Category: Technology

Every day new models of solar panels appear, which are used for different purposes. They can be divided into two broad categories:

• Photovoltaic panels, which convert solar energy into electricity;
• Solar thermal panels, which convert solar energy into heat.

In turn, thermal solar panels come in two types: pressurized and non-pressurized.

In the following, we will talk about non-pressurized solar panels, their characteristics and importance, as well as their advantages and disadvantages.

What is a non-pressurized solar panel?

Non-pressurized solar panels are becoming increasingly well-known and used in Romania because they do not consume any energy when in operation. Generally, they are known as solar panels for hot water, as their primary use is to heat water using solar radiation captured in the vacuum tubes.

We can say that the way non-pressurized panels function is similar to that of a thermos that keeps beverages hot. Therefore, it is a relatively simple mechanism.

The vacuum tubes of non-pressurized panels are composed of two layers of glass with a vacuum between them. The outer layer of glass is made of borosilicate glass, allowing up to 98% of solar radiation to pass through to the second layer of glass. This second layer of glass has anti-reflective properties, absorbing solar radiation and transferring it to the thermal agent inside the tube.

In solar hot water systems, the heating agent is heated directly in the evacuated tubes. The thermosiphoning principle causes the hot water to rise to the upper collection and pumping vessel, attached to the panel, being replaced by cold water.

Non-pressurized solar panel components

Solar panels for hot water have three main components:

1. Vacuum tubes;
2. Unpressurized tank;
3. Floating vessel, which regulates the supply of cold water to the tank.

Hot water is supplied to the household through gravitational flow. The fact that in Romania, the majority of houses have roofs and not flat platforms, at an approximate height of 5 meters, ensures a very good water pressure.

Advantages of non-pressurized solar panels

Non-pressurized solar panels are considered the best solutions for domestic hot water heating, offering multiple advantages:

• The investment cost is amortized within a maximum of 2 years from the installation of the system.
• Their purchase, installation, and maintenance costs are much lower compared to pressurized panels.
• Since they are non-pressurized, there are no risks of pressure or temperature buildup, and no water overflow, even when the water is not used for an extended period.
• Due to their straightforward installation process, they can be installed by almost anyone without specific knowledge.

Disadvantages of non-pressurized solar panels

Even though they are few, there are still some disadvantages of non-pressurized solar panels:

• Their installation requires some special accessories, which slightly increase the final cost;
• Cold water supply in summer can only be done in the morning or late evening. The tubes can be hot during the day and the difference in temperature can result in the tubes breaking. Even a single broken tube means the entire system is compromised;
• Also, in winter, the water can freeze and the pipes can break.

The Earth’s rotational movement causes the angle of sunlight radiation on photovoltaic panels to constantly change. This means that solar panels receive more solar energy if they are inclined at an appropriate angle.

Therefore, the positioning of photovoltaic panels is extremely important to achieve high efficiency in the solar installation. An analysis of this positioning considers both the mounting angles and shadow zones. Hence, there may be cases where a solar system is not the best investment because it cannot achieve the desired efficiency due to various obstacles.

The installation of a solar panel must take into account two angles:

• Azimuth Orientation: pointing the panel towards the South;
• Inclination: degree of inclination to the sun.

Azimuth Orientation

In order to harness as much solar energy as possible throughout the day and year, the Azimuth orientation (facing South) should be set to 0 degrees.

Summer solar systems involve a significant deviation from the 0-degree Azimuth to avoid significant energy losses. For example, if you are considering installing a solar system solely for heating the pool water during the summer, the Azimuth orientation must be calculated to ensure that the solar panels provide maximum efficiency during the warm season, without considering the other seasons.

On the other hand, if you are considering a solar system for heating purposes (used only during the cold season), the Azimuth orientation should be calculated exclusively for the winter months.

Tilt of Solar Panels

Similar to the Azimuth orientation, calculating the tilt angle of solar panels must take into account the purpose of the system.

For photovoltaic systems integrated to heat water or a pool (during the summer period), the tilt angle is lower, as the sun’s height is at its highest. Conversely, the optimal tilt angle for environmental heating systems (during the cold season) is higher, as the sun’s position is lower in the sky.

Shadow Generated by Obstacles

The sun follows a different trajectory in the sky each day. Therefore, the shadow cast by any obstacle in front of the solar panels will vary. That’s why solar panels need to be tilted and oriented in such a way that the average rate of solar energy loss due to shadows is minimized.

Optimal intervals for the tilt and azimuth orientation of solar panels

The table below presents the optimal intervals of tilt and azimuth angles, depending on the purpose of the solar system. Of course, these intervals do not take into account any potential obstacles that could cast shadows on the solar panels.

Use	Angles of inclination of the panels	Azimuth angles of the panels
Hot water	15° up to 45°	45° up to -45°
Pool	15° up to 45°	45° up to -45°
Hot water + Ambient heating	30° up to 60°	15° up to -15°
Hot water + Ambient heating + Pool	30° up to 60°	30° up to -30°

If last week we analyzed the characteristics of Lithium-ion solar batteries, today it is the turn of AGM and Gel solar batteries.

AGM solar batteries

AGM (Absorbent Glass Mat) or lead-acid solar batteries became known in the 1980s. At that time they were used in aircraft and vehicles, but later they also started to be produced for renewable energy storage.

Unlike other types of solar cells, the acid in AGM batteries is sealed by a fiberglass support that does not allow it to leak.

This type of batteries do not require maintenance and have a fairly long life. In addition, they are resistant to low temperatures, but very sensitive to high temperatures and overload due to the fact that they are sealed.

Advantages of AGM solar batteries

• They have a high charging capacity;
• Their acid cannot leak due to sealing technology;
• They have a longer lifespan compared to flooded batteries;
• They are resistant to low temperatures, vibrations, and water;
• Allow fast charging and discharging, with low internal resistance;
• They do not require maintenance;
• They need charging at long intervals, with a very low discharge rate: between 1 and 3% per month.

Disadvantages of AGM solar batteries

• Their manufacturing cost is higher than flooded batteries, but lower than gel ones;
• They are very sensitive to overload;
• Their charging voltage should be limited to a maximum of 14.1 – 14.4 volts at 20℃

AGM Solar Batteries: Tips for Use and Maintenance

The lifespan of AGM solar batteries can be extended if they are not allowed to discharge more than 60% before recharging.

Gel Solar Batteries

In the last 30 years, gel solar batteries have been used in multiple industries, offering a safer and more viable alternative to acid batteries.

This type of batteries does not require special maintenance and does not necessarily need to be stored in an upright position. This is because the electrolyte mixture takes place in a gel-based substance, reducing electrolyte evaporation.

Additionally, gel solar batteries are very safe. The gases produced during charging are transformed into liquids inside the battery, preventing their release.

Advantages of solar gel batteries

• They do not require maintenance, but their temperature must not exceed 80℃;
• Because they do not leak, they pose no risk of sulfuric acid burns. Thus, they are much safer than other types of batteries;
• They can also be recharged in places with poor ventilation as they do not emit hydrogen vapors.

Disadvantages of solar gel batteries

• Their cost is higher compared to other batteries;
• Their lifetime is shorter compared to the other types of batteries;
• They have a high sensitivity to high temperatures.

Lithium-ion solar batteries are the most commonly used for energy storage, being the best solar batteries from various perspectives. Their main advantage is their ability to release a large amount of energy in a very short period of time.

These batteries emerged in the 1970s but only in the 1990s did they start to be mass-produced and commercially available. Since then, lithium-ion battery technology has developed rapidly, being also used in electric vehicles.

Characteristics of Lithium-ion solar batteries

As the lightest metal, Lithium has the highest electrochemical capacity, providing a high energy density. Additionally, Lithium is a very reactive element, allowing it to store more energy.

In general, a Lithium-ion battery weighing one kilogram can store up to 150Wh of electrical energy. In comparison, a Ni-MH (Nickel Metal Hydride) battery with the same weight can store up to 100Wh, while a lead-acid battery stores only 25Wh per kilogram.

Being encapsulated, Lithium-ion batteries do not require water refilling or maintenance. Their regulating valve accomplishes the recombination of oxygen and hydrogen resulting from chemical reactions at the anode and cathode levels.

Temperature influences the battery’s lifespan, with the optimal operating range for a lithium-ion accumulator being 5°C – 20°C. If the batteries operate at temperatures above this range, their lifespan is significantly reduced. Lower temperatures also reduce the batteries’ storage capacity.

Advantages of Lithium-ion solar batteries

The main reasons why many consider Lithium-ion batteries the best are as follows:

• They have a high power, at a low current;
• They are much lighter compared to AGM batteries;
• They have the ability to withstand several hundred charge/discharge cycles;
• Does not require priming;
• They don’t need regular downloads because they have no memory.

Disadvantages of Lithium-ion solar batteries

• Requires a protection circuit to operate safely;
• Their lifespan decreases whether they are used or not;
• Their manufacture is more expensive than other types of solar batteries;
• They are still in the process of improvement, with other metals and chemicals being tested.

Lithium-ion Batteries: Tips for Use and Maintenance

In general, it is best to partially discharge the Lithium-ion battery, rather than fully deplete it. Similarly, when recharging the battery, it should be partially charged.

As mentioned earlier, Lithium-ion batteries are very sensitive to high temperatures. Most manufacturers recommend a storage temperature of around 15°C to slow down the degradation process.

The lifespan of Lithium-ion batteries is approximately two to three years. Considering that this duration starts from the date of manufacture, it is advisable to use the battery immediately after purchase. As mentioned earlier, batteries degrade even if they are not used.

Photovoltaic panels come in three types: monocrystalline, polycrystalline, and thin-film. This article will present the main characteristics of polycrystalline photovoltaic panels and thin-film panels.

Polycrystalline Photovoltaic Panels

Polycrystalline photovoltaic panels are made from melted silicon fragments, giving them a mosaic-like appearance. These panels have a square shape and a blue color. Due to being made from multiple silicon crystals, polycrystalline panels do not allow for a significant movement of electrons within each cell.

Characteristics of polycrystalline panels

• In the production of polycrystalline panels, not much raw material is used up. Crystals do not require individual placement and polishing;
• The maximum temperature supported is 85℃, while the minimum temperature is -40℃;
• They have a lower efficiency at high temperatures compared to monocrystalline panels;
• Installation of polycrystalline panels is cheap and simple.

Advantages and disadvantages of polycrystalline photovoltaic panels

Advantages:

• The price of polycrystalline solar panels is lower than monocrystalline ones. They are easier to make, using multiple silicon crystals;
• It does not involve exhaustion of raw material;
• Can be used with batteries;
• The manufacturing process requires very little fossil fuel.

Disadvantages:

• Lower efficiency compared to monocrystalline panels, resulting from the lack of pure silicon;
• Covers a larger area than monocrystalline panels;
• They may have a shorter lifespan;
• It deteriorates easily at high temperatures.

Thin film photovoltaic panels

Thin film photovoltaic panels have lower efficiency and capacity to produce electricity than monocrystalline and polycrystalline.

Characteristics of thin-layer panels

• The efficiency of converting solar energy into electricity is about 11%;
• Both their price and installation are cheaper than the other two types of panels. Thin layer panels weigh much less and are easier to handle;
• Most thin-film solar panels are often made from cadmium telluride, amorphous silicon, and copper selenide, each of which has a unique manufacturing process.

Conclusion

So now we know what are the main differences between polycrystalline and thin film photovoltaic panels. If you still don’t know which of these panels are more suitable for your home, our experts are at your disposal for any questions you may have.

Monocrystalline photovoltaic panels consist of monocrystalline cells. Each monocrystalline panel is constructed from a cylindrical ingot of silicon, which in turn is made of a single, pure silicon crystal like any other semiconductor. Since each cell is composed of a single crystal, electrons have more space to generate energy.

Performance of Monocrystalline Photovoltaic Panels

Monocrystalline photovoltaic panels have the highest efficiency and capacity to produce electricity among all three types of panels. Their efficiency in converting solar energy into electrical energy ranges between 15% and 20%.

As mentioned earlier, their performance is the result of cells that are made up of a single crystal of pure silicon. Therefore, the cells require less space to produce a certain electrical power.

Thus, fewer monocrystalline panels would be needed than polycrystalline panels in a solar system to generate the same amount of electrical power. This is one of the reasons why some prefer monocrystalline panels, especially if they have limited space on the roof of their house.

Other characteristics of monocrystalline photovoltaic panels include:

• The photovoltaic cells in these panels are distributed in a pyramid shape, providing a larger surface area to collect sunlight rays.
• The upper part of each panel contains phosphorus, creating a negative electrical orientation compared to the lower part, which has a positive orientation. This way, an electric field is created.
• To reduce the reflection of sunlight rays and increase their absorption level, the monocrystalline cells are covered with a layer of silicon nitride.
• The electricity produced is collected through metal conductors, present on each individual cell.

Advantages and disadvantages of monocrystalline photovoltaic panels

Advantages:

• High efficiency, between 15% and 20%;
• It requires a smaller area compared to the other panels;
• They have a lifespan of up to 25 years;
• It has a higher resistance to heat;
• They are more efficient than other types of panels in less sunny areas.

Disadvantages:

• Their price is higher compared to the other types of panels;
• Their performance tends to suffer at rising temperatures;
• A lot of raw material is lost to make them.

In one of the previous articles we saw how many photovoltaic panels are needed for a house. It’s time to also analyze which are the best photovoltaic panels.

There are 3 types of panels designed to produce electricity:

• monocrystalline (sc-Si)
• polycrystalline (mc-Si)
• thin layer panels

1. Monocrystalline Solar Panels (sc-Si)

Monocrystalline solar panels are considered the best photovoltaic panels, appreciated for their efficiency.

Manufactured using a single pure silicon crystal, these panels can convert between 15-20% of solar energy into electricity.

In addition to this remarkable efficiency, monocrystalline panels also have a very long lifespan of 25 years and can be easily maintained.

Being regarded as the best photovoltaic panels, their price is also higher compared to other types of panels.

2. Polycrystalline Solar Panels (mc-Si)

Unlike monocrystalline panels manufactured using a single pure silicon crystal, polycrystalline panels are made from leftover silicon.

Even though their lifespan is also about 25 years, these panels can only convert 13-16% of the captured sunlight into electricity. This explains their lower price compared to monocrystalline panels.

3. Thin-Film Solar Panels

At the bottom of the photovoltaic panel ranking are the thin-film panels. The major advantage of these panels is that they are not dependent on the intensity of sunlight and are very easy to install.

The price of thin-film solar panels is relatively low because their conversion process is only about 6-12%, which is why they are not the most favored ones.

Installation and Maintenance

In order to achieve high efficiency from photovoltaic panels, their installation and maintenance should be carried out by a specialist in the field.

However, it’s not wrong to know some basic aspects:

• Photovoltaic panels should be installed with a tilt of 15 degrees, facing south. This will ensure the efficiency of the photovoltaic panels and facilitate the self-cleaning process.
• One of the most important maintenance procedures is filling with solar antifreeze. It is crucial to have a specialist take care of this, as the antifreeze regulates circuit pressure and ensures the proper functioning of the system.

Photovoltaic panels: The price for a house

The price of photovoltaic panels for a house is the last step before you decide to invest in such a system. I left this topic at the end of the article, because it is more important to know first which are the best photovoltaic panels.

Unfortunately, we cannot determine an exact cost as it varies from household to household and depends on each customer’s needs.

A cheap photovoltaic panel system can start from €1000 per 1 KW installed. It is highly likely that such a system may not guarantee very high efficiency, and the quality of the equipment may be relatively low. On the other hand, a complete and high-performance system can reach up to €1600 per 1 KW installed.

Conclusion

Now you know what the best photovoltaic panels are and have a clearer picture of the types of these systems.

We know it can be daunting to search for all the necessary information, but if you are interested in installing such a system, we encourage you to contact us with any questions you may have.

Solar batteries are one of the main components of a photovoltaic system. Do you know what the role of batteries is within a photovoltaic system? How do you determine the best solar batteries?

The primary role of batteries in a solar system is to store surplus energy. As mentioned in one of the previous articles, solar panels produce less electric current during the cold season or on cloudy days.

When photovoltaic panels produce more electric current than is needed, the batteries store that extra amount to be used during times when the panels produce a lower amount of electric current or none at all, such as during the night.

Depending on the voltage and capacity of the battery, a specialist can determine how many batteries are needed for a solar installation.

How do you choose a solar battery?

When choosing a solar battery you need to consider the following factors:

• safety;
• initial cost;
• profitability;
• storage capacity;
• battery power;
• lifetime;
• the impact of the battery on the environment;
• maintenance cost;
• transportation cost;
• installation cost.

The storage capacity of a solar battery is expressed in kWh. This indicates the amount of current that can be stored by the battery and how long the house can be powered with this amount of current.

The power of the battery determines the amount of energy that can be delivered in a single charging cycle.

In addition to these two factors, consider the depth of discharge of the battery. This determines how much the battery can be used before it needs to be recharged. It is also essential to know the conversion and storage efficiency: how many units of electric current can be used as a percentage of the already stored electric current.

Types of Solar Batteries

Solar batteries can be confusing when you are searching for and evaluating the best option for your photovoltaic system, especially if you have little knowledge on this subject. But don’t worry, we can help you with all the necessary information according to your needs. We will guide you step by step, including which batteries are suitable for your photovoltaic system.

However, it is essential to be familiar with some details when discussing with a specialist.

Each type of energy storage battery has its advantages and disadvantages. In the following paragraphs, we will analyze the main three types of batteries.

• Lithium-ion solar batteries
• AGM solar batteries
• Gel solar batteries

What are the best solar batteries?

So, these are the most common types of solar batteries. Examining the characteristics, advantages and disadvantages of each, we can conclude that Lithium-ion solar batteries are the most suitable for most photovoltaic systems. It is no wonder that they are also the most used, both by domestic consumers and by commercial ones.

What are the characteristics of monocrystalline or polycrystalline panels? Do you know the difference between these two types of photovoltaic panels?

The sun is an incredible source of energy. Just think that the Earth receives more energy from the sun in one hour than the entire energy consumed by the world’s population in a year. Solar energy is converted into electricity by means of photovoltaic cells.

The technology of photovoltaic panels has evolved significantly in recent years, resulting in the emergence of increasingly innovative solar panels. There are many factors to consider when thinking about purchasing a solar energy system, one of them being the type of solar panels.

For residential users, most of the solar panels available on the market in Romania can be divided into three categories:

• Monocrystalline Photovoltaic Panels
• Polycrystalline Photovoltaic Panels
• Photovoltaic panels with thin layer

Although all these categories of panels are intended to convert solar energy into electricity, they still have different characteristics. Considering that most domestic consumers choose monocrystalline and polycrystalline photovoltaic panels, in this article we will compare these two types of panels.

What do we choose – monocrystalline or polycrystalline panels?

The table below shows the main differences between monocrystalline photovoltaic panels and polycrystalline photovoltaic panels:

Characteristics	Monocrystalline panels	Polycrystalline panels
Cost	Higher	Lower
Eficiență	Higher	Lower
Apperareance	Black	Dark blue
Lifespan	Up to 25 years	Up to 25 years
Space	Takes up less space on the roof	Takes up more space
Performance	Higher performance, even in regions with less natural light	Reduced performance in frequently cloudy areas

Conclusion

We can see that apart from the lifetime, which is similar for both types of solar panels, monocrystalline solar panels have many more advantages than polycrystalline ones. This also explains their higher cost.

Are you wondering how many solar panels are needed for a house? Are you also considering solar panels as a good energy-saving solution for your home?

In this article, we will try to answer these questions. We hope to convince you to choose this type of green energy source.

More and more Romanians are interested in solar panels for their homes and commercial spaces. We assure you that you are not the only person with numerous questions regarding this new energy source. However, the one mentioned above is just one of them.

But let’s see together how many solar panels are needed for a house and which are the best panels.

How many solar panels are needed for a house?

To determine the required number of solar panels for a house, we need to know the current monthly electricity consumption.

ATTENTION: We do not need the house’s surface area or the number of residents to determine this.

The simplest way to find out the current monthly energy consumption is to look at the last bill and check the total amount paid for one month. Then we divide this amount by the cost per kWh.

To make it easier, let’s use the following example: 180 RON (last month’s bill), 0.60 RON (cost per kWh). In this case, the energy consumed in one month is 300 kWh.

We divide the 300 kWh by 30 days (average monthly) and get a result of 10 kWh per day, which is the daily energy requirement.

So, we now know how much energy we consume daily. But how do we find out how many solar panels are needed for a house?

We divide the 10 kWh by a coefficient of 3.3 (explained below) and determine the INSTALLED POWER, which in our case is 3 kW.

ATTENTION: Energy is measured in kWh, and installed power is measured in kW.

Considering that most solar panels are 250W, we find that we need a total of 12 solar panels (1 kW = 1000W). If you are considering panels that produce less energy, adjust the calculation accordingly.

To determine an approximate price of a photovoltaic kit, in addition to the panels, take into account the other necessary elements:

• Inverter
• Cabels
• Battery
• Grip structure
• Wiring

Coefficient of 3.3: Annual Daily Average

The installed power produces energy based on the intensity of sunlight: less in the morning, more at noon. This also applies to summer vs. winter.

In our example, even though the 12 panels have an installed power of 3 kW, they will not produce 3 kWh (energy) every hour and every day. Considering that in summer, these 12 panels (installed power) can produce even 5-6 times more energy, the ANNUAL DAILY AVERAGE has a coefficient of 3.3.