimum required. Restrictions apply. Report incorrect product information Size: 700 Liter Single Coil, Slope Frame About This Item We aim to show you accurate product information. Manufacturers, suppliers and others provide what you see here, and we have not verified it. | | View this on Walmart.com > |
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Meg
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Meg Needle
Senior Associate
Lord Aeck Sargent - a Katerra Company
Atlanta, Georgia
mneedle@lordaecksargent.com
Original Message:
Sent: Mar 09, 2021 12:21 PM
From: Spencer Day
Subject: Thermal system
We removed our Solar Domestic Hot Water (SDHW) system in 2018. This was done because we were making the transition to solar PV using the same roof area. The presumed savings of SDHW was difficult to prove, and removing it was our best choice because solar PV would ultimately reduce our electric bill to near-zero.
Other considerations:
1/ the 80-gal tank had failed, and this would have been the 3rd time replacing it since installing the SDHW system in 1986;
2/ the circulation pump was using AC power and needed renewal or replacement;
3/ the requirement of recharging the whole system each time the tank was replaced was clearly reducing the overall cost-effectiveness of the system.
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Spencer Day
srdayg@gmail.com
Original Message:
Sent: Mar 08, 2021 09:14 AM
From: Mark Stahl
Subject: Thermal system
I agree with Mr Fitch. Older Thermal Systems are really durable!
Most thermal systems have in-line cartridge pumps; one can remove 4 bolts, and casing comes off. Then a new cartridge can be installed and casing put back. Or system needs recharged.
Systems were made in America, in the 80s, and were built to last !!
Or it could be a sensor. Someone who knows what they are doing, can give you a better idea of what is wrong.
Mark Stahl
719.325.6368
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Mark Stahl
Energy Consultant
EnergySaver Consulting
Colorado Springs CO
markstahl9@gmail.com
Original Message:
Sent: Mar 03, 2021 01:25 PM
From: Coreen Toll
Subject: Thermal system
I have a couple of large thermal panels on my house which ceased working quite a while ago. Our installer said it wasn't cost effective to fix it. I hope I can hire someone to disconnect the system.
Coreen Toll
719.321.9179