The best solar water heater will provide an ample supply of hot water at an affordable price. There are different ways to heat the water flowing into the household and each has its pros and cons. The climate they’re installed in also plays a factor in the right solar water heater for the job. Ultimately the best solar water heaters are those that can function under any conditions.
Best Solar Water Heaters at a Glance
- Overall Best Solar Water Heater – Duda Solar 200 Liter Water Heater Active Split System
- Runner-up Best All-Around – Sunbank 40 Gallon Solar Water Heater
- Best Tankless Solar Water Heater – Duda Solar 30 Tube Water Heater
- Cheap & Simple – Heliatos 4 Panel Solar Water Heater
- Most Affordable Solar Water Heater – Heliataos 2 Panel Solar Water Heater
There are two primary water heating methods used by these solar water heaters; vacuum tubes and solar panels. Which one works best depends on their climate and how much water needs to be heated.
Passive solar heaters for homes are typically vacuum tubes that use pressure to move the water. Active systems use pumps or similar mechanics to move the water. Generally speaking, passive is more cost-efficient, and active is more reliable.
Solar hot water systems are most commonly installed on the roof. As a result, they will see a lot of exposure to the elements. Having a solar heating system that can handle incremental weather, particularly hail, is important. Freezing can also be a major concern with solar water heating systems. Some are not designed for cold weather, while others use various methods to handle the cold.
Then as with any purchase, the price and subsequent warranty must be considered. Solar water heaters are not cheap, and even the low end will be thousand dollars. The warranties should also be reasonable to cover the repairs and replacements these complicated systems will need over time.
Our List of the 5 Best Solar Hot Water Heaters
1. Duda Solar 200 Liter Water Heater Active Split System
The Duda Solar 200 Liter Water Heater Active Split System is arguably the best solar water heater on the list. It is heavy duty and boasts a large storage tank, a built-in heating element, and greater flexibility compared to the others. It’s expensive but maybe worth the price for some who need something robust.
The Duda Solar 200 Liter Dual Coil Water Heater uses active systems to heat itself. The only other product on the list that does this is the Duda Single Coil. It comes with a working station, pumps, and a controller to maintain a steady hot flow of water.
Like the Sunbank, this solar water heater uses vacuum tubes to heat water. This product has 20 tubes which are less than the 30 tubes used by the Duda 30 Tube.
The heated water is funneled into a large 200 liter or 52-gallon stainless steel tank. Aside from the Duda Single Coil, this is the largest tank on the list. The Sunbank is smaller at 40 gallons or 151 liters.
On cloudy days when the solar heating system can’t take advantage of the sun, it has a heating element. It’s a 220V 1500 W heating element to ensure the flow of hot water never stops—only the Duda 200 Liter Single Coil.
What sets this product apart from the rest is the Dual Coil feature. One coil will funnel hot water as part of its own closed system. Functionally it’s no different than the Sunbank or Duda 200 Liter Single Coil.
But that second coil can incorporate a conventional hot water heater. Even if the sky is cloudy and the heating element fails, there would still be hot water. Alternatively, it could heat a pool or power a radiant floor heating system.
This makes the Duda 200 Liter Dual Coil the most versatile solar heater for those who need it.
The Duda 200 Liter Dual Coil has a built-in propylene glycol system like the Duda Solar 30 Tube Water Heater. This ensures that the solar collectors or any other part of the solar heating system won’t freeze.
The vacuum tubes are high boron silicon glass to help resist hail. It’s not as cold-resistant as the Duda Solar 30 Tube, but it can handle more than the Sunbank.
The water tank and piping are stainless steel. This puts it on par with the Sunbank in terms of corrosion and rust resistance.
Price & Warranty
The Duda 200 Liter Dual Coil is the most expensive of the solar water heaters reviewed. It is almost a thousand dollars more than the Sunbank. The Duda 200 Liter Single Coil is about 80 dollars cheaper by comparison.
For that price, you’d be getting a 52-gallon water tank, 20 tubes, a built-in heating element, and a second coil. If you don’t intend to use the second coil, the single-coil would be a much better option.
Possible federal tax credits and rebates make the overall price more manageable. It won’t impact the initial sale, but it does improve finances over time. Not to mention the cost savings in utilities by not using a conventional water heater.
The Duda 200 Liter Dual Coil comes with a 5-year manufacture warranty. This is low when compared to the solar collector warranties on the Sunbank and Duda Solar 30 Tube Water Heater. But it is better than the 1-year warranty those products have for the remaining components.
- The 52 gallons/200-liter tank is the largest list, and the Sunbank is only 40 gallons/151 liters.
- The built-in propylene glycol system makes it very durable in winter weather, more so than the Sunbank.
- The second coil can help cut heating costs or connect to a conventional water heater.
- The built-in water heating element works when the sun isn’t out, something the Sunbank and Duda Solar 30 Tube Water Heater don’t have.
- The 5-year manufacturer’s warranty for all components is better than most other solar water heaters.
- Most expensive product on the list, more than three times the cost of the Heliatas 4 Panel.
- Fewer vacuum tubes than the Duda 30 Tube.
- The 5-year warranty on collectors is low compared to the Sunbank, Duda 30 Tube, and Heliatos 4 Panel.
- A second coil is only useful under certain circumstances.
2. Sunbank 40 Gallon Solar Water Heater
The Sunbank has its own tank, utilizes vacuum tubes, is reasonably priced, and has a solid warranty. It may not be the best pick for every situation, but most users should be satisfied with what this product offers.
The Sunbank Solar Water Heater uses a series of vacuum tubes to collect solar radiation and heat water. This is almost identical to how the Duda Solara 30 Tube and other passive solar water heaters operate. Like other passive solar water heaters, the Sunbank obtains water through pressure from the source.
The Sunbank solar hot water heater differs because it has its own tank to store the water it heats. The tank can store up to 40 gallons or 151 liters of heated water for later use.
This tank is the smallest on the list, with the Duda Dual and Single Coil both holding 200 liters or 52 gallons. The 40-gallon tank could handle a family of two comfortably. Those with bigger families may consider getting a second one or choose one of the Duda 200-liter solar heaters instead.
The manufacturer says the vacuum tubes have a sun absorption rating between 92% to 96%. This is almost in line with the sun absorption rating of the Duda solar water heater.
This product will keep the water hotter longer than others on the list, thanks to high-density polyurethane insulation. Customer reviews have been satisfied with how long the water stays warm after sunset.
The manufacturer recommends using this product in a series with a conventional hot water heater. This is common with the others on the list, though the Duda Dual Coil is far more convenient.
The Sunbank solar water heater is designed to handle mild cold weather. Anything approaching -40 degrees Fahrenheit will be a problem. The Duda 30 Tube solar water heater has a version meant for this level of cold and might be a better pick.
One benefit of the Sunbank is that it doesn’t require propylene glycol to function in cold weather. Others like the Duda need a closed-loop glycol system to stay warm.
The stainless steel tank and tubing ensure the product will last a long time. The vacuum tubes are made of high-strength borosilicate glass or Pyrex. This will allow the product to resist one-inch hail, just like the Duda hot water heater.
One unique feature of the Sunbank is a temperature and pressure valve for overheating. When it detects temperatures rising too high, it will dump the water to avoid damage.
Price & Warranty
The Sunbank solar water hot heater sits in the middle of the list in terms of pricing. It’s nearly a thousand dollars cheaper than the Duda 200 Liter Dual Coil. It’s also almost a thousand dollars more than the Duda 30 Tube.
Fortunately, the cost of this solar water heater system can be brought down. Like many of the other solar heaters, it can be eligible for a federal tax credit. There may also be local rebate plans depending on where you live.
The product has a 10-year warranty on the collectors. The 10-year collector warranty is great, and it’s twice what the DudaDual Coil features. But it’s less than the Duda 30 Tube, which comes with a 15-year warranty.
There is also a 1-year warranty on the rest of the components. This is identical to the warranty offered by the Duda 3o Tube. It is much lower than the 5-year warranties offered by the Duda 200 Liter Dual and Single Coil heaters.
- No moving parts mean fewer breakdowns and problems compared to the Heliatos 4 solar panels.
- Middle ground pricing for a well-rounded product.
- It doesn’t require Propylene Glycol to handle cold, unlike the Duda.
- Can withstand one-inch hail.
- A 10-year warranty on solar collectors beats the five-year on the Duda 200 Liter.
- The 40-gallon tank is the smallest on the list, with the Duda 200 Liter’s being 12 gallons larger.
- The sun absorption of the collectors is a little lower than the Duda 30 Tube’s collectors.
- Having a 1-year warranty on everything but the collectors is low compared to the Duda 200 Liter’s 5-year warranty.
3. Duda 30 Tube Hot Water Heater
If you are looking for a tankless water heater, then the Duda Solar 30 Tube Water Heater is a great alternative after the Sunbank. It’s cheaper, handles cold better, has a slightly better sun absorption, and has a better warranty. However, it doesn’t come with its own tank, which can be a problem for some setups.
The Duda tube water heater uses 30 vacuum tubes to heat water. Like most passive solar water heaters, this water is fed into the tubes via pressure from the source. This is almost the same system the Sunbank hot water heater uses to heat water.
Unlike the Sunbank, this hot water heater does not have a built-in tank. There are maybe .9 liters or .23 gallons that sit in the manifold at any given time. This requires an external tank to hold the heated water.
In fact, the manufacturer recommends pairing this with an 80-gallon conventional water heater. This is the same setup as the Healiatos 4 Panel Solar Water Heater, which doesn’t have its own storage tank. The Sunbank or the Duda 200 Liter solar water heaters are better for getting a built-in storage tank.
The manufacturer claims that the solar collectors have a 93% to 96% sun absorption rating. This is a little higher than the Sunbank hot water heater, but not by much.
The sun absorption can be increased with solar aluminum reflectors that are not included. This makes this product better at heating water through solar radiation than the others.
The Duda Solar 30 Tube Water Heater is arguable the best on the list for cold weather. It has a built-in closed-loop Propylene Glycol system to keep the water from freezing. This is very similar to the Duda 200 Liter that also has a propylene glycol system.
Where this hot water heater stands out is that it has a stronger variation of the product. These Super Freeze Protection collectors are better at resisting freezing conditions. This makes it the best solar water heater for cold environments.
Like the Sunbank, this product has collectors made of high boron silicon glass. These can resist damage from one-inch hail at terminal velocity.
The piping and other components are copper. This makes them more rust-resistant than the stainless steel found in the Sunbank.
Price & Warranty
This solar water heater is the second cheapest on the list. Only the Heliatos 4 Panel is cheaper by about eight hundred dollars. The next price up is the Sunbank which costs almost a thousand dollars more.
This SRCC certified product has a great warranty. The solar collectors have a 15-year warranty which is better than the 10-year for the Sunbank. The manifold has its own 5-year warranty. This is in line with the warranty of the Duda Dual Coil.
The rest of the product has a 1-year warranty. This is identical to the warranty offered by Sunbank. Unfortunately, it’s less than the other Duda products that have a 5-year manufacture warranty.
Just like the Sunbank, this solar water heater is also eligible for tax credits and rebates. But even then, it’s affordable for what it offers.
- Second cheapest solar water heating system after the Heliataos 4 Panel.
- Has a better sun absorption than the Sunbank at 93% to 96%.
- The highest warranty at 15-years on the collectors, even better than Sunbank’s warranty.
- Built-in propylene glycol system to keep it warm, just like the Duda Solar Dual Coil.
- Super Freeze Protection collectors are more resilient to cold weather than the Duda 200 Liter.
- Like the Heliataos 4 Panel, it does not have a tank for water.
- The 1-year warranty on parts is lower than the 5-year warranty offered by Duda Solar 200 Liter.
- You must purchase the Super Freeze Protection solar collectors separately.
4. Heliatos 4 Panel Solar Water Heater
The Heliatos 4 Panel Solar Water Heater is easily the simplest system to set up on the list. It is also the only one to feature solar panels in the water heating system. It’s the bare bones of what a solar water heater is, but that may be all you need.
The Heliatos 4 Panel Solar Water Heater uses an active system to heat the water. Each of the four solar panels grabs the solar energy and uses it to heat the pipes passing underneath them, unlike the Sunbank, where the vacuum tubes heat the water.
This product uses a water pump to force the water along the pipes and through the panels.
The solar water heating system does not have its own tank. This is like the Duda 30 Tube solar water heater. Users will need a conventional tank to store the heated water. The water flows into the external tank with a bottom feed connector.
The water pump can support up to 20 liters or five gallons a minute. Its lowest setting will provide 10 liters or 2.5 gallons. Either should be sufficient for a standard shower.
The hybrid kit allows the system to be set up in series with a conventional water heater. This means the hot water heater can simply act as storage or conventionally when it’s cloudy. Users do not need to disengage or shut off the Heliatos 4 Panel hot water heater.
The Heliataos 4 Panel solar water heating system is the least resilient to cold on the list. It is not resilient to freezing in the slightest, and the warranty will not cover damage from freezing. The manufacturer even recommends a product that uses propylene glycol like the Duda 30 Tube.
Each of the pipes is stainless steel like the Sunbank hot water heater. The solar panels are aluminum and glazed polycarbonate. This makes these panels very resilient. Perhaps more resilient to hail than the Sunbank or Duda 30 Tube solar water heater.
This also means that these solar panels should work in the winter. They may not be very efficient, but they should collect something assuming there’s direct sunlight.
Price & Warranty
The Heliatos water heating system is among the cheapest of those reviewed. The next one up is the Duda 30 Tube, and it’s eight hundred dollars more. Even the Duda 200 Liter Dual Coil Water Heater is more than three times the price by comparison. Only the Heliatos 2 Panel is cheaper by about two hundred dollars.
Even this low-cost product can see further deals through federal tax credits and local rebate programs. It takes an already great deal and makes it even more feasible in the long run.
This solar water heater system features a 10-year warranty on everything. Most of the other solar water heating systems have different warranties. The Sunbank, for instance, has a 10-year warranty on collectors and 1-year on everything else. This makes the Heliatos 4 Panel warranty the best all-around.
One significant catch with this warranty is that it will not cover freeze damage. This is the only warranty on the list that has this requirement. So for those in cold climates, this is something to keep in mind.
- One of the cheapest solar water heaters, it’s a third the price of the Duda 200 Liter Dual Coil.
- Bests all around warranty at 10-years, the Duda 200 Liter Dual and Single Coil only cover 5-years.
- The solar panels are perhaps more resilient to hail than vacuum tubes.
- Like the Duda 30 Tube, it doesn’t have its own water storage tank.
- The warranty will not cover damage from freezing, unlike the other solar water heating systems.
- It is the least resilient to cold, doesn’t have a propylene glycol system like the Duda 200 Liter.
5. Heliatos 2 Panel Solar Water Heater
The Heliatos 2 Panel hot water heater has the same characteristics as the 4 panel. The obvious downside is it provides half the heating, but not at half the price. For a lone individual in a cabin, this may be enough. Otherwise, it’s probably not worth it.
Like the Heliatos solar water heater, the Heliatos 2 Panel uses an active heating system. The two panels are responsible for heating the water as it passes through them. Obviously, the Heliatos 2 Panel isn’t nearly as efficient as the Heliatos 4 Panel.
The other downside with the Heliatos 2 Panel is that it doesn’t have a storage tank. It relies upon the user already having something set up to collect the water. This makes solar water heaters like the Sunbank or Duda Dual Coil better choices.
The Heliatos 2 Panel was not designed with the cold in mind. Each panel is susceptible to freezing and prone to leaks as a result. Unlike many solar water heaters, such as the Duda 200 Liters hot water heater, there is no propylene glycol system.
The panels are very resistant to other forms of damage. Each covering is made of glazed polycarbonate that can handle debris from wind and even hail. If they don’t freeze, the panels should survive things better than the Sunbank can.
Price & Warranty
The Heliatos 2 Panel is the cheapest of the solar water heaters on the list. It’s about two hundred dollars less than the Heliatos 4 Panel. While this lower price is appealing, it does operate at half the capability of the Heliaatos 4 Panel.
It does have a great 10-year warranty on all parts of the system. The warranty covers everything from the collectors to the bottom-feed valve for 10-years. The catch is that this warranty will not cover freezing damage. As a result, picking the Sunbank or Duda 30 Tube, solar water heaters might be better.
- The cheapest product on the list is a fourth of the Duda Dual Coil price.
- The 10-year warranty is one of the best alongside the Heliatos 4 Panel.
- It can withstand damage better than other solar water heaters like the Sunbank.
- Does not have a water tank.
- Offers no protection against damage from freezing, the Duda 200 Liter water heater has a propylene glycol system.
- The warranty will not cover freezing damage.
A Solar Hot Water Heaters Buyer’s Guide
Heating Method in Solar Water Heater
When choosing the best solar water heater, it’s important to pay attention to how it heats the water. Vacuum tubes are very effective at heating large amounts of water quickly. But panels that use solar energy are more resilient to damage.
Passive systems will utilize gravity or natural water pressure to push the water along the lines. As a result, passive systems are more cost-effective but less reliable.
On the other hand, active systems use water pumps and other mechanics to force the water along the pipes. It does cost a little to run the pumps, but they provide reliable water pressure.
Some solar hot water heaters will have their own storage tanks, and others won’t. Each person needs about 20 to 25 gallons of water. So getting one with a large enough tank is important. Depending on the setup, a solar shower may be more appropriate.
Existing conventional water heaters can tie into those with tanks. This increases storage capacity and adds a heating element to the system. Some solar water heaters don’t have tanks, so they’ll need to be bought separately.
Second coil systems give a lot of versatility. These can heat other systems or draw hot water from elsewhere. Deciding whether to go with a heat pump or a solar heater can be based on using a second coil.
Many solar water heaters will struggle in cold climates. Those living in such areas may need one with a propylene glycol system to prevent freezing. These solar water heaters work much better as the temperature drops.
Generally speaking, solar water heaters with panels are more resilient than vacuum tubes. However, these types of solar water heaters won’t handle freezing as well as the tubes will.
Sometimes a manufacturer will offer variations to the design, so solar water heaters work better in the cold. It is often worth reaching out to see if they have better-insulated tubes or systems.
Price & Warranty
Warranties are strange beasts on solar water heaters. Sometimes it’s a blanket policy with a few exceptions, and other times it’s part-specific. The collectors often have the best warranty that can last a decade. The remaining parts could have a measly 1-year of coverage.
Many solar water heaters will also void the warranty if the damage is from freezing. This is especially the case with solar water heaters not meant for the cold.
Solar water heaters aren’t cheap, and this is true for the best solar water heaters. Those with large tanks, pumps, and extra features will be double or even triple that.
Currently, there are some programs meant to encourage solar energy use. The federal government sponsors a tax credit to incentive solar energy. It’s important to note this credit is going down each year.
Many local municipalities, states, and even cities can have programs to encourage solar use. These can often be rebates that will pay back many of the costs associated. This can include the product itself, installation, and other expenses.
While purchasing a solar water heater can be complicated, it can be advantageous. The savings on utilities alone is often enough to justify the hassle in many areas.
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