The majority of readers who turn to Energoporadna deal with heating and the suitability of photovoltaic installations. These questions are answered by Pavel Fajx, a product management specialist at ČEZ, which is a partner of the series.
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Good day. We will build a new family house, a bungalow. We have designed a water-to-air heat pump and collectors for electricity with batteries on the roof. A certain company betrays me and recommends electric underfloor heating, saying that it is more efficient and cheaper. Can you please tell me your opinion? Thank you.
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Hello, this is a difficult question. Your choice, i.e. connecting a heat pump, photovoltaics and a battery, is, in my opinion, one of the best and most economical options today. At the same time, a lot depends on how the system will be set up, dimensioned and how the implementation will take place. It will be important, for example, what the size of the photovoltaics will be and whether the photovoltaics and the heat pump will work together and, for example, “heat” the storage tank and hot domestic water in the event of an excess of electricity in the fall or spring, which would be the best solution.
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It also depends on the energy standard in which the house will be built, whether for example as low-energy or even passive… Under electric underfloor heating, one can imagine a number of technologies, from an electric boiler that will heat water for underfloor heating (classic pipes), to the installation of heating cables , mats and the like.
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How to save energy in a family home
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Each of the options offered has its advantages and disadvantages. For example, the possibility of heating and subcooling or the “installation height” of the given technology, as well as the initial costs that you will have with the acquisition.
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In today’s houses, both options can work very effectively, it depends on what the given user/investor expects from the technology: Quick return? Low entry price? An advantage in the form of cooling? Noise requirements, location of technology… Possibility of efficient hot water heating? This is variable and may vary from house to house (investor).
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More information is needed for better rooting. That is, the floor area, the expected TZ, the place of installation (for guidance – there may be a difference between Central Bohemia and Šumava), the number of people in the household and the expected load of the house, the size of the roof for photovoltaics, its orientation, slope, etc.
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We have a house with a heat loss of around 15 kW, we only live in a part where the loss is a maximum of 7 kW. We heat mainly during the day and evening to a maximum temperature of 22 °C. We still heat with pellets – we use three cubic meters of them per year plus about four meters of coal. We have small radiators, we heat direct heaters only as needed in some rooms. We have an electricity consumption of about 3.5 MW. We think that gas heating is the solution for us, because in the future, due to our age, it will be a problem for us to walk two floors down almost every hour. If we were to heat with an electric boiler – how many FVE panels and at what price would we need for this heating? If you would also recommend purchasing a battery, how much space does it take up and how much does it cost? We have a relatively large area for panels, what would be the return? Is it realistic and profitable to heat only with photovoltaics plus electricity from the grid?
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Hello, the answer in this case will not be simple, I would definitely recommend a visit to a specialist who would go over the given options with you and listen to what expectations you have from the new technology.
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For example: You no longer want to heat with coal or direct heaters, or do you want to keep this type of heating? In order to design the right solution, you need to know more about the heating system – to what temperature gradient are you heating to keep the room at 22 °C? How many heating circuits is your house divided into? How much heating water is in each circuit? Etc.
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Regarding the return of the panels, we cannot give a relevant answer – we do not know the size of the roof, its orientation or slope. It will also depend on the connection with other elements, for example with the heating of domestic hot water, and on what covering you have on the roof, whether the roof will be gable or flat, because the construction material will be used accordingly, and this will affect the price of the work.
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If you buy a photovoltaic system without a battery, then you have to take into account that the photovoltaic system produces the most in the summer and you need heating from autumn to spring. Even if we included a storage tank in the system that “heats up” during the day, we cannot say without calculation that in the winter months, when the day is short or it is cloudy, for example, photovoltaics can produce a sufficient amount of energy for heating. I would rather not rely solely on heating from my own electricity. As mentioned in the article you are responding to – photovoltaics can significantly help the efficiency of heating for spring and autumn when properly “oversized” and connected to the storage tank.
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In the case of the battery, it depends on the manufacturer, but in general it can be thought of as a refrigerator. The floor plan takes up approximately 60 × 60 cm, in the case of modular solutions e.g. 45 × 30 cm, 50 × 35 cm. Height varies according to capacity, manufacturer, etc. Expect a height between 100 and 170 cm. You always need some more space in the vicinity for the possibility of connection or service.
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Good evening, I am turning to you with the following request. I have a two-generation family house, since 2006 I have been using an IVT earth-water heat pump for heating and domestic hot water. Annual electricity consumption energy is a total of 18 MWh, of which only heating is 7MWh and 11 MWh is the annual consumption of other appliances in two households (6 people in total).
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I am considering photovoltaics, I have an offer for a PV plant with an output of 7.28 kWp, a Growatt battery with a capacity of 10.24 kWh. With regard to the above article, please let me know if a battery is necessary in my case when the PV power does not cover the annual electricity consumption. Thank you very much for the answer.
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Hello, according to the described situation, I think that batteries will generally be a suitable choice for you. Only the information that photovoltaics has less power than consumption, but it is not completely enough. The distribution of consumption (mainly the 11 MWh) during the year and also during the day will have to be taken into account in the final decision. If your main consumption was mainly between 10 a.m. and 4 p.m. (at this time you are at home, washing, cooking, using household appliances), it could be said that you can use most of the electricity produced for direct consumption. However, if the production curve does not overlap with electricity consumption. energy, you would send a large part of the generated electricity to the distribution network. That is not only the ratio of production vs. consumption, but mainly also the collection time.
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You write that you plan to connect photovoltaics with a heat pump – here I am definitely in favor. It is a great choice, because if the heat pump and photovoltaics communicate correctly, you can, for example, effectively preheat domestic hot water in the boiler during the day. In order to make the right decision, it would be good to know how much energy the heat pump consumes for water heating in individual months. But it can be said that thanks to the connection of the heat pump with photovoltaics, you will not only save energy for other appliances (for 6 people), but also part of the energy you use for heating water.
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Hello, we live in a one-story house from the 1960s with an area of 80 square meters, 2+1. We heat the house most of the heating season with an 8 kW electric boiler, sometimes also with solid fuels. We have already insulated the attic space with blown mineral wool and had the windows replaced with plastic ones. However, we still do not know which way to save energy. We are not sure if there will be moisture condensation in the wooden structure after the insulation of the perimeter walls.
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At the same time, we choose the most suitable source for heating. We have already approached several companies supplying heat pumps, but after consulting with their representatives we are quite disappointed, most of them suggested a specific type of pump immediately after finding out the current electricity consumption without prior calculations. We will be happy to recommend a suitable heat source for our house.
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Hello, unfortunately we cannot provide a relevant answer to this question because we do not have all the information for a proper calculation and evaluation of the options.
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Series SZ Byznys: How to fight against expensive energies
SZ Byznys advises how to save on expensive energy.
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Regarding the insulation of the walls, we recommend contacting renowned renovation and insulation suppliers, who will certainly find a suitable method of insulation so that moisture does not condense.
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More information would be needed for advice on the heating source. You need to know information about the heating system = if it is underfloor heating, radiators, what is the temperature drop, how much water is in the given system, what kind of radiators do you use, if and what kind of circulation pump, storage tank do you use… Do you heat all day long or e.g. 1 x a day for 5 hours? Do you heat both electricity and water? What boiler do you use for heating? It is good to contact a specialist. Only after knowing all this information can he recommend the suitability of a heat source.
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Insulation pays off
Questions about insulation are answered by Marcela Kubů, executive director of the Association of Mineral Insulation Manufacturers.
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We have a family house built from 40 cm ytong, 20 years old. The living area is approximately 200 m². I am asking whether to insulate or not, and if so, what.
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A classic aerated concrete block of 375 mm (with 40 cm plaster) does not meet the current standard requirements, therefore it is worthwhile to insulate such masonry with at least 15 cm of insulation. However, if we want to insulate not for 20, but for 50 years ahead, it is reasonable to proceed to even greater thicknesses and move the properties of the masonry to a low-energy to passive standard. For standard constructions, the thickness of the facade insulation is between 15 and 25 cm.
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Aerated concrete blocks are highly vapor permeable and respond well to the indoor climate in the house, so I recommend applying an insulation system with breathable insulation (e.g. facade mineral wool) or a ventilated facade to preserve the properties of the masonry and to prevent unwanted condensation of moisture in the structure. The designer will help you with the right composition.
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How much does it cost to insulate a house with 30 cm mineral wool? How much is the subsidy for this?
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The prices of building materials and works change very dynamically. It also depends on the condition of the house and its structure, local conditions, etc. It can be estimated that 30 cm of mineral wool insulation will cost between 2,300 and 3,000 CZK per m². The subsidy will be 600 to 1,000 CZK per m² depending on the extent of insulation (partial or comprehensive insulation) and the savings achieved. In other words and simply – those who use greater insulation thicknesses and save more energy will receive a higher amount.
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Good day. We have read your article, for which we thank you, because it wants to help with the “energy crisis”. We are pensioners, we live in the Náchod district in a family house that we built in 1970. And we would need someone to help us with insulation. How to plan, where to find suitable companies for implementation even with Zelena sproám?
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The first step should be to contact a designer who will propose the right insulation solution and help with arranging the subsidy.
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