FAQ: Frequently asked questions ☀ Autarq: Next Level Roofs

Yes, because regular roof tiles are used as a base and specially hardened solar glass as a surface.

Yes, because Autarq solar roof tiles are based on standard roof tiles with an identical interlocking system. The only difference is that there is a solar module attached to the top side. The feed-through of the cable to the back of the roof tile is behind the solar glass and absolutely watertight.

No. Rain, hail, storm: There are no restrictions compared to standard roof tiles. Autarq solar roof tiles have exactly the same functionality as the original tiles. Autarq solar roof tiles with specially hardened solar glass even meet the hail protection class 3.

No. As long as there is snow on Autarq solar roof tiles, they don’t produce electricity, while they are otherwise fully functional. Once light hits the solar roof tile – and the photovoltaic module heats up accordingly – the snow usually melts more quickly.

It is generally known that solar systems perform less the hotter they are. The dependency is approx. 0.4 % per degree Celsius. The reference value is 25 °C. Since roofs can reach temperatures of up to 80 °C in summer, this means that on these days they deliver roughly 22 % less power (i.e. the difference of 55 °C x 0.4 %) than they would theoretically deliver with the same irradiation and 25 °C. This is perfectly normal and applies to all solar systems. The question that remains is whether Autarq solar roofs become hotter than on-roof solar systems – and if so, by how much. According to our measurements, the temperature difference on normal (sunny to cloudy) days is about 5–10 °C, and the corresponding performance drop of 2–4 % is hardly significant. On very sunny and hot days (in Germany max. 50 days per year) a temperature difference of 10–20 °C is possible, that means the system produces up to 8 % less yield. If a solar system is to generate solar power that is primarily used in the home, this performance drop is irrelevant – because on those sunny and hot days at least 150 % of the required electricity is generated.

No, the temperature in the house is neither lowered nor raised by Autarq solar roof tiles.

No, the risk of a direct lightning strike is not increased by an Autarq solar roof. As a general rule for all solar roof solutions, the cables of a "mesh" should be kept as close together as possible to reduce the indirect risk from induced voltage due to a nearby lightning strike: the tighter the "mesh", the lower the risk. Because the positive and negative wires in the Autarq wire harness are kept at a constant distance of only 15 mm, the "mesh" is extremely tight – so there is much less danger than with conventional solar installations.

In the event of a direct lightning strike, the Autarq solar roof tiles will be destroyed – just like any other solar module. However, direct lightning strikes are very rare. In most cases, a lightning strike generates overvoltage in the surrounding area. The following rule applies: The larger the "meshes" formed by power cables, the more likely they are to capture such a surge – and the higher the captured surge. The horizontal bus cables with 15 mm centre bar represent a very small "mesh". In contrast, the cables in conventional solar module installations are often more than a metre apart and thus form a very large "mesh". In case of a given indication (e.g. exposed location, thunderstorm frequency) or depending on other building installations, we recommend a type I / II surge arrester to neutralise any residual surge voltages that are captured. This can be easily installed in the connection area of the Autarq PV converter.

The Autarq wire harness runs behind the roof tiles, so it's protected against the weather. The cables we use comply with the EN 50618 (H1Z2Z2-K) standard, which is the leading standard in the solar industry: They are resistant to UV and ozone, flame-retardant and suitable for a temperature range from -40 °C to +90 °C. The cables are double-insulated and designed for a system voltage of 600 V, i.e. for the Autarq system they are at least four times oversized. On the back of each solar roof tile there is a connection cable with a two-pole connector: Our connectors comply with the DIN EN 50521 (VDE 01263) standard with a degree of protection IP 54 (splash-proof). They are resistant to UV and ozone, flame-retardant and suitable for a temperature range of -40 °C to +90 °C.

All cables processed in an Autarq system are double-insulated and comply with the solar standard EN 50618 (H1Z2Z2-K). Cables of this type are designed for extremely harsh conditions, i.e. they could easily be exposed to the weather or laid directly in the ground. The cables are mechanically very robust and highly resistant to UV, heat, cold and chemical stresses. By installing them underneath the roof tiles, the cables are additionally protected from the weather and UV radiation – in this respect, there are no concerns regarding their longevity. Of course, care must be taken to avoid mechanical damage to the cables in the course of roofing work, and mechanically damaged cables must be replaced. There is no "invisible cable breakage" inside the cables: if a cable is really damaged, it is visible.

The adhesive used to bond Autarq solar modules to the original roof tiles is UV-resistant and has been used in the solar and building materials industry for many decades. It has TÜV type approval and meets the requirements of EOTA ETAG 002 for bonded glass constructions. According to our extensive climate chamber tests and calculations, the bond will last at least 40 years.