Solar Water Heating in Central Florida

This is the solar system Florida built a reputation on, and then mostly stopped talking about. The Florida Solar Energy Center, at the University of Central Florida, wrote the manuals. Thousands of houses in the state still have a collector or two over the garage. New installs are quieter now, because electric panels got cheap and a heat pump water heater does a similar job with less hardware. The machine itself did not stop working.

It heats the water you use inside. It does not heat the rooms. Florida houses are not built with radiators. If a salesperson says “solar house heating,” ask whether they mean showers or whether they mean the air conditioner. Those are different products.

Three different things people call solar

Electric panels, the photovoltaic kind, make electricity. A pool heater is a field of black plastic with pool water running through it, sized to the surface of the pool, and written up on the pool heating page. A solar water heater is the small one: glass over a dark plate, copper tubes, insulated pipes, and a tank that holds a day of showers.

A normal Florida house system has one collector of about 4 by 8 or 4 by 10 feet, or two of them. That is on the order of 32 to 64 square feet. A pool system is often 300 to 500 square feet and has no glass. You cannot swap them. Pool collectors will not make 120-degree shower water. House collectors on a pool are the wrong size, the wrong temperature, and a waste of glass.

Running the two ideas together is allowed. Electric panels can run the rest of the house, including a heat pump water heater. They do not replace the collectors unless you have decided to heat water with electricity on purpose.

What actually happens on a sunny morning

The type most common in Florida is a direct system, also called an open loop. Drinking water itself goes up to the roof.

1. A controller compares the temperature at the collector with the temperature at the bottom of the tank.
2. When the collector is warmer by a useful margin, often around 15 to 20 degrees Fahrenheit in the old Florida designs, a small pump turns on.
3. Water from the cool bottom of the tank goes through the collector, picks up heat, and returns to the top of the tank.
4. When the sun fades and the collector is only a few degrees warmer than the tank, the pump stops. You do not want it running at night and cooling the water you stored.
5. If the tank is not hot enough, or guests show up on a rainy Tuesday, the electric element in the tank turns on. You still get a shower.

The tank is usually about 80 gallons, sometimes 120 for a larger family. A plain electric tank in a Florida garage is often 40 or 50 gallons. The solar tank is bigger because it has to hold the afternoon’s heat until the next morning. It is also insulated more carefully. It lives in the garage or a utility room, not on the roof, in this kind of system.

Some pumps are powered by a tiny electric panel of their own, a few watts, mounted next to the collector. When the sun is out, the pump runs. When it is not, the pump stops. That version does not need a separate controller, and it can move water during a power outage as long as the sun is on that little panel. The tank you already heated is what you have. It is not an endless supply.

The other two layouts

An indirect system, or closed loop, keeps drinking water out of the collector. A mix of water and nontoxic antifreeze, usually propylene glycol, circulates on the roof and gives its heat to the tank through a heat exchanger. The Florida Building Code requires that exchanger to protect the drinking water. This layout costs more and loses a little heat in the handoff. It is the right one when the water is hard, which is common in Central Florida, or when you want the collector full of a fluid that will not freeze solid. The glycol is not forever. It gets acidic with heat and time, and someone has to test it.

A batch heater, also called an integrated collector-storage unit, puts the tank itself on the roof behind glass. No pump. The sun heats the water where it sits, and house pressure brings it down when you open a tap. It is simple. It is also heavy, so the roof structure has to be checked, and a cold night can steal back some of the heat because the storage is outdoors. You see them. They are less common as a retrofit than the pumped system.

Evacuated tubes, the rows that look like fluorescent bulbs, hold heat well on a cold cloudy day. They are a poor match for Florida wind. A glass tube that shatters in a storm is a repair, and Central Florida does not need the cold-climate advantage often enough to pay for the risk. Flat glass over a metal plate is the normal collector here.

How big, for a real house

Size it from how much hot water you use, not from the square footage of the house. A couple that travels half the month does not need the system a family of five uses. The Florida Solar Energy Center’s own comparison models used a collector of about 40 square feet with an 80-gallon tank, and a larger one of about 64 square feet with the same tank size. One collector is a common Central Florida starting point for a small household. Two collectors fit a house that runs the shower, the washer, and the dishwasher on the same evening.

The goal is not 100 percent. A system sized for the house is designed so the sun carries most of the year’s hot water, often talked about as roughly two-thirds to four-fifths, and the element covers the rest. A quote that promises every gallon, every day, including a week of rain in January, is selling a heater that does not exist. Cold inlet water in the north makes solar look more dramatic. Central Florida’s tap water is already mild, often the 60s and 70s, so the heater has less work to do and the dollar savings are smaller than a national brochure shows.

South or a little west of south is the roof you want. Shade from 10 in the morning to 3 in the afternoon is the same failure as it is for any other solar on this site. The collectors mount flat on the slope. They need less area than a pool array, so they can sometimes fit on a roof that is already partly covered by electric panels. Do not put them in the shade of those panels, and do not plan a reroof for the year after you bolt them down.

The comparison that matters in 2026

Twenty years ago the choice was a solar tank or a plain electric tank. The plain tank heats with a metal element, the way a toaster does, and it is the expensive way to make hot water. Today the third option is a heat pump water heater. It is a tank with a small heat pump on top. It pulls heat from the air in the garage and puts it in the water. In a Central Florida garage that air is warm all year, which is why these units do well here. They use on the order of one-third of the electricity of a plain electric tank. They need room to breathe, a drain for the water they pull out of the air, and a garage or a big utility room. A closet the size of a hall closet is a bad place for one.

	Solar water heater	Heat pump water heater	Plain electric tank
Where the heat comes from	The sun, through glass on the roof.	The air in the garage.	An electric element.
What you add to the house	Collectors, insulated pipes, a pump, a larger tank.	A taller tank and a condensate drain.	A tank. You may already own it.
A cloudy week	The element comes on. You still have hot water.	It keeps working. The garage is still warm.	It keeps working. That is all it does.
Best fit	High hot-water use, a clear roof, or pipes that are already there.	Most Central Florida garages, if the bill is what you care about.	The cheapest swap the day the old tank leaks.

Electric panels plus a heat pump water heater is the combination a lot of houses should price before they price collectors. The panels cut the whole electric bill. The heat pump cuts the water-heater slice of that bill. You do not add roof penetrations for plumbing. You do give up the idea of hot water that was heated by the sun directly, and you do need the garage.

Gas and tankless are a side note in this part of the state. Many Central Florida houses do not have a gas meter. A tankless electric unit can heat water as it passes, and it can demand a very large electric circuit to do it. It is not a solar system. Do not let the names get stacked into one quote.

What it costs, without the old credit

There is no state price. Published 2026 ranges for an installed solar water heater on a normal house cluster from about $3,500 to $7,500. One collector, a simple pipe run, and a garage tank sit toward the bottom. Two collectors, a tile roof, a long run, or a closed loop sit toward the top. Get three quotes that name the collector area, the tank gallons, whether the loop is direct or closed, the warranty, and whether the mixing valve and the permit are included.

The federal residential credit that used to cover a certified solar water heater ended for spending after December 31, 2025. It never covered pool heaters. It did cover this, if the system was certified and at least half the energy came from the sun and the water was used in the house. That door is shut for a 2026 install. The same law ended the separate credit for a heat pump water heater. Neither machine is a tax trick this year.

Florida sales tax is still off the qualifying solar equipment under Florida Statute 212.08(7)(hh). The invoice should show that. A heat pump water heater is not solar equipment, so do not expect the same exemption on that tank. The property-tax exclusion in Florida Statute 193.624 can keep the collectors and the parts of the solar device off your assessed value. It does not exempt a plain tank you would have needed anyway. File with the county property appraiser. Details are on the incentives page.

Utility rebates, where they exist in 2026, are aimed at the heat pump water heater, not at the roof collectors. Duke Energy Florida has been paying several hundred dollars on a qualifying heat pump model. FPL and OUC do not have a solar-water-heater check you should count on. Open the utility’s rebate page the week you buy. These programs change, and an old blog that mentions a state rebate of a few hundred dollars is describing a program that is gone.

Payback is your water-heater bill, times the share the sun will actually cover, divided into the price. Here is the shape of it, not your number. Suppose the electric tank is costing about $400 a year and a solar system covers about two-thirds. That is on the order of $250 a year. A $5,500 install is then roughly a 20-year payback, before a pump replacement or a flush. If the household uses enough hot water that the slice is $700 a year, the same fraction is closer to 12 years. A heat pump water heater that costs about $3,000 and cuts a $400 bill by about two-thirds is a shorter path to a similar saving, with no roof work. Use the last 12 months of your own use. A brochure that promises a five-year payback is using a northern fuel bill or a federal credit that no longer exists.

Collectors are often warranted for 10 years or more, and a glazed flat-plate collector can outlast that if the glass, the seals, and the mounts stay intact. The pump, the controller, the relief valve, and the tank anode are the parts you will replace. A tank is a tank. Ten to fifteen years is a normal life, not a failure.

Hard water, freeze, and the roof

A lot of Central Florida tap water is hard enough to spot a shower door. The same minerals settle inside a collector that drinking water runs through. Flow gets worse, heat transfer gets worse, and a neglected direct system scales up. If the fixtures already crust, tell the installer before they sell you an open loop. A closed loop keeps that water out of the collector. A direct system needs a flush plan, and some houses are better off with a softener either way. This is the unglamorous reason solar water heaters in this region get a bad name. The sun did not quit. The tubes narrowed.

Freeze is the other one people skip because January afternoons are pleasant. The Florida Building Code requires freeze protection when the winter design temperature in its local table is 32 degrees Fahrenheit or lower. For Orlando, the heating-design figure people use for equipment sizing sits right at 32. Counties north of there are colder on that table. Do not guess. Ask the building department which number is on your permit, or read the table. A direct collector full of water, pump off, on a night in the upper 20s, can split. Protection is a sensor that runs the pump long enough to bring tank heat up to the roof, a valve that lets the collector drain, or a closed loop with fluid that freezes lower than the design night. Test it once each fall. “It almost never freezes” is how a collector becomes a leak into the soffit.

The roof has to hold the collectors, and the pipes through it have to be flashed. Wind rules are the same idea as any other rooftop solar: into structure, with the hardware the manufacturer tested. A batch tank on the roof is a different weight. Do not let anyone set one on a deck that was not looked at. If the shingles are near the end, reroof first. Taking collectors off and putting them back is a second labor bill.

Permit, license, and the association

This is plumbing and roofing, not a gadget. The Florida Building Code covers solar thermal systems used for domestic hot water. Collectors should be listed and labeled. Parts that touch drinking water have to be listed for drinking water. A pressure-and-temperature relief valve is required. Where the system can send water hotter than 140 degrees toward the taps, the code requires a mixing valve, the kind that meets the ASSE 1017 standard, so the water leaving toward the house is tempered to 140 or below. That valve is not optional and it is not a suggestion from a careful plumber. Solar tanks regularly run hotter than a plain electric tank, because a bright afternoon with nobody home has nowhere to put the heat.

Pull a permit and keep the final inspection. The person on the permit needs a license that covers solar water heating. A Florida certified solar contractor’s scope includes it. So does the residential solar water-heating specialty license, which is aimed at domestic solar hot water on one-, two-, and three-family houses, and also at pool collectors. A plumbing contractor is the other lawful path into the drinking-water pipes. Look the license up with the Department of Business and Professional Regulation before you pay a deposit.

A homeowner association cannot ban the collectors. Florida Statute 163.04 is the same rule as for electric panels and pool collectors. The association can require a roof location that faces south, or within 45 degrees east or west of south, if that spot still works. Pushing you onto a shaded slope is a ban. Put the request in writing with a sketch.

Safety

Scald. This is the hazard that is different from electric panels and from pool collectors. A solar tank on a clear day with low use can climb well past 140 degrees, and stagnation, when the pump is off and the collector bakes, runs hotter than that. The mixing valve is what stands between that tank and a child at a bathroom tap. The valve can fail. The little dial at a shower is a second limit, not a replacement. If water at a tap is suddenly much hotter than it was last month, stop using that tap and have the mixing valve checked. Do not “fix” it by turning the backup element down so far that the tank sits lukewarm for days. Warm and still is a bad way to store water.

Pressure. Heat expands water. The relief valve is there to open before a tank or a collector becomes a problem. If it drips all the time, that is a fault, not a personality. If it never gets exercised, it can freeze shut with mineral crust. A plumber should know which is which.

The fluid in a closed loop is not for drinking. The heat exchanger has to keep it out of the taps. A cheap single-wall exchanger on a potable system is the thing the code is trying to prevent. If you taste or smell something chemical in the hot water and nowhere else, stop drinking it and call someone who can test the exchanger.

The roof and the pipes. A cracked glass cover is sharp and it is a leak path. After a hail or wind event, look up before you assume the system is fine. Insulated pipes in an attic that lose their insulation are a burn risk and a waste of the heat you collected. The pump is a small electric load. It still wants a proper connection, not a cord run across the garage floor.

If the house already has one

This is the Central Florida situation as often as a new install. The collector has been up since the 1990s or the 2000s. The pump is silent. The tank has been running on the element for years, and nobody noticed because the showers still worked. You have been paying for a plain electric tank plus a roof ornament.

Find out which of these is true before you replace the tank.

• The pump runs on a sunny afternoon, the pipes on the roof side get warm, and the element rarely clicks on. Keep it. Service the anode, the relief valve, and the mixing valve.
• The collector is intact, the pipes are sound, and only the pump or the controller died. That is a repair, and it is usually cheaper than a new system or years of element-only bills.
• The collector is faded, the glass is cracked, the pipes are crushed, or the roof under it is tired. Repairing the heater and ignoring the roof is backwards. Take it off when the roof is done, and decide then whether to put it back.
• Nobody can explain the piping, and the garage is a knot of valves. Have a plumber trace it before you buy the house, not after. An abandoned system that was never capped is a leak waiting on a hose bib.

On a purchase, add this to the closing checklist. Ask for the permit, ask to see the pump run, and ask who pays to remove it at the next reroof. A dead system is not a feature. A working one with paper is a modest plus, not a kitchen remodel. The home value note is about electric panels. The habit is the same: documents, then temperature.

Living with it

Once a month on a sunny day, look at the pump. It should be running by late morning if the tank is not already at the top of its range. The pipe coming down from the roof should be hot. The pipe going up should be cooler. If both are cold and the sky is clear, the pump, the sensor, or a valve is the problem, and the element is quietly doing all the work.

Once a year, before the first cold front, test the freeze protection if you have a direct system. Have the anode rod in the tank checked on the same schedule as any other tank. If the system is a closed loop, have the fluid tested. Acidic glycol eats the inside of the collector. Flush a direct system if the flow has slowed and the water is hard. Do not paint the glass. Do not box the collector in to hide it from the street. Trim the oak that grew into the morning sun.

If you leave the house for the summer, do not valve the collector off and forget it in the sun. Stagnation cooks seals and fluid. Ask the installer what “vacation” is supposed to look like on your controller. Some systems have a setting. Some need the pump able to run.

When it is the right tool, and when it is not

It fits if several of these are true. The household uses a lot of hot water. The roof has a clear south patch that is not already promised to electric panels. You plan to stay long enough that a long payback is acceptable, or you are repairing a system that already has good pipes. You want the heat to come from the sun even if a heat pump would win a spreadsheet. You have asked about hard water and freeze in writing.

Skip it, or do it later, if the water-heater bill is already small, the garage can take a heat pump water heater, the roof needs replacing, or the quote’s savings still include a federal credit. Skipping is not a failure of nerve. In 2026 the heat pump tank is the default efficiency upgrade for a Central Florida garage. Solar water heating is the specific tool next to it, not the tool that replaced it, and not the antique people sometimes imply when they say nobody installs these anymore.

Get the collector area, the tank size, the loop type, the mixing valve, the freeze plan, and the license on one piece of paper. Then compare that price with a heat pump water heater on the same piece of paper. Pick the one that matches the house, not the one with the older reputation.

This page is general information, not tax, engineering, or plumbing advice. Your water, your roof, your county’s winter design temperature, and your quotes control the job.