First field test system: short review
First kWh of green electricity and experiences with the Pellematic Smart_e
Depending on the outside temperature and heat consumption in a family household, the running hours of the Stirling engine varies and with it, the yield of green electricity. On peak days, up to 10 kWh can be generated in this household by the power-generating pellet heating. According to statements of the owner, this corresponds approximately to the daily consumption of electric power. The electricity is used by the Hopfners conscious and thrifty; unnecessary electrical consume are consciously avoided. You can read here further details on the entire heating system of the Hopfner family.
After initial unfavorable running hours of the Stirling engine (starts during night times, several starts and stops during day hours, etc.) a significant improvement could be achieved by optimizing the software and regulation settings. Now the Stirling engine produces in the morning, at midday and during the evening time, when the Hopfners are mostly at home and the most power is consumed in the household. On particularly cold days, the system runs briefly also in the night.
Quick Overview & "Eco-Balance sheet":
|Total performance (24.02.13):||401,5 kWh|
|average daily yield before optimization (05.12. - 09.01.)||3,74 kWh|
|average daily yield after optimization (10.01. - 24.02.):||6,01 kWh|
Overall, with the optimization the daily yield of the Stirling engine could be optimized but also increase. Especially the starts and stops, i.e. the timing behavior of Pellematic Smart_e has been optimized that the Stirling engine comes to the longest possible running hours and thus, used in the best possible operating conditions.
The two graphics show the outdoor temperature in °C (blue) as well as the burner demand. When the burner demand jumps from 0 to 1 (shown on the right vertical axis) the pellet burner is in operation. The graphs clearly show, the development of the optimization: A reduction of over 20 starts and stops to only 3 starts/stops of the burner, and of the Stirling, per day.
With the optimization, the thermal power output of the Pellematic Smart_e was reduced: from 14 kW to 10 kW. As can be seen in the two analyzes, the electric power from the Stirling engine is reduced due to the power output reduction. But otherwise (for example, when the outside temperature and lower heat demand) at a thermal power of 14 kW, the running hours of the Stirling engine would be reduced. In order to meet the heat demand (for heating and hot water) of the family Hopfner Pellematic Smart_e been adapted to the requirements.
After initial tests, it was found that a reduction to 10 kW power is optimally suited for the requirements of the Hopfner family. The Stirling engine generates a peak power of about 700 watts at 10 kW thermal output. Due to the longer running hours setting (at the same outside temperature), there is no electrical power losses.
Also in the future, data from the field test facility should be analyzed to detect potential improvements among others. Based on these evaluations, the data from the field test facility will be carefully analyzed in order to subsequently make additional settings changes. In the coming weeks and months, different optimizations will be performed and tested.