My experience with renewable energy
The energy prices in Europe are currently exploding. We hear it in the media daily. We may already be tired of it. Angry. Desperate. This post shall not provocate. Instead, I d’ like to share my experience with renewable energy and demonstrate its potential.
How it started
It all started in the summer 2020. At that time electricity prices were still low and noone seemed to be worried about the future. My main motivation was the reduction of carbon footprint. I was not sure whether the investment will pay off. But to be honest, that was not the most important thing. We simply wanted to contribute to a more sustainable world. If let’s say only 80% of the investment pays back over the lifetime then it would still fulfill its purpose.
Half of the roof of our house is directed south. Not south-west or south-east but pure south. That is a great preposition for photovoltaic. The roof is new so it can easily carry the solar panels. So what are we waiting for? Well, the first step is to convince my father. It went surprisingly easy. Although he is sometimes quite conservative in this case he agreed. Our motivation was slightly different. For me it was mainly the environmental impact. So far we have used coal-fired boiler. For my father the idea of being more self-sufficient was very attractive. It is because we have experienced couple of outages.
Stage 1
The scope of stage 1 was following:
Number of panels: 12
Panel rating: 360 Wp
Panel surface: 1.87 m2
Manufacturer: IBC
Installed power: 4.32 kWp
Energy storage: Battery
Technology: LiFePo4
Capacity: 7.2 kWh
Installation: 2020-12
Production
Below figure depicts the amount of electricity supplied into the grid. The figure is from 2021 and considers stage 1 only. Note that the total production of the plant was considerably higher. The values plotted inthe figure is only the surplus of electric energy (difference between total production and consumption of the house).
We can see that already in March the surplus of the electricity generation slightly exceeds the consumption from the grid. Obviously, the production is during day time while the consumption from the grid is mainly at night (heating of water) or during cloudy or foggy days. There is a battery storage system that tends to reduce the power exchange with the public grid. However, the given capacity (7.2 kWh) is not sufficient to be completely decoupled.
While in February the consumption from the public grid amounted 383 kWh (196 kWh in high tariff and 187 kWh in low tariff), in April the bilance is only 61 kWh of “imported” electricity (35 kWh in high tariff, 26 kWh in low tariff). At the same time, the exports into the grid rise sharply.
It shall be noted that all power consumers in the house are electric. The only non-electric consumer last year was he coal fired boiler which was decommisisoned this year (as described later).
Stage 2
In spring 2022 the solar plant was extended with stage 2:
Number of panels: 11
Panel rating: 460 Wp
Panel surface: 2.17 m2
Manufacturer: EXE Solar
Installed power: 5.06 kWp
Energy storage: Battery
Technology: LiFePo4
Capacity: 7.2 kWh
Installation: 2022-04
Stage 3
Finally, we have replaced coal-fired boiler with a heat pump.
Outdoor unit
Rated power: 14.0 kW
Manufacturer: Mitsubishi Electric
Outdoor temp. range: -25°C…+35°C
Coolant: R410a
Protection class: IP24
Indoor unit
Rated power: 6 kW
Manufacturer: TENGEO
Heat circuits: 2+1
And what is our operational experience with renewable energy so far?
The solar panels work as intended. During optimal weather conditions the plant generates up to 101% of the installed power (what I could randomly observe…maybe even more). During long summer days the plant reaches full capacity already between 9 AM and 10 AM. In the afternoon the instantaneous power usuall drops a bit. That is to be expected as the efficiency of the panels drops with temperature. Figure 5 shows two snaphots from summer afternoons with good weather. The instantaneus power is 7.744 kW and 9.509 kW, respectively. Note that the sum of the power sources and sinks (panels, grid, house) do not match perfectly. I am not sure whether it is a measurement inaccuracy or some averaging (the refresh rate of this panel is rather low). Anyway, this is just an indication. more accurate values can be obtained from the power meter belonging to the power distributor.
My dad is satisfied because…
– The house is not susceptible to power outages that sometimes occur.
– He does not need to handle coal anymore (with increasing age the manipulation of heavy coal is an issue).
My mom is satisfied because…
– There is no coal dust and no dirt anymore.
– The rooms have more stable temperature that can be pre-set (in our case 21°C during evening, then 17°C over night time).
I am satisfied because…
– We have reduced our carbon footprint and made a contribution towards sustainability.
– We do not support autocratic and pseudo-democratic countries that export fossil fuels and use the income for weapons, hybrid war methods or terrorism.
Final words
This post is not a sales pitch although it might look like that a bit. The aim is just to share the positive experience and motivate others. My initial driver was the goal of reducing emissions and being more environmental friendly. At that time I was not sure if the investment would pay off and it was also not a must. With current energy prices I am quite certain that it will pay off.
Since February 2022 the independence on fossil fuels got an additional dimension for me. Every kWh of clean energy is not just a win for nature and our budget but indirectly also less income for Putin and similar cowards. No matter whether you consume natural gas and oil or not (indirectly all of us use it anyway): the more electricity we can produce locally the less price pressure. This in turn lowers our cost, curbs the inflation and reduces the income of the Russian terrorist federation.
Finally since October 2022 there is one more crucial aspect: decentralized power generation helps to increase the robustness of the system. In “normal days” having a large thermal power plant may mean strong and stable grid while renewable sources provide bigger challenge due to their less predictable output. However, when idiot from Kremlin shoots rockets to civil infrastructure, the picture changes. With one missile strike into a critical substation an entire city or even a region can be cut off electricity supply. Having your own power generation suddenly has a totally new value…
We apologize for drifting away from our topic of variable frequency drives and drive systems. However, we just wanted to share this experience with renewable energy as the topic of energy self reliance is more relevant than ever.
Of course, in industrial applications VFDs remain a proven solution to reduce energy consumption of electric motors, particuarly in variable flow applications (such as fans, pumps or compressors). For more information refer to our posts in the category energy efficiency or use our support in energy saving assessments.
Now you know how to save energy both privately as well as in industrial scale 🙂
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