Interview: Skilful Czechs want to succeed with their own photovoltaics

Read the interview with technical director of the Czech company SunnyCold, Ing. Petr Rubeš. SunnyCold produces unique hybrid photovoltaic power plants and heat pumps.

When was the company SunnyCold founded and why did you decide to manufacture own solutions?

We have been on the market since 2010, however not as SunnyCold, we started as an installation company. We installed photovoltaics and heat pumps from various manufacturers. Later we added all heating types into our portfolio, such as radiators, floor heating etc. Basically, household technologies.

In the course of time, we began to find that technologies are more and more breaking into households, and most customers end up having some photovoltaics, a heat pump, some heat recovery, and then a system that distributes heat somewhere further, for example with floor heating. We’ve installed them all systems, always from another manufacturer.

So, to give the systems some added value, we began to connect them to each other using different logic that the systems allowed us, which was not always exactly as we imagined. As a result, the user had several systems, each of them with different user interface and on different platform. No all systems were used then, users hated some of them, or they did not even know how to set them up.

To us, as an installation company, the guarantee was an issue as well, since we as the installation company held guarantee for all systems we installed, while we were not satisfied with guarantees of some heat pumps manufacturers and we were not satisfied with how the how the hybrid photovoltaics started to produce.

So, as a customer, you bought a panel from one manufacturer, then you bought a converter from another manufacturer, batteries from another manufacturer, you had to make some sort of electric switch that you put yourself together, you had to have it certified, you had to make some battery case for it and so on.

So, as a result, if a problem occurs to this system, the battery manufacturer accused the converter manufacturer and the converter manufacturer accused the battery manufacturer. Therefore, we simply were not able to satisfy the need of the customer for the system to work better than it does.

We wanted to give our customers more

So, we thought, let’s do it ourselves. Let´s manufacture products that result from our experience, so their installation will be simple, we will supply the installation company everything they need for photovoltaics in one box and everything they need for a heat pump in one design and in the same box. At the same time, we wanted to make it as simple as possible, so the heat pump was really just about connecting it to electricity and connecting pipes with hot and cold water, and photovoltaics was just about pulling out two cables out of the panels and connecting them to the switch, from which another cable goes into the house switch.

Suddenly I have both systems installed and the whole house has electricity and heat, which can be used.

The greatest added value of our systems is, that if the household uses both systems, the user finds everything he needs in one user interface, in one application, and we see these systems online in our remote administration, so we are able to provide maintenance of much greater quality, than how it was in the past, with various manufacturers´ combinations.

We also certify the system, photovoltaics is registered as a product, so this product contains components which have been tested for a long time. In the end, the installation company does not need to drill and hang some things on the wall at the customer´s home, and then wire the switchboard and keep warranties of several manufacturers, but we take over the warranty for the entire system.

Introduce us the hybrid photovoltaic power plant Airsun SC and the heat pump Airsun HW and HY. What are their key benefits?

Photovoltaic power plants are named Airsun SC and we have two versions. We have a three-phase variant and a one-phase variant. This means that if the house has a three-phase supply, the entire house will be powered by photovoltaics. If I have a one-phase variant and I have a house with a three-phase power supply, I have to choose which phase I will cover with my photovoltaic.

We are able to offer both systems either with lithium or lead battery, but thanks to the prices 80% of installations are with the lithium battery. We, SunnyCold, do not offer network photovoltaic, because we believe that the hybrid one brings more benefits to the end customer, who produces electricity, accumulates it himself, man receives a subsidy for it and saves money since he does not need to buy so much, he is immune to issues coming from the electricity distributor, such as price changes, because he is more and more able to solve things himself.

The switch with photovoltaics contains everything I need to have at home for photovoltaics. I have only one box about the size of a fridge inside, into which two cables lead from the roof and one cable comes from the house switch. If the installation company has systems of various manufacturers assembled and connected on the wall, we need a room where the system is located, mark it as a technical room where only trained persons have access. In our case it is one safe and certified product I can place where I want.

What I have not mentioned yet, our photovoltaics can cooperate in electric cars charging. It is a part of our application, the user may choose whether to charge or not to charge electric cars, or whether to charge it only using surplus from photovoltaics.

Heat pumps Airsun HW and HY

As for the heat pumps, we also have two variants. One is the Airsun HW, which has the same “refrigerator” design as the photovoltaic and has a 205-litre hot water accumulation tank. The tank is integrated in the device, it is connected hydraulically, we have a switch there so I need to connect the “box” to radiators and pipes leading to taps and I have a system which I use for heating and thanks to which I have hot, utility water.

Second variant is Airsun HY, which is a smaller version for a wall, which does not contain the hot water tank. It is designed for houses, where I do not care about heating utility water, or on the other hand, for houses where I need more water than is the volume of our tank, so I need to connect an external tank to the system, of the size I need.

The individual heat pump variants then have two versions according to the power needed for the application, i.e. 6 to 28 kW. The three-phase photovoltaic power plant has a 10-kW converter and a single-phase photovoltaic has a 5.5 kW converter. Then I can choose how many panels and what battery to install.

Can this system be connected into home automation system, such as Domotron?

Definitely yes. The implementation with Domotron is the best out of all other systems, because we use control units from Czech company Teco as well as Domotron. We have our own custom boards from them which we use to control and regulate these systems.

What’s new in SunnyCold? What are you working on now?

Next year, we would like to work on the third technology we previously had in the portfolio, even before the Airsun system, but now we would like to bring recuperation units back to the Airsun line. We see great benefit there, given that the system runs in one user interface, the system will not inadvertently ventilate, when we need heating. A great competitive advantage will be, that the photovoltaic system generates some residual heat and we have a system ready, which extracts the residual heat using recuperation and the residual heat can be processed in household heating. This should be the last puzzle piece that fits our systems.

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