It is possible

It is possible to use a solar panel to power low voltage, direct current (DC) blowers (for air collectors) or pumps (for liquid collectors). The output of the solar panels matches available solar heat gain to the solar collector. With careful sizing, the blower or pump speed is optimized for efficient solar gain to the working fluid. During low sun conditions the blower or pump speed is slow, and during high solar gain, it runs faster.

When used with a room air collector, separate controls may not be necessary. This also ensures that the system will operate in the event of utility power outage. A solar power system with battery storage can also provide power to operate a central heating system, though this is expensive for large systems.

The heart of the control

The heart of the control system is a differential thermostat, which measures the difference in temperature between the collectors and storage unit. When the collectors are 10° to 20°F (5.6° to 11°C) warmer than the storage unit, the thermostat turns on a pump or fan to circulate water or air through the collector to heat the storage medium or the house.

The operation, performance, and cost of these controls vary. Some control systems monitor the temperature in different parts of the system to help determine how it is operating. The most sophisticated systems use microprocessors to control and optimize heat transfer and delivery to storage and zones of the house

SELECTING AND SIZING A SOLAR HEATING SYSTEM

SELECTING AND SIZING A SOLAR HEATING SYSTEM

Selecting the appropriate solar energy system depends on factors such as the site, design, and heating needs of your house. Local covenants may restrict your options; for example homeowner associations may not allow you to install solar collectors on certain parts of your house (although many homeowners have been successful in challenging such covenants).

The local climate, the type and efficiency of the collector(s), and the collector area determine how much heat a solar heating system can provide. It is usually most economical to design an active system to provide 40% to 80% of the home's heating needs. Systems providing less than 40% of a home’s heat are rarely cost-effective except when using solar air heater collectors that heat one or two rooms and require no heat storage. A well-designed and insulated home that incorporates passive solar heating techniques will require a smaller and less costly heating system of any type, and may need very little supplemental heat other than solar.

The cost of an active sola

The cost of an active solar heating system will vary. Commercially available collectors come with warranties of 10 years or more, and should easily last decades longer. The economics of an active space heating system improve if it also heats domestic water, because an otherwise idle collector can heat water in the summer.

Heating your home with an active solar energy system can significantly reduce your fuel bills in the winter. A solar heating system will also reduce the amount of air pollution and greenhouse gases that result from your use of fossil fuels for heating or generating the electricity

Simple "window box collectors"

Simple "window box collectors" fit in an existing window opening. They can be active (using a fan) or passive. In passive types, air enters the bottom of the collector, rises as it is heated, and enters the room. A baffle or damper keeps the room air from flowing back into the panel (reverse thermosiphoning) when the sun is not shining. These systems only provide a small amount of heat, because the collector area is relatively small.

TRANSPIRED AIR COLLECTORS

Transpired air collectors use a simple technology to capture the sun's heat to warm buildings. The collectors consist of dark, perforated metal plates installed over a building's south-facing wall. An air space is created between the old wall and the new facade. The dark outer facade absorbs solar energy and rapidly heats up on sunny days—even when the outside air is cold.

A fan or blower draws ventilation air into the building through tiny holes in the collectors and up through the air space between the collectors and the south wall. The solar energy absorbed by the collectors warms the air flowing through them by as much as 40°F. Unlike other space heating technologies, transpired air collectors require no expensive glazing.

Transpired air collectors

Transpired air collectors are most suitable for large buildings with high ventilation loads, a fact which makes them generally unsuitable for today's tightly sealed homes. However, small transpired air collectors could be used to pre-heat the air passing into a heat recovery ventilator or could warm the air coil on an air source heat pump, improving its efficiency and comfort level on cold days. No information is currently available on the cost effectiveness of using a transpired air collector in this way, however.

ECONOMICS AND OTHER BENEFITS OF ACTIVE SOLAR HEATING SYSTEMS

Active solar heating systems are most cost-effective in cold climates with good solar resources when they are displacing the more expensive heating fuels, such as electricity, propane, and oil. Some states offer sales tax exemptions, income tax credits or deductions, and property tax exemptions or deductions for solar energy systems.

ROOM AIR HEATERS

ROOM AIR HEATERS

Air collectors can be installed on a roof or an exterior (south-facing) wall for heating one or more rooms. Although factory-built collectors for on-site installation are available, do-it-yourselfers may choose to build and install their own air collector. A simple window air heater collector can be made for a few hundred dollars.

The collector has an airtight and insulated metal frame and a black metal plate for absorbing heat with glazing in front of it. Solar radiation heats the plate that, in turn, heats the air in the collector. An electric fan or blower pulls air from the room through the collector, and blows it back into the room. Roof-mounted collectors require ducts to carry air between the room and the collector. Wall-mounted collectors are placed directly on a south-facing wall, and holes are cut through the wall for the collector air inlet and outlets.

Although some early

Although some early systems passed solar-heated air through a bed of rocks as energy storage, this approach is not recommended because of the inefficiencies involved, the potential problems with condensation and mold in the rock bed, and the effects of that moisture and mold on indoor air quality.

Solar air collectors are often integrated into walls or roofs to hide their appearance. For instance, a tile roof could have air flow paths built into it to make use of the heat absorbed by the tiles.

Most solar air heating systems are room air heaters, but relatively new devices called transpired air collectors have limited applications in homes.

CONTROLS FOR SOLAR HEATING SYSTEMS

Besides the fact that designing an active system to supply enough heat 100% of the time is generally not practical or cost-effective, most building codes and mortgage lenders require a back-up heating system. Supplementary or back-up systems supply heat when the solar system cannot meet heating requirements. Backups can range from a wood stove to a conventional central heating system.

CONTROLS FOR SOLAR HEATING SYSTEMS

Controls for solar heating systems are usually more complex than those of a conventional heating system, because they have to analyze more signals and control more devices (including the conventional back-up heating system). Solar controls use sensors, switches, and/or motors to operate the system. The system uses other controls to prevent freezing or extremely high temperatures in the collectors.

VENTILATION PREHEATING

VENTILATION PREHEATING

Solar air heating systems use air as the working fluid for absorbing and transferring solar energy. Solar air collectors can directly heat individual rooms or can potentially pre-heat the air passing into a heat recovery ventilator or through the air coil of an air-source heat pump.

Air collectors produce heat earlier and later in the day than liquid systems, so they may produce more usable energy over a heating season than a liquid system of the same size. Also, unlike liquid systems, air systems do not freeze, and minor leaks in the collector or distribution ducts will not cause significant problems, although they will degrade performance. However, air is a less efficient heat transfer medium than liquid, so solar air collectors operate at lower efficiencies than solar liquid collectors.

It is also not

It is also not completely transparent since it describes (ANNEX C) the reference heating/cooling demand and the number of hours in each operational mode (active mode, thermostat off mode, standby and crankcase heater mode) is decided from weighted climate, type of building, internal gains, set back setting and so on, but there is no reference that describes the calculations. Therefore it is not possible to recalculate the hours to fit specific needs. The climate hours that describes the temperature bins does not seem to be adjusted in any ways since it is the same hours that is used in Ecodesign LOT 1.   Another weakness is that the model does not include domestic hot water.  
Possibility The model could be developed so that it would be possible to decide the energy demand of the house. It could also be a possibility to fit the model to your own climate. Maybe the ground water temperature and thereby the bore hole temperature could be climate depending.  It should be obvious how interpolations or extrapolations of capacity and/or COP should be performed to avoid differences between users

since they are only tested a

Risk The performance of water/water heat pumps can be overestimated, especially at the cold climate, since they are only tested at +10°C at the cold side (in reality the ground water temperature can be lower than this). This can also be the case for other ground source heat pumps.  
The degradation coefficient Cc might be a disadvantage for a ground source heat pump when default values are used. Cc =0.9 is a larger degradation of GSHP’s than what is shown in reality. There is a risk that the requirement of having heat pumps tested in part load might lead to extensive laboratory tests, which is costly. It is also difficult to get sufficient data from existing laboratory tests, since few heat pumps are tested in part loads

This model is very

This model is very wide and thorough in its content. It treats both room heating and tap water production. The model is adaptable to different climates and the resolution of the temperature bins can be chosen.  
The model specifies the requirements and losses of the certain house and defines recoverable respectively unrecoverable energy.  
It is not necessary to test the heat pump at the part loads, since there are default values that can be used.  
The model can be used to calculate the SPF for the entire system with the building included or only for the heat pump.

Risk There

Risk There is a present danger of doing mistakes when using the model. The large amount of data that is taken into account will probably result in much estimation that will differ from case to case and will therefore result in incomparable outcome of the model. Also the same heat pump installation can probably give different results depending on the way it is calculated, (choosing method, input, accuracy and test points).
7.3 EuP LOT 1  In general, the Energy Using Products (EuP) Directive have broadened to include also Energy Related Products (ErP), but for the treatment in this report, we choose to use the term EuP, since heat pumps are energy using