The amount of solar power needed to run an air conditioner will mainly depend on 2 factors:
- Daily Energy Consumption: This is measured in Watt-hours (Wh) or kiloWatt-hours (kWh), indicating the electricity usage of your air conditioner and any additional appliances. This amount of energy needs to be generated by your solar panels daily.
- Daily Peak Sun Hours (PSH) in Your Location: This represents the daily sunlight available for your solar panels to convert into energy. More sunlight means fewer solar panels are needed.
Once these variables are accounted for, the amount of solar power, in Watts, that you’ll need to run your 5000 BTU air conditioner could be calculated as follows:
Solar Watts = (Daily Energy Consumption (Wh/day) ÷ Daily Peak Sun Hours) x 1.25
In this article, I’ll begin by discussing the electricity usage of 5000 BTU air conditioners, providing estimates, and explaining simple methods to accurately determine it. Then, I’ll show you how you can determine the exact amount of sunlight, or Peak Sun Hours, that you get in your location.
Once we’ve covered these aspects and determined the solar array size needed for your 5000 BTU AC, we’ll delve into the other components required to complete your solar system and help you size them correctly.
Let’s get started.
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How many solar panels do you need to run a 5000 BTU air conditioner?
As a general guideline, you’d typically need approximately 70 Watts of solar panels for every hour your 5000 BTU air conditioner runs each day. For instance, if you intend to run the 5000 BTU unit for 8 hours daily, you would typically require 500 to 600 Watts of solar power.
To provide an initial reference, here’s a table that estimates the solar power needed to operate a 5000 BTU air conditioner based on its daily usage (hours/day), assuming an average of 5 Peak Sun Hours per day:
|Daily Runtime||Required Solar Power (Watts)|
|1 hour||60 – 80 Watts|
|2 hours||120 – 150 Watts|
|3 hours||180 – 220 Watts|
|4 hours||250 – 300 Watts|
|6 hours||350 – 450 Watts|
|8 hours||500 – 600 Watts|
|10 hour||600 – 750 Watts|
|12 hour||750 – 900 Watts|
|16 hour||1000 – 1200 Watts|
These figures in the table offer a good initial estimate of the solar power needed to operate your 5000 BTU AC. However, as mentioned earlier, the exact solar power requirement depends on the precise energy consumption of your AC unit and the amount of sunlight available.
To begin sizing your system accurately, the first step is to determine the daily energy consumption of your AC unit.
How much energy does your 5000 BTU air conditioner consume on a daily basis?
In general, a 5000 BTU air conditioner typically uses somewhere between 250 and 450 Watt-hours (0.25 – 0.45 kWh) of energy for each hour it operates. If you assume an average daily usage of 8 hours, this translates to an energy consumption ranging from 2 to 3.6 kWh per day.
However, it’s essential to keep in mind that the precise energy consumption of your AC will depend on the specific model, its efficiency, and various operating factors, like outdoor temperature, indoor temperature settings, insulation quality, and more.
So, how can you accurately measure your air conditioner’s energy consumption?
The most accurate method is to utilize an electricity monitoring device.
Devices such as the Kill-A-Watt meter can measure various aspects of your 5000 BTU unit’s electricity usage, including Wattage and Amperage. More importantly, they can provide precise measurements of the AC’s energy consumption over a specific timeframe.
ll you need to do is plug the monitor between your air conditioner and the electrical outlet, and then collect energy consumption data after your typical daily usage.
If those readings are in kWh (kiloWatt-hours), multiply by 1000 to determine the energy consumption in Wh (Watt-hours).
However, if, for now, you’re okay with estimates, a less accurate but quicker method would be to use the efficiency rating of your air conditioner. Let me explain.
The 5000 BTU rating on your air conditioner represents its cooling capacity, specifically, the amount of heat it can remove in an hour. The energy required by the air conditioner to remove these 5000 BTUs of heat within an hour depends on its energy efficiency.
This energy efficiency is typically tested by manufacturers and provided as an EER (Energy Efficiency Ratio) rating, or more recently, a CEER (Combined Energy Efficiency Ratio) rating.
In any case, this efficiency rating can be used to estimate the hourly energy consumption of your 5000 BTU air conditioner in Watt-hours:
Hourly Energy Consumption (Watt-hours per hour) = 5000 BTUs ÷ Energy Efficiency (EER or CEER)
For instance, consider this EnergyGuide label on a 5000 BTU AC unit:
The label displays a CEER rating of 11. Using this rating, you can calculate the hourly energy consumption of this unit as follows:
Hourly Energy Consumption (Watt-hours per hour) = 5000 BTUs ÷ CEER
Hourly Energy Consumption (Watt-hours per hour) = 455 Wh/hour
You can then combine this hourly energy consumption with your daily usage duration in hours to determine the daily energy consumption of the unit:
Daily Energy Consumption (Wh/day) = Hourly Energy Consumption (Wh/hour) x Daily Usage (hours/day)
If you plan to operate additional appliances, it’s important to consider their energy consumption as well.
To save you the trouble of figuring out the energy usage of each appliance, I’ve created an Appliance Energy Consumption Calculator that allows you to list your appliances and estimate their power consumption.
Once you have measurements or estimates for the energy usage of your AC unit and any extra appliances, the next step is to assess the amount of sunlight available for the solar panels to convert into electricity.
How much sunlight do you get?
Solar panels are rated under specific conditions, known as Standard Test Conditions (STC), and one of these conditions is Solar Irradiance.
Solar Irradiance represents the amount of sunlight a certain area receives at a given moment and is measured in W/m² (Watts per square meter).
For testing solar panels, the standard Solar Irradiance is set at 1000W/m². This level of artificial light simulates the ideal conditions of clear skies and the sun directly overhead.
In essence, before a manufacturer assigns a rating to a solar panel in Watts, they expose it to 1000W/m² of light, and the power it generates during this test becomes its wattage rating.
For instance, a 100-watt solar panel can only generate 100 Watts of power if it receives 1000W/m² of sunlight at that specific moment.
However, the actual power received from the sun is not always 1000W/m²; it varies based on weather, seasons, and time of day. Consequently, a solar panel can practically produce anywhere from 0% to 100% of its rated power.
Since it’s challenging to constantly measure this solar irradiance, a more practical approach involves estimating the amount of sunlight energy an area receives using historical data. This leads us to Peak Sun Hours.
What are Peak Sun Hours?
Peak Sun Hours represent the quantity of sunlight energy an area receives within a specific timeframe, typically 1 day. 1 Peak Sun Hour is equivalent to 1kWh/m² or 1000Wh/m² (Watt-hours per square meter).
The value of Peak Sun Hours in a certain location is a highly valuable piece of data because it allows us to estimate the energy production of a solar system:
Energy Production (Watt-hours) = System Wattage (Watts) x Peak Sun Hours
For instance, imagine a 100W solar panel exposed to 5 Peak Sun Hours per day (5kWh/m²/day). You can calculate the panel’s daily energy production as follows:
Daily Energy Production (Watt-hours per day) = System Wattage (Watts) x Daily Peak Sun Hours
Daily Energy Production (Watt-hours per day) = 100 Watts x 5
Daily Energy Production (Watt-hours per day) = 500 Wh/day
Conversely, if you know the amount of energy your solar system needs to generate daily and how many Peak Sun Hours you receive, you can determine the system’s required wattage:
System Wattage (Watts) = Required Daily Energy Production (Wh/day) ÷ Daily Peak Sun Hours
However, due to inherent system imperfections, energy losses are inevitable. In other words, you won’t be able to make use of all the energy generated by your solar panels.
To account for these inefficiencies and losses, it’s advisable to factor in a multiplier of 1.25 when sizing your solar system:
System Wattage (Watts) = (Required Daily Energy Production (Wh/day) ÷ Daily Peak Sun Hours) x 1.25
How do you determine the daily Peak Sun Hours in your location?
The National Renewable Energy Laboratory (NREL) utilizes geostationary satellite technology to gather solar radiation data and provides free access to it. You can access this data through their PVWatts Calculator.
Here’s how it works: Simply visit the tool and input your address. The tool will then calculate the monthly and yearly average Peak Sun Hours that your location receives each day.
To give you an example, I’ll submit Tuscon, Arizona as my address:
In the results section, the tool estimates that the city receives an average of 6.54 Peak Sun Hours per day over the year.
Additionally, the tool offers monthly Peak Sun Hours data. If you intend to utilize the solar system during specific seasons, you can select a corresponding Peak Sun Hours value from that particular season.
To keep it simple, I’ll be using the annual average value of 6.54 Peak Sun Hours.
Let’s illustrate this with an example:
Imagine you have a 5000 BTU air conditioner consuming 1500 Watt-hours (1.5 kWh) of energy daily. Additionally, you have various other appliances like a fridge, TV, lights, etc., with a combined daily consumption of around 1500 Watt-hours (1.5 kWh).
Your total daily energy consumption sums up to 3000 Watt-hours per day (1500 Wh + 1500 Wh). Using this figure, you can calculate the solar power required to run the AC and other appliances as follows:
System Wattage (Watts) = (Required Daily Energy Production (Wh/day) ÷ Daily Peak Sun Hours) x 1.25
System Wattage (Watts) = (3000 Wh/day ÷ 6.54) x 1.25
System Wattage (Watts) = (458.7 Watts) x 1.25
System Wattage (Watts) = 573.4 Watts
According to these calculations, in Tucson, AZ, you’d need approximately 600 Watts of solar capacity to generate an average of 3000 Watt-hours of daily energy throughout the year.
Now, so far, we’ve only discussed solar panels, which are only one component of the system that you need. A complete solar setup consists of the following components:
- Solar panels
- A battery bank
- A solar charge controller
- An inverter
- And of course, wires and fuses/circuit breakers
With these components wired together, the solar setup would look something like this:
Let’s break down the importance of each component in a solar system and how to properly size them, starting with the battery bank.
In an off-grid solar system, batteries play a crucial role in storing the energy generated by solar panels during sunny periods and ensuring that this energy is accessible throughout the day. Without a battery bank, a solar system will not function properly.
To properly size a battery bank for your solar setup, you need to consider two main factors:
- The daily energy consumption of your AC unit and any additional appliances.
- The type of battery you’ll be using.
We’ve previously discussed how to estimate or measure the daily energy consumption of your AC unit and other appliances. For this explanation, we’ll continue using the example of a daily energy consumption of 3000 Wh (3 kWh).
The type of battery you choose impacts its usable capacity, and this is often indicated by its recommended Depth of Discharge (DOD).
For instance, lead-acid batteries typically have a recommended DOD of 50%, meaning a 100Ah battery of this type can provide around 50Ah of charge before needing a recharge or disconnecting to prevent damage.
Conversely, lithium batteries like LiFePO4 have a DOD of up to 100%, which means a 100Ah battery of this type can provide the full 100Ah of charge. However, most manufacturers recommend an 80% DOD for these batteries.
While lithium batteries tend to be more expensive upfront, they last significantly longer than lead-acid batteries.
Given the daily energy consumption and DOD, you can calculate the battery bank’s size using this equation:
Battery Bank Capacity (Watt-hours) = Daily Energy Consumption (Watt-hours) ÷ Depth Of Discharge (%)
For instance, if we assume a daily energy consumption of 3000 Wh (3 kWh) and plan to use lithium batteries with an 80% recommended DOD, the required capacity of the battery bank can be calculated as follows:
Battery Bank Capacity (Watt-hours) = Daily Energy Consumption (Watt-hours) ÷ Depth Of Discharge (%)
Battery Bank Capacity (Watt-hours) = 3000 Watt-hours ÷ 80%
Battery Bank Capacity (Watt-hours) = 3000 Watt-hours ÷ 0.8
Battery Bank Capacity (Watt-hours) = 3750 Watt-hours
Now, batteries are rated in Ah (Amp-hours) and Volts (e.g., 12V-100Ah). Combined, these ratings determine the Energy Capacity of the battery in Watt-hours:
Watt-hours = Amp-hours x Volts
You can divide the required capacity of the battery in Watt-hours, by the voltage rating of the batteries you intend to use to get the required battery capacity in Amp-hours. This will indicate the number of batteries you need:
For example, if you plan on using 12 Volt batteries, the battery bank’s capacity in Amp-hours can be calculated as follows:
Battery Bank Capacity (Amp-hours) = Battery Bank Capacity (Watt-hours) ÷ 12 Volts
Battery Bank Capacity (Amp-hours) = 3750 Watt-hours ÷ 12 Volts
Battery Bank Capacity (Amp-hours) = 312.5 Amp-hours
According to these calculations, you would need 312.5 Amp-hours of battery capacity at 12 Volts. An affordable choice might be to use 4 of these 12V-100Ah Li-Time batteries, while a higher-end option could be 4 of these 12V-100Ah Battle Born batteries.
Either choice would provide you with 400 Amp-hours, which at 12 Volts equals 4800 Watt-hours of battery capacity. This should be more than sufficient to power your AC unit and additional appliances during sunny days and provide some extra backup in case of cloudy days.
A more secure option would be to opt for a larger battery bank. This would provide autonomy in case of consecutive cloudy days, ensuring continuous power supply. Alternatively, consider having a backup generator like the Champion 2500W generator.
Now that we have determined the number of solar panels and batteries required to run the 5000 BTU AC, the next step is to size the solar charge controller.
Solar charge controllers are also essential components in a solar power system. They serve as a connection point between the solar panels and the battery bank, ensuring that the batteries are charged safely and efficiently.
There are two main types of solar charge controllers: PWM (Pulse Width Modulation) and MPPT (Maximum Power Point Tracking).
PWM charge controllers are more affordable but are generally less efficient than MPPT controllers. MPPT controllers, on the other hand, are known for their higher efficiency and ability to maximize the output of solar panels.
In this example, we’ll focus on MPPT controllers due to their superior performance. However, if you’re on a budget and want to use a PWM instead, feel free to use this PWM charge controller calculator.
To properly size an MPPT (Maximum Power Point Tracking) solar charge controller for your solar energy system, you can use the provided MPPT charge controller calculator. This calculator takes into account specific details about your system to determine the appropriate size for the charge controller.
The calculator has 6 fields that will describe your solar energy system:
1- Solar panel wattage: This is the power rating of each of the solar panels you’ll be using.
2- Solar panel open-circuit voltage: You can find this value in the nameplate on the back of your solar panels, or by looking up the specific model. For example, a 12V solar panel will usually have an Open-Circuit Voltage (Voc) between 18 and 23 Volts.
3- Battery bank voltage: The voltage of each battery is usually written on the casing. If you have more than one battery, the voltage of the battery bank is equal to the voltage from one string of batteries. For example, if you have 4 12V batteries, all connected in series, the nominal voltage of your battery bank is 48 Volts. If these batteries are connected in parallel, the battery bank voltage is 12 Volts.
4- Lowest temperature during sunlight hours: In this field, choose the lowest value of temperature that you estimate your solar panels are going to be exposed to during sunlight hours.
5- Number of strings: In your solar array, how many parallel strings are there?
6- Number of solar panels in each string: In each string, how many solar panels are wired in series?
Let’s illustrate this with an example.
Following our previous example, we’ve determined that we need a minimum of 573.4 Watts of solar power to run our 5000 BTU air conditioner and additional appliances, so we’ll round that up to 600 Watts.
In this example, we’ll use six 12V-100W Renogy solar panels, each with the following specifications:
- Wattage Rating: 100 Watts
- Open-Circuit Voltage (Voc): 22.3 Volts
For an effective configuration in this setup, we can organize these solar panels into two strings. Each string will consist of three solar panels connected in series (3S2P). This setup would look like this:
For our battery bank, we’ve settled on 4 12V-100Ah lithium batteries. A good configuration for the battery bank would be 2S2P, which means 2 strings in parallel, with 2 batteries in series in each string. Kind of like this:
The nominal voltage of this battery bank is 24 Volts.
For the temperature, I’ll assume that the lowest temperature these solar panels will be exposed to during the daytime is 25°F.
I described this setup to the calculator, and here are the results:
The calculator indicated that the MPPT should have an Input Voltage rating of at least 75 Volts and a Rated Current of 23.4 Amps or more. It should also be compatible with a 24 Volt battery bank.
In this example, a suitable choice could be a 30A Victron MPPT charge controller.
After determining the size of your MPPT charge controller, the next step is to size the final component of our system: the inverter.
An inverter’s job is to convert the DC (Direct Current) power generated by the solar panels and stored in the battery bank, into the AC (Alternating Current) power that your 5000 BTU Air conditioner requires to operate.
But these inverters come in different sizes and with different characteristics. So, what size inverter will you need?
In general, you would typically need a 1500W inverter if the 5000 BTU air conditioner is the only load connected to the inverter.
If the inverter will be supplying power to other appliances simultaneously with the air conditioner, you may require an inverter with a capacity ranging from 2000 to 4000 watts, depending on the total load.
In any case, it’s essential to choose a Pure Sine Wave inverter for reliable performance.
A practical approach to sizing the inverter is, to begin with 1500 watts of inverter capacity dedicated to the air conditioner, and then add the maximum load that will run simultaneously with the air conditioner.
For instance, if you plan to power two 60-watt light bulbs, a 50-watt laptop charger, and a 150-watt fridge in addition to the air conditioner, the additional load would be:
Load (Watts) = (2 x 60 Watts) + 50 Watts + 150 Watts
Load (Watts) = 320 Watts
In this case, a 2000W inverter would be a suitable choice. However, ensure it’s a Pure Sine Wave inverter rather than a Modified Sine Wave inverter for stable and efficient performance.
Another inverter specification to consider would be its input voltage. The inverter should be compatible with the voltage configuration of your battery bank.
To learn more about this, please refer to this article: What size inverter do you need to run a 5k BTU AC?
Once you’ve sized all of the components that we’ve discussed, the final step is to size the wires and over-current protection devices (fuses or circuit breakers) that connect these components. To ensure you do this correctly, please refer to these sizing guides:
- What size wire from the solar panels to the solar charge controller?
- What size fuse or circuit breaker from solar panels to charge controller?
- What size wire from the solar charge controller to the battery?
- What size fuse or circuit breaker from the solar charge controller to the battery?
- Battery to inverter wire size calculator
- What size fuse or circuit breaker between the battery and the inverter?