The whole truth about solar panels - 2
Two years ago, in the fall of 2015, I installed two solar panels and an inverter on the roof of a country house. From that moment on, I constantly monitor production and annually share statistics. The first year of operation showed that I will be able to return my investments in solar energy in about 30 years. For more information on statistics and calculations can be found in the article "The whole truth about solar panels"(magSpace).
But over the last year there have been changes both in network tariffs and in the equipment used. I replaced the inverter and the output increased ...
... but the miracle, unfortunately, did not happen.
Let me remind you that in my system there are no drives in the form of batteries, because firstly, they are completely unnecessary (all the energy produced by solar panels is guaranteed to be consumed), and secondly, they only increase the cost of equipment and require regular replacement every few years (in the current configuration, the system does not require maintenance during the entire service life).
Initially, for the system, I bought a 300-watt grid that was installed in the house. He had two drawbacks - firstly, it was the noise of the fan, which was periodically turned on to cool the internal components, and secondly, the losses on the wires from the solar panels to the inverter. But during the operation revealed another flaw. It turned out that the purchased grid was designed for 500 watt panels and this is the case when the inverter should not have a power reserve. My panels with a total power of 200 watts could not load it completely and as a result it had low efficiency in cloudy weather and the generation was often disrupted.
I decided to replace the grid with another one. For these purposes, I purchased a micro inverter in a sealed enclosure that is installed in close proximity to solar panels with a maximum power of 230 watts. And from it to the network at home stretched wire with a voltage of 220 volts. Already the first inclusion showed that this grid is capable of delivering energy (albeit a bit) even in cloudy weather.
Solar panels are installed on a fixed frame on the roof and are directed strictly to the south. About 4 times a year, I change their angle of inclination.Almost horizontally in summer, at an angle of 45 degrees in the off-season and as close as possible to the vertical in winter. But still in the winter they fall asleep with snow. Periodically they need to be cleaned from dust and dirt. I do not use the turning mechanism (tracker). its value will never be repaid.
September began: a little sun, a lot of clouds - the output has fallen very much. On rainy days, it is simply negligible (less than 50 watts • hours per day).
Here is the power generation schedule for the last 6 months. A new grid was installed in mid-May. By the way, if during the day the electricity is cut off in the CNT, then the output also stops (this happened several times this summer).
But the statistics of monthly production for this year. The most fundamental change is not that production has increased, but that in our CNT tariffs have decreased - now SNT are equal to rural settlements and electricity has become cheaper by 30%. At the same time, replacing an inverter increased efficiency by about 15%.
Let me remind you that solar energy in the Moscow region has two problems:
1. Low tariffs for mains electricity.
2. A small number of sunny days.
Energy production for the summer of 2017 by months (in brackets the output for the last year):
May - 20.98 (19.74) kWh
June - 18.72 (19.4) kWh
July - 22.72 (17.1) kWh
August - 22.76 (17.53) kWh
To date, the total output for 2017 amounted to 105 kWh. At current rates (4.06 rubles / kWh), this is only 422 rubles. The main peak of production is over, cloudy autumn and winter are ahead. Let's assume that the output for this year will be 500 rubles. And I invested 20,000 rubles in equipment (it was possible to replace the grid without surcharges).
At the same time, let me remind you that last year generation amounted to 650 rubles (due to the fact that the cost of electricity was 5.53 rubles / kWh).That is, despite the increase in the efficiency of the solar system, its payback period has increased from 32 to 40 years!
Even if one imagines and imagines that there will be no clouds in the Moscow Region for a whole year, then a year with 200 watt panels you can get only 240 kWh (the theoretical maximum at the maximum efficiency of solar panels currently produced). Or about 1000 rubles. That is, anyway, the payback period will be 20 years. And this is only in theory, because in real life this can not be. And these are tariffs of the Moscow region, while in some regions of Russia electricity costs less than 2 rubles per kWh.And if you add batteries to the system, then this system will never pay off.
Therefore, solar panels are profitable only where there is no mains electricity, and its connection is either impossible in principle or is very expensive.
And in order to save on the maintenance of a country house there are many other, more effective solutions: compliance with construction technology, the use of modern materials (aerated concrete, extruded polystyrene foam), insulation without cold bridges, the use of a heat pump (air conditioner), the use of night rates.
In the current configuration, my energy efficient house does not require air conditioning at all in the summer, it maintains a comfortable temperature all year round (even if nobody is in it), and the annual energy consumption is about 7,000 kWh. This is 3 times cheaper than the maintenance of an apartment of a similar area in Moscow.