Skip to content
Can You Use Solar Batteries to Run Your AC. Solar home ac unit

Can You Use Solar Batteries to Run Your AC. Solar home ac unit

    How Many Solar Panels To Run Air Conditioner?

    For most home appliances it’s quite easy to work out exactly how many solar panels you would need to run them.

    This is because they pull a constant current, so once you know an appliance power rating in watts, you can match that with solar panel output.

    Some appliances, like fridges, freezers and air conditioners, are not so straight-forward, as they contain compressors with motors. This means that the power they draw varies and needs to be averaged out.

    How Many Solar Panels To Run Air Conditioner?

    An air conditioner would need 1200 watts of solar panels for each Ton of cooling capacity, assuming irradiance of 4 Peak-sun-hours/day. A 100Ah battery (such as this one by Renogy) is recommended per Ton for each hour anticipated running time. This will allow running when irradiance is low and also provide a reservoir to supply motor surge current.

    • Why air conditioners are rated in tons
    • AC power rating (kW)
    • What is surge current and power factor?
    • How long will the air conditioner be running?
    • Are batteries needed to run your air conditioner?
    • What type of batteries are best suited for solar energy storage?
    • How much energy do solar panels generate?
    • Solar panel sizes you’re going to use
    • Inverter sizing (and why you need one)

    Video – How many solar panels are needed to run AC on an RV?

    Solar powered air conditioning is a really good thing to have, specially in countries with hot humid conditions and plenty of sun!

    Solar AC makes a great DIY project, but we need to explore AC electrical and cooling characteristics before answering the question ‘how many solar panels do I need to run an air conditioner unit?’

    Can you run air conditioner off solar panels?

    When talking about d.c. loads, power calculations are quite easy. Power rating is found by multiplying volts x amps.

    For example, when a d.c. resistive load has a 12 volt supply and pulls 12 amps, we use this formula to find the power:

    12V x 12A = 144watts

    In a.c. circuits, volts x amps doesn’t always equal watts (although sometimes it does!) Read on …

    A.C. power calculations take into account the voltage and current waveforms

    Home appliances use a.c. power and the calculation is handled in a different way. Voltage and current waveforms constantly move from positive to negative in a sinusoidal shape.

    If V and I are maximum at the same time, they are said to be ‘in phase’ and volts x amps will really equal watts.

    If volts and amps are not in phase, then the equation doesn’t work. We’ll take a look at this later.

    How much electricity does a solar powered air conditioner use?

    Why is AC rated in tons and not watts?

    All air conditioning units have different efficiencies, so if we used their electrical kilowatt ratings for comparison, it wouldn’t reflect their cooling power.

    This means that 2 AC units rated at 1.5 kW might not have the same cooling power.

    So what is a ton in AC ratings? It represents the amount of cooling required to melt 2000 pounds of ice in one day. It’s commonly known in the trade as a short ton.

    The bigger the tonnage, the more air can be cooled each hour. One ton can also be represented as 12,000 BTU/h (British Thermal Units per hour) or 3.5 kW (kilowatt).

    This means that a 1 Ton air conditioner has a cooling capacity in Watts of:

    (12000BTU x 1055) / 3600 = 3516 Joules per sec = 3516W (cooling)

    What is EER value in AC?

    EER means ‘energy efficiency ratio’ and it tells you how well an air conditioning unit cools. If you divide an ac unit’s BTU number by it’s electrical rating in Watts you come up with a ratio which indicates it’s efficiency.

    An efficient air conditioning unit could have an EER of 11, for example. AC units with an EER rating of more than 10 are recommended for countries or locations with hotter climates.

    The EER rating system is based on an outdoor temperature of 95°F, a temperature inside of 80°F, and 50% humidity.

    The SEER rating is more common nowadays, as it takes into account an air conditioner’s cooling capacity over a range of outside temperatures – the S means the ratings are ‘seasonal’.

    The table below shows the SEER/EER for popular home AC units.

    Lennox are making particular gains in supplementing their designs with solar panel support and this will probably become the industry-standard in the not-too distant future.

    Table – SEER and EER ratings compared for 5 popular AC brands

    Air Conditioner Brand and Model

    SEER Rating

    Lennox Signature Series XC25

    Amana AVXC20 Daikin DX20VC

    Lennox Signature Series XC21

    Carrier Infinity 20 24VNA0

    How much does it cost per hour to run an air conditioning unit?

    • what is the efficiency of the AC unit?
    • how often during the day you run it
    • how long the AC unit runs
    • the outside temperature
    • the cost per kWh of your electricity

    As you can see, it can get complicated but is it worth going into all this detail? Let’s examine the factors you need to be aware of.

    Air conditioning and solar installers have rule-of-thumb guides for sizing systems. One of these rules states that an air conditioning unit pulls around 7 amps for every 1 Ton of it’s cooling capacity rating.

    • 2 ton equates to 15 amps
    • 3 ton equates to 18 amps
    • 4 ton equates to 21 amps

    For sizing and installation purposes, this is good. In my case, when I’m designing a solar panel installation, I really want to know exactly what’s going on electrically!

    You can get confused about RLA (Rated Load Amps), which can be found on the air conditioning label tag – see image below:

    What does it cost to run AC per hour?

    The RLA value is not the AC normal running current – it is the maximum current the compressor motor will pull while the AC unit is running.

    In addition, this is not the same as the LRA value, which is Locked Rotor Amps. This occurs is when the compressor motor is stalled, can’t rotate and pulls maximum current.

    This value is the same as inrush or surge current when the compressor motor starts from standstill.

    solar, batteries, your, home, unit

    The real running current depends on other things.

    Air conditioner surge current

    When an a.c. motor starts it pulls several times more current than when it runs continuously.

    This running current will be dependent on the load, but the surge or inrush current is the highest amps the motor pulls, unless the motor is locked solid and can’t move at all (this is very bad.)

    The size of the wiring is based on maximum current when running plus 10%. Surge currents only last for a few seconds normally and the heating effect in the wiring isn’t significant.

    However, breakers and fuses need to be sized accordingly, so that they can accommodate this surge without tripping out.

    This also has important implications for any solar panel system designed to run air conditioning.

    If running during the day without a battery bank used as an energy reservoir, the solar panels wattage rating needs to be big enough to supply this motor surge current.

    Solar panel systems designed to run home appliances make use of a device called an inverter to change d.c. (direct current) voltage produced by solar panels into the a.c. (alternating current) power for domestic use.

    Solar panels can only run air conditioning using an inverter

    RENOGY are fast becoming the preferred source for solar panels, kits, batteries and solar control accessories. Based in the US, where the products are manufactured, they are widely known and respected for innovation and quality. Check the latest RENOGY Prices

    How many solar panels to power ac unit?

    Now we’ve explored what happens in an air conditioning unit on the the load side, we can take a look at the supply side in some depth.

    I’m going to base the rest of the post on using 300 watt fixed solar panels, because the higher panel ratings are a better buy in terms of installed dollars/watt.

    This is the 300 watt solar panel I’m talking about.

    How much power can a 300 watt solar panel generate?

    A solar panel’s output power in watts depends on these factors:

    • solar panel efficiency (monocrystalline panel efficiency is between 20% and 22%)
    • solar panel area in square meters
    • irradiance (the sun’s energy, which depends on your geographic location)
    • orientation (what is the angle to the horizontal and vertical)
    • will you be using fixed or auto-tracking for the solar installation

    Solar panel ratings given by the manufacturer follow the guidelines laid out in the Standard Test Conditions or STC.

    Basically, the panel rating is stipulated when the solar irradiance is 1000 watts/m2 and the temperature is 25 degrees C.

    This assumes that the panel is directly under the sun at 90 degrees, but this is hardly ever the case!

    Solar panel output reduces when the angle to the sun becomes more acute. Unfortunately, it also reduces at other angles, if the temperature is above 25 degrees C.

    The power output goes down at a rate of 0.5 watts for every degree increase in temperature.

    If the sun’s energy is low because of the irradiance level in your geographical location, then solar panel output will go down proportionately.

    How does a solar inverter work? Some basics

    Solar panels produce direct current (d.c.) but home appliances need alternating current (a.c.) – that’s why you need an inverter to convert d.c. to a.c.

    An inverter chops up the direct current into packets or pulses, and re-shapes them electronically into the smooth sinusoidal waveform, just like the power fed into your home by utility companies.

    How many solar panels to run 5 ton ac unit?

    Air conditioner is needed when it’s hottest, which is the four hours around noon-time in most locations.

    This is a lucky break, because this is the same window of time when the sun’s energy is high and solar panel power output is at a maximum.

    1 Ton of air conditioning cooling capacity is about 1.2kW, so if you run it for 4 hours it would consume 4.8kWh over that time.

    Logically, a 5 Ton air conditioning unit will consume:

    4.8kWh x 5 = 24kWh

    A 300 watt solar panel can produce 300 watts x 4 hours for the same time period (if the sunshine conditions are ideal) which equal 1.2kWh.

    The basic formula for finding the number of solar panels to run a 5 ton ac unit is:

    AC energy consumption (24kWh)/energy produced (1.2kWh) = 20 solar panels (300 watt rating)

    How many solar panels to run a 2 ton ac unit?

    Let’s say we’re going to run the AC for 4 hours again in the hottest part of the day.

    The basic calculation appears below, and assumes continuous running, surge current ignored:

    9.6kWh/1.2kWh = 8 solar panels (300 watts)

    Can I run a 1.5 ton AC on solar without batteries?

    So it’s possible run a 1.5 Ton AC unit on 6 x 300 watt solar panels, provided the sun is shining!

    What about the AC inrush current?

    Inrush current is pulled when the compressor motor starts from being stationary, for example when it starts a compression cycle when the temperature drops.

    Starting when the motor is cold is the worst possible situation and in this case the motor could pull 3 or 4 times it’s normal current in. In fact,it’s best to assume 4 times for safety.

    This means a 5 ton air conditioner could need 4 times more energy to get the cycle started, which would mean installing 80 solar panels!

    Clearly, this isn’t practical, so what is the answer? And what about running the AC unit on a cloudy day or at night?

    The solution is to install a bank of batteries for energy storage. This ensures a reservoir of extra power when it is needed and means you can run air conditioning when there’s no sun.

    Key takeaways about solar air conditioners

    Unlike an RV air conditioner a central air conditioner has a much higher power consumption and a solar array needs to have enough power to accommodate the current surges.

    Generally, it’s better for a solar power system to incorporate solar batteries, even for a relatively low power appliance such as a window air conditioner. (A 5000 BTU air conditioner is considered small for window use.)

    Battery systems also have the advantage of delivering energy during a power outage, so the home isn’t deprived of cool air. In general, 1000 watts of solar panels is needed for every 1000 Btu of ac. The size of the battery bank will determine the number of hours air conditioning can run. A solar charge controller is required for any solar system using batteries and lithium batteries are strongly recommended as solar battery storage.

    A single solar panel will not have enough power to run AC, even in direct sunlight. The heavier the AC then the higher number of panels needed.

    An off-grid system may be used and adequate roof space is needed, which should be sized up to make sure the amount of power generated is adequate, which depends on the energy consumption of your air conditioner.

    The exact number of solar panels is determined by the average annual energy consumption taken from the manufacturer’s name plate. As a general rule, 2.5kw of power with batteries is adequate for a small AC unit.

    DC Solar Air Conditioner Heat Pump – HotSpot Energy

    Back in the 70s solar thermal heating was all the rage. That’s to say, it was very cool but in many Western countries people needed a little convincing. The systems often didn’t look conventional enough for the average home-owner.

    How much power does 1 acre of solar produce? In Portugal where I live, huge solar farms are appearing throughout the countryside as many farmers are quickly seeing that there may make more revenue to be earned in selling solar pow.

    Designing a DIY solar pergola Can You Put Solar Panels On A Pergola? A pergola is an structure with a roof and four or more pillars supporting it. In some circumstances it can be a great idea to use that extra roof space for mount.

    Can You Use Solar Batteries to Run Your AC?

    One of the largest summer concerns for Arizonans and those that are new to the Grand Canyon State is being able to run cooling equipment to keep their homes comfortable and safe, especially during a power outage. For homeowners that are considering going off-grid with their solar. or incorporating battery storage into their existing solar PV systems, the prevailing question is, can you use solar battery storage for an air conditioner?

    The short answer is yes. However, because an air conditioner requires a large amount of electricity, there are some things you should know about setting your home up for a solar powered air conditioner.

    You Can Run an Air Conditioner on Stored Solar Power, if:

    You have enough solar panels to cover all of your energy usage

    Proper design and sizing is essential to any solar PV system, but in the case of using solar energy to power your air conditioner, you will need to have enough energy available to cover the hottest days of the year.

    You have enough battery storage space to cover your 24/7 energy usage

    Solar energy storage systems like solar batteries save solar electricity for use after the sun goes down and panels stop converting sunlight to electricity.

    Similar to the number of solar panels your home needs to run, your solar batteries need to have the capacity to dispense the amount of electricity needed on the hottest day of the year if you plan to run your air conditioning system without the help from grid-supplied electricity.

    Your inverter is powerful enough

    The most important factor when running your AC during a power outage is having an inverter that is powerful enough. AZ homes are most often cooled by large 3-5 ton AC units. These big units require a large surge of power to turn on and run. Most solar installs are done with grid-tied inverters, which are designed for efficiency but they cannot keep up with the surge of power necessary to start a big air conditioner. For that task, it is usually best to use an off-grid type of inverter – which are designed to start and run large motors without the help of the utility grid. When hooked to the grid, off-grid inverters like the Outback Radian can save you money all year long and keep your AC running during an outage.

    Arizona Uses AC Four Times Than National Average

    There is plenty of sunshine (and heat) to deal with here in Arizona, so thank goodness that sunshine can be put to good use! Because Arizonans use over four times the national average on air conditioning, the amount of solar electricity needed to use a solar battery for an air conditioner in AZ is higher than other areas of the country.

    Despite, the added expense, solar batteries offer a number of benefits, including:

    • Protection from power outages
    • A reliably comfortable home
    • Elimination of time-or-use and demand response charges
    • Greatly reduced carbon footprint

    Get A Solar Battery Quote from SouthFace Solar Electric

    If you are wondering if you can run your existing air conditioner on solar power, or you are planning your first foray into solar and want to have your solar panels directly power your AC, call the experienced and trusted team at SouthFace Solar Electric.

    With over 35 years of combined experience designing and installing residential and commercial solar PV systems in the Phoenix area. we know what it takes to battle the rising heat of the desert using solar powered air conditioning. With your customized solar quote, we can also advise you on how to reduce your energy consumption before going solar, which will require a smaller sized system for your initial solar investment.

    Solar home ac unit

    Solar-assisted air conditioning (solar thermal air conditioners) are becoming more popular by the year in California. It sounds simple enough – install panels, and the unit, get off the grid, and you’re done! But there are some things you should know first. Solar isn’t for everyone. But it is an attractive option most California homeowners should at least explore.

    As renewable energy as source is on the rise, it also makes sense to use sun as power when it is at its hottest with solar thermal air conditioning units.

    How Much Money Can I Save With Solar Powered Air Conditioning?

    The amount you save with a solar thermal air conditioner is determined largely by the size and geolocation of your home, the average price of solar energy in your area, and how long you stay at your home after your investment.

    Likewise, as an added bonus, they will increase the value of your home if you’re trying to sell.

    Research Your Solar Assisted Air Conditioning Unit

    So what should you figure out before you decide to invest? First, you should get a quote on your home for solar panels. Different homes sit in different areas of shade and sun. The area your home is in can make or break the cost/benefit ratio for investing in solar thermal air conditioning.

    Generally, California receives plenty of sun, and per watt of solar panels are low in the area. Also, the size of your home can play a large role in your budget for mounting and installation.

    So what can you to do perform some preliminary research on the viability of upgrading to solar? Measuring the efficiency of your current system can be done by finding the SEER rating (seasonal energy efficiency ratio). This is usually labeled on your compressor or in a reference guide. If your existing A/C Unit is at a “7” SEER Rating and you upgrade to a “16” SEER rated unit, your savings per month would be approximately 69% with the SolarCool System.

    What Is Solar Assisted Air Conditioning?

    Solar-assisted air conditioner systems are available in both packaged and split system configurations.

    Solar powered air conditioners also can be used for heating when configured with a heat pump system for colder months in the winter.

    Solar-powered AC units can save you money in the long term, and keep you cool – even on cloudy days. The low-maintenance evacuated tube collectors produce thermal energy that can keep even the most power-hungry units going strong.

    One way solar thermal air conditioners save money is the qualification for tax credits and rebates. To learn more about these ways you can save by installing energy-efficient systems, call us or click here.

    Some Advantages Of Solar Thermal Air Conditioning

    We now offer the SolarCool™ Solar Thermal Air Conditioner. This system combines a state-of-the-art high-efficiency 2-stage air conditioning system integrated with a proprietary solar thermal collector panel. This is the most energy-efficient solar thermal AC system available today!

    The key element is the integrated solar thermal collector super heating the air conditioning system’s refrigerant, which in turn reduces the required workload of the compressor. This lowers the overall power consumption of the system, saving the environment, energy and money.

    Interested in learning more about smart72 solar air conditioning installation? Contact us today!

    Solar Powered Air Conditioning Unit.

    Most people would like to have their homes cooled by the strength of sunlight which ironically causes heat. How to achieve energy efficient cooling of your abode by harnessing sunlight?

    I have successfully implemented a solar powered air conditioning unit for my living room which has been working great since June 2013. Let me tell you how I have done it.

    solar, batteries, your, home, unit

    Notes to keep in mind:

    What I have implemented is an off grid power system. My home generates its own power and can run without utility power. As a result my system is typically much more expensive than one that ties to the grid (feeds power back). I just prefer the option having of power should our utility fail or natural disaster strikes (such as hurricane or a drunk neighbor knocking over a utility line pole with a car).

    I have fulfilled the electrical code requirements (NFPA 70, TTS-171 Part 1) and power utility mandates for my area. Grid tie or feeding power back to our utility is both not currently possible and highly illegal in my country (the death of a linesman occured due to a customer violation). This instructable is an overview of how I implemented my system and the cost absorbed by myself. If my implementation cannot meet your electrical code needs, utility mandates, budget constraints and design criteria then I cannot assist you on this. You need to conduct your necessary reseach for a safe design and I’m always happy to try my best in answering technical questions you may have.I published an instructable on how I solar powered my home with design calculations.

    Read on and I hope you can find it interesting.

    Step 1: Solar Panels for Harvesting Sunlight.

    Harvesting? Yes you read it right. Harvesting a renewable resource allows powering of my air conditioning unit and most of my household electrical loads.

    An air conditioning unit uses lots of energy to remove heat from a room. To provide that energy you need enough solar panels installed properly to capture the radiant energy of the sun. When it comes to solar power. the bigger, the better!

    I currently have eight 225watt panels on my roof, wired 4 in series and in parallel with the other string of 4. These give me the energy to power my lights, automation pc, refrigerator, dog feeder, Wi-Fi, small appliances and of course that wonderful air conditioning unit.

    Mounting can be with a roof rail kit or you can do your own custom mounts made with metal and/or rigid pvc.

    Step 2: Solar Charge Controller.

    For 1 kilowatt and higher you want a maximum power point tracking (MPPT) charge controller. Basically it gives higher efficiency, can accept a higher voltage to deliver the amps into the battery bank.

    I use the outback flexmax 80amp mppt controller. It’s the best in class for the industry and it’s worth every cent of its cost. It’s fully programmable and can handle up to a 60 volt Dc battery bank.

    Notice the happy face I drew? Not even the evil scientist guy in despicable me would be as happy making his evil plans.

    Step 3: The Battery Bank.

    My battery of choice is the Lifepo4 chemistry. Long life, zero toxicity, enviromentally friendly, high energy density and best of all completely safe (won’t blow up! Lol).

    My system is 25.6v and uses 16 batteries in parallel.

    I previously used lead acid batteries but they simply didn’t last long. In 14 months their capacity was approximately 40% of their original. This was a costly mistake and I gave away these and made my Lifepo4 bank. They have been performing admirably and even though at higher upfront cost, the higher service life is well worth it. Please read my instructable for this bank.https://www.instructables.com/ID/Lifepo4-solar-stor.

    Now for anyone doubting the capabilities of LifePO4 batteries, there are many good sources on the web detailing this chemistry. Also think about this: why dont your mobile devices use lead acid batteries? Hmm. Lithium is superior plus I even have a LifePO4 battery to start my car! Take a look.

    Step 4: The Air Conditioning Unit.

    The only option for solar powered air conditioning is to use an inverter air conditioning unit. This is the most energy efficient type in the industry and it is simply amazing. I actually gave away my original 18000btu unit to install a 10000btu inverter.

    My inverter AC unit can use as little as 240Watts right up to its maximum rating. This unit runs off 240 volt so I needed a means to power it.

    Step 5: Going From 25.6v Dc to 240v AC!

    How to make this happen? Easy! I used a 1000watt inverter accepting 25.6v dc and outputting pure sine wave AC at 120v. Next I used a 1500watt autotransformer to boost the 120v to 240v. I included a thermal image of the transformer under load. Autotransformers have higher efficiency at the expense of no galvanic isolation once the voltage ratio is 3:1 or less. I could not obtain a 240volt inverter at a reasonable price at the time of the installation, perhaps in the future I will get rid of that, urgh, transformer.

    Protection for my battery bank is provided by a mini circuit breaker 100amp.

    Since my pure sine wave inverter can only deliver 1000Watts, the lowest temperature I can get to on battery power is 26C which is pretty good. If you can afford a bigger unit then all the more power to you!

    A side note: isn’t it damn confusing reading about a pure sine wave AC inverter and also an inverter air conditioning unit? Don’t blame me for that weird terminology.

    Also if you don’t know if your inverter is pure sine wave here are ways to find out:

    It would be clearly labeled on its nameplate as pure sine wave output.

    You can use an oscilloscope.

    Plug a AC powered fan into the output and if it buzzes while operating then it is NOT a pure sine wave inverter.

    If the advertised specs claim for example 1000Watt power and a surge rating of 2000Watt, then that inverter may not be pure sine wave. Pure sine wave inverters typically don’t have a large surge rating (i.e. 2x its maximum continuous rating).

    Step 6: Enjoying Green Energy Air Conditioning!

    With the inverter on and the air conditioning unit powered, I enjoy comfortable air from my battery bank. I included a thermal image of the unit running off the batteries.

    A special note here. This system I have described is part of a larger system for my home. My design was for an off grid system to deliver maximum reliability. The cost for all components is higher than a grid tie system. It has been my aim to introduce some basic design and implementation concepts to others so they may gain ideas for possible installations on their own. It’s not the purpose of this instructable to mandate to anyone that this is the ONLY way solar powered air conditioning can be achieved. It’s one way and I’m happy to have executed it.

    Please note that with my setup I don’t have a large enough battery bank to run the unit all night. Therefore I implemented an automatic transfer switch to power the unit from our utility when a low voltage dc threshold is reached.

    The transfer switch is fully software controlled by my home automation pc. Take a look at the third and forth pics. The software was created from FLOWSTONE. Take a look at my home automation instructable.

    Leave a Reply

    Your email address will not be published. Required fields are marked *