What solar panel sellers will never tell you

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

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 the production and share statistics every year. The first year of operation showed that I can return my investment in solar energy in about 30 years.

But over the past 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 storage devices in the form of accumulators. firstly, they are completely unnecessary (all the energy generated by solar panels is guaranteed to be consumed), and secondly, they will only increase the cost of equipment and require regular replacement every few years (in the current configuration, the system does not require maintenance during its entire service life).

I originally bought a 300 watt grid for the system, which was installed in the house. It had two drawbacks - firstly, 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 in the process of operation, another drawback came to light. It turned out that the purchased grid was designed for the power of the panels of 500 watts and this is the very case when the inverter should not have a power reserve. My panels with a total power of 200 watts could not fully load it and as a result it had a low efficiency in cloudy weather and the generation often failed.

I decided to replace the grid with another one. For these purposes, I purchased a micro-inverter in a sealed case, installed in close proximity to solar panels with a maximum power of 230 watts. And from it to the network of the house a wire with a voltage of 220 volts will be stretched. The very first inclusion showed that this grid is capable of delivering energy (albeit a little) even in cloudy weather.

The solar panels are mounted on a fixed roof frame and are directed strictly south. About 4 times a year, I change their angle of inclination. Almost horizontal in summer, at an angle of 45 degrees in the off-season and as close to vertical as possible in winter. But all the same, in winter, they are covered with snow. From time to time they need to be wiped from dust and dirt. I do not use the rotary mechanism (tracker). its value will never be repaid.

September has begun: there is little sun, a lot of clouds - production has dropped very much. On rainy days, it is simply negligible (less than 50 watts • hours per day).

Here is a graph of the power generation for the last 6 months. The new grid was installed in mid-May. By the way, if the electricity is turned off in the SNT during the day, then the production also stops (this happened several times this summer).

And here are the statistics of monthly output for this year. The most dramatic change is not that the output has increased, but that in our SNT tariffs have decreased - now SNT are equated to rural settlements and electricity has become 30% cheaper. While replacing the inverter increased efficiency by about 15%.

Let me remind you that solar energy in the Moscow region has two problems:

1. Low tariffs for network electricity.

2. Few sunny days.

Energy generation for the summer of 2017 by months (in parentheses, the generation 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

At the moment, the total generation for 2017 is 105 kWh. At current tariffs (4.06 rubles / kWh), this is only 422 rubles. The main production peak is over, with cloudy autumn and winter ahead. Let's assume that the output for this year will be 500 rubles. And I invested 20,000 rubles in the equipment (I managed to replace the grid without additional payments).

Let me remind you that last year the output was 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, the payback period has increased from 32 to 40 years!

Even if you fantasize and imagine that there will be no clouds in the Moscow region for a whole year, then in a year with 200 watt panels you can get only 240 kWh (theoretical maximum at the maximum efficiency of solar panels produced at the present time). Or about 1000 rubles. That is, the payback period will still be 20 years. And this is only in theory, because in real life this cannot be. And these are the 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 money on maintaining 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 the night rate.

In the current configuration, my energy efficient house does not require air conditioning at all in summer, it maintains a comfortable temperature all year round (even if there is no one in it), and the annual energy consumption is about 7000 kWh. This is 3 times cheaper than the maintenance of an apartment of the same area in Moscow.

Solar Power: Ancestor Experience

I don't believe in a 10 year battery life. Practice dispelled my illusions. In fact, solar energy turned out to be quite an expensive pleasure.

For 10 years our settlement Milenki lived in an autonomous mode. Various inverters, controllers, generators, wind turbines and solar panels have been in operation for 10 years. This is enough time to separate advertising nonsense from reality and draw sober conclusions. The conclusions are as follows.

First - It is very important WHERE you live. In Krasnodar this is one thing, in the Kaluga region it is quite another. We, (especially in autumn and winter) have few sunny days. Therefore, in the darkest time of the year (when just the maximum amount of electricity is needed), it is impossible to charge the batteries with the sun. At this time of the year, the generator - charger - battery circuit works. That is, in fact, you have to live on gasoline and a generator, which in general is not so environmentally friendly. The noise, the stench, the constant filling of gasoline are definitely not encouraging.

Second, batteries are still the weakest link in solar energy. Their maximum service life (the one that I saw in our settlement) is six years. Other owners, including myself, had batteries out of order much earlier, on average, in 3-5 years. The gel batteries were completely disappointing. Insanely expensive with dubious advantages. Therefore, many have switched to conventional car batteries. I currently use a 225 Ah Warta Super Heavy Duty. I am very satisfied with the price ratio for a.ch. and the possibility of battery recovery. Plus, Warta is not afraid of frost. The main thing, when operating batteries, do not lower the voltage in them below 12 volts. Cut a voltmeter into the circuit and look at it constantly, like a thermometer in winter. It got to 12 volts - forward into the street. We start the generator, connect the charger.

Third - Do not buy branded advertised checkers Morningstar, Xantrex. They are senselessly expensive and no better than their Chinese counterparts - EPsolar. You need to buy controllers on Ali Baba or E-BAY. I like the 20 amp model - EP Solar Tracer 2215. Although the Chinese have 30 and 45 amp models, I find it better to buy two 20 amp controllers and have two independent systems than one big one. With a big one, I just started. Foolishly spending your money.

Fourth - Don't chase power. Don't try to fool yourself into buying a powerful inverter. A three kilowatt inverter is already pointless. (Especially for 6 kW). It will quickly suck all the life out of the battery when the sun goes down behind the clouds, and you forget to remove the load. Forget it three or four times and the battery will begin to sulfate. It is better to immediately get used to the fact that a serious load - a pump in the well of over 800 watts, a vacuum cleaner, a washing machine with hot water, an iron, an electric kettle, a circular for 1500 watts, an electric saw, a trimmer, a gas mower, will have to be powered from a generator. A good (reasonable) solution is a low-power 1500 W inverter from companies A - Electronics and Novosibirsk Sibkontakt. But I like two 600 watt inverters in the house better. The Sibkontakt company has a nice 300 watt inverter. Its peculiarity is that it does not have a fan. Therefore, the idle speed is small and there is no noise. And still a pure sine gives out. Krosota - I recommend.

Fifth - Charger. It is better to take it more powerful. It is desirable from 40 amperes. 50 amps is even better. I bought on E BAY Promariner ProNautic C3. They have 40, 50 and 60 amp models. Before that, I used a lot of domestic chargers. The main sadness was in the long exercise. The generator rumbles, smokes, annoys. Promariner charges much faster. A very big plus. (Gas consumption is less and the generator lasts longer).

Fifth - Generator. Now I have the third generator. Now I stopped at the Vepr 2.7 kW. with a Honda engine. Satisfied. The main advantage is that it starts up reliably in winter. Plus, gasoline consumption is quite modest. Before that he had Makita and Hitachi. Strange, but the most capricious turned out to be Hitachi, it was hard to start up in winter. In the cold, the oil seals were squeezed out. And the fuel consumption of the 5-kilowatt model was high. It is better to have a generator with optimal power so that the washing machine can be pulled by the vacuum cleaner. And this is a little more than 2 kW. Even 3.5 kW, like my Makita, is a bit overkill and a waste of extra money.

Sixth - Bulbs. Now, it is already obvious that they should be LED. But when we started, they weren't there yet. Then they appeared with a terrible spectrum of light (like in a morgue). It's all right now. The light is warm and the price is finally down. I buy bulbs in Ikea. They serve reliably and for a long time. This spring, 1000 lumen models have already appeared there. at the price of 399 rubles. With a color of 2700 k. It would be good to add a motion sensor to the lamps that are in corridors and other little-used places (hallway, toilet). Many have done just that. Such a sensor on the porch is especially pleasing. You approach the house on a dark evening - BOOM! and your porch shines with light in a civilized manner. A trifle, but how happy.

Seventh - Solar panels. This is exactly what everyone pays attention to. There is smart talk about monocrystalline and polycrystalline advantages and disadvantages. Nonsense. On a sunny day, any panel will clog your battery very quickly and the controller will cut off the overflowing energy. That is, on a sunny day, the panels will work idle most of the time. Well, in winter, in cloudy weather, any panel will be helpless. In any case, on a long winter evening (with a laptop and lighting), you will drop your battery and you will have to go to pull the generator. I settled on the power (which type does not matter) of 400 watts panels. From my point of view, this is optimal. You can supply more power, but this is again a waste of money. It is advisable to install more panels when you are connected through the meter to the general power system and your green kW - the hours are carefully counted. But this is not for our country. It's a pity. A huge amount of energy is stupidly cut off. When installing the panels, place them vertically so that later in the winter they do not suffer from clearing the snow. Moreover, if the panels are located high on the roof. Snow practically cuts off all the light.

Eighth - Solar collectors. This is where solar energy is used to its fullest. None of the controllers clip anything. ALL the sun's energy is used to heat water. And I have two whole tanks of 200 liters each heating up. Heats up to 90-92 degrees. When I wash dishes with hot water or take a warm shower, I feel happy. I have a large water analysis. Especially when the preparations begin in the kitchen. And to heat such an amount of water with gas is very long and costly enough. And here every day 400! liters. There is so much hot water that I take some of it to the radiators. In the spring (when there is a lot of sun), and the nights are still cold, it is wasteful to heat the house. And a pair of batteries does a pretty good job of heating. (In the heat, the batteries are simply closed). Therefore, I recommend starting to use the energy of the sun with solar collectors. Plus, your wife will thank you again. And the good mood of the wife is worth a lot.

Since last year, our settlement began to connect to the power transmission line. Now there are about 20 sites, they forgot about the generators. We started using electric kettles and vacuum cleaners. The settlement became quieter. Now you can hear more roosters than the noise from the many generators. There is more light in the windows. And in some courtyards, garlands on Christmas trees were burning in winter. It has become more practical, calmer, brighter.

Solar power is good. It is especially good in summer, in Sochi and Krasnodar, or in a small country house. In winter, at the latitude of the Tula, Tver, Leningrad or Kaluga regions; with PERMANENT residence of a large family. When you need to constantly wash, cook, clean, solar energy is not enough - you have to use a generator. And this is quite expensive, inconvenient, not very environmentally friendly. An ideal situation would be when in the summer our solar installations, generating excess power, would give it to the grid. And in winter, these kilowatt hours would be offset back. Without any money. Simple offset. Another option would be nice if there were really big storage batteries on the market. 1000 a.h. 5000 a.h. Moreover, so that their price is adequate.

Over the years of using solar energy, I have come to the conclusion that it is better to have two or even three parallel small systems than one large one. One small but effective system might look like this - One 225 Ah battery. Warta Super Heavy Duty - 17 thousand rubles. One solar panel for 300 watts - 20 thousand rubles., Controller for 20 A. (EP Solar) - 8 thousand rubles. Inverter for 600 watts - 4 thousand rubles. Total - 49 thousand rubles. This is a very, very decent system. For example, you plant laptops on it. At the same time, put (of the same configuration) a second system and connect, for example, a refrigerator and lighting to it. In total, your system costs 98 thousand rubles.

A kilowatt hour now costs about 6 rubles for Milenok. This means consuming 10 kWh. a day, you can live like that for 1633 days. Four and a half years. But for four and a half years, I personally have already parted with the battery. That means costs again. The payback period is again postponed.

Solar energy certainly has its advantages, especially when you are in a desperate situation when, in principle, it is impossible to connect to power lines. You just need to spend your money jewelry, buying really necessary and practical elements of the system. And do not pin excessive hopes on it in the autumn-winter period.