Run AC off Solar Panel

The simple and outright answer is, Yes. without doubt, Air Conditioners has become essential electric appliances today. However, AC is a high power consuming machine that leads to more power consumption. Hence, the comfort of using ACs becomes quite painful when the electricity bill arrives.so,the goal as a consumer is to reduce power consumption and utility bills while continue to using ACs. One of the most efficient ways to achieve both the goals at the same time is by getting solar systems installed and using solar energy to run ACs.

How many watts does an air conditioner use per hour?

To determine how many watts an air conditioner use per hour it depends on rating of AC, and the air condition is rated by unit called Tonnage or Ton .

What is Ton ?

It is defined as the power required to melt or freeze 2000 pounds, also known as one short ton, of ice per day. The ton is more often a unit of mass. A ton of refrigeration is approximately equal to 12,000 BTU/h or 3.5 kW. Therefore, the more tonnage an AC unit is rated at, the more air it can cool so,

1 ton of cooling power means heat removes by a 1-ton AC in an hour,

Since 1 BTU = 1055 Joule,

therefore, cooling capacity of 1 Ton AC in terms of Watt will be

(12000 x 1055) / 3600 = 3516 Joules / sec.

= 3516 Watt

The AC is also rated in Energy Efficiency Ratio (ERR)

EER- Amount of heat removed in Watt/ power consumed in Watt. (ERR=W/W)

Input power wattage = Heat removed (watts) / EER. Ratings for various Star ratings:

• 1 star – 1302 Watts
• 2 star – 1212 Watts
• 3 star – 1134 Watts
• 4 star – 1065 Watts
• 5 star – 52 Watts

Considering a 5 star split AC with 1 tons cooling capacity is rated for 3516 Watts, it will consume 1134.52 watts per hour

For calculation, how many watts an Air condition per hour, we use 1 ton AC

As we know that

Energy =Power x time

For ,1 ton: P= 3.516 kW

Energy =3.516kWh

Now, considering a 5 star split AC with 1 tons cooling capacity is rated for 3516 Watts, it will consume 1134.52 watts per hour

• 1000 watts per hour is one unit of power consumed
• Thus the AC will consume 1.1 units per hour
• But compressor runs only 70 percent of the time during normal use. Hence adjusted power consumption will be 0.7 units per hour
• For 1 hour it will consume 0.79 units
• Four 5 hours usage per day it will consume 3.9 units (Approximately)

Average solar panel output per day.

Before answering the question average solar panel output per day, we need to the understand different type of solar panels and insolation/ irradiance level in your area.

Solar Panels Types

Three main solar technologies are commercially available:

• Mono-crystalline
• Poly-crystalline
• Thin Film

Now, irradiance is the amount of sunshine it is a measure of the solar energy that shining on a specified area over a set period of time. A useful measure is in KWh per square meter per day. This insolation calculator at the NASA web site gives daily insolation averages for each month for a given year.

The solar power meter can be used to measure watts per square meter, in standard condition Solar panel power ratings are based on insolation of 1000 watts per square meter.

For average solar output let’s assume 250-watt mono solar Panel, it can give maximum 250 watt of solar power under standard condition that is, solar radiation is 1000 watt per square meter and temperature of panel is 25℃. The standard condition can be created in laboratory but actually if solar radiation is 1000 watt/sq meter then it is difficult that temperature is 25℃. And it is rarely that solar radiation is 1000 watt per square meter, so actual power output of solar Pane will be lower than its rated output,

Let assume average output of 250W panel is 250Wattshour, on average we take 4 solar hours, that is from 11 am to 2 pm,

So, a 250W panel will produce 1kWh per day.

Similarly, if we can 300W panel it will produce 300W*4= 1.2kWh

This is under ideal condition and temperature which is impossible as per thumb rule (4 units are generated from 1 kWp in a day).

So, a 250 W panel will produce 1unit per day .

How many solar panels to run an air conditioner?

As discussed earlier it depends on the size of air conditioner for instance

For a 5 star 1-ton Ac = 1.1kWp

As per thumb rule 4 units are generated from 1kWp in a day .so, if we use 250W panel the number of modules will be 1.1/0.250 = 4.4 round off to 5.

So,1.2 kWp will be require to run an air condition with 5 modules of 250W to run a 5 star 1-ton AC.

Can run ac on solar without batteries?

Yes, we can run a ac without battery as describe above to run a 5 star 1-ton AC you need to have 1.2 Kwp solar System installed. To run a 5 star 1-ton Ac lets calculate

As we know that for above calculation the power input of AC is 1134.52W that calculated by

Power Input = Power in Ton/ERR, 3517/3.1 =1134.52W

*AC runs for 6 Hours per day with power requirement 1134.52W

Total electricity consumption = 1134.52*6 = 6,807.12Wh

Now Considered a 48V Battery having efficiency 90% with a charge controller with efficiency of 95%.

The total unit of electricity to be generated by solar panel = 10610W

Total Ah required = 10610/48 = 221.04Ah

Ok, as consider previously the thumb rule is to 4 hours solar in minimum condition

Current required: 221.01/4 =55.26A

For 250 solar panel, Jinko JKM250P-60 

VOC = 37.7 and Isc =8.85A

6 Solar panels of 250Wp to be connected in parallel to have 55.26A .

To run a solar power on backup you need to have a battery with having 48V. Normally, batteries are connected in series to meet current requirements. So, 2 batteries connected in series with 48V and 100Ah are required.

Do portable solar powered air conditioners exist?

Portable solar power air conditioner is not in main stream usage till now but in future, we will see portable ac but for now dc power air conditioner do exist they operate from two sources of electricity: photovoltaic as a priority and the electricity grid as a backup and when there is no more sun, with an automatic switching of sources without cutting off power supply. So, during the day time they Ac will run on solar by night it will shifts to electricity.

There also exists off grid solar power air conditioner air operate directly using DC 48V voltage from photovoltaics and batteries, without converting energy into AC 230V power and therefore without loss of efficiency.

When the sun is shining, our air conditioners are powered by the photovoltaic source which simultaneously recharges batteries. A MPPT controller optimizes this charge with an efficiency greater than 95%.

A DC-powered solar air conditioner needs batteries, an inverter and solar charge controller to work in non-daylight hours – so it costs more than an AC unit.