GEMS ACT COMPLIANCE:
SOLAR-BOOSTED AIR CONDITIONER TESTING 2016
- Purpose
This report presents the results of the testing of models of solar-boosted air conditioners conducted during 2016.
- Background
In recent years several air conditioners supplied in the Australian market claimed enhanced performance and energy savings through the application of solar-boosting technologies. Solar-boosting comes in two main forms: solar thermal and solar photovoltaic (PV) boosting. Further details on these technologies are included at Annex A. In 2016, as a result of industry and consumer interest in these claims,the GEMS Regulator tested three solar thermal boosted models and one solar PV boosted model at Vipac Engineers & Scientists; a Melbournebased National Association of Testing Authorities (NATA) accredited test laboratory.
The tests sought to determine:
1)if the models complied with the Greenhouse and Energy Minimum Standards Act 2012 (GEMS Act) GEMS level (also known as minimum energy performance standards or MEPS) and GEMS labelling requirements
- in these tests, solar-boosting inputs were minimised or disconnected
2)the validity of the claims of enhanced performance and energy savings when the models wereoperating with the solar-boosting inputs connected, activated,and operational in accordance with manufacturers’ instructions.
- GEMS Level and GEMS Labelling Compliance
The GEMS (Air Conditioners and Heat Pumps) Determination 2013 (Determination) references AS/NZS 3823.2:2013 which states “solar-boosted air conditioners and heat-pumps fall within the scope of this Standard[1] andshall meet the relevant labelling and/or MEPS requirements … when configured to operate as an air source air conditioner or heat pump (with anysolar input minimized or disconnected, as far as possible).”As such, in accordance with the Determination, all four models were tested with solar-boosting inputs minimised or disconnected.
3.1.Results
The following GEMS level requirements were tested:
Table 1. GEMS Level Requirements
Model / Type / AEER[2](cooling) / ACOP[3]
(heating) / Power factor (cooling) / Power factor (heating) / Maximum cooling test / Overall Result
1 / Solar PV / Pass / Pass / Pass / Pass / Pass / Pass
2 / Solar thermal / Fail / Fail / Pass / Pass / Pass / Fail
3 / Solar thermal / Fail / Fail / Pass / Pass / Pass / Fail
4 / Solar thermal / Fail / Fail / Pass / Pass / Pass / Fail
The following GEMS labelling requirements or declared values were tested:
Table 2. GEMS Labelling Requirements or Declared Values
Model / Type / Effective power input (cooling) / Capacity (cooling) / AEER / Effective power input (heating) / Capacity(heating) / ACOP
1 / Solar PV / Pass / Pass / Pass / Pass / Pass / Pass
2 / Solar thermal / Pass / Fail / Pass / Pass / Fail / Pass
3 / Solar thermal / Pass / Fail / Fail / Pass / Fail / Fail
4[4] / Solar thermal / Pass / Fail / Fail / NA / NA / NA
Only the solar PV boosted model met all GEMS requirements.
The three solar thermal boosted models failed to meet GEMS level requirements in both heating and cooling mode in addition to a number of GEMS labelling requirements or declared values such as capacity and efficiency (AEER and ACOP). As such, in accordance with the GEMS Check Testing Policy, the GEMS Regulator cancelled the registrations of two of the solar thermal boosted models: aSolAir WorldSWW(R)-7.2GW and an ICE SolairICE(RC)-60WM. As a result, these models can no longer be supplied in the Australian market. The third model had not yet been supplied in Australia andwas therefore not registered.Further information is available at
- Effectiveness of Solar-boosting Technologies
To assess the impact of the solar-boosting technologies on energy efficiency,the results of the tests conducted in accordance with the Determination, that is, with solar-boosting inputs minimised or disconnected,were compared to the results of the tests conducted with the solar-boosting inputs connected, activated, and operational (with solar radiation present) in accordance with manufacturers’ instructions.
4.1.Effectiveness of Solar Thermal Boosting
The test results indicated solar thermal boosted models did not meet the energy efficiency and performance claims made by manufacturers and suppliers.
4.1.1.Cooling mode
For all three solar thermal boosted models, the solar-boosting inputs reduced the energy efficiency between 4% and 21% when operating in cooling mode, compared to those tests where the solar-boosting inputs were minimised or disconnected. These results contradicted published claims of energy efficiency improvements ranging from 30% to 50% when using solar-boosting technologies.
The solar-boosting inputs decreased the cooling output in all three solar thermal boosted models between 4% and 17%.Furthermore, the solar-boosting inputs increased the power input in two of the models in cooling mode by 3% and 5%. These results do not support claims that solar-boosting inputs in cooling mode reduce the compressor input power.For the third solar thermal boosted model, the solar-boosting input appeared to have no impact on the power input in cooling mode.
4.1.2.Heating mode
For two of the solar thermal boosted models, the solar-boosting inputs significantly reduced, rather than improved, the energy efficiency of the models when operating in heating mode. The overall changes in energy efficiency in heating mode were-27% and -49.5% when compared to the energy efficiency with solar-boosting inputs minimised or disconnected. These results contradicted published claims of energy efficiency improvements ranging from 30% to 50% when using solar-boosting technologies. The third solar thermal boosted model showed an overall 10% improvement in energy efficiency in heating mode with the solar-boosting input connected.
The solar-boosting inputs decreased the heating output in two of the solar thermal boosted models by 24% and 37%. The third solar thermal boosted model showed an 8% increase in heating output with the solar-boosting input connected. The solar-boosting inputs increased the power input in two of the models in heating mode by 4% and 25%. The third solar thermal boosted model showed a 1.5% decrease in power input.
Table 3 summarises the overall energy efficiency impact in cooling and heating tests for the three solar thermal boosted models. Note, this is the change in measured energy efficiency when comparing tests without solar-boosting inputs connected to tests with solar-boosting inputs connected and with solar irradiance.
Table 3: Change in energy efficiency with solar thermal boostinginputs connected
Model / Solar input / Change in efficiency (cooling) / Change in efficiency (heating)2 / Solar flat plate no irradiance[5] / -17% / -46%
2 / Solar flat plate with irradiance / -21% / -50%
3 / Solar flat plate with irradiance / -8% / -27%
4 / Solar tube with irradiance / -4% / +10%
This data suggests the decrease in energy efficiency, when compared to tests with solar-boosting inputs minimised or disconnected, is mostly due to the addition of the solar-boosting inputs. The additional application of solar irradiance appears to make the performance slightly worse again when compared to no irradiance.Detailed test results for each model are included at Annex B.
4.2.Effectiveness of Solar PV Boosting
For the solar PV boosted model, the solar-boosting inputhad minimal impact on the heating and cooling capacity (output). However, the addition of PV energy significantly reduced the required mains power input up to 75% with an equivalent 700W DC input from the PV panels. This can result in substantial energy reductions when the modeloperates during the daywith PV panels attached and properly orientated.
The solar PV boosted model could therefore deliver significant improvements in efficiency[6] in both cooling and heating mode in some cases, particularly for the optimal PV output, which in this case was determined to be 700W DC. However, above 700W DC input from the PV panels(that is,where the four 250W rated panels were operating at more than 75% of their rated capacity), the modelbecame unstable and switched between DC power and AC mains power operation, thereby negating the efficiency benefits otherwise available at, or below, 700W DC input.
A consumer is unlikely to be aware this is occurring as the change from solar electricity to mains electricity is seamless. So whilst a consumer may assume a sunny day meansPV panels are offsetting their electricity bill, the panels may, in fact, be contributing nothing.
Table 4: Change in energy efficiency with solar PV boostinginputs connected
Model / Solar input / Change in efficiency (cooling) / Change in efficiency (heating)1 / Solar PV – 350W DC input / +61% / +56%
1 / Solar PV – 700W DC input / +299% / +231%
Detailed test results for the solar PV boosted model are included at Annex C.
The model’s literature suggested the mains power input could be reduced to as little as 30W through the use of solar PV panels. However, testing found the minimum external (AC) input required for the model to operate was 220W (at 700W DC input from the PV panels). Testing was conducted at rated capacity only, so a reduced AC input may be possible at part load. However, this would also reduce the overall power input to the model, thus limiting savings potential.
Whilst the savings for the solar PV boostedmodel appear impressive, it must be noted the energy savings from the PV panels were only achieved when the model was operating. When the model is not being used, power generated from the PV panels cannot displace energy used in other household appliances as the system does not permit export to the mains power supply in the home.
Long term data on solar PVsystems reveal they are able to generate power for around 11 hours per daywhen optimally sited. On average, solar PV output is low in the morning and evening, and high around midday, with no output at night. Even for heavy users of space conditioning equipment, there are likely to be many hours the solar PV system generates power but the air conditioner is not being used. This means potential energy will go to waste.
There may also be significant demand for space conditioning (heating or cooling) when there is little or no solar radiation or solar PV output which also means there will be no benefit from the solar PV panels attached to the air conditioner during these periods.
A much more effective use of solar PV panels is the grid connected system where the full output potential of the panels is realised at all times, either through the displacement of energy used in other appliances in the home or business when the air conditioner is not in use, or via export to the grid.
The results were provided to the supplier of this model for consideration.
- Conclusions
When tested with solar-boosting inputs minimised or disconnected as required by the Determination:
- the three solar thermal boosted models failed to meet GEMS level requirements in both heating and cooling mode in addition to a number of GEMS labelling requirements such as capacity and efficiency
- the solar PV boosted model met all GEMS level and GEMS labelling requirements
These results were compared to the results of the tests conducted with the solar-boosting inputs connected, activated, and operational (with solar radiation present) in accordance with manufacturers’ instructions.
In most cases, the solar thermal boosted models performed worse, with the solar-boosting inputs making the air conditioners less efficient than they would have otherwise been without the solar-boosting inputs connected.However, one model did show a slight improvement in performance in heating mode only.
The test results indicatedthe solar thermal boosted models did not meet the performance claims of manufacturers and suppliers.Solar thermal boosting appears to be a marketing gimmick that offers no improvement in the performance or amenity of the air conditioner.
The solar PV boosted model showed good reductions in energy consumption up to a point. However, the system appeared unable to accept the maximum PV power claimed by the manufacturer.Additionally, thesolar PV boosted modelconfiguration means energy savings from the solar PV array occur only in the daytime (when there is sunlight) and only when the air conditioner is in use. This severely limits the potential energy savings. Some initial analysis also suggestedmuch of the potential energy that could have been generated by the solar PV array will be wasted over a typical year.
Annex A
Solar-boosting technology
- Solar thermal boosting technology
Solar thermal boosting appears to be the most popular form of boosting technology used in so called “solar boosted” air conditioners in Australia.Almost all suppliers of this type of boosting technology cite the following basis for energy savings (or similar) which has been compiled from a range of product literature:
In a standard split system air conditioner (without solar thermal boosting) after the refrigerant gas exits the internal evaporator (in cooling mode) it then passes through a compressor which pressurises the gas with a consequent increase in its temperature (according to the ideal gas law). This high pressure/high temperature refrigerant gas is then passed through the external condenser coil where significant amounts of heat are dissipated from the gas to the outside air as the refrigerant liquefies (changes phase).
In the caseof solar thermal boosting, an external heat source in the form of a solar collector (either flat plate or evacuated tube type) is used to impart additional heat to the refrigerant (before it enters the condenser coils) thereby increasing its pressure. This process reduces the load on the compressor, the prime function of which is to pressurise the refrigerant gas. As the compressor in an air conditioner is typically responsible for 80% or more of its total electrical power consumption, any reduction in the load on the compressor will consequently reduce the overall electrical consumption of the air conditioner (claims of savings of between 30% and 50% in terms of electrical energy consumption are routinely made in product literature).
- Solar PV technology
Solar PV boosting technology works on a relatively simple basis. PV cells supplied with the air conditioner unit are mounted in a position subject to significant levels of solar radiation and are connected to the outdoor unit.When solar radiation levels are high enough, the PV panels convert the incident solar radiation into electricity, which is fed into the air conditioner.As inverter driven systems have a DC component of power in any case, it is relatively straight forward to use the PV DC power directly to displace external power used to drive the compressor once this is converted to the correct voltage.The PV generated electricity supplants a portion of the electricity that would have otherwise been obtained from the mains supply thereby reducing the energy consumption from the mains supply. Some systems may use a synchronous inverter to provide general mains power inside the unit that can be used to displace any part of the mains power requirement of the air conditioner.
Annex B
Solar thermal boosted models – Test results
Unit 2(solar flat plate) / Rated Value / Solar Booster Bypassed
(Base Case) / Solar Booster Connected
(No irradiation) / Solar Booster Connected
(With irradiation)
Parameter Measured / Tested Value / % diff.
to base / Tested
Value / % diff.
to base
Total Cooling Capacity (W) (output) / 6000 / 5206 / 4468 / -14.2% / 4322 / -17%
Cooling Power input (W) (input) / 1860 / 1797 / 1866 / +3.8% / 1888 / +5.1%
Cooling EER (efficiency) / 3.226 / 2.897 / 2.349 / -17.3% / 2.289 / -21%
Total Heating Capacity (W) (output) / 6600 / 5838 / 3909 / -33.0% / 3687 / -36.8%
Heating Power input (W) (input) / 2040 / 1851 / 2274 / +22.9% / 2314 / +25%
Heating COP (efficiency) / 3.235 / 3.145 / 1.719 / -45.5% / 1.593 / -49.5%
Unit 3
(solar flat plate) / Rated Value / Solar Booster Bypassed
(Base Case) / Solar Booster Connected
(No irradiation) / Solar Booster Connected
(With irradiation)
Parameter Measured / Tested Value / % diff.
to base / Tested
Value / % diff.
to base
Total Cooling Capacity (W) (output) / 7200 / 5589 / Not / Tested / 5257 / -5.9%
Cooling Power input (W) (input) / 2230 / 2069 / Not / Tested / 2126 / +2.8%
Cooling EER (efficiency) / 3.229 / 2.701 / Not / Tested / 2.437 / -8.4%
Total Heating Capacity (W) (output) / 7900 / 5892 / Not / Tested / 4487 / -23.8%
Heating Power input (W) (input) / 2320 / 2167 / Not / Tested / 2256 / +4.1%
Heating COP (efficiency) / 3.405 / 2.719 / Not / Tested / 1.989 / -26.8%
Unit 4
(solar tube) / Rated Value / Solar Booster Bypassed
(Base Case) / Solar Booster Connected
(No irradiation) / Solar Booster Connected
(With irradiation)
Parameter Measured / Tested Value / % diff.
to base / Tested
Value / % diff.
to base
Total Cooling Capacity (W) (output) / 3.5 / 2.800 / Not / Tested / 2.688 / -4.0%
Cooling Power input (W) (input) / 1.025 / 1.063 / Not / Tested / 1.063 / 0.0%
Cooling EER (efficiency) / 3.415 / 2.634 / Not / Tested / 2.529 / -4.0%
Total Heating Capacity (W) (output) / N/A / 3.178 / Not / Tested / 3.44 / +8.2%
Heating Power input (W) (input) / N/A / 1.306 / Not / Tested / 1.287 / -1.5%
Heating COP (efficiency) / N/A / 2.433 / Not / Tested / 2.672 / +9.8%
Annex C
Solar PV boosted model – Test results
Unit 1(solar PV) / Rated Value / Solar Booster Bypassed
(Base Case) / Solar Booster Connected
(350W DC solar) / Solar Booster Connected
(700W DC solar)
Parameter Measured / Tested Value / % diff.
to base / Tested
Value / % diff.
to base
Total Cooling Capacity (W) (output) / 3500 / 3358 / 3373 / +0.4% / 3392 / +1.0%
Cooling Power input - mains (W) (input) / 880 / 875 / 546 / -37.6% / 221 / -74.7%
Cooling EER (efficiency) / 3977 / 3.839 / 6.181 / +61% / 15.331 / +299.3%
Total Heating Capacity (W) (output) / 3800 / 3796 / 3869 / +1.9% / 3845 / +1.3%
Heating Power input - mains (W) (input) / 950 / 966 / 633 / -34.5% / 296 / -69.4%
Heating COP (efficiency) / 4000 / 3.930 / 6.112 / +55.5% / 13.00 / +230.8%
For the solar PV system, the input power is the net mains power input that the system uses with the specified DC boost power nominated.
Solar-boosted air conditioner testing 2016
1
[1] No Australian or international standard has been developed to test air conditioners with solar-boosting technology incorporated.
[2] Annual Energy Efficiency Ratio
[3]Annualised Coefficient of Performance
[4] This model was provided to the GEMS Regulator by an importer considering the supply of the model in Australia. The model was not yet registered and a declaration of GEMS labelling requirements had not been made. However, the tested values were “declared” on the model rating plate.