December 14, 2021

Production of hot water - cheap and efficient

my-PV GmbH

Photovoltaics is no longer a novelty. In fact, it has become part of our sustainable and ecologically aware society - and yet it still does not receive the attention it might deserve, especially when it comes to the preparation of hot water.

The reason for this and how you can use a photovoltaic system for the production of hot water is exactly what this article is about.

 

Hot water and electricity - Why choose when you can have both?

Does photovoltaics suffer from an image problem? The question may make you smile, but it is true. Still many believe that photovoltaic is an expensive technology. However, this is not true. Photovoltaic panels are much cheaper today than they used to be, and at the same time they are far less costly than solar panels, which many use to produce hot water.

Both photovoltaics and solar thermal energy offer us the possibility of harvesting solar energy and using it to generate either electricity or heat - or both. While solar collectors, i.e. solar thermal energy, can only be used to obtain heat, a photovoltaic system can basically be used to obtain both heat and electricity. This is exactly what we at my-PV are building on.

By the way, you can read more about the comparison between photovoltaic heat and solar thermal energy in this article.

 

Generate hot water from excess solar power

Quite simply, we support laying cables instead of pipes. Why? Because it's more cost-effective and sustainable. Hot water pipes simply lose a lot of energy that is not used. We want to avoid that by encouraging pipes to be laid only where they are needed. How can this work?

Nowadays, more and more residential projects or renovations are installing a photovoltaic system. Here, the direct energy demand is usually very manageable - many apartments tend to be unused during the day when solar power would be available - and excess solar power is fed into the public grid to a large extent, but this is unfortunately unattractive financially.

Making better use of the generated PV electricity is therefore a perfectly justified desire. But you don't need a battery storage system or a sound understanding of the so-called "tenant electricity model" to do this. A much simpler solution is to generate heat, for example in the form of hot water. For example, you can bring the solar power from your photovoltaic modules directly to the built-in hot water storage tank, which is heated by a solar-electric heater. The entire hot water supply is electric.

 

Production of hot water through photovoltaics also in residential buildings

You may be wondering whether this simple hot water model is also suitable for multi-apartment buildings. The good answer is: yes, it is!

If you bring the solar power directly to the hot water boilers of the tenants, without the possibility to connect further electrical devices, there is no (!) tenant power supply here. Decentralized hot water boilers thus become "daytime storage tanks" for the solar power excess during the day, while in the evening the residents can then shower without any problems with the photovoltaic heat that was stored for them during the day.

Apart from a fresh water pipe, all water-carrying installations to the apartments are therefore obsolete - the solar energy is only converted into heat where it is needed. The horrendous energy losses at circulation and riser lines would thus be a relic of the past.

The easy part about this concept is that a tenant power model, as mentioned earlier, is not required. Although the physical energy source is electricity, from the point of view of operating cost billing it is heat. This is true for Austria as well as for Germany!

The only thing to note is that no household consumers may be connected to the power line of the heat generators. If, however, no sockets are installed on these circuits, then this requirement is already fulfilled.

The future of home technology will be solar-electric!

 



 

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