If you’re looking for an efficient system for solar hot water, the solar panels that power the heating pump are not easy to beat.
Although each of the panels and heat pumps needs to perform at a high level the two can surpass the solar hot water method which is generally considered the most effective method.
An average heat pump system for hot water is three times more effective than a standard electric water heater which utilizes electricity resistance to heat. This is because instead of creating heat with electricity it uses electricity to transfer heat. Water heaters work in the exact similar way that refrigerators, aside from the fact that they operate in totally different ways. This means that refrigerators pump the heat to help keep the contents inside cool, whereas warm water from a heat pump pumps warmth in to keep things warm. 1..
Because heat pump hot water systems are energy efficient, they can qualify for Renewable Energy Certificates called STCs which reduce their costs. These are the exact certificates you receive for installing solar panels on rooftops but the number of certificates awarded is calculated differently.
Although they’re efficient and efficient, hot water from heat pumps has been plagued by a variety of disadvantages that have kept the technology from being widely accepted. They include:
- A high initial cost.
- Poor reliability.
- Repairs are expensive.
- The high volume of noise.
- Manufacturers make false claims.
Despite this apparent abundance of dead albatrosses hanging around the heat pump hot water’s neck, I’m confident that the technology will continue to improve and we’re likely to be seeing an increasing amount of heat pumps hot water systems in Australia.
What Is A Heat Pump?
The first heat pumps were developed in Austria in the year 1856, by Peter Ritter of Rittinger He devised a method that took advantage of the fact that gas is heated when it is compressed into a liquid and then cools after it evaporates, which allows it to move heat across. This means that heat can be pushed into a restricted area, for instance, using a heat pump hot water system as well as out of restricted areas, like refrigerators. Air conditioners in homes are able to both and can transport heat from the home during summer and transfer heat into the home in winter.
They can transfer energy between the water cycle, ground, and air. In Europe where temperatures can drop as low as -30oC to punish those who are not living in Australia, Ground heat pumps are popular because the ground just a few feet below is much warmer in winter than the air. However, there is Australia where temperatures aren’t often above the freezing point, most heat pumps run on air and they are often referred to as air-sourced heat pumps.
Sometimes, hot water heat pump systems are referred to as solar heat pumps because 99.98 percent of the heat they produce was originally derived via solar But I believe this is a bit misleading since they don’t need sunlight for operation. In winter, most of the heat generated by the air conditioner pump produced inside your home originated from the sun and no one has ever referred the solar power as cooling.
Heat Pumps Use CO2 As A Working Fluid
Nowadays, heat pumps typically employ CO2 (CO2) as their primary fluid . While CO2 is a green gas, however, the amount is typically lower than one kilogram that’s about the amount that is released when generating one Kilowatt-hour of electricity using coal. There is no need to be concerned about the heat pump frying the earth should it leak. If it can displace more than one-kilowatt hour of coal production throughout its life, you’re good to go.
Additionally One kilogram worth of CO2 isn’t enough to pose a threat to your health unless it’s in an extremely restricted space like your lung.
The heating element of a traditional electronic hot-water system converts all electrical energy it consumes into heat and transfers around 98% of the warmth to the hot water inside tanks for storage. This is close to 100 percent for me. However, it’s more efficient to transfer heat in a different direction instead.
On the right-hand edge of the far rectangular area is the energy input to heat in Kilowatts or electricity. Following that is the output of capacity in Kilowatts of heat. Thus, the air conditioner could absorb 0.86 Kilowatts of power and make use of it to transfer 4.45 Kilowatts of heat within. This is more than 5:1. Below the 4.45 figure, it says that the power of heating at 2°C is only 3.6 Kilowatts, and it reduces that ratio by 4.2 to 1. This is due to the colder it gets the less efficient the heat pump of the air conditioner is at transferring heat due to the higher temperature difference. However, heaters that are hot from a heat pump aren’t going to prove as efficient as this air conditioner. For every kilowatt-hour they use, they’ll offer around 3-kilowatt hours of heat. This makes them three times as efficient as the conventional electrical water heater. The precise efficiency can vary throughout the year due to the more difference there is between the temperature of the air and the temperature of hot water the less efficient. If you read the information on water heaters with heat pumps on the web, you’ll notice that they are generally claimed to be three times more efficient. However, this might not be the case.
Manufacturers May Mislead About the Efficiency
The most commonly used measure of the efficiency of a hot water heat pump system is the Coefficient of Performance or the COP. It is a simple measurement. If a heat pump consumes 1-kilowatt hour of electricity to produce 3 Kilowatt-hours of heat, it has three COP. If it consumes one kilowatt-hour of electricity to generate four kilowatts worth of heat, it has a COP of 4.
The majority of heat pump hot-water systems claim to have a COP of between 3 and 4.5 or higher. A 4-COP doesn’t mean that the system will use 25% the electricity than a traditional hot water system. This is because it uses energy for much more than controlling its heat pump. For instance, in the case of extreme cold, ice may develop on the outside exchangers of heat pumps and it might require defrosting every couple of minutes. It is either necessary to run heaters to melt the ice or, more frequently, the unit is designed to be a standard heating element to heat water and therefore in cold temperatures, it can function like a traditional electrical water heater.
The highest usage of hot water occurs in colder weather, their lower effectiveness at lower temperatures, and their habit of having to work to defrost, or just giving up functioning as a heat pump could significantly raise the volume of energy they consume.
Heat Pumps Can Be More Efficient Than Solar Thermal
Hot water from solar sources has typically been regarded as the most efficient method to heat water by sunlight. This graph that I copied out of the Apricus solar thermal hot water brochure illustrates the effectiveness that flat plates and evacuated tubes solar thermal system, both for the gross, or total surface of collectors and in addition to the smaller absorber area
“The “Delta-T” in the lower left of the graph represents the difference between the temperature of the air and the temperature of the collector and is expected to be at around 40 degrees. If we assume that it’s 40 degrees, then the maximum efficiency of the gross collector area is approximately 54 percent for solar thermal that is flat.
The hot water from a heat pump can perform better than the heat pump, however, it’s not always the case. These days, solar panels tend to be about 17 percent efficient, and at the point that their electrical energy to a heat pump, it’s not unusual to find different losses to reduce the output of their panels by 20 percent. This would reduce the performance of the 17% panel to 13.6 percent. If a heat source provides three times the heat of the standard electrical water heater, its total efficiency is 41%.
However, if highly efficient panels are employed like SunPower’s X-22 panels which are 22.1 percent efficient, even if losses decrease down to 17.7 percent, if they are used with an energy source that has a capacity of 3.5 times better than a standard hot water system, the total efficiency will be 62%.
If you are willing to pay for top-quality panels, pairing them with a high-efficiency heater hot water pump could be the best way to make the most of your limited area on the roof.
Heat Pump Hot Water Can Receive STCs
Although heat pump hot water does not produce electricity like solar on rooftops it reduces its usage compared to traditional hot-water systems and the amount of electricity saved is equal to or more than a kilowatt-hour of pure electricity produced. This is why heat pumps are eligible to receive Small-scale Technology Certificates (STCs) to help meet the Australian government’s Renewable Energy Target.
This webpage lets you download an inventory of all authorized heaters for hot water heating and how many STCs that are created after installation.
If you’re interested in knowing precisely how many STCs an equipment will receive You can visit the following page and input the model, brand, and postcode it will be located.
The exact amount you receive will depend on the zone you’re in. However, these zones differ from the ones that are for roof solar PV. This is the map of hot water zones of both hot water from solar thermal and the hot water from a heat pump:
The number of STCs received will depend on the amount of electricity expected to be saved through the system in every area and this is influenced by how much hot water users make use of and its efficiency. Therefore, in the zone 1 heat pump hot water is used effectively all the time because it is never really cold however, people in zone 1 don’t make use of a lot of hot water as a result of the fact that it is never extremely cold, which is why zone 1 gets fewer STCs than zones that are colder.
What’s not on the map is special zone 5, which is found only found in areas like the Snowy Mountains and mountains of Tasmania. These are the coldest regions in Australia and you would think they’d get the most STCs since the use of hot water in these areas is expected to be the most efficient. But since the hot water from a heat pump tends to operate at lower effectiveness in zone 5 will get fewer STCs than in zone 4.
The number of STCs received will be reduced by one-tenth at the beginning of 2022 and reduced each year following this until the STCs are eliminated at the end of 2030.
Solar Power, Timers, And Heat Pump Hot Water
I have recently written about the possibility of putting traditional heating systems with hot waterso that they can switch on during the day when they should be able to make use of surplus solar energy which would otherwise be absorbed by the grid and receive a feed-in rate.
It is simpler for heat pumps to operate water heaters using the excess solar energy by using a timer, as they typically draw just 1 kilowatt or less, that’s about half as much as the tiniest conventional heating element that is used in traditional electrical water heaters. This lower energy draw means it is more likely that solar panels on rooftops can provide enough power to power them without the need to tap into grid power.
Since the temperature average is greater than the average temperature, hot water from a heat pump is more efficient in the morning and will be less likely to spend energy on defrosting or operating as a conventional hot-water system.
The hot water from a heat pump offers the benefit of typically being equipped with built-in timers. In addition to setting them to shut off when an excess of solar power is expected as well, they let homeowners who are on time-of-use tariffs to benefit from cheap off-peak power at a low cost.
Solar Hot Water Diverters Cannot Be Used
Hot water diverters from the solar that supply surplus solar energy into the heating components in conventional hot water systems that can’t be used in conjunction with heat pump hot water. The kind of electricity they provide does not work with electronics or pumps and could cause damage to them.
Threshold Power Can Be Used
Devices that send home AC energy devices while there’s enough excess solar energy to run can be used in conjunction with heat pumps. Examples include such devices They also allow users to set the minimum activation time and delay the activation process once the excess solar power threshold is met to stop clouds from rapidly switching the heat pump on and off the heat pump.
Controlled Load Or Economy Tariffs Can Be Used
Water heaters that are heated by a heat pump can be utilized when paired with controlled load tariffs which are often referred to as economic tariffs. There are some models where the manufacturers recommend they connect to electricity for longer than eight hours per day, which could make them incompatible with most load tariffs controlled.
Lukewarm Water Is Dangerous
Whichever technique is used to drive the hot water heating system, it’s vital to ensure that the storage tank is kept at a temperature of and life that storage tank reaches minimum temperature of 60 degrees each three days to prevent the spread of dangerous microorganisms like Legionella.
They Aren't Cheap
A hot water heating system using a heat pump will likely cost between approximately $2,500-$4,500 with the cost reductions due to STCs. Residents of Victoria may also be eligible for Lewater Energy Efficiency which is worth around $500 for replacing an existing traditional hot water system.
The cost of the whole system is usually between 2 and three times that of an equivalent traditional electric hot water system.
Warranties Are Often Short
Warranties for hot water heat pump systems are usually extremely limited and can be as small as a year. The longest I’ve ever seen is six years. Although they could have longer warranties for their tanks that store water but that’s not the component that is likely to wear out.
The short warranty length suggests that their operational life can’t be anticipated to last for long and when you add in their high cost of purchase and the high expense of repairs A lot of people do not see them as a worthwhile investment.
They Can Be Noisy
Certain heating systems that use hot water from a heat pump create an enormous amount of sound. The quietest I’m familiar with is Sanden Eco Plus which operates at 37 decibels. This is about as loud as a quiet fan operating a low-speed mode that shouldn’t be a surprise since that’s what causes the noise that it creates.
Due to their similar operation and energy consumption, the majority of hot water heating systems that use heat pumps produce a noise similar to that of room air conditioners. The noise may range from a quiet noise to a tinny loud cacophony. Some can be so loud that they’ve been prohibited from operating during the night, so they don’t disturb neighbors.
Potential Savings
The most affordable place in Australia to set up a heater hot water unit probably includes Western Australia. This is because controllable load tariffs that decrease the price of conventional hot water systems aren’t in place and the price of electricity is very high.
In Perth, the majority of households have natural gas hot water heating systems. But if one family despite the warm weather, was heavy use of hot water and was equipped with a standard electric hot water system they could decrease the number of kilowatt hours they spend heating water each year by 1,500 using the use of a heat pump hot water system. If their power came from the grid, it could cost them about $400 per year.
And in Australia, the savings will generally be significantly lower.
My parents who lived in rural Queensland were massive consumers of hot water and were able to reduce the annual use of electricity by 1500 kilowatt-hours through the installation of an electric hot water heat pump system, given that the hot water service they have is the tariff 31, which would mean they could reduce their annual electricity bill by around $260.
In other parts of Australia where the controlled load is typically less and feed-in rates are often higher, the benefits are likely to be less.
Environmental Benefit
Although the financial benefits of using a heat pump to heat water aren’t yet favorable it can offer significant environmental benefits by decreasing carbon emissions from fossil fuels that a home is using for heating water or by allowing solar power generated by rooftops to be fed to the grid, where it will decrease the use of fossil fuels.
Many households will find that they will benefit financially and will have a greater impact on the environment with the funds to invest in a bigger solar roof system that they might have installed.
People who have installed the largest solar system as they can manage could find hot water from a heat pump an efficient way to reduce carbon emissions. Many can benefit from this even if the ROI on a hot-water system is minimal and even zero.
The Future Of Heat Pump Hot Water May Be Lewater
While the heat pump hot water hasn’t seen a huge amount of success in Australia at present, however, shortly, its chances could increase. The number of STCs they receive won’t begin to decrease for more than four years and at this point, the cost of heat pumps will likely fall and reliability will improve. Many countries around the world are working to improve heat pumps and we will gain from their effort.
One drawback I see with the heated water produced by heat pumps is that the price of operating traditional hot water systems could fall because the cost of solar rooftops is continuing to decrease and growing renewable generation reduces the pressure on the controlled load tariffs and the off-peak rates for time-of-use tariffs.
