Related Topics:
Optimization Capacitor Voltage Control-
What to do if there is no voltage in solar power generation
This is quite a common problem, and the most likely causes are a fault or failure with the charge controller or inverter or a panel in your array that has failed. To troubleshoot this issue, you will need to test the inverter, the charge controller, and the solar panels to determine where the fault lies. To do this, you will. This is the most straightforward step, as most inverters have warning systems and indicators that activate when it detects a fault. If you find there is no voltage, check the inverter and see if the. You can test the charge controller using a multimeter. Connect your multimeter carefully to the positive and negative outputs and see whether there is a voltage reading or not. The controller regulates the voltage and amperage to. Aside from the above, high temperatures, shading, panel damage, and faulty connections can cause a lack of voltage from solar panels. Because solar panels in an array are connected in series and if one fails, the whole system goes down and there will be no voltage or current as a.
[PDF Version]
FAQs about What to do if there is no voltage in solar power generation
What causes a solar panel to register no power?
These are actually common problems and there are ways you can fix them. A faulty inverter or charge controller are the most likely reasons for a solar panel to register no voltage. Other possible reasons for low to zero power are a damaged PV module, poor wiring, shading and temperature higher than the ideal operating range.
What are some common problems with zero voltage solar panels?
Common problems with zero voltage include a faulty inverter or charge controller, a solar panel that has failed, shading, increased temperature, hotspots in a solar panel, poor connection or faulty wiring, and delamination caused by water entering one of the solar panels. We will look at the most common scenarios where PV systems fail:
Do solar panels have no voltage?
No Voltage From Solar Panel (Solutions) - Solar Panel Installation, Mounting, Settings, and Repair. It can be frustrating to find you don't have voltage from your solar panels, but the potential problems are relatively straightforward to diagnose as there can only be a few issues that cause the lack of power.
Why isn't my solar panel generating volts?
If your solar panel is not generating volts, it's likely due to lack of sunlight. Environmental issues like shading, a dirty solar panel, high temperature, and bad weather can also prevent the panel from producing volts. In extreme cases, these factors can cause the voltage to drop to zero.
What causes a lack of voltage from solar panels?
Aside from the above, high temperatures, shading, panel damage, and faulty connections can cause a lack of voltage from solar panels. All electronic devices, including solar panels, operate far better at lower temperatures.
What should I do if my solar panel system is disconnected?
If you are considering disconnecting your solar panel system, seek guidance from a qualified solar installer or electrician. Additionally, install backup power solutions to ensure an interrupted power supply when your solar panels are disconnected and not generating electricity. This could include backup generators or UPS systems.
-
High voltage design of energy storage power supply
s an overview of the critical aspects of an HVES design. It compares the possible topologies and control techniques, identifies the pitfalls and design challenges of the recharge and holdup modes, .
FAQs about High voltage design of energy storage power supply
How to design a high-voltage power supply?
Design Your Transformer. One of the main things required in a good high-voltage power supply design is designing the transformer correctly for your applications. The transformer is generally the energy-conversion element in a high-voltage design, which also provides isolation between the primary and secondary.
What is high voltage energy storage (hves)?
high-voltage-energy storage (HVES) stores the energy ona capacitor at a higher voltage and then transfers that energy to the power b s during the dropout (see Fig. 3). This allows a smallercapacitor to be used because a arge percentage of the energy stor d choic 100 80 63 50 35 25 16 10 Cap Voltage Rating (V)Fig. 4. PCB energy density with V2
What is a high voltage power supply?
High voltage power supplies are ubiquitous whether you are designing an AC/DC adapter or your high voltage on-board power supply for industrial applications. You find them commonly to step down your high voltage input voltage to a lower intermediate voltage before you power your point-of-load (POL) converters.
How does energy storage work at high voltage?
considerably depending on specific system requirements. Energy storage at high voltage normally requires the use of electrolytic capacitors for which th ESR varies considerably, particularly over temperature. These variables need to be conside
Why is energy storage important?
Energy storage is one of the most important technologies and basic equipment supporting the construction of the future power system. It is also of great significance in promoting the consumption of renewable energy, guaranteeing the power supply and enhancing the safety of the power grid.
How can a power supply reduce energy storage demand?
The addition of power supplies with flexible adjustment ability, such as hydropower and thermal power, can improve the consumption rate and reduce the energy storage demand. 3.2 GW hydropower, 16 GW PV with 2 GW/4 h of energy storage, can achieve 4500 utilisation hours of DC and 90% PV power consumption rate as shown in Figure 7.
-
The battery pack has a string of high voltage
High-voltage batteries are rechargeable energy storage systems that operate at significantly higher voltages than conventional batteries, typically ranging from tens to hundreds of volts.
FAQs about The battery pack has a string of high voltage
How many volts does a battery pack produce?
Portable equipment needing higher voltages use battery packs with two or more cells connected in series. Figure 2 shows a battery pack with four 3.6V Li-ion cells in series, also known as 4S, to produce 14.4V nominal. In comparison, a six-cell lead acid string with 2V/cell will generate 12V, and four alkaline with 1.5V/cell will give 6V.
What is a hybrid battery pack?
Cell, modules, and packs – Hybrid and electric vehicles have a high voltage battery pack that consists of individual modules and cells organized in series and parallel. A cell is the smallest, packaged form a battery can take and is generally on the order of one to six volts.
What determines the operating voltage of a battery pack?
The operating voltage of the pack is fundamentally determined by the cell chemistry and the number of cells joined in series. If there is a requirement to deliver a minimum battery pack capacity (eg Electric Vehicle) then you need to understand the variability in cell capacity and how that impacts pack configuration.
How does a high voltage battery work?
Battery Cells: A high-voltage battery consists of multiple cells connected in series. Each cell generates a small amount of voltage, and the total voltage increases by linking them. For example, three 3.7V cells in a series create an 11.1V battery. Power Delivery: The stored energy flows through the device's circuit when the battery is used.
What is a battery pack?
A battery pack consists of multiple battery modules integrated to form a complete energy storage solution. Packs are engineered to deliver the required power and energy for specific applications. Modules: Combined in series and parallel to achieve the desired voltage and capacity.
What is a high voltage battery?
Voltage: Voltage is the measure of electrical force. High-voltage batteries have higher voltage than standard batteries, which means they can provide more power to devices. The voltage is determined by the battery's type and number of cells. Battery Cells: A high-voltage battery consists of multiple cells connected in series.
-
Lithium battery pack charging voltage range
Discover the optimal charging voltages for lithium batteries: Bulk/absorb = 14. Avoid equalization (or set it to 14. 4V if necessary) and temperature compensation.
FAQs about Lithium battery pack charging voltage range
What is a lithium ion battery voltage chart?
Lithium-ion battery voltage charts are a great way to understand your system and safely charge batteries. Lithium-ion batteries are rechargeable battery types used in a variety of appliances. As the name defines, these batteries use lithium-ions as primary charge carriers with a nominal voltage of 3.7V per cell.
How many volts does a lithium ion battery have?
50% capacity in a lithium battery often correlates to approximately 3.6V to 3.7V per cell for most lithium-ion batteries. This voltage range represents the mid-point of the battery's discharge cycle. What is the cutoff voltage for a 12V lithium-ion battery?
What is a lithium battery state of charge chart?
Here's the lithium battery state of charge chart: A typical lithium-ion battery voltage curve is the relationship between voltage and state of charge. When the battery discharges and provides an electric current, the anode releases Li ions to the cathode to generate a flow of electrons from one side to the other.
How many volts does a 24V lithium ion battery pack need?
A 24V lithium-ion or LiFePO4 battery pack typically requires a charging voltage within the range of about 29-30 volts. Specialized chargers designed for multi-cell configurations should be considered, and adherence to manufacturer guidelines is crucial for safe and efficient charging.
What are the key parameters of a lithium battery?
The key parameters you need to keep in mind, include rated voltage, working voltage, open circuit voltage, and termination voltage. Different lithium battery materials typically have different battery voltages caused by the differences in electron transfer and chemical reaction processes.
What is the maximum charge voltage of a lithium ion battery?
The Li-ion battery might have a maximum charge voltage of 4.2 volts per cell. The LiFePO4 battery would have a lower maximum charge voltage of 3.6 volts per cell. Discharge Cutoff Voltage Discharge cutoff voltages also vary across different lithium battery types:
-
Solar Street Light High Voltage Battery
Which Battery is Used in Solar Street Light? The best battery for a street light is typically a lithium-ion or LiFePO4 (Lithium Iron Phosphate) battery.
FAQs about Solar Street Light High Voltage Battery
What is a solar street light battery?
In the field of renewable energy, solar power generation, one of the most common and advanced technologies, is becoming more widely used and developed. A solar street light battery is a device that can convert solar energy into electricity and store it, and it is also a key component of a solar power generation system.
How much battery does a 12V solar street light need?
To power a 12V solar street light for 12 uninterrupted hours (19:00 to 07:00) considering losses due to an 80% round-trip efficiency, a DOD of 50%, and taking 2 days of autonomy, you would require a 75Ah@12V battery for the 1,500-lumen fixture and nearly 600Ah@12V battery bank for the 12,000-lumen street light.
Which battery is best for solar street lights?
AGM and Gel batteries are the most commonly used Lead-Acid batteries for solar street lights. Lithium-Ion (Li-Ion) batteries are among the most popular batteries for solar street lights, but also the most expensive ones. They use a lithium metal oxide cathode and a lithium-carbon anode, immersed in a lithium salt electrolyte.
Should you switch to solar street lighting?
One aspect of switching to solar street lighting that's always of concern for new adopters is the type of battery used to power the light. Customers want to get the best battery for their new solar light that saves money, lasts as long as possible, and requires the least amount of maintenance.
How much power does a solar street light use?
To size the capacity required for the battery, it is valuable to use the expression below: As an example, we can take a 1,500-lumen fixture that consumes nearly 15W, while a 12,000-lumen solar street light consumes 120W.
Are solar street lights safe?
Solar street lights require a battery with UL-8750 certification or a safer one. One major aspect to consider in safety measures is avoiding batteries falling under thermal runaway, this can rapidly heat the battery and cause it to explode or release hazardous gases.
-
Does the voltage stabilizer come with its own battery How do I use it
The embedding of microprocessor chip technology and power electronic devices in the design of intelligent AC voltage stabilizers(or automatic voltage regulators (AVR)) led to produce high-quality, stable electric power supply in the event of significant and continuous deviation of mains voltage. As advancement to the. A voltage stabilizer is an electrical appliance which is designed to deliver a constant voltageto a load at its output terminals regardless of the changes in the input or incoming supply voltage. It protects the equipment or. Generally, each and every electrical equipment or device is designed for a wide range of input voltage. Depending on the sensitivity, the working range of the equipment are limited to a specific values, for instance, some. Basic Principle of voltage stabilizer to Perform Buck and Boost Operations In a voltage stabilizer, voltage correction from over and under voltage. Voltage stabilizers have become integral part of many electrical appliances of home, industries and commercial systems. Earlier, manually operated.
[PDF Version]
FAQs about Does the voltage stabilizer come with its own battery How do I use it
How does a stabilizer work?
When this input voltage deviates from the preset acceptable range, the stabilizer's control system springs into action or adjusts the output voltage accordingly. It tweaks and nudges the outgoing voltage back into line. To do this, it uses handy tools like transformers, voltage regulators, and semiconductor devices.
What is the difference between voltage stabilizer and voltage regulator?
Voltage Stabilizer: It is a device or circuit which is designed to deliver constant voltage to the output without in changes in incoming voltage. Voltage Regulator: It is a device or circuit which is designed to deliver constant voltage to the output without in changes in load current.
How does an automatic voltage stabilizer work?
Think of an automatic voltage stabilizer like a watchful guardian who works by continuously monitoring. It never takes its eyes off the incoming power voltage. When this input voltage deviates from the preset acceptable range, the stabilizer's control system springs into action or adjusts the output voltage accordingly.
Do you need a voltage stabilizer?
Most of the time there is need of using a voltage stabilizer because the power supply is not coming sufficient or there is lot of fluctuation. In order to safeguard our appliances like TV, fridge, AC, etc. we must go for suitable and good brand voltage stabilizers.
What is a voltage stabilizer?
It is also called as automatic voltage regulator (AVR). Voltage stabilizers are preferred for costly and precious electrical equipment to protect them from harmful low/high voltage fluctuations. Some of these equipment are air conditioners, offset printing machines, laboratory equipment, industrial machines, and medical apparatus.
Why do you need a power stabilizer?
Stabilizing the power stops our gadgets from getting damaged when the voltage is too high or too low, keeping them safe. It also shields against sudden voltage jumps that can cause serious damage.
-
How to change the voltage parameters of solar panels
What is VOC? VOC is the maximum voltage of an open circuit produced by a solar panel. Open Circuit Voltage (VOC) and is a product of the forward biases of the solar cell. You cannot go by the volts rating on the solar panel box because a 12v solar panel will produce as much as 18v-22v. However, you can use a. The first thing to do is double-check your calculations before you buy solar panels and your solar regulator. Your goal is to keep the voltage from the panels at 2/3s of the average maxim voltage of the controller. For example, if. A VOC solar charge controller is a device that limits the amount of energy that passes through it. We often see these in solar array systems where a solar battery storage system is in place. They are sometimes called step.
FAQs about How to change the voltage parameters of solar panels
How do I change the voltage on my solar charge controller?
You can do this by adjusting the voltage setting of the charge controller. The voltage setting determines how fast your solar cells can recharge. You can change these settings Via PC software, or on your charge controller. It is recommended that you follow the manufacturer's recommendations to get the most from your solar energy system.
Can you reduce solar panel voltage?
And that would cause problems. So can you reduce your solar panel voltage? The easiest way you can reduce your Solar Panel's Voltage is by using either an MPPT Charge Controller or a Step-Down Converter (aka Buck Converter). Other solutions are to use resistors or modify the solar cells' connections via the junction box.
How do I use a solar charge controller?
While solar panels can be connected in parallel to provide maximum output voltage, a basic charge controller may only accommodate a maximum input voltage of 12 or 24 volts. To use a solar charge controller, you need to set the voltage and current parameters. You can do this by adjusting the voltage setting of the charge controller.
How do solar panels increase voltage?
The overall system voltage is increased by connecting solar panels in series. When a grid-connected inverter or charge controller requires 24 volts or more, solar panels in series are typically employed. Solar cells are comprised of silicon that has been carefully processed to absorb as much light as possible.
What is a solar system voltage?
Generally, the system voltage is 12V, 24V or 48V. The system voltage value can be 110V and 220V for medium or large charge controllers. The maximum charging current refers to the maximum output current of solar panels or solar array.
What is the voltage output of a solar panel?
In solar photovoltaic (PV) systems, the voltage output of the PV panels typically falls in the range of 12 to 24 volts. However, the total voltage output of the solar panel array can vary based on the number of modules connected in series.
-
High current and low voltage battery
Choosing between high voltage (HV) and low voltage (LV) batteries requires an understanding of their fundamental differences, including voltage ratings, efficiency, applications, costs, safety cons.
FAQs about High current and low voltage battery
Are high voltage batteries better than low voltage batteries?
For a given energy capacity, high voltage systems require less expensive cable materials compared to low voltage systems, resulting in cost savings for installation and maintenance. As the energy storage industry evolves, high voltage batteries are proving to be the superior choice for modern home energy systems.
How do I choose between high voltage and low voltage batteries?
Choosing between high voltage (HV) and low voltage (LV) batteries requires an understanding of their fundamental differences, including voltage ratings, efficiency, applications, costs, safety considerations, environmental impacts, lifespan, cycle life, and emerging technologies.
What is a low voltage battery?
In energy storage applications, batteries that typically operate at 12V – 60V are referred to as low voltage batteries, and they are commonly used in off-grid solar solutions such as RV batteries, residential energy storage, telecom base stations, and UPS. Commonly used battery systems for residential energy storage are typically 48V or 51.2 V.
Are low voltage batteries safe?
Yes, low voltage batteries tend to have lower risks associated with electric shock compared to high voltage systems. How do I determine which battery type is right for my application?
What is a high voltage battery?
· High-Voltage Batteries: Typically operate at voltages exceeding 100V, such as 300V to 500V. This higher voltage enables rapid charging and discharging, making them suitable for managing sudden power demands and high-energy applications. · Low-Voltage Batteries: Generally have voltages below 100V, such as 12V or 48V.
How many volts does a high voltage battery run?
High-voltage batteries typically operate at tens to hundreds of volts, significantly higher than conventional batteries that operate below 12 volts. How long do high-voltage batteries last? The lifespan of high-voltage batteries varies depending on the type and usage.
-
Voltage distribution of series-connected batteries
When batteries are connected in series, the positive terminal of one battery is linked to the negative terminal of the next battery, resulting in an increased voltage output.
FAQs about Voltage distribution of series-connected batteries
What happens if a battery is connected in series?
When batteries are connected in series, the voltages of the individual batteries add up, resulting in a higher overall voltage. For example, if two 6-volt batteries are connected in series, the total voltage would be 12 volts. Effects of Series Connections on Current In a series connection, the current remains constant throughout the batteries.
How does a series connection affect voltage?
In a series connection, batteries are connected one after the other, creating a chain-like structure. This connects the positive terminal of one battery to the negative terminal of the next, resulting in a cumulative increase in voltage. However, the current remains constant throughout the series connection. Effects of Series Connections on Voltage
What is the difference between a series and parallel battery?
Series Connection: In a battery in series, cells are connected end-to-end, increasing the total voltage. Parallel Connection: In parallel batteries, all positive terminals are connected together, and all negative terminals are connected together, keeping the voltage the same but increasing the total current.
Can a battery cell be connected in series?
Battery cells can be connected in series, in parallel and as well as a mixture of both the series and parallel. In a series battery, the positive terminal of one cell is connected to the negative terminal of the next cell.
What is the capacity of a series connected batery?
the series-connected bateries would also be 100Ah. In a parallel connection, the total capa ity is the sum of the individual batery capacities. So, connecting two 100Ah bateries in parallel would result in a total capacity of 200Ah.Impact on Current Flow: In series connections, the current flowing through each batery is the sam
What is the difference between a battery and a series battery?
Battery Cells Definition: A battery is defined as a device where chemical reactions produce electrical potential, and multiple cells connected together form a battery. Series Connection: In a battery in series, cells are connected end-to-end, increasing the total voltage.
-
What is the voltage of a 5V lead-acid battery
The nominal voltage of lead acid is 2 volts per cell, however when measuring the open circuit voltage, the OCV of a charged and rested battery should be 2.
FAQs about What is the voltage of a 5V lead-acid battery
What is the voltage of a lead acid battery?
The 24V lead-acid battery state of charge voltage ranges from 25.46V (100% capacity) to 22.72V (0% capacity). 48V Lead-Acid Battery Voltage Chart (4th Chart). The 48V lead-acid battery state of charge voltage ranges from 50.92 (100% capacity) to 45.44V (0% capacity). Lead acid battery is comprised of lead oxide (PbO2) cathode and lead (Pb) anode.
What is a 6V lead acid battery?
Here we see that a 6V lead acid battery has an actual voltage of 6V at a charge between 40% and 50% (43%, to be exact). The voltage spans from 6.37V at 100% charge to 5.71V at 0% charge. It is also important to note that lead batteries have a depth of discharge (DoD) close to about 50%.
What is a 12 volt lead acid battery?
For example, a 12-volt lead acid battery has a nominal voltage of 12 volts. However, the actual voltage of a lead acid battery can vary depending on its state of charge, temperature, and other factors. The state of charge (SOC) of a lead acid battery refers to the amount of charge remaining in the battery.
What is a 48V lead acid battery?
The 48V lead-acid battery state of charge voltage ranges from 50.92 (100% capacity) to 45.44V (0% capacity). Lead acid battery is comprised of lead oxide (PbO2) cathode and lead (Pb) anode. The medium of exchange is sulphuric acid. Most common example of lead-acid batteries are car batteries.
What is the float voltage of a 12V lead acid battery?
Meanwhile, the float voltage of a sealed 12V lead acid battery is usually 13.6 volts ± 0.2 volts. The float voltage of a flooded 12V lead acid battery is usually 13.5 volts. It is important to choose a battery with a voltage range that is appropriate for the application in which it will be used to ensure optimal performance and longevity.
What is the state of charge of a lead acid battery?
The state of charge (SOC) of a lead acid battery refers to the amount of charge remaining in the battery. The SOC of a lead acid battery can be determined by measuring its voltage using a multimeter or other device. As the battery discharges, its voltage level decreases. Conversely, as the battery is charged, its voltage level increases.
-
Battery charging status monitoring voltage
In this project, we will build an IoT based Battery Monitoring System using ESP8266 where you can monitor the battery charging/discharging status along with Battery Voltage & Percentage. As we know, the battery is the most important component for any device as it powers the entire system. So, it is important to monitor. You will need the following components for the IoT Based Battery Monitoring System Project. You can purchase all the components online from. A lithium-ion battery or Li-ion battery is a type of rechargeable battery. Lithium-ion batteries are commonly used for portable electronics and electric vehicles. In this battery, lithium ions move. In order to Monitor the Battery Data on ThingSpeak Server, you first need to Setup the Thingspeak. To set up the ThingSpeak Server, visit. We will design a system to monitor this battery voltage along with charging and discharging status. For the microcontroller, we use WeMos D1 Mini which has an ESP8266 wifi-enabled.
[PDF Version]
FAQs about Battery charging status monitoring voltage
How to monitor battery status in Arduino IoT based battery monitoring system?
In this IoT-based Battery Monitoring System, we will use the NodeMCU ESP8266 board to send the battery status data to the Arduino IoT cloud. The IoT Cloud Dashboard will display the battery voltage along with the battery percentage in both the charging and discharging conditions.
What is a battery voltage status monitor circuit using 4 LEDs?
The proposed battery voltage status monitor circuit using 4 LEDs makes use of comparators in the form of opamps from the IC LM324. This IC is much versatile than the other opamp counterparts due to its higher voltage tolerance level and due to the quad opamps in one package.
How to set up battery status indicator circuit?
How to Set up the above explained battery status indicator Circuit. It's pretty simple. Apply the full-charge voltage level across the point indicated "to battery positive" and ground. Now adjust the preset such that the last LED just illuminates at that voltage level. Done! Your circuit is all set now.
How does a battery monitoring system work?
This allows users to monitor the battery status remotely from anywhere in the world via their smartphones or computer dashboards. The server displays the battery voltage, load voltage, current, and power, providing a comprehensive overview of the battery's condition in both charging and discharging states.
Why is it important to monitor the voltage level of a battery?
Battery is the most important component for any device as it powers the whole system. And it is important to monitor the voltage level of the battery as improper charging and discharging of a lithium battery may lead to a big safety issue.
How IoT-based battery monitoring system works?
In this IoT-based Battery Monitoring System, we will use Wemos D1 Mini with ESP8266 Chip to send the battery status data to ThingSpeak cloud. The Thingspeak will display the battery voltage along with the battery percentage in both the charging and discharging cases.
-
Solar panel storage voltage
Solar Panel Voltage: Understanding, Calculating and OptimizingTypical Solar Panel Voltage Ranges Generally, solar panels intended for residential or commercial installations typically have voltage outputs ranging from 12 volts to 48 volts. Solar Panel Voltage Professional Terminology. FAQ: Frequently Asked Questions.
FAQs about Solar panel storage voltage
What is solar battery storage?
Together with solar panels, solar battery storage allows you to store and use more of the renewable energy they generate, reducing your electricity bills and carbon footprint. So what is it and how does it work? How much do solar batteries cost? How do solar panels work? Why use battery storage with solar panels?
How to choose a solar battery storage system?
When you decide to use a battery storage system, you should always ensure that it is the appropriate size and quality for the amount of solar power that it will be required to store. They should also be a deep cycle battery, unlike a car battery which is classed as a shallow cycle.
Does battery storage work with a solar panel system?
Adding battery storage to work in conjunction with a solar panel system allows you to use more of the renewable electricity generated and reduce reliance on the grid. For example, you could store electricity generated via your solar panels during the day to then use at night.
Is it worth getting a solar storage battery?
A solar battery allows you to store electricity produced by your solar panels and use it later or, in some cases, sell it back to the grid to make a few quid – but they're not cheap. Read on to see if it's worth getting a solar storage battery for your home... This is the first incarnation of this guide.
How much solar battery storage do I Need?
The amount of solar battery storage you need depends on your household's energy consumption and how much you want to rely on solar power. Here's a general guideline: Small Households (1-2 Bedrooms): Typically need around 2-4 kWh of battery storage. Medium Households (3 Bedrooms): Usually require about 8 kWh of battery storage.
Can a solar panel charge a battery?
Charging a battery with solar panels requires careful consideration of the battery's capacity and the panel's voltage output. For instance, to charge a 100Ah battery: Lead-Acid Batteries: At least two 100-watt panels are needed. Lithium-Ion Batteries: Three 100-watt panels are typically required. How many volts does a solar panel produce?