How To Design A Super Efficient Passive Solar

How does passive solar energy work?

“How does passive solar energy work, you may ask?” It involves capturing the sun's energy within the “thermal mass” of a building. This refers to the walls, floors, and other substances which absorb and store heat during daytime, and when the temperature cools down at night, these heated substances release their stored heat.

What is passive solar design?

Well in the collaborative powers of Wikipedia, passive solar design (or passive solar building design) can be defined as purposeful construction of “windows, walls, and floors to collect, store, reflect, and distribute solar energy in the form of heat in the winter and reject solar heat in the summer.”

What is passive solar heating?

Passive solar uses components to control the heat generated by the sun. Examples include: the construction of walls, floors, roofs, windows, exterior building elements, and landscaping. Solar heating designs attempt to trap and store thermal energy from direct sunlight.

What are the benefits of passive solar?

Savings on heating and cooling is one of the most obvious benefits of passive solar. By harnessing the sun's natural heat and avoiding thermal losses, passively designed buildings require less energy to maintain a comfortable temperature, reducing energy bills in the long run.

What is a passive solar cooling system?

Passive solar cooling systems use shading, thermal mass, and natural ventilation to reduce unwanted daytime heat and store cool night air to moderate temperatures. For more information about passive solar design, visit the following resources from the U.S. Department of Energy:

What is the difference between active and passive solar energy?

Using passive solar energy. The main difference is that in active solar energy there is a process of energy transformation. Using photovoltaic panels we transform sunlight into electrical energy. On the other hand, using thermal solar panels we transform radiation into heat energy.

How to design a solar PCB board?

A critical parameter to consider when designing your solar PCB board is the duration of the system once the photovoltaic power source is reduced to 0% efficiency. Several environmental factors can affect the solar panel's performance, and you'll need a battery that has adequate capacity to keep your device going for an extended time.

How do solar PCB boards work?

Solar PCB boards integrate solar cells and circuit boards to convert solar energy into electricity through the photovoltaic effect. The manufacturing process of solar PCB boards is similar to that of traditional PCB boards, but with variations in material selection and process flow.

What is the PCB layout of a solar inverter?

The printed circuit board (PCB) layout of a solar inverter is a critical aspect of its design, as it affects the overall performance and efficiency of the inverter. The PCB layout of a solar inverter involves the placement and routing of components on the board to minimize noise and optimize the flow of current.

Are solar PCB boards eco-friendly?

The focus on eco-friendliness and renewable energy has led to significant advancements in PCB manufacturing, specifically in the realm of solar PCB boards. These boards, also known as solar panels, play a crucial role in solar power generation systems.

What makes a solar panel a good PCB design system?

The world's most trusted PCB design system. 3. Sunlight Exposure In a way, solar technology is pretty straightforward. Without sunlight, no electricity is generated. However, having 8 hours of daylight does not necessary means that your solar panel is producing electricity efficiently for 8 hours.

Why are solar PCB boards important?

High-quality solar PCB boards are crucial for the overall efficiency of solar power generation systems. Environmental Friendliness and Energy Efficiency: Solar PCB boards have minimal impact on the environment and do not produce harmful substances such as carbon dioxide.

How to choose a solar energy street light?

Analyze the area size and choose suitable system brightness: pick a location that receives the maximum light exposure during the day, and if you live in a shady area, select systems with larger panels. Likewise, find out a suitable weather-resistance level for your solar energy street light.

Should you install a solar Streetlight?

Installing a solar streetlight is an economical, eco-friendly and low-maintenance solution for outdoor lighting. With their long lifespan, bright illumination and easy installation, they are perfect for providing reliable lighting to areas where regular lighting isn't available or practical.

How do you mount a solar LED street light?

If you are unsure how to connect the battery to the panels, look for pre-assembled options. The mounting point is usually on the pole's top, so you should use the ladder to reach it. Carefully position the light's panels onto your solar LED street light.

How do you charge a solar Streetlight?

Some solar streetlight models require an initial battery charge before the light will operate. Refer to the manufacturer's instructions for charging procedures. It may involve connecting the battery to an external charger. Locate the light switch and turn it on. Observe the light operation for a few minutes.

How long does it take to install a solar street light?

The time required for installing a solar street light varies depending on the model and complexity of the system. Generally, most models can be installed in less than an hour if you have all the necessary components and tools on hand. However, more complex systems may require additional preparation time to ensure that everything is properly done.

How do solar street lights work?

Components of Solar Street Lights Solar Panels: The heart of the solar street light system, solar panels capture sunlight and convert it into electrical energy. Batteries: Store the energy generated by the solar panels to power the LED lights during the night. LED Lights: Energy-efficient lights that provide bright illumination.

How long can a solar battery hold a charge?

The lifespan of a solar battery and how long it can hold a charge largely depend on factors including battery type, storage capacity, and the size of essential home devices. Some solar batteries can hold a charge for a period ranging from a few hours to a full day.

How long does a solar panel take to charge a battery?

Now divide the battery capacity after DoD by the solar panel output (after taking into account the losses). Turns out, 100 watt solar panel will take about 9 peak sun hours to fully charge a 12v 100ah lead acid battery from 50% depth of discharge. how fast should you charge your battery?

How many solar panels do I need to charge a 50Ah battery?

You need around 180 watts of solar panels to charge a 12V 50ah Lithium (LiFePO4) battery from 100% depth of discharge in 4 peak sun hours with an MPPT charge controller. Related Post: How Long Will A 50Ah Battery Last?

How to charge a solar battery?

First of all, you need to start by converting the battery capacity of your solar battery from Ampere hours to Watt hours, ie: Watt-hours (Wh) = Amp-hours (Ah) x Voltage (V) Substituting the data gives you 960Wh for your solar battery. Then, you need to know how much you need to charge your solar battery, i.e.:

How to calculate solar battery charge time?

Output power (W) = total watts (W) x conversion efficiency of the solar system x (1 – charge controller's power consumption rate) Substitute the data to get the output power of your solar panel is 1615W, and then finally divide the solar battery charge by the output power of the solar panel to get the charging time, i.e.:

How long does a solar battery last?

Every time a battery is charged and then discharged, it undergoes a cycle. A high number of cycles will gradually reduce the battery's efficiency. For example, a solar battery with 4,000 cycles will typically last about 10 years if cycled daily.

How many watts a solar panel to charge a battery?

You need around 360 watts of solar panels to charge a 12V 100ah Lithium (LiFePO4) battery from 100% depth of discharge in 4 peak sun hours with an MPPT charge controller. What Size Solar Panel To Charge 50Ah Battery?

How many solar panels to charge a 120ah battery?

You need around 350 watts of solar panels to charge a 12V 120ah lithium battery from 100% depth of discharge in 5 peak sun hours with an MPPT charge controller. Full article: Charging 120Ah Battery Guide What Size Solar Panel To Charge 100Ah Battery?

How many watts a solar panel to charge 130ah battery?

You need around 380 watts of solar panels to charge a 12V 130ah Lithium (LiFePO4) battery from 100% depth in 5 peak sun hours with an MPPT charge controller. What Size Solar Panel To Charge 140Ah Battery?

How many batteries can a 400 watt solar panel charge?

As we can see, a 400-watt solar panel will need 2.7 peak sun hours to charge a 100Ah 12V lithium battery. If we presume that we get 5 peak sun hours per day, we can actually fully charge almost two 100Ah batteries (or one 200Ah battery).

How long does a 100 watt solar panel take to charge?

Turns out, 100 watt solar panel will take about 9 peak sun hours to fully charge a 12v 100ah lead acid battery from 50% depth of discharge. how fast should you charge your battery? Deep cycle or solar batteries are designed to charge and discharge at a specific rate, which is referred to as the c-rating.

How many watts of solar panels do I Need?

You need around 310 watts of solar panels to charge a 12V 150ah lead-acid battery from 50% depth of discharge in 4 peak sun hours with an MPPT charge controller. You need around 550 watts of solar panels to charge a 12V 150ah Lithium (LiFePO4) battery from 100% depth of discharge in 4 peak sun hours with an MPPT charge controller.

How to connect solar panels?

Here are the different methods of connecting solar panels. (Source: Alternative Energy Tutorials) To connect solar panels in series, wire the positive terminal of the first module to the negative terminal of the second panel and the positive terminal to the negative terminal of the third panel.

How do I wire a solar panel?

Prepare Solar Panels for Wiring: Attach the MC4 connectors to the solar panel cables. Ensure a proper connection and use the crimping tool to secure them in place. Connect the Solar Panels: Begin the wiring process by connecting the positive terminal of one solar panel to the negative terminal of the next panel.

How do you connect a solar panel to a battery?

Connecting a solar panel to a battery is fairly simple. Start by connecting the positive wire from the solar panel to the positive terminal of the battery, then connect the negative wires from both components. Make sure that all connections are secure and in accordance with local wiring regulations.

How to wire solar panels in parallel?

Wiring solar panels in parallel is achieved by connecting the negative terminal for two or more modules, while doing the same thing with the positive terminals. The process is the following: Take the male MC4 plug (positive) of the modules and plug them into an MC4 combiner.

How to wire solar panels in series?

Wiring solar panels in series requires connecting the positive terminal of a module to the negative of the next one, increasing the voltage. To do this, follow the next steps: Connect the female MC4 plug (negative) to the male MC4 plug (positive). Repeat steps 1 and 2 for the rest of the string.

How do I connect a grid-tied solar panel system?

Always refer to the NEC code in effect or consult a licensed electrician for safety and accuracy. There are two basic approaches to connecting a grid-tied solar panel system, as shown in the wiring diagrams below. The most common is a "LOAD SIDE" connection, made AFTER the main breaker.

What is the solar panel recycling process?

The solar panel recycling process is a detailed system with several steps that start with panel collection and transportation to a recycling facility. The panels go through a detailed process at the facility to ensure all recyclable and reusable components are stripped.

How do I recycle a solar panel?

Here are a few examples: Consult the manufacturer: Start by contacting your solar panel manufacturer and ask for guidance on recycling. Some manufacturers offer take-back or recycling programs for their customers, or they may have partnerships with recycling facilities.

Is recycling solar panels worth it?

Unfortunately, there are often limited financial incentives for recycling. Thus, many organizations and individuals may think that recycling their solar panels is too expensive and simply not worth it, especially when they are required to invest in additional equipment and infrastructure. Environmental and health risks.

Why should you recycle solar panels?

By recycling solar panels, we can keep harmful materials out of landfills and the environment. Besides environmental protection, recycling solar panels will be economically impactful as well. Some rare elements in photovoltaic (PV) cells, like gallium and indium, are being depleted from the environment over time.

What are the different types of solar panel recycling?

There are three broad types of solar panel recycling: re-use, mechanical, and chemical/thermal. Solar recycling is far more advanced in Europe than in the U.S. – primarily due to overseas policy structures that require manufacturers to recycle their panels. To start your solar journey today, visit the EnergySage Marketplace.

What is thermal recycling of solar panels?

Thermal recycling techniques of solar panels involve heating the solar panels to high temperatures in the presence of oxygen or other flammable gases to break down the materials into their basic elements. Here are the steps involved in the thermal recycling process:

When is a solar battery charging system complete?

The solar battery charging system is only complete if these components are in working order: the array or panels, the charge controller, and the batteries. Here is what happens right from when sunlight hits the panel to when the battery receives and stores energy:

How do I know if my solar battery is full charge?

In addition to relying on the battery state of charge displays, you can confirm your solar batteries reach full charge by monitoring system performance over longer periods. Tools like solar charge controllers and inverters record data over time that reveals charging and discharging patterns.

How does a solar panel charge a battery?

1. Bulk Stage (first stage) The bulk phase is primarily the initial phase of using solar energy to charge a battery. When the battery reaches a low-charge stage, typically when the charge is below 80 percent, the bulk phase will begin. At this point, the solar panel injects as much amperage as it can into the cell.

How does solar battery charging work?

Charging your battery involves several stages and includes different parts of the PV system. This is called the charging system. As you'll learn below, the solar battery charging process is also a controlled chain of events to prevent damage.

What is a solar battery charging system?

This is called the charging system. As you'll learn below, the solar battery charging process is also a controlled chain of events to prevent damage. The solar battery charging system is only complete if these components are in working order: the array or panels, the charge controller, and the batteries.

Why is my solar battery not charging?

Note that these do not always mean a failed system; they can also indicate a bad battery. The solar battery charging problems and their solutions are discussed below. A solar battery not charging can indicate issues with many things: improper wiring, faulty charging components such as charger controllers, panels, or even the battery itself.

How do I wire a solar charge controller?

To wire a solar charge controller, firstly, connect the battery to the controller, ensuring the positive and negative terminals are correctly matched. Next, connect the solar panel to the controller, again matching the terminals correctly. Always make sure everything is safely disconnected from power sources while working.

What is a solar panel charge controller wiring diagram?

A standard solar panel charge controller wiring diagram includes the solar panels (PV Array), the charge controller, battery, and load. Each of these components is interconnected, with specific points of contact, as shown in the wiring diagram. Familiarize yourself with these diagrams and the specific make and model of your charge controller.

How do you connect a solar panel system to a battery?

To connect your solar panel system, first, disconnect all components. Connect the charge controller to the battery, then attach the solar panels to the charge controller. Finally, connect the inverter to the battery. Always turn on the charge controller before the inverter and check that all indicators are functioning properly.

How do I connect a PV array to a solar charge controller?

Connecting the PV Array to the Solar Charge Controller These will be labeled as 'PV Array', 'Solar Panels', or 'Panel'. Again, pay close attention to the indicated polarities. Once more, match the polarity. The positive wire goes to the positive solar panel terminal, and the negative wire connects to the negative terminal.

How do I wire a solar panel?

Prepare Solar Panels for Wiring: Attach the MC4 connectors to the solar panel cables. Ensure a proper connection and use the crimping tool to secure them in place. Connect the Solar Panels: Begin the wiring process by connecting the positive terminal of one solar panel to the negative terminal of the next panel.

How to connect a solar inverter to a battery?

Proper Connection Steps: Follow a systematic connection process: disconnect power, connect the charge controller to the battery, attach solar panels to the charge controller, and finally link the inverter to the battery.

How to charge a lithium battery with solar power?

To charge a lithium battery with solar power, make sure you have solar panels, charge controllers, batteries, and inverters. Match the solar panel wattage, charge controller amperage, and battery specifications carefully. High-quality charge controllers enhance safety and efficiency.

How to charge a solar panel?

Follow Charging Steps: Set up your solar panel in a well-lit area, connect it to the charge controller, and then attach it to the lithium battery while monitoring the charging process.

How does a lithium battery work on a solar panel?

Solar panels capture sunlight and convert it into electricity, which is then stored in lithium batteries through a charge controller. The energy can later be used to power devices or provide backup power. What type of lithium battery is best for solar charging? The best lithium battery for solar charging depends on your needs.

Can a solar panel charge a 6 volt battery?

Both regulators will help the solar panel charge your six-volt battery and do that safely. Another consideration for charging batteries with a solar panel is a battery backup bank. While charging a single battery, you can also charge a battery bank. The energy in the bank will allow you to charge your devices when the solar panel is inactive.

Which solar panel is best for charging lithium batteries?

Monocrystalline Panels: Known for their higher efficiency and space-saving design, they are ideal for charging lithium batteries efficiently. Properly matching the size and wattage of the solar panel to the battery capacity is essential for efficiently charging lithium batteries with solar power.

How to charge a lithium battery effectively?

Utilize advanced technology and efficient charging methods for battery longevity. Charging lithium batteries effectively requires essential components like solar panels, charge controllers, batteries, and inverters. When it comes to solar power, the efficiency of the charging process hinges on the quality of these components.

What is a J V scan of a perovskite solar cell?

(A) J – V scan of a perovskite solar cell at various sweep rates from short-circuit to forward bias (forward scan). (B) J – V scan of the same device from forward bias to short-circuit (reverse scan) conditions at various rates.

What is a reversed scan?

Reversed scan means that a scan is done from positive voltages to negative voltages at certain intervals of voltage. Sometimes these two ways of voltage sweeping are called forward bias and reverse bias. The reason behind the two directions of voltage sweeping is to find the Voc and Jsc.

How does the solar cell scan work?

The Solar Cell Scan utilises a single windows interface in which all device parameters can be set.All control parameters can be saved as method files and reloaded at any time to restore the measurement conditions. These method files can also be transferred between instruments to allow experiment replication.

What is a forward scan in a solar cell?

Scientific Reports, 7, 11790 (2017) In fact, when the forward scan is mentioned in the measurements of a solar cell, it refers to the direction of voltage sweeping from negative voltages to positive voltages with certain intervals such as 0.1mV.

What is the difference between reverse scan and hysteresis?

J−V curves by reverse and forward scan for devices based on (a) amorphous TiO 2 and (b) anatase TiO 2 substrates. (c) Hysteresis of solar cells based on amorphous TiO 2 and anatase TiO 2 substrates. The hysteresis is defined as the difference of PCE between reverse scan and forward scan. [...]

How to read I V & V curves of solar cells?

You can use an electronic load and set different voltage values (or current values) and read I and V values. Using the source measure unit. This is the most famous method to plot the I-V (or J-V) curves of solar cells. The source meter contains a power source and voltage and current measuring facility.

How do you drill holes for solar panels?

To mark the holes for drilling solar panels, use a dry erase marker. Once you've got the solar panels placed where they're going to live permanently, mark the mounting holes with the marker. Make sure you double and triple check everything is where you want it before drilling holes in your ceiling.

Can you install solar panels without drilling holes?

You can also use silicone sealant in any holes or exposed areas to ensure that they are waterproofed. You can install RV roof-mounted solar panels without drilling holes by using silicon sealant with any existing pre-drilled holes and attaching your wires there instead of creating new ones yourself.

Can RV solar panels be installed without drilling holes?

You can install RV roof-mounted solar panels without drilling holes by using silicon sealant with any existing pre-drilled holes and attaching your wires there instead of creating new ones yourself. This will prevent water from getting into the wiring system where it shouldn't harm anything.

Should you drill into tile to install solar panels?

Installing solar panels on a tiled roof requires drilling into the tiles to attach each mounting bracket. However, drilling into tiles is not recommended due to the risk of breaking them and potential leaks. If you still choose to drill, you assume the risk at your own expense.

Do I need to drill a hole in the frame?

I really do need to drill a few holes in the side of the frame horizontally, very carefully so as not to touch the panels or Drill down vertically through the L section and through the very edges of the panels. Drilling down might be more accurate a bit easier and possibly more effective at letting the water out.

What is control of solar energy systems?

Control of Solar Energy Systems details the main solar energy systems, problems involved with their control, and how control systems can help in increasing their efficiency. Thermal energy systems are explored in depth, as are photovoltaic generation and other solar energy applications such as solar furnaces and solar refrigeration systems.

How does a solar meter work?

Solar meters accumulate PV yield production and local energy consumption to monitor and analyze PV plant performance. It often comes with a monitoring function to alert plant owners of PV plant performance issues, allowing them to resolve problems quickly, letting them quickly resolve problems and maximize return on investment.

What are the 59 essential solar calculations?

Learn the 59 essential solar calculations and examples for PV design, from system sizing to performance analysis. Empower your solar planning or education with SolarPlanSets 1. Solar Irradiance Calculation 2. Energy Demand Calculation 3. PV System Size Calculation 4. Structural Calculations 5. Electrical Calculations 6. Battery Capacity Calculation

Do solar panels use kilowatt-hours?

Power companies use kilowatt-hours to measure and bill your household energy usage, so keeping track of your energy output in these units helps you see how much energy your solar panels are contributing to your needs.

How do solar panels measure power output & efficiency?

These two metrics are essential for determining the power output and overall efficiency of your solar panels. Voltage (V) measures the electrical potential or pressure that drives the flow of electricity in a circuit. In the context of solar panels, voltage indicates the potential energy generated by the panels.

How to apply generalized predictive control to a solar power plant?

Application of generalized predictive control to a solar power plant Modelling and simulation of a solar power plant with a distributed collector system Self-tuning control of a solar power plant with a distributed collector field A survey on control schemes for distributed solar collector fields. part i: modeling and basic control approaches

What wattage should a solar panel be?

The higher the solar panel wattage, the more solar cells are needed, and the bigger the panel will be. Solar panels that are used on homes are typically in the 300-400 Watt range. Panels of this size are great for home installations due to their size, weight and cost.

How to choose a battery for a solar panel?

Let's look at how to choose the battery for a solar panel. A good general rule of thumb for most applications is a 1:1 ratio of batteries and watts, or slightly more if you live near the poles.

Are 500 watt solar panels a good size?

Panels of this size are great for home installations due to their size, weight and cost. While larger, 500 Watt solar panels do exist on the market, the larger size doesn't necessarily translate to greater benefits. The size and wattage of a solar panel system depend on how many panels you need for your home.

How many Watts should a solar panel inverter have?

For example, if your total solar panel wattage is 5,000 watts, you would ideally choose an inverter with a continuous power rating of around 5,000 watts and a peak power rating of at least 6,000 watts (5,000 watts + 20% buffer). How to Calculate Your Solar Panel Size?

How many watts a solar panel to charge a battery?

You need around 360 watts of solar panels to charge a 12V 100ah Lithium (LiFePO4) battery from 100% depth of discharge in 4 peak sun hours with an MPPT charge controller. What Size Solar Panel To Charge 50Ah Battery?

How many solar panels are in a 100 watt solar panel?

They usually contain 72 PV cells but can have up to 98. A third category of solar panel size, the “portable” 100 Watt solar panel is the smallest at around 40 inches by 20 inches. These are typically used to power small appliances when camping or for emergency power.

Do solar panels have a 12V voltage?

This might sound weird, but both are correct and useful: Nominal 12V voltage is designed based on battery classification. With solar panels, we can charge batteries, and batteries usually have 12V, 24V, or 48V input and output voltage. It is the job of the charge controller to produce a 12V DC current that charges the battery.

How many solar panels do you need to charge a 12V battery?

You only need one 12V solar panel to charge a 12V battery. For instance, a 100 watt solar panel is a common solar panel size you could use to charge some of the most common 12V battery capacities.

How many watts a solar panel to charge a lithium battery?

You would need a 160 watt solar panel to charge a 12V 50Ah lithium battery from 100% depth of discharge in 5 peak sun hours with an MPPT charge controller. You would need a 200 watt solar panel to charge a 12V 50Ah lithium battery from 100% depth of discharge in 5 peak sun hours with a PWM charge controller.

How many watts do you need to charge a 12V battery?

For a 12v battery, you'll ideally need a panel of 200 watts to charge a 100ah battery — the most common 12v battery size. Given that a 200-watt panel can produce around 60 amp-hours per day — on a sunny day under ideal conditions — you should be able to fully charge a 100ah battery with a 200-watt panel in 5–8 hours.

Can a solar panel connect to a 12V battery?

Technically, you can connect a solar panel directly to a 12v battery as long as it's not more than 5 watts, but connecting any higher-rated panels is not a good idea. Solar panels will produce varying voltage outputs depending on the amount of sun hitting them, and this dipping and spiking of the voltage can quickly damage your battery.

Can a solar panel charge a 100Ah battery?

Pretty much any solar panel will be able to charge a 100Ah battery. It just depends on how long it will take. Here are some examples we calculated along the way: A 100-watt solar panel will charge a 100Ah 12V lithium battery in 10.8 peak sun hours (or, realistically, in little more than 2 days, if we presume an average of 5 peak sun hours per day).

How do you calculate solar energy consumption?

Divide the actual solar panel capacity by the capacity of a single panel to determine the number of panels needed. For example, if your average daily energy consumption is 30 kWh and the system efficiency is 80%, and you have an average of 5 hours of sunlight per day, you would calculate your daily energy production requirement as follows:

How do you calculate a solar panel size?

To calculate the solar panel size for your home, start by determining your average daily energy consumption in kilowatt-hours (kWh) based on your electricity bills. Then calculate your daily energy production requirement by dividing your average daily energy consumption by the system efficiency.

How do you calculate energy production per solar panel?

To calculate the energy production per PV module, use the formula: Energy (kWh) = Area × Solar panel yield × Annual average solar radiation on panels × Performance Ratio The performance ratio (PR) is typically a default value of 0.75, but BONJOUR SOLAR Solar Panels can reach up to 0.85 for higher efficiency.

How does the solar panel installation calculator work?

The formula driving the Solar Panel Installation Calculator is simple yet effective. It calculates the number of panels by dividing the daily electricity usage by the product of sunlight hours and panel efficiency: Needed Panels = Daily Usage / (Sunlight Hours * Efficiency)

How do I determine the cost of a solar panel system?

To determine the cost, you can use a solar panel cost calculator or consult with a solar panel installation company. The payback period represents the time it takes for a solar panel system to generate enough energy savings to offset the initial investment.

How do I choose a solar panel for my home?

To make the most use of solar panels, here are some calculations to consider before you invest in them: To calculate the solar panel size for your home, start by determining your average daily energy consumption in kilowatt-hours (kWh) based on your electricity bills.