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Solar panels are so common now they are used to run all kinds of appliances including TVs, refrigerators, microwaves and even washing machines. There are a lot of factors that determine how many solar panels are needed to run a washing machine, but modern units are quite energy efficient.
A 250-300 watt solar panel can run an energy efficient four cubic foot washing machine for an hour. But if the washing machine uses hot water, you will need a 2000 watt solar array.
Calculate Washing Machine Solar Power Requirements
The equation to find washing machine watt usage is the following. We are using 4 cu ft as the example, but you can substitute it with whatever is the capacity of your washer.
Washing machine power rating (kwh or w) x usage hours = solar panel watts required
Let us look at some examples.
A 4 cu ft energy efficient washing machine with no heating usually has a 250W power rating.
250W x 1 hour of use = 250W. One 250W-275W solar panel is required. Even better would be a Renogy 300W Solar Panel Kit so your washing machine gets even more power.
A 4 cu ft, non-energy efficient washing machine with no heating usually has a 500W power rating.
500W x 1 hour of use = 500W. Two 250W solar panels is the minimum requirement. Two 270W PV modules (total 540W) is a better option.
A 4 cu ft washing machine with hot clearing water has a 1000W-2000W rating.
1000W-2000W solar panels are the absolute minimum per hour. If you run this on a full load it might need more than 2000W. of solar panel power. You may want to use a battery bank to complement the solar panels. In this scenario the ExpertPower 100ah Lithium battery is the best option.
The key points are:
- Energy efficient washing machines demand the lowest amount of sola panels.
- An energy efficient model requires only half the wattage power of a regular washer.
- Hot water necessitates several solar panels or a large solar generator. Use normal water unless you have a large solar power system set up. You will also need a large inverter to run a washing machine at full power.
A washing machine draws power from two components, mainly the heating mechanism and the motor. The motor consumes 25%-30% power and the rest is used by the heating component. That is why there is such a huge spike in watts when hot water is used.
There will be some deviation depending on the model, capacity and design, but always expect power requirements to jump when heating is activated. Bottom line: you can save power by choosing “use regular water” than “hot water”. Even with an Energy Star washer, the difference in wattage between hot and cold water is significant.
Washing Machine Solar Power Usage
There are many types of washing machines, but for this chart we will divide them into two categories, the traditional washing machine used at homes, and portable models designed for RVs and single users. The estimates that follow are for home clothes washers but applicable to portable washing machines too. However their watt use will be much lower.
|Capacity||Water Used||Solar Panel Power Required Per Hour|
|4-4.5 cu. ft. Energy Efficient||No Heating, Cold Water||275W|
|4.5-5 cu. ft. Non Energy Efficient||No Heating ,Cold Water||500W|
|5-5.4 cu..ft. Energy Efficient||With Hot Water||1000W-2000W|
- The best products are all energy efficient. Older models consume more power.
- This chart also assumes regular use.
- Longer usage at full capacity will require more solar panel power.
- These are for washers only, using a dryer will increase power use up to 3000W or more.
You can find a washing machine’s rated power on the back, user manual or the manufacturer website. The power specs listed on the label for watt hours are with normal use. You can find more details about power in your product manual. You will also need this info if you want to run a washing machine on an inverter.
The label contains several pieces of information, but the most important for power are the following.
- Watts (W): how much power a washer uses when it is running. Watts is equal to voltage, power factor and amps.
- Average Cumulative Power Consumption: how many kilowatts (kwh) the washer consumes a year.
- Amps (A): how much current a washer uses when it runs.
- Voltage (V): the voltage of the washer.
What Affects Washing Machine Solar Power Consumption?
The biggest factors are load, capacity, energy efficiency, design (top load or front load), settings, age (older models are less efficient) and many more.
The following numbers are for a typical home washing machine running at full load. The numbers will be lower if it is an Energy Star model and not running at full capacity. Using cold water lowers power consumption, and hot water increases it.
- Filling: 9W-20W
- Wash; 300W-400W
- Rinse: 300W-600W
Load size is important because the heavier the load, the more power the washer has to draw. This falls on the motor which in turn pulls from your power source. A heavy load puts strain on the system and also on your solar panels.
This is related to load size but is not the same. In the past, higher capacity washers demanded more power because of the larger motor. However that is no longer always the case, as more efficient models have been coming out regularly.
This is where the hot water factor comes in. Cold water is preferable because it keeps power consumption down. If you turn on the heat water, the solar power usage will double or triple. It is going to be similar to an air conditionerLNK and be difficult to run on solar panels.
Do Portable Washing Machines Use a Lot of Electricity?
Standard washing machines have a 3 to 4 cu ft capacity. Larger models are in the 4 to 6 cu ft range. Portable models are around 2.5 cu ft to less than a cu ft. A 2.0 cu ft portable washing machine needs about 120W-135W solar power.
Portable washing machines are just like regular washers, except they are smaller. They do not have the same capacity as regular size, but they also don’t use as much power. These machines are best suited for small homes, RVs, campers and individuals. They are more affordable than typical washers and you will save solar power because consumption is small.
For families, anything less than 3 cu ft may not be enough, but otherwise you should consider portable washers. Features wise they are not lacking and can handle regular use. Most important, their watt consumption is way smaller than even the most efficient 4 cu ft washer.
Front Load vs. Top Load Washers – Which is More Energy Efficient?
A front load washing machine is more expensive but it uses less power and water than a top load. If your main concern is power usage, buy a front load washing machine. Yes you will pay more now, but you can recoup that cost as your power consumption drops. This is particularly important if you wash clothes frequently.
A top load washing machine may be a better option if you use it less often. Less use may make up the difference in solar power consumption, and you save money on the purchase. It comes down to how often you use it so you have to do some calculations to figure out which is best suited for you.
Another thing you have to consider is the manufacturer. Competition has accelerated washer development on both sides, so be sure to check each model. They may have special features that you need or even more energy efficient mechanisms.
How to Reduce Washing Machine Power Consumption
A energy saving washing machine is mandatory for any solar power user, but that is only the beginning. There are many other ways to keep washing machine power needs manageable.
- Get an Energy Star washer. Buying a new unit is cheaper than settling for the old one. Older washing machines are too inefficient and will waste a lot of solar power. If you run other solar appliances, an Energy Star model is a must.
- Shut off the machine when you are done. The standby mode still uses power. This might not seem like a lot, but when you are on solar power, every watt counts. That small amount you neglect could be substantial in a year.
- Use regular water. We have gone over this already so no need to repeat what has been said. It is enough to say that even with Energy Star washing machines, not using hot water is ideal.
- Wash three times a week at most. You save energy by washing clothes at the same time for longer periods than washing every day. Yes we said that a full load uses more power, but compared to washing a few clothing items a day, it is cheaper.
- Stains should be soaked first. The less work the washing machine does, the less power it will consume.
- Use as few cycles as possible. You want to keep your clothes clean, but do not overdo it. If you can get the job done in a few cycles, that is even better.
Not only are washing machines efficient, but the rise of portable and solar powered clothes washers mean you’ll be able to use them more efficiently with solar panels. These days you can even depend on portable washers that demand even less power and can fit in your camper.
I am an advocate of solar power. Through portablesolarexpert.com I want to share with all of you what I have learned and cotinue to learn about renewable energy.