Stratification heating can be realized by two ELWA units. Usually one of the devices is installed in the lower third and one in the upper third of the tank. Both devices are set to the same desired temperature and communicate with each other via the DC cabling.

With the AC ELWA-E, in combination with the my-PV Meter, even up to eleven devices can  be controlled according to priorities. And with Smart-Home control, even more, depending on the type of system.

The AC•THOR and AC•THOR 9s or the AC ELWA-E require information about the available excess PV-power at the metering point in order to control the heater accordingly.

This is received either from the my-PV Power Meter or from a compatible energy management system (inverter, smart home or battery storage).

The data transfer takes place via the local network.

A proper network setup is required for the function!

Your AC ELWA-E or AC•THOR remains on standby. The surplus is not used despite an upright Power Meter connection?

The measuring point of the Power Meter may be installed incorrectly!

In some house installations, three phases lead from the post-metering fuses to the house distribution and three phases to the photovoltaic system. For proper surplus detection, however, both areas must be recorded during measurement.

If the AC ELWA-E or the AC•THOR remains on standby, the current transformers are probably attached to the three phases of the house distribution and the energy from the photovoltaic system remains "unseen".

Solution

If the cross-section of the phases allows it, both wires can be enclosed together by a current transformer. If this is not possible, the current measurement can also be placed between the post-meter fuses and the electricity meter of the energy supply company.

Image excerpt from the Power Meter assembly instruction

The AC•THOR and AC•THOR 9s or the AC ELWA-E require information about the available excess PV-power at the metering point in order to control the heater accordingly.

This is received either from the my-PV Power Meter or from a compatible energy management system (inverter, smart home or battery storage).

The data transfer takes place via the local network.

A proper network setup is required for the function!

In all houses with a PV system and a hot water boiler, the PV surplus can be used for domestic water heating.

Optional: In buildings with low heating demand, electric space heating can also be supported from photovoltaics.

Maximization of self-consumption is the goal!

As it is the case with heat pumps, the seasonal performance factor (SPF) describes the ratio heat generation to electricity demand (without household electricity consumer). However, while a heat pump additionally receives energy from the environment, the energy for my-PV products comes from the sun. The big advantage is that electricity is now available instead of heat for energy distribution. "Cables instead of pipes" make the system much easier and less expensive. A fact that also has a significant impact on maintenance costs.

Thanks to smart excess management, AC•THOR draws less power from the public grid than heat pumps do. For all those who want to build or renovate a house, AC•THOR offers a considerable potential for savings: The building services can be installed in the smallest space and save up to 30% of the acquisition or operating costs compared to heat pumps.

How much electricity from the grid is required can be directly influenced by the size of the PV system. This is easily possible for energy-saving detached houses with, for example, 10 kWp PV.

In addition, a heat pump can "only" generate heat. There is no contribution to the electrical consumers in the building. In contrast, photovoltaics gives priority to normal household electrical consumers before heat generation and thus contributes to the reduction of operating costs to the highest degree.

Depending on whether only hot water has to be heated or the space heating is supported, a PV system between 3 and 10 kWp makes sense for a detached house.

All popular poly, mono and thin film PV modules. Only the voltages and currents have to be considered!
The ELWA operates in a voltage range of 100 -360 VDC.

Click here for our practical calculation tool.

The advantages are manifold. In new buildings this means significantly lower investment costs.
In the refurbishment considerably less interference with the building substance than with the replacement of a water-based heating system.

In addition, PV yields can be used in all energy sectors of the house (electricity, heat, electric mobility).

Nothing happens. The device continues to work normally. Only the optional boost-backup function is not available.

In an ELWA system, no power is fed into the grid. Any excess energy remains unused as in a solar thermal system. The main technical difference is that this does not result in any material fatigue compared to solar thermal energy. 

In addition, the share of excess energy with ELWA is very low. Practically it is 5-8 percent. That would be about 100-150 kWh per year for a 2 kWp system, or at best 15 euros per year.

If you need an inverter, an electricity meter with meter rental, a feed-in point and the grid connection, then the additional effort is not worth it at all.

Linearly controlled heating elements are electric heat generators which output can be adjusted from 0 to 100%.

They are not switched off and on by a thermostat as it is the case with conventional thermostats.

This linear power function is essential for operation with photovoltaic electricity because the available power is constantly changing due to irradiation and other consumers in the house.

Pay attention to the technology: Only so-called "high-frequency clocked" converters do not cause mains disturbances and can be connected without any problems.

ELWA is not only much easier, but also much cheaper than solar thermal systems. This applies both in a single-family home and in apartment buildings. The advantages over solar thermal are multifarious:

·         Due to the elimination of the pipes you can save up to 90% valueable copper

·         No cost-intensive components like pumps, valves, expansion tanks, frost protection mixtures, insulations,...

·         Photovoltaic heating even works with low solar irradiance

·         No lossy start-up procedures (clocking, loop warm-up)

·         Maintenance-free (frost protection)

·         No material fatigue during system downtime

·         Efficiency independent from system temperature

·         More efficient at lower ambient temperatures

·         Nearly loss-free energy transmission from the roof to the boiler

·         Mounting in the boiler/tank quickly and not complicated, even when tank is filled

·         Nearly no internal consumption (2W)

·         Grid feed-in of the energy surplus instead of stagnation (with AC ELWA and AC ELWA-E)

·         Cost development and technical development of photovoltaics are rapid

·         ELWAs can be used decentrally, thereby no distribution losses in multi-family houses.

The solar energy is converted into heat right where it is needed!

The answer to this question essentially depends on whether you have a subsidised feed-in tariff. If you feed in without an increased feed-in tariff, then you will receive about 3 to 6 euro cents per kWh, depending on the country. In Germany, you still get 10 to 12 Euro cents feed-in tariff for small systems.

If you use this energy yourself, then it corresponds to the value of the displaced energy source. With gas, for example, one kWh costs approx. 8 euro cents, then the efficiency and maintenance costs of the gas appliance are added, i.e. another 2-4 euro cents. With biomass, the costs for efficiency and maintenance are even higher.

Thus the self-consumption pays off under these conditions. In addition, they displace depending upon heating system fossil energy consumption. This improves your CO2 balance and your ecological footprint.

Yes, AC•THOR can also support conventional, water-based heating systems.

For example, the pellet boiler or the heat pump for hot water preparation do not need to be started in summer.

Combined operation with heat pumps is also possible: Since heat pumps cannot control their electric power input linearly, the AC•THOR takes over the exact control of the PV-excess output with a heating element. This optimizes your self-consumption significantly.

Yes, with my-PV Power-Meter. With the feed-in point, the my-PV Power-Meter detects whether surplus energy is available and transmits the information to AC•THOR or AC ELWA-E.

No. Both devices can independently control the power on their own.

Advantage of AC ELWA-E: It is a fully integrated solution. An extra heating element is not required. This has significant cost advantages.

Advantage of AC•THOR: Almost every electric heat generator can be linearly controlled. So also existing immersion heaters or even those with a connection thread other than 1.5 inches.

In addition, AC•THOR can also infinitely control two heating elements one after the other. As a result, stratification heating with two elements can be realized at minimal costs.

No. You can use the AC•THOR also for water heating only.

The connection of an electric heating system is optional.  If a buffer storage is available, of course, the water-based space heating can also be supported. The heating element is then installed in a buffer tank, or 2 heating elements (hot water boiler, buffer tank) are connected.

Yes. AC•THOR system is one of the cheapest on the market in terms of acquisition and operation.

In existing buildings it significantly reduces the load on your existing heat generation system, in new buildings it can completely replace conventional water-based building services.

No, it is an AC device and plugged into a standard mains socket. From this it takes only as much power as is currently available as surplus.

Since there is no interconnection with the components of the photovoltaic system, it is possible to combine them with all commercially available grid-connected PV systems.

Solar thermal energy is often said to have an efficiency of 80 percent. However, this is only a snapshot taken at the collector test bench (without any heat release), that means: the value has no practical relevance!

It is much more objective to compare the annual energy yields of both technologies. Well-functioning solar thermal systems with flat-plate collectors supply about 350 kWh of heat per square meter per year. A photovoltaic system with the same area earns about 200 kWh per square meter. In between there is a factor of 1.7. That means, for a typical hot water system you need 6 square meters of thermal collectors, or 10 square meters of photovoltaic modules. But this only matters if there is not enough space on the roof, because the sun is shining for free and there is no direct correlation between cost and efficiency.

Incidentally, the area factor for solar thermal energy was still 2 in 2015, another indication of how fast the technology is evolving.

The standard 1.5 inch thread makes ELWA or AC ELWA-E easy to screw into storage. 

This is possible even when the storage tank is full. Learn here (German) how this works. 

Yes! »Cable instead of pipes« leads to significant savings in operation by avoiding the thermal distribution losses on a ring main. Also hygiene regulations are easier to fulfil.

The energy of the sun is converted into heat at the place of consumption!

The AC•THOR is sometimes misunderstood. It is not.

Technically speaking, it is an AC power controller.

It linearly controls the power of electrical heat sources as a function of PV energy supply and heat demand.

No, it is an AC device and plugged into a standard mains socket. From this it takes only as much power as is currently available as surplus.

Since there is no interconnection with the components of the photovoltaic system, it is possible to combine them with all commercially available grid-connected PV systems.

According to our recommendation, direct solar-electric space heating only makes sense in buildings with a low heating energy demand. By this we mean objects with a specific energy index of maximum 50 kWh/m² (low-energy house, or better).

Depending on the area heated, there is an annual energy requirement. In the case of a single-family house, for example, this should be in the order of about 4,000 kWh, i.e. roughly the same amount of energy that is required for electricity and hot water generation in such an object. The power of the photovoltaic system should then be in the order of 8 to 10 kWp.

Building the space-heating system purely solar-electric, is only useful in houses that have been built according to low energy standards or that are thermally renovated!