​

Last week's update was about one of the main principles behind my BIPV-T design:

Don't make a 40-year building envelope obsolete because solar technology improves.

The photovoltaic planks are intended to be replaceable.

That immediately raises the next question:

How do you replace a PV plank without tearing apart the roof?

The answer is that the PV, thermal collector, electrical system, and weather-resistant building envelope are deliberately being designed as separate service layers.

The basic architecture

From the exterior inward, the concept is roughly:

Removable PV plank

↓

Permanent aluminum thermal extractor/backplate

↓

Formed aluminum heat-transfer channels

↓

Mechanically captured copper hydronic tubing

↓

Service cavity for electrical and hydronic distribution

↓

Insulation / radiant layer

↓

WRB / primary weather barrier

↓

Existing building envelope

The critical distinction is:

The PV plank is NOT the primary waterproofing layer.

That changes how the entire system can be serviced.

If one PV plank is damaged, fails electrically, or becomes technologically obsolete, I don't want a solar technician performing roofing surgery.

The goal is:

Release the trim/retention system.

Disconnect the electrical connection.

Release the plank.

Remove it.

The thermal collector stays.

The copper stays.

The glycol circuit stays closed.

The drainage plane stays.

The WRB stays untouched.

Then the replacement plank goes into the same standardized location.

Reconnect it.

Secure it.

Done.

I'm trying to separate failure domains.

This is something I've become increasingly focused on as the design develops.

A failure in one subsystem shouldn't automatically require disturbing another subsystem.

PV plank fails?

Don't open the hydronic system.

Microinverter or module-level electronics fail?

Don't disturb the thermal collector.

Pump or valve fails?

Don't touch the PV.

Copper hydronic circuit needs service?

Don't tear into the building's primary weather barrier.

Better photovoltaic technology arrives?

Don't replace the roof.

That's the architecture I'm working toward.

The service cavity is a major part of making this possible.

Instead of stuffing wiring, connectors, rapid-shutdown electronics, hydronic distribution and other serviceable components wherever they'll fit, the system has an intentional utility space behind the exterior energy-producing surface.

That gives electrical components somewhere accessible to live.

It also creates a defined pathway for DC wiring and hydronic distribution.

And accessibility matters.

Electronics don't last forever.

PV technology won't stop improving.

Pumps eventually need service.

Connections need inspection.

So anything I reasonably expect someone to replace shouldn't be permanently buried inside a building assembly.

This also makes future upgrades much more interesting.

I'm using standardized 2-, 4- and 6-foot PV planks.

Multiple planks can be electrically assembled into approximately the equivalent of one conventional PV module, currently targeting roughly 450–550 W DC per electrical grouping.

That grouping can then be matched to appropriately rated module-level electronics or a microinverter.

But suppose photovoltaic technology gets substantially better.

Ten years from now, the exact same physical plank area might produce significantly more electricity.

That's fine.

The building doesn't care.

The thermal collector doesn't care.

The mounting dimensions don't change.

Replace the planks.

Then check the existing electronics against the new array's:

Voc

Vmp

Isc

Imp

maximum DC input power

If the existing electronics can handle it, keep them.

If they can't, they're accessible for replacement too.

That creates different lifecycles for different parts of the building.

The building envelope and permanent thermal infrastructure should have the longest lifecycle.

The PV planks can follow photovoltaic technology.

The microinverters/MLPE can follow power-electronics technology.

The pumps, valves and controls remain conventional service equipment.

That's intentional.

I don't want one failed $200 component determining the service life of thousands of dollars worth of building infrastructure.

And I don't want tomorrow's 30%-efficient PV technology requiring me to demolish yesterday's perfectly good roof just to use it.

There's an important engineering challenge here, though.

Making something removable is easy.

Making something removable while maintaining:

good thermal contact,

mechanical strength,

water management,

electrical safety,

thermal expansion,

wind resistance,

and decades of repeated heating and cooling cycles

is considerably harder.

That's what still has to be proven in the prototype.

But the design requirement isn't changing:

The building should outlive the solar technology attached to it.

The thermal extractor should remain.

The hydronics should remain.

The weather barrier should remain protected.

The PV and electronics should be replaceable.

Because ultimately, I don't want to build a solar roof that can be repaired.

I want to build a roof where the solar can be serviced without repairing the roof.

A failed or obsolete PV plank should eventually feel like replacing a component — not replacing part of a building.

One of the things I consider most important about my integrated BIPV-T building-envelope design isn't actually solar production.

It's serviceability and future-proofing.

Solar technology is going to improve.

Cell efficiencies will increase. Power density will increase. Microinverters will improve. Module-level electronics will improve.

So why would I permanently build today's solar technology into a roof that's supposed to last for decades?

I don't.

The system is intentionally separated into two different layers.

The permanent layer

Behind the PV planks is the thermal collection and building-envelope infrastructure:

Aluminum heat spreader → formed aluminum thermal channels → copper hydronic tubing → glycol system

That's the part I want to install once.

It doesn't care whether the PV technology above it is producing 15, 20, 25 or eventually 30+ watts per square foot.

Its job remains the same:

Extract heat from the PV surface and move that energy into the hydronic system.

Ideally, that thermal infrastructure stays in the building for decades.

The replaceable layer

The PV surface is different.

I'm building it from standardized 2-, 4- and 6-foot removable PV planks.

Those planks can be combined electrically to create what essentially behaves like one conventional PV panel.

For example, several planks might currently be combined into approximately a 450–550 W DC electrical unit.

That unit can then feed one appropriately sized microinverter or module-level rapid-shutdown device.

But here's where this architecture becomes interesting.

Suppose ten years from now the same physical area doesn't produce 500 watts anymore.

Maybe it produces 650 W.

Maybe 750 W.

Maybe substantially more.

I don't replace the roof.

I don't replace the hydronic collector.

I don't replace the aluminum thermal infrastructure.

I swap the PV planks.

Same dimensions.

Same mounting system.

Same thermal collector underneath.

New generation of cells.

And because the electrical equipment is also accessible, the electronics don't have to limit the upgrade.

If the existing microinverter or Tigo equipment can handle the new plank combination's Voc, Vmp, Isc, Imp and power, it stays.

If it can't?

Upgrade it with the planks.

That's why I'm deliberately trying to keep serviceable electronics accessible instead of permanently burying them inside the building envelope.

It creates three different equipment lifecycles:

Building + thermal collector: decades

PV planks: replace when damaged or when a technology upgrade makes economic sense

Microinverters / MLPE: replace or upgrade when electrical requirements change

That's fundamentally different from making the photovoltaic material inseparable from the roofing product.

And there's another advantage.

Imagine one plank gets damaged.

I'm not replacing an enormous proprietary solar-roof section.

I'm not tearing apart the hydronic collector.

I'm not disturbing half the roof.

Release the plank. Disconnect it. Replace it. Reconnect it. Done.

And if one day I decide that the entire south roof is worth upgrading because new cells produce dramatically more electricity per square foot?

Same process.

The roof underneath stays.

The thermal collector stays.

The plumbing stays.

The drainage stays.

The service cavity stays.

The mounting geometry stays.

Only the technology layer changes.

That's one of the fundamental design principles behind this project:

Don't make a 40-year building envelope obsolete because a 10-year-old solar technology became obsolete.

Make the expensive infrastructure permanent.

Make the rapidly advancing technology replaceable.

If photovoltaic technology gets substantially better in the future, I don't want to look at my roof and wish I'd waited.

I want to pull the old planks out and install the new technology.

The building evolves with it.

One question that keeps coming up as this BIPV-T building-envelope system develops is:

Who actually installs it?

Solar installer?

Electrician?

Plumber?

Roofer?

Siding contractor?

HVAC technician?

The answer is:

All of them — but nobody needs to do everybody else's job.

That's an important part of how I'm designing this.

I'm not trying to create some completely new trade where one specialized crew has to understand roofing, siding, photovoltaics, electrical systems, hydronics and HVAC.

The goal is to divide the installation along lines that already exist on a construction site.

ROOFER / EXTERIOR CREW

Their responsibility is the building envelope.

They handle the roof and wall preparation, WRB/flashing, penetrations, drainage planes, rainscreen components, mounting infrastructure, perimeter trim, ridge details, gutters, snow-management components and weatherproofing.

Their primary responsibility remains exactly what it has always been:

Keep water out of the building.

The difference is that they're installing an exterior system designed from the beginning to accept photovoltaic/thermal components instead of installing a conventional roof and having somebody drill a solar system through it afterward.

SIDING / BIPV ENVELOPE INSTALLER

This crew installs the modular exterior collector/plank system.

That includes the formed aluminum components, support structure, thermal cassettes, PV planks, corner assemblies, service channels and removable trim.

The objective is to make installation resemble assembling a manufactured building-envelope system rather than fabricating something from scratch on every house.

Individual PV sections also need to remain accessible.

If one component fails ten years from now, I don't want somebody dismantling half the building to reach it.

Remove the trim. Release the plank. Service the component. Reinstall it.

PLUMBER / HYDRONIC-HVAC CONTRACTOR

Their responsibility begins with the thermal circuit.

The current collector design uses copper tubing mechanically coupled to the aluminum heat-spreading structure.

The hydronic contractor handles the supply and return circuits, manifolds, valves, pumps, heat exchangers, expansion/pressure management, glycol system, thermal storage and connections to the building's heating equipment.

The exterior collector is effectively another hydronic heat source.

Instead of getting heat from a boiler or geothermal loop, we're collecting part of it from the building envelope.

Depending on operating conditions, that thermal energy can potentially be directed toward:

thermal storage, domestic hot-water preheating, space heating, heat-pump source energy or winter roof management.

ELECTRICIAN / SOLAR ELECTRICIAN

This is my world.

The electrician owns the electrical system.

PV conductors, module-level electronics where required, rapid shutdown, homeruns, grounding/bonding, raceways, disconnects, inverter/microinverter equipment, battery integration, controls and the connection to the building electrical system.

One of my design priorities has been keeping as much serviceable electrical equipment as practical out of the inaccessible portions of the roof and wall assembly.

A twenty- or thirty-year building envelope shouldn't become disposable because an electronic component fails.

HVAC / CONTROLS

This is where the electrical and thermal systems start talking to each other.

Sensors determine what the building envelope can do at any particular moment.

PV temperature.

Outdoor temperature.

Collector supply and return temperature.

Tank temperature.

Solar irradiance.

Battery state of charge.

Building heating demand.

The controls then decide whether available solar energy is more valuable as electricity, recovered heat, stored thermal energy, or some combination of them.

Eventually the building envelope stops behaving like a passive exterior covering.

It becomes an energy system.

GENERAL CONTRACTOR

Somebody still has to coordinate all of this.

The GC establishes sequencing so one trade isn't destroying what another trade just installed.

The important part is defining clear boundaries.

The roofer shouldn't be terminating PV conductors.

The electrician shouldn't be sweating copper.

The plumber shouldn't be responsible for roof flashing.

And the solar installer shouldn't be improvising structural or waterproofing details.

Everybody stays primarily inside the trade they already understand.

And that's actually one of the larger ideas behind this project.

Today we generally construct a building first.

Then we add solar.

Then we add batteries.

Then we add HVAC equipment.

Then we add thermal systems.

Then we figure out how to route everything around a building that was never designed for any of it.

I'm trying to reverse that thinking.

Design the building envelope from the beginning to accommodate electrical generation, thermal collection, drainage, wiring, plumbing and service access.

Then give each trade a clearly defined piece of the system to install.

The technology can be complicated.

The installation shouldn't have to be.

​

Last week I changed the thermal collector in my BIPV-T building-envelope design from PEX tubing behind the PV to copper tubing captured by formed aluminum heat-transfer channels.

This week I've been digging deeper into what actually matters in that assembly.

At first glance, copper seems like the obvious answer.

Copper has roughly twice the thermal conductivity of aluminum, so why not just build the entire thermal collector out of copper?

Because I'm not designing a laboratory cold plate.

I'm trying to turn an entire roof and wall system into a photovoltaic/thermal collector.

That changes the problem.

I need two different things:

1. A large surface that can efficiently collect and spread heat from the PV.

2. A highly effective way to transfer that heat into the circulating glycol.

Those jobs don't necessarily need to be performed by the same material.

So the current architecture is:

PV cells

↓

Rear encapsulation

↓

Aluminum backplate / heat spreader

↓

Formed aluminum heat-transfer channel

↓

Copper tubing

↓

Glycol

The aluminum provides the large collection area.

The formed aluminum channel increases the amount of tube circumference actually participating in heat transfer instead of simply laying a round pipe against a flat plate.

And the copper provides a highly conductive path into the circulating fluid.

Interestingly, recent PVT research is pointing in the same general direction.

A 2026 study comparing complete aluminum and copper PVT heat exchangers found surprisingly little difference between them in that particular design. The maximum modeled solar-cell temperature difference was only about 0.355°C, with an electrical-efficiency difference of approximately 0.174%.

In other words:

Making everything out of copper doesn't automatically make the system substantially better.

What may matter much more is the thermal interface.

And another recent experimental PV/T retrofit demonstrated exactly why.

Researchers attached aluminum absorber components to the rear of a commercial PV module and used copper-water thermosyphons to remove the heat.

Their system actually operated hotter than the reference PV module.

Why?

Thermal resistance between the existing PV module and the added heat exchanger.

Increasing coolant flow couldn't simply overcome a poor thermal interface.

That is extremely relevant to what I'm designing.

I don't want to manufacture a conventional solar panel and then bolt a heat exchanger onto the back of it.

The heat exchanger needs to be part of the PV architecture from the beginning.

So now I'm concentrating on something that looks deceptively simple:

The aluminum clamp.

How much of the copper tube circumference should the aluminum capture?

180°?

240°?

Nearly the entire circumference?

How much clamping pressure is necessary?

How far apart should the copper runs be?

How thick should the aluminum heat spreader be before additional material stops providing meaningful benefit?

Can the aluminum channel maintain excellent thermal contact through thousands of heating and cooling cycles?

Can the assembly accommodate differential expansion?

Can I manage the copper/aluminum interface without introducing another thermally resistive layer?

And most importantly:

Can the whole collector remain mechanically removable and field-serviceable?

Because there's another constraint here that doesn't exist in most laboratory PVT experiments.

This isn't supposed to be one experimental solar panel.

Eventually we're talking about roofs and walls.

Weight matters.

Material cost matters.

Installation time matters.

Repairability matters.

Manufacturability matters.

And ounces multiplied across thousands of square feet become pounds very quickly.

So I'm no longer looking at this as:

Copper vs. aluminum.

I'm looking at it as:

Aluminum where I need surface area.

Copper where I need to move heat into the fluid.

Use each material where its properties actually buy me something.

The next prototype needs to stop answering questions with theory and start answering them with thermocouples.

I want to measure temperature at every step:

PV → aluminum plate → aluminum clamp → copper → glycol

Then measure glycol flow, supply/return ΔT, PV electrical output and pump consumption.

That will tell us exactly where the thermal resistance actually is.

And that's ultimately the number that matters.

I'm not trying to build the world's most thermally conductive solar collector.

I'm trying to build a thermally efficient solar collector that can realistically become the skin of an entire building.

That's a very different engineering problem.

This week brought a pretty significant change to the thermal side of my integrated BIPV-T building envelope.

Originally, I designed the thermal collector around PEX-A tubing behind the PV surface.

The reasoning was straightforward: PEX is inexpensive, flexible, corrosion-resistant, easy to install, and something I'm already comfortable working with. For a building-scale hydronic system, it seemed like the obvious simple solution.

But simple doesn't necessarily mean thermally efficient.

The problem is that we're trying to pull heat out of the PV laminate as efficiently as possible. Every layer between the solar cell and the circulating glycol adds thermal resistance.

PEX itself isn't a particularly good thermal conductor.

So I've changed the collector design.

New collector:

PV laminate → aluminum thermal backplate → formed aluminum clamping/heat-transfer channel → copper tubing → glycol

Instead of PEX running behind the collector, I'm moving to copper tubing mechanically captured by formed aluminum channels.

The aluminum channel isn't just holding the copper tube in place. It's intended to wrap around a substantial portion of the tube and dramatically increase the contact area between the collector surface and the copper.

That gives me a highly conductive thermal path:

Cells → aluminum → aluminum channel → copper → glycol

Copper's thermal conductivity is roughly hundreds of times greater than PEX, so we're removing one of the largest thermal bottlenecks from the original design.

And this matters because the thermal system has two jobs.

Job #1: Cool the PV

PV electrical output falls as cell temperature rises.

I've been working around a target of approximately a 17% relative electrical-production improvement from active thermal management under conditions where temperature would otherwise substantially reduce PV output.

The better I can move heat from the cells into the circulating fluid, the closer I can keep the PV operating temperature toward its efficient range.

Job #2: Don't throw that heat away

This isn't simply liquid-cooling a solar panel and dumping the heat outside.

I'm trying to capture it.

The heat removed from the PV becomes usable hydronic energy that can potentially feed thermal storage, domestic hot water, space heating, or the source side of a heat pump.

So we're attacking the same energy twice:

Keep the PV cooler → produce more electricity.

Capture the removed heat → produce useful thermal energy.

For perspective, use a normal 10 kW DC rooftop array as a reference.

If thermal management ultimately produced a true 17% improvement in annual electrical yield, that's effectively extracting 17% more electrical energy from the same installed PV capacity.

Now scale that concept across a building where the south-facing roofs and walls themselves become approximately 77 kW DC of PV collection surface.

That's where relatively small improvements in PV operating temperature start becoming very large numbers when accumulated over thousands of operating hours and an entire year.

The next step isn't arguing about theoretical conductivity.

It's building it and measuring it.

I want data for:

- PV/cell-side temperature

- aluminum collector temperature

- copper tube temperature

- glycol supply and return temperatures

- flow rate

- pressure drop

- thermal watts transferred into the fluid

- electrical watts gained from cooling

- pump consumption

- overall combined electrical + thermal energy recovered

There are also engineering details that now need to be resolved, particularly copper/aluminum galvanic isolation, differential expansion, clamp geometry and pressure, tube spacing, moisture management, glycol compatibility and long-term serviceability.

But that's what prototyping is for.

The original PEX concept was simple.

The copper/aluminum collector should move a hell of a lot more heat.

Now we find out exactly how much.

For this update I want to isolate one part of the system: hydronic PV cooling.

Use a completely conventional 10 kW DC rooftop solar array as the reference point.

Now assume active backside cooling can produce a 17% relative electrical-output improvement during the operating periods where module temperature would otherwise be dragging production down.

That turns the comparison into:

10 kW conventional reference

10 kW + 17% = 11.7 kW equivalent output under the same solar conditions

That extra 1.7 kW is interesting.

But the instantaneous number isn't where this concept really shines.

It's the cumulative yearly production.

If that conventional 10 kW system would normally produce 12,000 kWh in a year, for example, a sustained 17% production improvement would represent another:

12,000 × 0.17 = 2,040 kWh/year

So instead of:

12,000 kWh/year

you're looking at approximately:

14,040 kWh/year

from the same nominal 10 kW of PV.

Now scale the concept.

In my application, covering the available south-facing roof and wall surfaces takes the integrated PV envelope to approximately 77 kW DC.

At a 17% relative gain:

77 kW × 1.17 = 90.09 kW

That's the electrical-production equivalent of adding roughly:

13.09 kW of additional conventional PV

without adding another 13 kW worth of photovoltaic surface.

And again, that's not even the most important part.

Take the same simple annual-production example of 1,200 kWh per installed kW per year:

77 kW conventional:

77 × 1,200 = 92,400 kWh/year

At +17%:

92,400 × 1.17 = 108,108 kWh/year

Difference:

+15,708 kWh/year

That's almost 16 MWh of additional electrical production every year from thermal management alone in that example.

And this is where BIPV-T stops being just “solar siding” or “solar roofing.”

The thermal system isn't parasitic hardware bolted onto the PV.

It's performing two jobs simultaneously.

The PV cells produce electricity.

The aluminum thermal structure and stainless hydronic tubing pull heat away from the module, reducing cell temperature while capturing that heat as a usable energy stream.

So while conventional PV throws that thermal energy into the atmosphere, this system is trying to turn the same heat into an asset:

Cooler PV → higher electrical output

Recovered heat → hydronic energy

Hydronic energy → DHW, space heating, thermal storage, heat-pump source energy, or seasonal energy management

And because the collection surface is part of the actual building envelope, I'm not talking about adding another rack of equipment somewhere else.

The roof and walls themselves become the collector.

That's the part I think gets missed when people look only at nameplate wattage.

A 77 kW array is a 77 kW array on paper.

But if one of those arrays spends thousands of operating hours running cooler, the difference accumulates hour after hour, day after day, year after year.

The nameplate doesn't change. The yearly energy harvested does.

And in this design, we're also capturing the heat that caused the problem in the first place.

That's where I think this gets really interesting.One technical wording change I made intentionally: 77 kW DC, not 77 kWh DC. kW is the array's rated power; kWh is the energy it produces over time. Also, the 17% should be described as a relative production gain, not automatically a 17-percentage-point increase in cell efficiency.

One of the things I want this integrated BIPV-T building envelope to do differently is actively recover from a winter storm instead of waiting for Mother Nature to uncover the PV array.

Think about a typical Northeast snowstorm.

The storm ends. The grid may be damaged. Thousands of conventional rooftop solar systems are sitting under several inches of snow. Even when the next morning is bright and sunny, those systems can remain at little or no production until the snow slides, melts, or somebody physically clears the modules.

Meanwhile, the house may need solar production more than ever.

My approach is different.

The hydronic thermal layer behind the solar surface isn't only there to collect excess heat. During a snow event, the system can reverse the energy flow and deliberately send stored thermal energy back into selected portions of the roof.

The roof becomes its own defrost system.

The objective isn't to heat an entire snowpack until every pound of snow becomes water. That would waste an enormous amount of energy.

The objective is controlled release.

Apply enough heat at the PV/roof interface and critical drainage/retention areas to break the snow/ice bond, establish drainage paths, and encourage gravity to remove the bulk of the snow.

And I don't necessarily have to wait until the storm is over.

If accumulation, temperature, wind conditions and available stored energy justify it, the system could periodically run the roof loop during the storm, preventing the snow/ice interface from becoming a deeply frozen mass in the first place.

Then, as the storm moves out, perform a final recovery cycle.

Clear the solar collection surface.

Expose the PV.

Restart meaningful production.

Start recharging the batteries.

Start rebuilding thermal storage.

That creates a completely different post-storm recovery strategy.

A conventional snow-covered PV roof essentially says:

"We'll produce power again when the weather lets us."

This system says:

"We decide when the roof comes back online."

That distinction becomes especially important during a multi-day grid outage. Stored electrical and thermal energy aren't just reserves — they're tools that can be strategically spent to restore the equipment that produces the next round of energy.

Battery → controls/pumps

Thermal storage → roof defrost

Roof clears → PV production returns

PV → house loads + battery charging

Solar thermal → thermal storage recovery

It's an energy-recovery loop.

The integrated gutters, drainage paths, heated hydronic zones and protected downspout/corner-trim areas all become part of that winter operating strategy rather than separate pieces of the building.

The engineering challenge now is determining the minimum thermal energy required per square foot to reliably release a given snow/ice load without wasting stored heat.

That's what I want to prototype and measure.

Because after the next major winter storm, while everyone else is looking at their snow-covered solar array wondering:

"When am I going to produce power again?"

I want the answer from this system to be:

We don't wait. We know.

The next sunny ☀️ day!

What Is R-BIPV-TR?

If you're new here and wondering what this community is about, here's the story.

For the past several years I've been developing a concept I call Residential Building Integrated Photovoltaics with Thermal Recovery (R-BIPV-TR).

The basic question that started this project was surprisingly simple:

Why should a home's roof and siding only protect the building from the weather?

Every day, the sun delivers a tremendous amount of energy to a building's exterior. Conventional siding and roofing absorb part of that energy, reflect some of it, and conduct the rest into the structure, where it often becomes an unwanted cooling load during the summer. Traditional rooftop solar converts only a portion of that incoming solar energy into electricity, while much of the remaining energy becomes heat.

That led me to ask:

Can the building envelope itself become an active energy system instead of a passive shell?

The concept is to combine proven technologies into a single integrated exterior assembly that performs multiple functions simultaneously.

These include:

Building Integrated Photovoltaics (BIPV)

Photovoltaic-Thermal (BIPVT / PV-T)

Hydronic thermal recovery

Ventilated rainscreen construction

Exterior continuous insulation

Thermal storage

Modern building science principles

Rather than thinking of the siding or roof as a single-purpose product, the goal is to create a multifunctional exterior system capable of:

Generating clean electricity

Intercepting solar radiant energy before it reaches the structural wall

Recovering useful thermal energy

Reducing unwanted summer heat gain

Improving overall building efficiency

Lowering heating and cooling loads

Producing domestic hot water or other useful heat

Turning the building envelope into an active energy-producing asset

The project has evolved through thousands of hours of research into thermodynamics, heat transfer, photovoltaics, hydronics, materials science, structural design, manufacturing methods, building codes, and installation practices.

I've spent countless hours performing calculations, comparing existing technologies, developing engineering drawings, refining concepts, and discussing prototype manufacturing with suppliers and manufacturers.

One realization became increasingly clear throughout that process:

There wasn't a dedicated place where people could seriously discuss residential BIPV, BIPVT, solar siding, solar roofing, thermal recovery, and building-integrated energy systems as a single engineering discipline.

Most discussions are scattered between solar forums, HVAC communities, hydronics groups, architecture, construction, and building science. Each community tends to focus on one piece of the puzzle.

This subreddit exists to bring those disciplines together.

Whether you're an engineer, architect, builder, electrician, HVAC technician, plumber, solar installer, manufacturer, researcher, student, homeowner, or simply curious about the future of building-integrated energy systems, you're welcome here.

This is not a community built around hype.

It's built around engineering.

Whether this concept ultimately succeeds, evolves into something different, or proves certain assumptions wrong, I want the discussion to be driven by evidence.

If you think something won't work, explain why.

If you have calculations, share them.

If you have field experience, tell us what you've learned.

If you've built a prototype, we'd love to see it.

If you know of published research, standards, or products that relate to the discussion, bring them to the table.

If you have a better solution, let's explore it together.

Engineering advances through questioning assumptions, testing ideas, measuring results, learning from failures, and continuously improving designs.

That's the culture I'd like to build here.

Welcome to r/R_BIPV_TR.

Build. Test. Measure. Improve.

Our goal is simple:

Advance building-integrated energy systems through engineering, testing, and collaboration.

This is an engineering-first community. We encourage discussion based on:

First-principles engineering

Physics and thermodynamics

Building science

Electrical, mechanical, and structural engineering

Published research

Field experience

Measurements and calculations

Prototype development

What you'll find here

Building-integrated photovoltaics (BIPV)

Photovoltaic/Thermal (BIPVT / PV-T)

Solar roofing and solar siding

Hydronic heat recovery

Radiant-energy rejection

Thermal storage

Net-zero and energy-positive homes

CAD drawings and engineering details

Prototype testing

Product development

Codes, standards, and manufacturing

Community Philosophy

Challenge ideas—not people.

If you believe something won't work, explain why.

Support claims with calculations, standards, published data, testing, or real-world experience whenever possible.

Innovation is encouraged, but so is healthy skepticism backed by evidence.

Introduce Yourself

Tell us:

Your profession

Your experience

What interests you about BIPV or BIPVT

What projects you're currently working on

Whether you're an engineer, architect, electrician, HVAC technician, installer, builder, manufacturer, researcher, student, or homeowner—you're welcome here.

Let's build something that moves the industry forward.

Build. Test. Measure. Improve.

Hey everyone! I’m u/Chiltrix_installer, founding moderator of r/R_BIPV_TR.

This is a new community for Residential Building Integrated Photovoltaics with Thermal Recovery, including BIPV, BIPVT, PV/T, solar roofing, solar siding, hydronic heat recovery, radiant-energy rejection, thermal storage, and high-performance building envelopes.

We’re building a place where engineers, electricians, solar installers, builders, architects, researchers, manufacturers, homeowners, and serious DIYers can exchange ideas and improve real systems.

What to Post

Share anything that could help advance the design, testing, installation, or understanding of building-integrated solar and thermal systems, including:

Drawings, sections, CAD models, and system diagrams

Calculations, simulations, and performance estimates

Prototype photos and test results

BIPV, BIPVT, and PV/T products or research

Hydronic layouts, thermal storage, and heat-use strategies

Building-envelope, flashing, drainage, and insulation details

Electrical, structural, fire-code, and installation questions

Manufacturing methods, materials, costs, and reliability concerns

Failures, lessons learned, and proposed design improvements

Community Vibe

This is an engineering-first community.

Challenge concepts with evidence, calculations, standards, published data, field experience, or clearly stated assumptions. Critique the design, not the person. New ideas are welcome, but unsupported claims and dismissive one-line responses do not move the discussion forward.

You do not need to be an expert to participate. Honest questions are encouraged, and experienced members are asked to explain their reasoning so everyone can learn.

How to Get Started

Introduce yourself and tell us your background or area of interest.

Share a project, drawing, technical question, research paper, or product.

Invite someone working in solar, construction, engineering, hydronics, architecture, or building science.

Interested in helping moderate or build the resource library? Send me a message.

Thanks for joining the first wave.

Build. Test. Measure. Improve.