Cooling with the heat of the sun: How many solar panels for a refrigerator. Solar hybrid fridge

Cooling with the heat of the sun: How many solar panels for a refrigerator?

Refrigerator is the hardest worker in the house. It keeps our food fresh and frozen round the clock, seven days a week. Running it on solar energy is extremely tempting since the refrigerator ends up making from 5% to 10% of your annual electricity bill. There is one problem though: unlike the fridge, solar panels take a break at night. Maybe we’ll find a way around it?

Refrigerator stands for 5-10% of your electric bill

A refrigerator by itself doesn’t need a lot of energy. At the same time, we don’t really turn it off – usually it works 24/7 so that the food doesn’t go bad. This is why a refrigerator accounts for about 5 to 10% of your electrical bill.

The power ratings of refrigerators usually range from 100 W to 400 W. You can check the rating of your fridge or refrigerator on its label. If there are only volts and amps, multiply them to get the power.

However, calculating how much energy a refrigerator exactly needs is tricky. Much like an AC unit, most of the time it maintains low temperature inside, rather than cools your food. Therefore, it works differently when it’s full or empty, when it’s dirty or clean, when it’s cold or hot in the kitchen.

Some energy experts just assume that a fridge works at its full power for roughly 8 hours a day, so it consumes from 1 to 2 kWh per day. You can use an electrical meter to get the exact number for its daily energy consumption, but it’s going to vary from day to day.

Fridge vs Refrigerator A refrigerator usually has a built-in freezer and is typically more powerful than a fridge.

tips for making your fridge more energy efficient

It is possible to make your fridge consume less on a regular basis. These tips will make your refrigerator more energy-efficient and lower your electricity bill:

1.Keep the refrigerator full. A refrigerator needs more energy to cool itself when it’s empty than when it’s full.

2.Move the fridge away from the stove and radiators.

3.Defrost your freezer from time to time – it improves the efficiency of the unit. When the thickness of frost reaches 1/4, it is time to get to work.

4.Clean the doors and sides of the fridge. Dirt and dust makes it harder for a fridge to cool down.

5.Cover all the liquids and soups that you put in the fridge. They release moisture and it increases the burden on the fridge compressor.

6.An old fridge draws more energy than a new one. Make an upgrade to make your home more energy-efficient! Look for Energy-Star labels on devices – it assures low energy consumption.

7.Don’t set the temperature inside too low. The lower the temperature to be maintained, the more energy it takes. 37 °F is ideal for a fridge and 0 °F is perfect for a freezer.

One solar panel can power a refrigerator

Now that we have some numbers to work with, let’s figure out how many panels we need for a refrigerator. Let’s say it needs approximately 1.5 kWh daily to function. Across the USA there are 5 peak sun hours on average, during which panels perform at their maximum. Therefore, to power a refrigerator, our array has to generate

1.5 kWh ÷ 5 h = 300 W As you can see, we can actually support our fridge with one 300 W solar panel. We can add 25% to our energy needs, assuming that panels are going to perform at 75% of their maximum capacity due to imperfect weather, angle and positioning. In this case we’ll need

1.5 kWh 1.25 ÷ 5h = 375 W To be safe you can get one 380 W or 385 W solar panel. Should it produce a little extra, this energy will come in handy someplace else.

At night you rely on batteries or utility grid

While solar panels don’t work at night, a fridge usually does. The way you will feed it depends on the type of the solar system you have:

With a grid-tied system you can rely on the utility grid. The night rate is usually lower, so it won’t cost you much.

However, it makes sense to demonstrate how to size a battery not only for a night support, but also for an emergency situation. Let’s calculate the size of a battery that would support the refrigerator on its own all day and night long. Assumed daily consumption of a refrigerator is still 1.5 kWh.

If the battery is lithium-ion, its capacity is measured in kWh as well. Its efficiency is close to 100%, so we won’t take it into account. However, you don’t want to discharge it further than 80% on a regular basis. Therefore you need at least

1.5 kWh ÷ 0.8 = 1.875 kWh If you have a lead-acid battery, its capacity is measured in Amp/hours. Its depth of discharge is around 50%, so the capacity should double the needs of your fridge. Plus, efficiency of lead-batteries is considerably lower – at around 80%. Power = Voltage Amps, so assuming we’ll get a 12V battery, its capacity should be bigger than

1.5 kWh 2 ÷ 0.8 ÷ 12V = 312.5 A/h

We’ve calculated the minimum capacity for two types of batteries to run a refrigerator without any support for 24 hours. The same principle can be used for other appliances. We hope that these calculations give you an idea of how to figure out the energy needs of your refrigerator, the number of panels to support it and the battery capacity to run it independently.

Calculate your solar system

Our Grid-Tied Solar System Calculator will help you choose the right solar panels and accessories to cover your energy needs.

How much solar power do I need to run a refrigerator: A complete guide to running a refrigerator on solar power

Running your refrigerator on solar power is quite feasible since fridges consume a relatively low amount of energy. However, it’s important to note that relying solely on solar panels won’t be sufficient to make this project a reality.

• Solar panels: To produce the amount of energy necessary to run your refrigerator.
• A battery bank: To store all the energy produced by the solar panels and make it available to the refrigerator.
• A solar charge controller: To maximize power production and to protect the solar panels and the battery.
• An inverter: To convert low voltage DC power from the battery bank into a higher voltage AC power that the refrigerator can use.

In this article, I’ll discuss in detail the amount of solar power that you would need to run your refrigerator, which will mainly depend on the energy consumption of your fridge and the amount of sunlight that’ll be available to your solar panels.

Once we’ve covered that, I’ll show you how to size each of the other components that I’ve mentioned above. Let’s dive in.

I get commissions for purchases made through links in this post.

How many solar panels do I need to power a refrigerator?

On average, full-size refrigerators (16 – 22 Cu. ft.) consume between 1500Wh and 2000Wh (Watt-hours) of energy per day, equivalent to between 1.5kWh and 2kWh (kiloWatt-hours) of energy.

Therefore, to run a full-size refrigerator on solar power, you would need a solar array that produces around 1500-2000Wh of energy per day. A solar array that produces this much energy would be rated at 300 to 600 Watts of power. Smaller refrigerators will consume less energy, and will therefore require less solar power to run.

The exact amount of solar power that you need will mainly depend on the energy consumption of your refrigerator, and on the amount of sunlight that you receive in your location.

To accurately determine how many solar panels you need to power a fridge, you will mainly need 2 pieces of information:

• An estimate of your refrigerator’s daily energy consumption, measured in Watt-hours (Wh) or kiloWatt-hours (kWh).
• An estimate of the amount of sunlight your solar panels would receive each day, measured in Peak Sun Hours (kWh/m 2 ).

Before I explain how you can determine these 2 variables, to provide some perspective, here’s a table that estimates the energy consumption of different refrigerators of different sizes, as well as the amount of solar power that would be required to run each of them:

Now that we know how much solar power you’d need to run your fridge, let’s discuss the other components that you’ll require.

What size battery to run a refrigerator on solar power?

To run a refrigerator on solar power you’re going to need a battery bank that stores every bit of energy generated by the solar panels during the day, and make it available to the fridge at all times.

• The Daily Energy Consumption of The refrigerator.: The battery bank should be big enough to store and supply the refrigerator’s daily energy requirements. The greater the energy consumption of your refrigerator, the bigger the battery bank.
• The Depth Of Discharge (DOD) of the battery bank: The Depth Of Discharge (DOD) of a battery indicates the recommended percentage of its total capacity that should be utilized. For instance, if a battery has a rating of 1200 Watt-hours and a recommended DOD of 50%, it means that only 600 Watt-hours of the battery’s energy capacity can be effectively utilized. The remaining 50% is best preserved to maintain the battery’s performance and longevity. The greater the permissible depth of discharge for the battery bank, the smaller the required size of the battery bank can be.
• Days Of Autonomy: This is essentially an energy backup plan. Days Of Autonomy represent the number of days for which you suspect a low solar input and would have to rely solely on the battery bank to run the refrigerator.

Once these variables are determined, the Energy Capacity (in Watt-hours) of the battery bank that you need is calculated as such:

Energy Capacity (Wh) = (Daily Energy Consumption of the refrigerator (Wh) x Days Of Autonomy) ÷ (Depth Of Discharge (%) x 0.85)

Please note that the 0.85 factor in the formula is used to account for system losses (mainly inverter inefficiency).

To better explain this, consider the following example:

Let’s say I have a 14 Cu. Ft. refrigerator that uses around 1000 Wh (1 kWh) of energy on a daily basis, and I want the battery bank to be able to run the refrigerator for 3 days in case there’s not enough sunlight to rely on the solar panels.

So, the fridge’s daily energy consumption is 1000 Wh, and the Days Of Autonomy are 3. But, what about the Depth Of Discharge (DOD)?

Well, the DOD that we use in the formula will depend entirely on the type of batteries we’re going to use.

The most common types of batteries uses in these applications are Lead-Acid batteries and Lithium batteries.

Generally, Lead-Acid batteries have a recommended DOD of 50%, meaning that it is not recommended to discharge them below 50% of their rated capacity.

12V-100Ah Lead-Acid Batteries

On the other hand, Lithium batteries have a recommended DOD of at least 80%, meaning that they can be repeatedly discharged to 20% of their rated capacity without sustaining any permanent damage.

Some Lithium battery suppliers will even guarantee a 10-year life span (3500 daily charge/discharge cycles) at a 100% DOD.

12V-100Ah Lithium batteries

To illustrate how much of a difference the recommended DOD of a battery makes, let’s continue our example, and calculate the required battery size for each case.

Lead-Acid Battery Bank:

If we use Lead-Acid batteries for our system, the size of the battery bank is calculated as such:

Energy Capacity (Wh) = (Daily Energy Consumption of the refrigerator (Wh) x Days Of Autonomy) ÷ (Depth Of Discharge (%) x 0.85)

Energy Capacity (Wh) = (1000 Wh x 3) ÷ (50% x 0.85)

Energy Capacity (Wh) = (3000 Wh) ÷ (0.5 x 0.85)

Energy Capacity (Wh) = (3000 Wh) ÷ (0.425)

Energy Capacity (Wh) = 7058 Watt-hours

If we use these WindyNation batteries, which are rated at 1200 Wh each (12V – 100 Ah), we would require 6 batteries:

The number of batteries = Energy Capacity of the battery bank (Wh) ÷ Energy Capacity of each battery (Wh)

The number of batteries = 7058 Wh ÷ 1200 Wh

The number of batteries = 5.88 batteries

Lithium Battery Bank:

Let’s say we choose to use these LiTime batteries, which are LiFePO4 (Lithium Iron Phosphate) which the supplier claims would last 4000 Charge/Discharge cycles even at a 100% DOD.

The size of the battery bank that consists of these batteries is calculated as such:

Energy Capacity (Wh) = (Daily Energy Consumption of the refrigerator (Wh) x Days Of Autonomy) ÷ (Depth Of Discharge (%) x 0.85)

Energy Capacity (Wh) = (1000 Wh x 3) ÷ (100% x 0.85)

Energy Capacity (Wh) = (3000 Wh) ÷ (1 x 0.85)

Energy Capacity (Wh) = (3000 Wh) ÷ (0.85)

Energy Capacity (Wh) = 3529 Watt-hours

These LiTime batteries are also rated at 1200 Wh each (12V – 100 Ah). So, we would require 3 batteries:

The number of batteries = Energy Capacity of the battery bank (Wh) ÷ Energy Capacity of each battery (Wh)

The number of batteries = 3529 Wh ÷ 1200 Wh

The number of batteries = 2.9 batteries

12V-100Ah Lithium batteries

Click here to read more about batteries, their types, their electrical ratings, and how many of them you would need to run your refrigerator.

Now, that we know how many solar panels and batteries you’ll need to run your fridge, let’s talk about another component that you’ll need for your system: The solar charge controller.

In the next section, I explain what a solar charge controller is, why you’ll need one, and how you can size it properly.

What size solar charge controller do I need to run a refrigerator on solar power?

Solar charge controllers are electronic devices that connect the solar panels to the battery and are used in solar energy systems to maximize power production and protect the battery bank and the solar panels.

There are 2 types of solar charge controllers that you could use:

While PWM charge controllers are the cheaper option, MPPT charge controllers are a newer and more efficient technology. In fact, using an MPPT charge controller can boost your system’s efficiency by up to 25%.

That’s why in this section, I’ll be focusing on MPPT charge controllers, as they offer a significant advantage in terms of efficiency compared to PWM controllers.

However, if you’re convinced that a PWM charge controller is more suitable for your needs/budget, feel free to check out this PWM charge controller calculator that’ll help you choose the right PWM for your system.

• Their Output Current Rating (in Amps): This rating indicates the maximum amount of Electrical Current (Amps) that the MPPT is capable of delivering at its output.
• Their Input Voltage Rating (in Volts): This rating indicates the maximum Voltage that the MPPT can handle at its input.
• Their Output Voltage Rating (in Volts): This rating represents the Voltage that the MPPT is designed to output.

I’ve written a comprehensive guide on how to choose the right MPPT charge controller for your system. In this guide, I use an example system to illustrate the necessary calculations for determining the appropriate ratings of the MPPT controller.

But to make things even easier for you, I’ve gone a step further and created an MPPT calculator. By simply describing your system, the calculator will do the work for you, suggesting the ideal MPPT controller that matches your specific needs.

For example, let’s say you’ve determined that you’ll need a 200W solar array, and 12V – 100 Ah battery to run your refrigerator.

• For your solar array, you chose to use 2 of these 100W-12V Monocrystalline Solar Panels from Renogy wired in series to make a 24V solar array.
• For your battery bank, you chose to use this 12V – 100Ah LiTime LiFePO4 battery.

Now, if we go to our MPPT calculator (here), here are the inputs that describe our system:

1- Solar Panel Wattage: This is the watt rating on each of your solar panels. In our case, each solar panel is rated at 100 Watts.

2- Solar panel Open-Circuit voltage (Voc): You can find this value in the specification label on the back of your solar panels, or by looking up the specific model. In our example, the 100W Renogy solar panels each have an Open-Circuit Voltage rating of 22.3 Volts.

3- Battery bank voltage (Nominal Voltage): In our example, the battery bank is rated at 12V.

4- Lowest temperature during sunlight hours: In this field, you should enter the lowest temperature that you suspect your solar panels are ever going to be exposed to during daytime hours. For the sake of this example, we’ll assume the temperature does not go below 20°F during daytime hours.

5- Number of strings: The solar panels in our example are wired in series, so the number of strings is 1.

6- Number of solar panels in each string: We have 2 solar panels in series, so we’ll enter 2 in this input.

After submitting these details to the calculator, here are the results:

According to the calculator, the MPPT charge controller that we need for this system needs to have an Input Voltage rating of 51 Volts or more and an Output Current rating of 21.8 Amps or more.

The calculator took these ratings into account and provided a couple of direct links to MPPT charge controllers that match the system’s requirements.

Now that we know how much solar power, what size battery, and what size charge controller we need to run a refrigerator, one more essential component is left to discuss: The inverter.

What size inverter do I need for a refrigerator?

Solar panels generate DC (Direct Current) power, but most refrigerators require AC (Alternating Current) power to operate. To bridge this gap, an inverter is necessary to convert the low-voltage DC power from the batteries (ranging from 12-48V) into higher-voltage AC power (typically 110-130V) that the refrigerator can use.

Inverters are rated in Watts, indicating the amount of power they can continuously supply. For instance, a 500W inverter can consistently provide 500 Watts of power.

However. when selecting an inverter for your refrigerator, it’s important to ensure that it can handle both the running wattage (continuous power consumption) and the power surges required for starting up the fridge.

Power consumption of a 150W refrigerator.

Inverter manufacturers specify both the Continuous Power and the Surge Power capacities for their inverters. So, in order to find an inverter that matches your refrigerator’s requirements and could run it, you’ll have to figure out:

1- The refrigerator’s running wattage:

Which can be calculated by multiplying the rated Voltage (Volts) of the refrigerator by its rated Current (Amps) as specified on the fridge’s specification sheet:

Running Wattage = Rated Voltage x Rated Current

2- The refrigerator’s starting wattage:

Which is typically estimated since it’s not commonly provided by the manufacturer. On average, the starting wattage of a refrigerator ranges from 3 to 10 times its running wattage.

To err on the safe side, let’s assume a multiple of 10:

Starting Wattage = Rated Wattage x 10

However, it’s worth noting that a more accurate method for determining the starting wattage of your refrigerator is by referring to the Locked Rotor Amps (LRA) rating, typically indicated on the compressor.

This specification provides a more precise estimation of the power surge required during startup.

To calculate the starting wattage based on the LRA rating, you can use the following formula:

Starting Wattage = Rated Voltage x Locked Rotor Amps

Click here to learn more about the starting wattage of your refrigerator.

For example, consider this LG refrigerator.

The running wattage of this fridge can be calculated as such:

Running Wattage = Rated Voltage x Rated Current = 127 V x 2.4 A = 305 W

This means that the inverter that could run this refrigerator should have a Continuous Power rating of more than 305 Watts. But we still need to factor in the starting wattage of the refrigerator.

If the Locked Rotor Amps (LRA) rating of the refrigerator’s compressor is unknown, we can estimate the starting wattage using the assumed multiple of 10.

For example, if the running wattage of the refrigerator is 305W, the estimated starting wattage would be 305W x 10 = 3050W.

To find an appropriate inverter, we need one that can supply both the continuous running wattage (305W) and the estimated starting wattage (3050W).

2000W Pure Sine Wave Inverters

While this 2000W Renogy inverter would meet these requirements, it might be overkill for most refrigerators since the starting wattage is more commonly around 5 times the running wattage. Therefore, rounding down the calculated starting wattage to 3000W would be more appropriate for this example.

In this case, the Aims 1500 Watts Inverter appears to be a suitable choice. It can provide 1500 Watts of continuous power and handle 3000 Watts of peak power, making it well-suited for running the refrigerator.

1500W Pure Sine Wave Inverters

It’s also important to consider both the Waveform and Input Voltage compatibility of the inverter for optimal performance.

Firstly, it is recommended to choose a Pure Sine Wave inverter rather than a Modified Sine Wave Inverter. This ensures a cleaner and more stable power output, which is important for sensitive devices like refrigerators.

Secondly, the Input Voltage of the inverter should match the voltage of your battery bank. For instance, if your battery bank operates at 24 Volts, select an inverter explicitly rated for 24 Volts at its input.

For more detailed information on sizing an inverter for your refrigerator, I recommend reading the article I wrote specifically addressing this topic. It will provide you with valuable insights and guidance in selecting the right inverter for your specific needs.

Once you have correctly sized all the components for your system, it’s essential to also consider the sizing of wires and over-current protection devices such as fuses and circuit breakers that connect these components together.

To assist you further, here are some resources that provide information on wire sizing and fuse selection for specific connections within your system:

1- Solar panels to charge controller wire sizing: This resource will guide you in selecting the appropriate wire size for connecting your solar panels to the charge controller.

2- Solar charge controller to battery wire sizing: Here, you’ll find information on wire sizing for the connection between the solar charge controller and the battery bank.

3- Battery to inverter wire sizing: This resource will help you determine the suitable wire size for connecting the battery bank to the inverter.

4- What size fuse between solar panels and charge controller?: Here, you’ll find guidance on selecting the correct fuse size for protection between the solar panels and the charge controller.

5- What size fuse between charge controller and battery bank?: This resource provides information on determining the proper fuse size for protection between the charge controller and the battery bank.

6- What size fuse between battery bank and inverter?: Here, you’ll find details on choosing the right fuse size for protection between the battery bank and the inverter.

Solar Powered Refrigerator!

Here is an after the fact implementation of how I power my refrigerator from the sun. This off grid system has been working great since may 2013. It is truly reassuring to know my groceries are safely stored regardless of utility power.

I have fulfilled the electrical code requirements (NFPA 70, TTS-171 Part 1) and power utility mandates for my area. If you have to perform the same on your home, all relevant certifications and approvals are needed.

Remember for solar power systems, bigger is always better. Never go borderline else your system will not be reliable for off grid applications.

Grid tie is NOT ALLOWED in my country. Also don’t ever assume you will have utility power during a nationwide disaster (bad weather, riots, energy rationing, terrorism etc).

Here is a detailed write up on how I solar powered my entire home: https://www.instructables.com/ID/Solar-Powering-My-.

Step 1: The Refrigerator.

Ideally an inverter refrigerator is the best bet but my old refrigerator needs 300watts when on. Basically any fridge will do but the more energy efficient means a smaller solar setup is needed.

There are the rare dc powered refrigerators that are actually more efficient than the inverter types. However should this unit fail on me, there are none sold in my country. I want to be able to go to a store and buy a replacement or repair my unit if possible in the event of failure.

Step 2: The Solar Panels.

I use eight 225watt monocrystalline panels to power my home and by extension, the refrigerator. They are wired 4 in series and 2 strings in parallel. I harvest up to 8kwh per day with these panels.

Mounting the panels on the roof can be via manufacturer mounting solutions or you can make your own with rigid pvc. I actually did a hybrid approach.

Step 3: The Charge Controller.

I have an outback fm80 charge controller to route energy from the panels to the batteries. Mppt chargers are more efficient and economical for large solar systems.

Step 4: The Batteries.

I use 16 lifepo4 batteries at 25.6v. They are all wired in parallel with an energy meter per pair of batteries. Each battery has a switch for isolation. For the work I did on my battery bank, please read: https://www.instructables.com/ID/Lifepo4-solar-stor.

My refrigerator uses 1.2kwh per 24hour period. My battery bank has 4kwh capacity.

My country’s climate is hot. Lead acid batteries, although cheaper, have failed in less than 10months of use. If your maximum temperature is below 25C then you should be able to use lead acids. I have long abandoned lead acid technology in my home and car. Lifepo4 is safe, powerful and environmentally friendly.

Step 5: DC Distribution.

With the appropriate sized conductors, I have circuit breakers to protect all my components and also provide easy isolation for maintenance.

The attached chart shows the conductors sizes for DC power.

Step 6: The Inverter.

To get 120vac from 25.6vdc I have a 1000watt power bright pure sine wave inverter. Always use pure sine wave especially for motor applications.

Step 7: The AC Distribution.

I made a panelboard with din circuit breakers to get power to my house loads. I have a breaker dedicated to the kitchen area. Since my refrigerator uses 2.5Amp the circuit breaker for it is 6Amp single Pole. Here is how I built the panelboard: https://www.instructables.com/ID/DIY-Circuit-breake.

Also in the panelboard I have an automatic transfer switch (ATS) shown at the bottom of the pic. This switch is controlled by my home automation system which will switch to utility power if the batteries get depleted.

My local power utility is actually my backup power source.

Step 8: Powering the Refrigerator.

The outlet for the fridge is protected with a motor protector. This is only needed should I switch to utility supply. The inverter gives clean power.

So that is how I powered my refrigerator via the sun!

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Комментарии и мнения владельцев

I am looking for someone who has successfully developed a solar powered cooler that can be used for keeping medicine or even infant formula fresh in areas of the world that have no access to refrigeration. Can you adapt your instructions to help me accomplish this?

Coolatron makes 12v coolers/fridges that work fairly well in remote areas. I believe they keep around 17degres C below the surrounding temperatures when operating normally.

Yes definitely. I just emailed you. We must talk in real-time.

Can we get an update on how it’s working in 2020

I would be interesting in this as well.

Thank you very much for sharing all this information. Being in an off-grid region, I have already been using a 12 volt set-up. just for lights in the house. Works fine.

Now, i try to budget for the fridge. I’m a little confused with your description.

You talk about a 300w fridge. And after, you say : My refrigerator uses 1.2kwh per 24hour period is it possible. I understand do not work 24hs continuously. But 1200 wh / 24hs = 50w. Does this means that it use only 50w / 300w = 16% of the time.

Or is it that my knowledge is very bad, and so. please help me understand.

By the way. by any chance, do you know the fridge capacity. ( in gallons. liters. )

Just use a watt-hour meter.

Very nice. Answers a lot of the questions that I have about a day-to-day system. I’m not comfortable though with building my own transfer switch. I love that it is automatic and is something that has dis-satisfied me with local solar vendors. Is there a commercial ATS that you could recommend? Are the requirements different if you want to default to solar and use mains as the backup?

I couldn’t tell from scanning your instructable what the profile is for failover.

Check your electrical suppliers for ATS. My default source is solar and the fail back is utility.

But how about having scaled down versions each powering different gadgets. A set-up for the TVs, another set up for the fridge and water dispenser, a pure 12 volt set up for the lights and another smaller set up for charging USB devices. I envisage that may be less fund guzzling.

It is my future trying, also. I have been running lights on 12 volt set for more than 10 years, with good results. My next step should be the fridge. I believe that it requires 24 volts panels, and a serious battery bank.

On a very far future, all the house ( A/A ; kitchen appliances etc. ) would be added on a different set-up.

hi, how much did it cost you to do this system? I want to do it for a small shed, that has a chest freezer, TV and lights.

For the whole house or the fridge alone?

Pheew! Sadly, LifePO4 cells are a luxury in my area. I have thought of Li-ion as an alternative because I should be able to salvage for cells in used laptop batteries, but then I’ll also be wary. I’ve mistakenly shorted a Li-ion cell during a tweak and I wouldn’t imagine having hundreds of it hanging on a wall in my home. AGM has less lifespan but that’s what’s affordable, easily accessible and readily available. I’ll have to check your other ‘ible on the entire solar set up. Good job.

Super Insulation can make this simpler in my opinion. I am in Africa a lot, about 3-4 months per year. By the way ,about 1/5 the planet lives off the grid. And, they have freezers, seldom have fridges. But I am going to do an experiment soon for what I see, or call super insulation. I am going to measure electrical use for 30 days as they use normal. The add about 2 foot thick insulation around the sides. They are the same as Americans, they do not want things to look silly. Then make a night blanket about a food thick. This will cost about 15 USD because they use some form of grass to make beds, not normal, but normal for the off grid 1.5 billion. The off-grid are just in time eating. Here is a too expensive, but great idea, using thermal mass, or the cooling of the earth method, very old tech, just forgotten, nothing new. There has been in the ground cellars for cooling since the beginning of time. Thanks, Andy Lee Graham of HoboTraveler.com. I am in Tours France, and will go to Togo on August 15, 2016 again. http://mikeshouts.com/groundfridge-underground-ref.

one perspective I would like to share is that the cost/payback rate of solar should not necessarily be looked at as a benefit, because it largely seems to be a detractor. Solar is expensive, can be very expensive, but the cost of not going solar is eventual and increasingly fast-paced destruction of the environment caused by an increasing reliance on dirty fuels and energy sources. You can finance a 17,000 (us) car for about 250 a month, which is not cheap, but people do it all the time, and in fact people finance much more pricey vehicles all the time. You can buy you solar set up in chunks. Save for a few months and buy the distribution components, then later the panels, etc. I know this is not the most convenient, but it makes it feasible. You can also down size the system and make it modular, so the it can be expanded upon later; buy the components that have to be for a larger system, then only buy a couple batteries, maybe one solar panel, then later add other panels, batteries, and so on. To give you an example of the effectiveness of this method, I make less than 20,000 annually, I pay about 1,500 in monthly expenses, which includes car cost mentioned earlier, and over the course of the last six months I have saved approximate 700 to build a homemade CNC mill. I opened a savings account at a new bank, that has no transaction capabilities. 35 from every paycheck, from each of my 2 jobs, gets automatically deposited into the account, and unless I go to the bank to withdraw it, I don’t have access to it. Any payment from any side jobs I do to make extra cash gets deposited here as well. So, every few months, I make a larger purchase towards my CNC mill. The same principle can be applied to the purchase of a solar power solution. When looked at like this it becomes a simple matter of timing and patience. I hope this helps.

The cold that came from the sun

Many objects have a history. But that of an inconspicuous Liebherr refrigerator from 1994, which stood forgotten for decades in a warehouse, is a very special one: It tells of historians and developers, the sun, Africa and the birth of Liebherr’s modern energy-saving household appliances.

An unexpected discovery

Sometimes coincidence is the best detective. And it was just such a coincidence that led Hansjörg Steinhorst of the Liebherr Archive on the trail of an almost forgotten invention. It all began in autumn 2019 with a tour of the plant in Biberach an der Riss, where he met the engineer and local historian Johannes Angele. While the two history-enthusiasts walked through the production facilities, they had a lively conversation about historical collectors’ items. “I have something at home, too,” Johannes Angele suddenly said. “A Liebherr solar fridge. It’s been in my company’s warehouse for years.” Hansjörg Steinhorst could hardly believe what he heard. Although he had heard of this refrigerator, it had been missing for almost three decades. Could this be it?

A few days later, Johannes Angele sent two photos of his treasure to the archive man: a KT 1580 Solar, which was originally packed in a yellowed cardboard box on a wooden pallet. “When I saw the pictures, I was absolutely thrilled,” says Hansjörg Steinhorst. “I wanted to find out more and immediately started researching.” He had so many questions that needed answering: Why had the photovoltaic refrigerator been built? Who had invented it? And why had it turned up in the possession of a local historian in Ochsenhausen 25 years later?

Innovation in the times of the ozone hole

The early 1990s were a time of upheaval for Wilfried King, Herbert Gerner and Matthias Wiest, the development team at the Liebherr-Hausgeräte GmbH in Ochsenhausen (Germany). In 1989, the United Nations had agreed on a ban on chlorofluorocarbons (CFCs) with the Montreal Protocol, which was to come into force in 1995. “The entire cooling industry worked flat out to develop fridges and freezers without CFC refrigerants,” recalls Matthias Wiest, who is now head of the Cooling Division. Like everyone else in the industry, the Liebherr developers were working on the future of cooling in their research laboratory between wooden walls, cables and measuring rooms. Wilfried King, Head of Basic Technological Development at the time, remembers it well: “Those were exciting, but also difficult times. CFCs were on everyone’s lips because of their contribution to the greenhouse effect and the continuous enlargement of the ozone hole. You could really feel that you were in the middle of a generational change.”

It happened everywhere: the media reported almost daily on the environmental damage caused by greenhouse gases such as CFCs and FCs (fluorocarbons). Greenpeace drew attention to environmental protection with sensational campaigns. And people took to the streets for the climate. Climate change had become a reality. Finally, in 1993, the three developers’ dream became true. For the first time, Liebherr added a CFC- and FC-free refrigerator with the insulation of a freezer to its portfolio: their KT 1580 model. For Liebherr, it was the turning point towards consistent energy-saving thinking.

CFCs, FCs and the greenhouse effect

The greenhouse gases CFC (chlorofluorocarbon) and FC (fluorocarbon) were used as foam blowing agents and refrigerants in refrigerators and freezers. They were known to promote global warming. CFCs in particular played a central role in the destruction of the ozone layer and the formation of the so-called ozone hole. Starting with the KT 1580, Liebherr switched to CFC- and FC-free refrigerators from 1993.

Solar power for the energy revolution

“For its time, the KT 1580 was a pioneer in terms of energy-saving and, in 1994, was awarded the rating ‘very good’ by the leading German consumer safety group Stiftung Warentest,” recalls Herbert Gerner, now Head of Appliance Electronics. But the development team wanted more, because the electricity used for the refrigerator still came from the socket, thus promoting the indirect greenhouse effect. After careful consideration, the developers came up with the solution: solar energy. “I had already studied photovoltaics during my studies. In the meantime, the technology had made great strides and you didn’t need many solar panels to power a fridge anymore. Meaning, in terms of efficiency, costs, availability and performance, things became really interesting,” explains Herbert Gerner. Thus, the developers began to upgrade their CFC- and FC-free refrigerator with solar power. “The KT 1580 was predestined for the conversion to solar. It was our technology project. With it, we wanted to position Liebherr as an innovation driver,” says Wilfried King. And it worked. They had thought of everything. You could even buy the refrigerator as a modular system, individually or with a solar panel and battery. With it, the appliance could cool for a week without sunlight. “And we looked even further ahead,” recalls Wilfried King. “Our idea was to bring our solar fridge to small villages in Africa that weren’t connected to the power grid, for example, to cool medications in rural hospitals.” Their dream would come true in unexpected ways.

As one of 250 exhibitors, Liebherr presented its KT 1580 Solar with a specially designed booth in Berlin from 4. 7 April 1995. The exhibition took place as part of the symposium Success Cases of Urban Climate Protection in Europe.

At the first Climate Protection Trade Fair in Berlin, 1995

As one of 250 exhibitors, Liebherr presented its KT 1580 Solar with a specially designed booth in Berlin from 4. 7 April 1995. The exhibition took place as part of the symposium Success Cases of Urban Climate Protection in Europe.

Liebherr is the first company to develop a refrigerator that is completely free of CFCs and FCs and that is powered by the rays of the sun. The Liebherr KT 1580 Solar is thus the very first refrigerator that doesn’t harm the ozone layer (ODP Ozone Depletion Potential =0) and doesn’t contribute to the greenhouse effect (GWP Greenhouse Warming Potential =0). What is more, the KT 1580 Solar is more spacious than conventional 12 V refrigerators, it’s suitable for use in the tropics, it utilises the famous Liebherr refrigeration technology and because it’s battery-powered it can be used absolutely anywhere.

The KT 1580-Solar flyer from 1994

Liebherr is the first company to develop a refrigerator that is completely free of CFCs and FCs and that is powered by the rays of the sun. The Liebherr KT 1580 Solar is thus the very first refrigerator that doesn’t harm the ozone layer (ODP Ozone Depletion Potential =0) and doesn’t contribute to the greenhouse effect (GWP Greenhouse Warming Potential =0). What is more, the KT 1580 Solar is more spacious than conventional 12 V refrigerators, it’s suitable for use in the tropics, it utilises the famous Liebherr refrigeration technology and because it’s battery-powered it can be used absolutely anywhere.

In this development laboratory, the KT 1580 and the KT 1580 Solar were also screwed and tinkered with. The picture is from the early 2000s, a few years later a new, ultra-modern development centre was built.

In the 1990s developers’ lab

In this development laboratory, the KT 1580 and the KT 1580 Solar were also screwed and tinkered with. The picture is from the early 2000s, a few years later a new, ultra-modern development centre was built.

Hansjörg Steinhorst’s research unveiled many insights into working at Liebherr-Hausgeräte in the early 1990s.

Finds from the Liebherr Archive

Hansjörg Steinhorst’s research unveiled many insights into working at Liebherr-Hausgeräte in the early 1990s.

Aerial view of Liebherr-Hausgeräte GmbH 1990s

Since the time of the KT 1580 Solar, the company premises have been regularly expanded. Most recently, the Liebherr-Hausgeräte Customer Centre was added to the front left of the picture.

Aerial view of Liebherr-Hausgeräte GmbH 2019

Since the time of the KT 1580 Solar, the company premises have been regularly expanded. Most recently, the Liebherr-Hausgeräte Customer Centre was added to the front left of the picture.

When ideas become trees

1995 finally became the year of the KT 1580 Solar. In April, Liebherr dedicated an entire booth at the first Climate Protection Trade Fair in Berlin to the model, which had been awarded the then brand new European energy label “A” – “top saver”. In August, the fridge was even mentioned in one of Germany’s most renowned newspapers, the Frankfurter Allgemeine Zeitung: “With 144 litres, this washing-machine-sized cabinet has more volume than previous 12-volt appliances. It is suitable for use in the tropics and can be operated independently of the mains supply,” the newspaper headlined. Despite all the attention, only around 50 units were produced. “We were very proud of our invention. But as it is with new technologies, sometimes you’re simply ahead of your time,” says Matthias Wiest looking back. Wilfried King agrees: “Nothing is big right away. You never have certainty that a development will last. A new idea is like a small plant. It can grow and then quickly wither. Or it can grow slowly, leaf by leaf, until it becomes a tree.

In the end, the idea behind the KT 1580 did turn into a tree – even without photovoltaics. It is still considered the prototype of Liebherr’s energy-saving household appliances today.

Africa after all

Only one question remains: How did solar refrigerator reappear almost three decades later in the warehouse of local historian Johannes Angele? The answer is as simple as it is exciting. In 1998, after the KT 1580 Solar had almost disappeared from the product portfolio, Johannes Angele contacted Liebherr in Ochsenhausen on behalf of the friends’ association ‘Förderverein Piela Bilanga e.V.’ which supports charitable projects in Burkina Faso (Africa). The association had already equipped the school of the village Piela with photovoltaic panels in 1991 and wanted to support the inhabitants with further solar technology. Now, they were looking for refrigerators that could be powered by solar energy. They were lucky and some models of the solar fridge were still available. The association purchased two. One of them would go on a long journey.

“At that time, our association supported Souleymane Sow, a young local who, with his technical knowledge, had made a big impression on us and the German sisters of the protestant mission, while he helped build the solar modules for Piela. We decided to collect money for him to enable him to train as a technician in Germany,” says Johannes Angele. After my successful graduation I went back to Burkina Faso and founded a company for solar and computer technology, says Souleymane Sow. “One year later, adds Johannes Angele, proud of his friend’s achievement, we sent him one of the two solar fridges. By the way, it is still in operation today. It serves as a training example on how to create cold from the sun.

Back to where it all began

The last remaining refrigerator from Johannes Angele’s warehouse fell into oblivion. Hansjörg Steinhorst from the Liebherr Archive ultimately took care of it personally. In return for a donation to the Piela Bilanga Förderverein, he brought the piece of Liebherr history back to Ochsenhausen. There, in the very development laboratory in which it was once created and under the watchful eyes of its inventors Wilfried King and Herbert Gerner, it was reconnected to its solar panel after 22 years.

Today, as part of the collection of historic appliances, the KT 1580 Solar is a reminder of the times when the Liebherr household appliances became energy-saving professionals.

Developer Wilfried King unpacks the KT 1580 Solar in the new development centre of Liebherr-Hausgeräte.

Homecoming

Developer Wilfried King unpacks the KT 1580 Solar in the new development centre of Liebherr-Hausgeräte.

A first check

Together with Oliver Bopp and Herbert Schäfer from the Development Centre, Wilfried King is reinstalling the original solar panel on the roof of the old Climate Protection Trade Fair booth.

Now attach the solar panel

Together with Oliver Bopp and Herbert Schäfer from the Development Centre, Wilfried King is reinstalling the original solar panel on the roof of the old Climate Protection Trade Fair booth.

Fully assembled, the developers Herbert Gerner and Wilfried King can present their invention from 1994.

Proud inventors

Fully assembled, the developers Herbert Gerner and Wilfried King can present their invention from 1994.