Author: Casiana Pridea

The choice of an Off-Grid or On-Grid photovoltaic system is made according to the way in which the home is supplied with electricity at the moment.

Off-Grid Photovoltaic Systems

If your home is in an isolated area, not connected to the National Energy System, then you will have to opt for an Off-Grid photovoltaic system (with batteries).

Off-Grid photovoltaic systems are the most complex on the market, containing:

• Photovoltaic panels (or wind turbines);
• Charge controllers (regulators);
• Solar batteries;
• Inverters.

Unlike On-Grid inverters, those for Off-Grid systems have several functions, which allow you to control:

• supplying energy to different consumers in your home;
• photovoltaic panels;
• the use of alternative sources as fuel generators or cogeneration systems.

On-Grid Photovoltaic Systems

If you are connected to the National Energy System, you can choose between 3 types of On-Grid photovoltaic systems:

1. Photovoltaic system that aims to inject all energy production into the national grid (or Full Feed-In System).
2. Complex photovoltaic system, where the priority is the consumption of energy by you, for your home, and the National Energy System acts as a back-up, providing you with additional energy if needed or receiving surplus energy produced by your system.
3. Hybrid photovoltaic system (On-Grid with batteries) that helps you store the surplus energy produced by your panels. In this case, the National Energy System only serves as a back-up in case of overconsumption, charging the batteries when needed or even taking over the surplus energy if the batteries are already fully charged. These types of photovoltaic systems require hybrid inverters with built-in charge controllers.

The performance of an On-Grid photovoltaic system is determined by:

• Efficiency and quality of photovoltaic panels: geographical location, orientation and degree of inclination of the roof, manufacturer;
• Efficiency of inverters: they strictly depend on the manufacturer.

It is important to remember that for the installation of an On-Grid photovoltaic system, you need a Technical Connection Approval (ATR), to connect the panels to the National Energy System.

Solar lamps represent an excellent choice for illuminating your garden from several points of view. Due to their cable-free and accessory-free nature, solar lamps are very easy to install anywhere in your yard.

Continue reading to discover the benefits of solar lamps for the garden.

How Do Solar Lamps Work?

Solar lamps for the garden only light up in the evening, as they capture solar energy during the day. Each lamp has one or two photovoltaic cells on the top, which absorb sunlight and convert it into energy.

Solar energy is stored in a small battery inside each lamp. When the sun sets, a photoresistor activates an LED light, using the energy stored in that battery.

How Long Do Solar Garden Lamps Illuminate?

For maximum charging, the battery of a solar lamp needs at least 8 hours of exposure to sunlight on a sunny day. Thus, the battery can provide light for about 12 to 15 hours.

On cloudy days or during the winter season, it may be challenging for the battery to fully charge, so the lamp may not illuminate for the entire night.

Benefits of Solar Garden Lamps

Solar garden lamps have multiple benefits, with the top 3 advantages being the following:

1. It consumes no electricity at all

As already mentioned, each solar garden lamp has one or two photovoltaic cells built into it that collect sunlight and convert it into electricity. This is then stored in a small rechargeable battery. Thus, solar garden lights do not need an external power source. All you have to do is make sure they are installed/placed in places with direct access to sunlight.

2. It does not harm the environment

Since solar garden lights do not require power from external sources, they are an environmentally friendly lighting solution for your yard or garden, doing absolutely no harm to the environment

3. Reduced costs

Apart from the initial investment of their purchase, solar garden lights have no other cost. In this way, you can enjoy an illuminated garden or yard, while your electricity bill will not increase.

If you are also considering installing photovoltaic panels for domestic use, below you will find all the documents and permits you need. These do not apply to thermal panels, which can be installed by a plumber or a specialized company.

Urban Planning Certificate

The urban planning certificate can only be requested by the homeowner from the local town hall and is issued within a maximum of 30 days, with a validity between 6 and 24 months from the date of issue (depending on the purpose and complexity of the investment).

To obtain the Urban Planning Certificate, you will need the following documents:

• Standard Request;
• Ownership documents, cadastre, land book extracts;
• Copies of the sales-purchase contract, inheritance act, and land registration certificate;
• Copy of ID card/identification document;
• Proof of payment for the issuance of the urban planning certificate. The fee is calculated based on the land area: 5 Lei for an area up to 150 square meters, up to 14 Lei for areas of 1000 square meters.
• Cadastral plan at scales 1:500 and 1:2000, and topographic location plans (2 copies each) issued by the Land Registry and Cadastre Office;
• Plan of the current situation and the proposal for the photovoltaic system;
• Brief memorandum summarizing the purpose of the request.

Environmental Agreement and Environmental Approval

Both documents are issued by the National Environmental Protection Agency/Agenția Națională pentru Protecția Mediului (NEPA/ANPM), the Central Public Authority for Environmental Protection, or the Territorial Public Authority for Environmental Protection, within 30 days.

To obtain the Environmental Agreement (fee of 4000 lei, without VAT), you will need:

• The application for obtaining the Environmental Agreement;
• Copy of the Urban Planning Certificate;
• Copy of the Site Plan attached to the Urban Planning Certificate;
• Copy of the Zoning Plan;
• Proof of payment for the initial evaluation of the request.

To issue the Environmental Notice (fee of 1000 lei, excluding VAT) you will need:

• Notification;
• Draft Plan;
• Proof of publication of the Notice and the Draft Plan in the Mass Media.

Approval from the State Inspectorate in Construction (ISC)

The fee for the Approval from the State Inspectorate in Construction is paid subsequently, with a value of 0.25% of the investment value, and it is issued within 30 days. The documents required for its issuance are:

• Application for requesting the approval;
• Copy of the Urban Planning Certificate;
• Architectural Technical Memorandum;
• Zoning Compliance Plan;
• Site Plan, scale 1:500 or 1:2000;
• DTAC Project (2 copies);
• Copy of the owner’s Identity Card;
• Proof of property ownership/lease.

Sanitary Permit

Issued within 15 days, the Sanitation Permit is issued by the local sanitation company, based on the following documents:

• Copy of the owner’s Identity Card;
• Copy of the property/rental deed;
• Copy of the proof of payment of the fee, which differs depending on the company that provides the sanitation services

ISU Approval

The ISU opinion is issued by the Inspectorate for Emergency Situations, within 30 days. The required documents are:

• Standard Application Form in two copies;
• Two copies of the Urban Planning Certificate;
• Technical documentation at the design phase for the Building Permit;
• Report issued by the person who verified the project for fire safety;
• Site Plan, scale 1:500 or 1:2000;
• Two copies of the inventory with the list of submitted documents.

The Telephone Connection Approval

The Telephone Connection Approval is issued by the telecommunications provider, against a fee that can vary between 3 and 9 Euros, within 15 days, based on the following documents:

• Standard Application Form;
• Copy of the Urban Planning Certificate;
• Two copies of the Site Plan, scale 1:500 or 1:2000;
• Zoning Plan

Energy Supplier Site Approval

The Site Approval is issued by the electricity distribution operator, subject to a fee of 55 Lei (excluding VAT), within 15 days. The required documents are:

• Standard application form;
• Copy of the Urban Planning Certificate;
• Copy of the Zoning Plan, endorsed by the issuing authority and attached to the Urban Planning Certificate;
• Site Plan;
• Coexistence Study to determine the level of compatibility with the power grid;
• Proof of payment of the fee.

Technical Connection Approval

The Technical Connection Approval is issued by the distribution operator within 30 days, against a fee of 42 lei (excluding VAT).

You will need the following documents:

• Standard Application Form;
• Free Mandate;
• Copy of the Site Location Approval / single agreement;
• Solution Study for connection to the electricity network (if elaborated);
• Technical and energy data of the consumption site;
• Copy of the Urbanism Certificate;
• Copy of the Site Plan, scale 1:500 or 1:2000;
• Copy of the zonal urban plan;
• Building Permit for the objective;
• Copy of the identity document;
• Copy of the property deed;

Building Permit

The fee for obtaining the Building Permit is 0.5% (individuals) and 1% (legal entities) of the investment value. It is issued by the local town hall within 30 days and is valid for 12 months from the date of issue.

The required documents are as follows:

• Standard Application Form;
• Certified copy of the property deed;
• Self-declaration stating that there are no disputes regarding the property;
• Copy of the urban planning certificate;
• Copy of the updated cadastral plan extract;
• Copy of the updated land book extract;
• Approvals and agreements specified in the urban planning certificate;
• Technical documentation for obtaining the Building Permit;
• Contract with a waste disposal company for the transport of construction waste;
• Proof of payment for the fee.

The following two documents are only required if you wish to become a prosumer (injecting surplus energy produced by you into the centralized energy system).

Electricity production license and accreditation

Issued within 60 days and 30 days respectively, both documents are issued by the National Energy Regulatory Authority (ANRE).

Connection Certificate

The Connection Certificate is issued free of charge, within 30 days, issued by the electricity distribution operator

Wind is caused by 3 factors: uneven heating of the atmosphere by the sun, irregularities on the earth’s surface, and the sun’s rotation. That is why wind is considered a form of solar energy.

Air currents change depending on the landforms, water bodies and existing vegetation. Captured by wind turbines, these air currents can generate electricity.

Wind farms

According to the latest statistics, the number of wind farms, on land or on water, increases annually by more than 35%.

Wind farms are a reliable source of renewable energy that does not require the consumption of natural resources and does not pollute the environment. Wind turbines are installed at an average height of 30 meters where the wind is stronger so that they can capture more wind energy.

On average, a minimum wind speed of 4-5 m/s (14-18 km/h) is needed for wind turbines to operate, while maximum power is produced at a wind speed of 15 m /s (54 km/h). If the wind speed exceeds 25 m/s (90 km/h), the wind turbines cannot operate and are stopped. Therefore, a wind turbine produces electricity 70-85% of the time.

Water wind farms are installed at depths of 100-200 m, anchored to the seabed, their wind turbines being floating.

The advantages of Wind Energy

1. Air currents are an inexhaustible source of energy.
2. Wind energy contributes to the national security of the producing state, reducing its dependence on imported fossil fuels.
3. Wind farms can represent an additional income for traditional farm owners. Agricultural land can be leased for the installation of these parks, the main agricultural activity not being affected.
4. As already mentioned, solar energy does not pollute the environment and does not produce toxic gases.

Disadvantages of Wind Energy

1. Wind turbines pose a danger to wildlife. Birds can be hit or even killed if they get close to them.
2. Since the efficiency of turbines depends on the strength of the wind, wind energy can only be captured in areas with sufficiently strong winds throughout the year.
3. The noise produced by windmills can be disturbing to nearby residential areas.
4. In order to be installed, wind farms require extensive areas.

Romanians are more and more careful when it comes to monthly expenses, especially household expenses, the electricity bill being one of them.

We all want to pay as little as possible for the electricity used in the previous month, and sometimes we make drastic decisions that don’t always bring the desired result. That’s because we don’t know exactly who are the big consumers of electricity in our house.

Following a market study, which meant calculating the household energy consumption of over 100 Romanians, we discovered who are the 5 biggest consumers of electricity in almost every home.

You too can reduce your electricity consumption if you watch how much you use these 5 big consumers. Also, if you are thinking of investing in a photovoltaic panel system, it will help you a lot to know these 5 consumers in order to correctly choose the type of panels, but also their number.

1. Home Heating System

Heating systems (radiators, electric convectors, air heaters) consume approximately 31% of the total electricity consumption in a home.

One of the common causes of high energy consumption is heat loss, usually caused by:

• Lack of insulation or superficial insulation;
• Improperly fixed windows showing cracks or gaps.

2. Boiler

Boilers or other water heating systems consume up to 13% of the total energy required for a home.

Of course, the first and simplest advice we can give you would be to try to reduce the consumption of hot water, or at least the frequency, throughout the day.

Another effective solution is to install a boiler without a storage tank. It heats water only when needed, instead of continuously accumulating a reserve of water to heat.

The most sustainable solution in this regard, however, is an investment in a thermal panel system.

3. Home Cooling System

A cooling system consumes about 10% of the total electricity consumption, especially during the summer.

As with heating systems, poor home insulation leads to cold air loss. In addition to revising the insulation, we also recommend purchasing a more modern and efficient air cooling system.

4. The refrigerator

Being in operation all the time, refrigerators consume up to 4% of the total electricity used in a home.

If you haven’t done it yet, we recommend purchasing a refrigerator with a higher energy class: A, A+, A++ or A+++. In addition to lower energy consumption, such a refrigerator will also allow you to set an optimal temperature between 1 and 5 degrees Celsius.

5. The TV

Televisions, together with other entertainment gadgets (laptop, PC, smartphone) are on the 5th place in the list of the biggest consumers of electricity.

To reduce the energy consumption of these appliances always make sure to turn them off when not in use. Attention, in stand-by mode, the device continues to consume electricity!

Conclusion

Now you know who are the biggest consumers of electricity in your home. Analyze each one separately and keep in mind the tips mentioned above!

The energy sent by the sun to our planet is divided into two categories: light and heat.

While photovoltaic panels facilitate the transformation of light into electrical energy, solar thermal panels use the heat from the sun to produce domestic hot water or for heating purposes.

The electrical energy produced by photovoltaic panels can be used for self-consumption, and the surplus can be used in two ways:

• Stored in accumulators;
• Injected into the network to be used where needed.

How much energy do we get from the sun?

To realize the importance of this energy source, remember the following two aspects:

1. The energy that reaches a roof in a 14-day interval could power a home for a year.
2. Every hour, enough energy arrives on Earth to ensure the consumption of the entire planet for a year.

Currently, only a portion of this solar energy can be converted into electrical energy. However, over time, we will undoubtedly use an increasingly larger portion of this solar energy, producing energy at much lower costs compared to conventional energy and storing it with ease.

Electricity Production: The negative impact on the environment

Currently, electrical energy comes from various sources. The main advantages of renewable energy, compared to energy produced from fossil fuels, finite resources, or other highly polluting sources, are its availability and reduced environmental impact.

In 2017, solar energy accounted for only 2.55% of Romania’s national energy mix. However, the potential is enormous, considering that half of the total 7.5 million households across the country are suitable for installing photovoltaic systems.

In the same year mentioned above, CO2 emissions generated by energy production reached a historical peak of 32.5 gigatons, with energy being the primary global pollutant.

By 2030, the European Union aims to reduce CO2 emissions by around 45% and increase the share of renewable energy in total consumption to 32% (from 20% in 2020).

Impact of Using Photovoltaic Panels:

DURATION	365 days
INSTALLED POWER	3 kW (12 panels)
ENERGY PRODUCED	3.720 kWh/ year
CO2 REDUCTION	2,79 tCO2/ year
EQUIVALENT TREES PLANTED	14/ year

Recovery of Investment in Photovoltaic Panels

Due to their increasingly widespread use, the price of photovoltaic systems has steadily decreased in recent years. Today we meet photovoltaic cells everywhere:

• Garden lighting systems;
• External batteries for mobile phones;
• Boats;
• Trains;
• Airplanes.

Photovoltaic panels are becoming more and more affordable. The high rate of their promotion, the increasingly extensive research in the field and the fact that most states have or are planning subsidy policies for these systems are some of the factors that contribute to easy access to this technology.

In general, the investment in a photovoltaic panel system is recouped in about 7 years through lower electricity bills and increased property value. Also, the lifespan of the panels is at least 25 years.

Considering that more and more Romanians are interested in purchasing electric or plug-in hybrid vehicles, this article will provide detailed information about an electric charging station.

There are still many misconceptions among the population regarding electric cars, including how and where they can be charged.

What is the difference between an electric car and a plug-in hybrid car?

Before discussing charging stations, it is crucial to understand the difference between an electric car and a plug-in hybrid car.

While an electric vehicle is powered 100% by an electric motor, a plug-in hybrid vehicle has two motors: one electric and one conventional gasoline-powered.

The electric motor can be recharged from an external source or while driving, through a generator that takes energy from the conventional engine.

Electric Charging Stations

Electric charging stations usually have between 2 and 5 charging points. You can find them in the parking lots of large shopping centers, such as Dedeman, Ikea, malls, Lidl, Kaufland, and others.

Like any market, the number of these charging stations will increase in the future based on the number of users. The more electric and plug-in hybrid car owners there are, the greater the number of stations will be.

On average, electric car owners travel around 30 km daily in Europe. As a result, they can charge their cars at home without the need to use other stations throughout the day. These stations are generally required for longer distances of 300+ km.

Charging Time for an Electric Car

The charging time for an electric car depends on two factors: the power of the charging station (kW) and the battery’s capacity to store this energy.

In general, charging stations fall into 4 types:

1. Slow Charging stations have a power of approximately 3 kW. On average, a full charge at such a station from 0 can take up to 8 hours.
2. Fast Charging stations have a power between 7-22 kW and are the most common. A full charge takes about 3-4 hours.
3. Rapid Charging stations have a power of 43-50 kW, and not all cars are compatible with them. Such a station can charge a battery from 0 to 80% in less than 30 minutes. It should be noted that this type of stations is rarely found in Romania.
4. Ultra-rapid charging stations are relatively rare at the European level, with a power of 100-350 kW.

When purchasing an electric car it is very important to look at the capacity of the battery. For example, only high-end electric cars are compatible for Rapid Charging stations, such as the Tesla Model S or the Kia Soul EV.

Use of charging stations. Etiquette rules.

There are some common sense rules when using a shared charging station:

• Be sure to release the station if the battery has charged. Other drivers may also need it.
• An unwritten rule says that a plug-in hybrid car driver should give priority to an electric car driver. This is because the plug-in hybrid car can be powered by the classic (thermal) engine in case of emergency.
• Never disconnect someone else’s car from the station.

We hear and read about electric vehicles every day, which is normal, as it is the latest global trend in the automotive industry. Most manufacturers are developing future strategies to commit to producing only such “green” cars, but this is likely to happen after 2035.

Until a few years ago, the range of electric vehicles was the main reason why most buyers avoided them. However, zero-emission vehicles are gaining popularity over traditional combustion engine cars precisely because major manufacturers have found innovative solutions that provide a greater range.

Top 5 electric cars according to range

How comfortable are you when it comes to the range of an electric vehicle? 200, 300, 400 kilometers? Technology has advanced, and electric vehicles now offer increasingly better range. There are many such cars available in Romania.

Below, we will show you the top 5 electric cars on the market with the longest range.

Mercedes EQS 450+

Range: 785 km

Power: 385 kW (523 HP)

Consumption: 19.8 – 15.6 kWh/100 km

Recharge time: 31 minutes

Price: starting from €113,000

Rear-wheel-drive vehicles have one, while 4MATIC all-wheel-drive versions have two propulsion systems. The high-voltage battery is located between the front and rear axles on the vehicle floor.

The Mercedes EQS models are the first to benefit from the newly developed EVA2 platform structure. The electric powertrain eATS consists of a permanent magnet synchronous motor, a two-speed transmission, and the electronic power system. Depending on the power stage, one of the eATS operates on the rear or front axle.

The battery is situated in a secure area on the car’s body floor, between the front and rear axles.

Mercedes EQS 580 4matic

Range: 676 km

Power: 385 kW (523 HP)

Consumption: 18.4 – 21.1 kWh/100 km

Recharge time: 32 minutes

Price: starting from €140,000

The technology of the EQS 580 4matic model is similar to that of the EQS 450+. One of the differences between the two models worth mentioning is that the EQS 580 4matic has all-wheel drive.

Tesla Model S

Range: 652 km

Power: 500 kW (670 HP)

Consumption: 18.1 kWh/100 km

Recharge time: 30 minutes

Price: starting from €97,000

The Model S features the Dual Motor All-Wheel Drive technology, which provides greater range compared to any other Tesla vehicle. This technology combines the performance of the drivetrain and battery for unmatched range and efficiency.

BMW iX xDrive 50

Range: 598 km

Power: 385 kW (520 HP)

Consumption: 19.8 – 23 kWh/100 km

Recharge time: 37 minutes

Price: starting from €98,000

The BMW iX is an electric car with exceptional range and remarkable acceleration from a standstill, thanks to the BMW eDrive technology (pure electric propulsion with all-wheel drive).

Ford Mustang MACH-E

Range: 580 km

Power: 261 kW (351 HP)

Consumption: 18.7 kWh/100 km

Recharge time: 35-40 minutes

Price: starting from €52,000

The Mustang MACH-E is the first electric SUV from Ford, equipped with a 351 HP engine, managing to sprint from 0 to 100 km/h in 6.2 seconds. The battery with a capacity of 98.7 kWh helps the MACH-E run up to 580 km on a single charge and reach a top speed of 180 km/h.

Electric cars are becoming increasingly popular, both globally and in Romania. Just like solar panels, the main reasons why electric cars are gaining more and more interest are the potential for cost savings and concern for the environment.

That’s why we thought of clarifying some aspects regarding electric cars, which sometimes cause confusion among the public.

What is an electric car?

An electric car is propelled by an electric motor (exclusively or assisted by an internal combustion engine) and is powered in whole or in part by a battery. Some electric cars fall under the category of hybrid vehicles, having some CO2 emissions, but much lower than the classic ones, powered exclusively by internal combustion engines.

Electric car categories:

The main categories of electric cars are:

1. BEV (Battery Electric Vehicle)
2. EREV (Extended Range Electric Vehicle)
3. PHEV (Plug-In Hybrid Electric Vehicle)
4. HEV (Hybrid Electric Vehicle)
5. MHEV (Mild Hybrid Electric Vehicle)

BEV (Battery Electric Vehicle)

Cars in this category are powered exclusively by one or more electric motors, powered by a battery.

The battery of an electric car must always be recharged at a specially designed station or at home, at a regular outlet. Recharging a battery varies between 30 minutes and 12 hours, depending on the cable and method.

In Romania, the most popular cars in this category are:

• Renault Zoe 
• Nissan Leaf
• Volkswagen e-Gold

EREV (Extended Range Electric Vehicle)

Unlike a BEV (Battery Electric Vehicle), an EREV also has a small power generator that assists the motor in covering a longer distance.

This small generator is a very small internal combustion engine (500-600cc) that provides additional energy to charge the electric batteries. As a result, CO2 emissions only occur when this small generator operates, but not when the electric motor runs on its own energy.

The best example of an EREV car is the BMW i3.

PHEV (Plug-In Hybrid Electric Vehicle)

PHEVs are propelled by both an internal combustion engine and an electric motor. The electric motor’s battery can be charged separately, as well as with the help of the internal combustion engine. Specifically, part of the energy is used directly by the engine, and the surplus energy is stored in batteries. As a result, the internal combustion engine operates at optimal speeds, resulting in lower fuel consumption.

The most popular PHEV cars in Romania are:

• Mutsubishi Otlander PHEV
• Peugeot 508
• Toyota RAV 4 PHEV 

HEV (Hybrid Electric Vehicle)

In the case of HEV cars, the electric motor works simultaneously with the thermal engine (internal combustion), reducing fuel consumption. The most popular HEV cars are:

• Toyota CH-R 
• Toyota Prius

MHEV (Mild Hybrid Electric Vehicle)

An MHEV car is based on a classic internal combustion engine, but also uses a small electric thruster as a mechanism to conserve energy when braking, cruising or starting from a standstill. This electric motor is not powerful enough to move the vehicle by itself, but it assists the thermal engine in the conditions mentioned above. The results are lower fuel consumption, but also the reduction of polluting emissions.

In one of the previous articles we talked about solar panels for hot water (non-pressurized solar panels). So, today we are going to discuss about pressurized solar panels.

In order not to create confusion, we remind you that solar panels are divided into two large categories:

• Photovoltaic panels;
• Thermal panels: pressurized and non-pressurized;

Before introducing you to the features of pressurized panels, we will also talk about the advantages of thermal panels in general.

Advantages of Solar Thermal Panels

For those of you who are thinking about an economical solution to heat domestic water, solar thermal panels (both pressurized and non-pressurized) have three great advantages:

1. The investment in a thermal solar panel pays for itself very quickly. Apart from the purchase and installation costs, the system has no additional costs, using entirely solar energy.
2. Thermal solar panels have a very long lifespan: 20-25 years. Even though the purchase and installation price may seem high, these panels are a convenient, long-lasting investment.
3. Considering that solar thermal panels use entirely solar energy, their degree of pollution is equal to 0. Thus, you will also contribute to protecting the environment.

Pressurized Solar Panels

Both types of thermal panels, both pressurized and non-pressurized, are used to heat domestic water. The main differences between them are the way of manufacture and the specifications related to mounting.

How do pressurized solar panels work?

The Heat Pipe technology is the basis for pressurized solar panels. Similar to non-pressurized panels, the tubes of pressurized panels are made of two layers of glass with a vacuum between them.

In non-pressurized panels, we already know that water is heated inside the tubes and then rises to the storage tank following the thermosiphon principle. In contrast, pressurized panels rely on the exchange of energy between the collector and the water in the tank. The vacuum tubes absorb solar energy (heat) and transfer it to the water in the tank through a Heat Pipe made of copper. Consequently, the water is constantly heated and supplied to the household under pressure.

Installation of pressurized solar panels

Since the water is not heated directly in the glass tubes of the panels, pressurized systems can be used throughout the year. The only element that should not be forgotten during their installation is the thermal conductive paste. This prevents the erosion of the Heat Pipe or reduces the transfer of heat to the tank.

Once the panel is installed and the system is powered, the water will reach a temperature of 40℃ in approximately 8 hours, depending on the intensity of sunlight.

Advantages of pressurized solar panels:

IMPORTANT!!! Unlike non-pressurized panels (which cannot be used in winter), the main advantage of pressurized panels is that they can be used throughout the year without any exceptions.

Additionally, as already mentioned, these panels have a very long lifespan, and the investment can be recovered within 3-4 years from the installation date.

Furthermore, this type of thermal panel does not require special maintenance, except when one of the tubes breaks and needs to be replaced. However, unlike non-pressurized panels, the pressurized system can function without any problem even with a broken tube.

Disadvantages of pressurized solar panels

One of the main disadvantages of these panels is that their installation is more complex compared to non-pressurized ones. Therefore, they require installation by a specialist.

Due to being made of more durable materials and having a more complex operating system, pressurized panels have a slightly higher price compared to non-pressurized ones.

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.