Battery Backup Power Packs and Solar Panels

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Summary

Portable battery power packs are popular for camping and also useful as a power source during electric outages. In an extended power outage, having a solar panel can recharge a battery power pack when no other energy source is available. If sufficient sunlight is available over several days for recharging, then continuous power of small devices could be provided with a solar and battery combination.

A person would need to plan ahead based on their anticipated electric demand — how much energy is needed and for how many hours or days. If you want uninterrupted use of a cell phone, that could be achieved with a simple power pack and solar panel like the Jackery Explorer 300 described below for about $600.

If you want to run several power hungry appliances, then you might need 10 to 20 solar panels or more, and many batteries at a cost of $10,000 or more. The cost of batteries and solar panels can increase significantly depending on your needs.

This document offers more information and resources to explore solar and battery power.

Understanding Solar Panels

Solar panels are typically given a rating in watts capacity. You can purchase small affordable 100-watts panels on Amazon for camping, RV use, or putting in your back yard. The advantage of 100w panels is their smaller size and lower cost. Some are foldable and have handles. Typical roof-mounted solar panels are larger and may be rated at 300w to 450w. This wattage rating is a standardized lab measurement. In real world conditions, the output of a 100w panel might be 65 watts. The estimate daily output for a 100-watt solar panel is 300 to 450 watts depending on the location, time of year, and position of the panels. [More]

Considerations for Five Goals

People looking at solar power and battery backup systems may have a few goals in mind. Here are some considerations regarding those goals.

• COST — The least expensive source of electricity is typically from the power company through the grid. If you buy a gas generator or create a DIY renewable power solution, you’ll be paying much more per watt than if you buy from the power company. The cost of 1,000 watts from the power company is about 10 cents. By comparison, ten 100-watt solar panels might cost $1,000. It will take 10,000 hours of use over 5 years or more before your cumulative average cost is 10 cents per kilowatt. That’s just the cost of solar panels, with no consideration for batteries and other electronics required. So, there’s no quick cost savings with solar. Solar may be a good option for someone with their own home who plans to be in that home for 10 or more years. These calculations are based on 100-watts output from a 100-watt solar panel which is almost never achieved. About 65 watts would be typical without very precise tracking of the sun position.
• INVESTMENT — As a long-term investment, solar power can provide a valuable source of power and also could increase the resale value of a home. When you improve a home in a way that positively impacts the environment, there is a sense of satisfaction even if you break-even financially. You have the satisfaction of knowing that you or a future owner of the home will have a reduced carbon footprint.
• OUTAGES — If your main concern is having power during brief outages, having some battery packs and keeping them charged up would be sufficient. No solar panels would be needed unless you anticipate an extended disruption to the grid. A gas generator is noisy, pollutes, and is costly to operate, but if you need one only briefly a few times every 10 years, then that might be a more cost effective alternate power solution compared to solar. The environmental impact of a 5HP gas engine (with 5 kWh capacity) sitting unused 99% of the time is fairly low. It’s small, inexpensive, and doesn’t require the materials of a large solar power backup system.
• REMOTE — It’s costly to have power grid service delivered to remote areas. Solar, wind, and other renewable power sources are a good choice for those situations.
• RENEWABLE — The most cost effective way to deliver renewable power to many people would be for municipal power services to adopt solar and wind or other renewables and use the existing power grid. It is better for the environment to have a scaled efficient power solution rather than everyone having their own power system. People living in apartments, condos, townhouses, duplexes, and other housing arrangements can’t setup huge solar arrays. So, as a broad option, renewable energy is best delivered to many people at a time. Perhaps at the scale of a neighborhood or quadrants of a city, it would be possible to have local power produced with a slight surplus. That would be a good goal. A “power outage” would be limited to the localized area.

NOTE: A factor that impacts the cost and environmental benefits is that solar panels may need to be replaced after 25 to 50 years. As with electric cars needing new batteries periodically, these greener solutions aren’t without waste and they also require heavy equipment and intense manufacturing to create. They are consumables with an environmental impact. Hopefully less impact than other sources.

Home Owners

If you are a home owner with the option to have a generator, that would be the most economical way to have power on the rare occasions of a power outage. A hybrid fuel generator capable of producing 12,000 watts of power might cost $1,000 to $2,000. [View Examples] You’ll notice that cheap models are available, but presumably made with poorer quality materials and parts. The 12,000 watt generators are typically noisy and smelly, but work well for construction sites and short-term. Quiet multi-fuel generators are available for about the same price, but with less wattage. [View Examples]

Rather than having a generator on wheels, most home owners would consider having a home generator system installed. [Example] These are quieter more durable systems patched into your home electric system. [Learn More]

Solar with batteries require a significant expense and need more space compared to a generator if your goal is to have backup power for your entire home. A solar and battery system able to produce 12,000 watts might cost $24,000 if you use portable battery packs. There would be cost savings if you have a single unified system, but nowhere close to the cost of a hybrid fuel generator.

If your goal is to spend a bit more initially for your electricity, but work toward renewable, quiet, emissions free power, then solar may be a good choice for you.

For solar power to be practical, and have a shorter payback time, you would need a clear view of the sky (no shade) and have a good view of the sun throughout much of the day. Good installation locations would be a south-facing roof or side of home where panels could be mounted, or a big open yard. Having panels that move to face the sun would increase their efficiency.

Whether having a coal-burning power plant or large solar farm, with energy production, in general, it’s most practical to have housing and power stations in separate locations due to the space requirements, efficiencies of scale, and for solar there are location efficiencies. For example, it’s nice to have plenty of shade for homes to reduce cooling demands in the summer. Most people enjoy having trees and a well shaded home. People seek out and desire older neighborhoods with trees, streams, birds, squirrels and other wildlife. This desire competes with clearcutting all obstructions and installing massive solar panels.

Apartment, Condo, or Townhouse Dwellers

As described above, even someone owning a home with land may not have ideal conditions for solar power. If you are in an apartment, condo, or townhouse, your options for solar are probably more limited. You may not be able to use a gas generator at your home either.

In a serious extended power outage, you could have a set of solar panels and battery packs that you take to an open parking lot, park, or field. You can have a lunch picnic, or use your smartphone to catch up on emails while the battery packs charge up.

If your budget, power needs, and time constraints don’t allow for 3-4 hours of solar recharging, you could use a quiet generator to charge up your battery packs remotely, reaching about 80% power in about 2 hours using dual AC charging, then bring the battery packs back home. The dual AC charging is available on some battery packs allowing both USB-C PD and a Jackery or similar power cord.

Quiet Generators

Quiet generators are available for about $340 for a cheap unit [Example] or $1,200 for a very durable Honda system. [View] These are used at events and also by people camping or needing power in remote locations.

Quiet generators can run about 3 hours on full load, or about 8 hours on 1/4 load. The 1/4 load would be sufficient to simultaneously charge four Jackery units. So, in other words, you could charge four Jackery units in 2 hours to 80% to give you about 1,000 Wh of power (4 units of about 250 Wh each). The fuel tank of the generator could provide four sessions of charging. If you limit your power usage, you may be able to go a few days between charging sessions. If you need 1,000 Wh per day, then you’d need to spend 2 hours per day charging.

If you have an apartment with a deck that is south-facing, and are able to manually adjust the orientation of your solar panels every few hours to keep them optimized, you could generate quite a bit of electricity from home on days that are not overcast.

If you’re not a solar purist and are willing to use a mixed source of power, you could have a solar panel plugged into the primary charging port of your battery, and then use a USB-C PD cable from a generator or grid source. If you are pre-outage and just wanting to be charged up in the event of an outage, you can get a quick partial solar charge this way. Or use the generator with solar for faster charging during an outage.

Portable Power Packs

Small-scale inexpensive power packs are a good supplement or alternative to full-home systems. Rather than building an off-grid power system to serve an entire home, identify a few smaller essential electronic devices and appliances they may need during a few days without power.

All-in-one portable power systems can cost a few hundred dollars or more depending on their capacity. The battery pack includes a built-in charger and inverter (to convert from 12 volts to 110V AC).

Even if you are on the power grid and rarely lose power, having a battery system can be helpful for those rare occasions. Batteries are always required with a solar configuration to provide constant power during times when there is no sunlight. The constant power will last as long as your battery capacity allows.

Power Demand Scenarios

MINIMAL POWER NEEDS — The most minimal power backup system in an extended outage would be possible given the following conditions.

• CLIMATE — The temperature and climate are mild due to the time of year or your location, so air conditioning and heating are not needed.
• COFFEE — If you have bottled shelf stable coffee or can be without coffee or tea for a few days. Or, you have a gas cook stove for boiling water.
• COOKING — Many canned and shelf-stable foods do not need to be heated or cooked to eat. If you don’t mind eating room-temperature foods, or if you can use a small camping cook stove to warm food, then no high energy cooking appliances would be needed (microwave or toaster oven).
• FLOOD — There is no flooding that requires a water pump for your home or property.
• FOOD — You are willing to let your frozen and refrigerated foods go bad. You have sufficient canned and shelf stable foods for your needs over a few days or more.
• HUMIDITY — The humidity level is agreeable without needing a dehumidifier.
• INTERNET — You plan to use your cell phone for internet, email, and basic communications.
• MEDICAL EQUIPMENT — You do not need any medical equipment that requires electricity, like a CPAP machine.
• MEDICINE — You do not need any medicines like insulin that require refrigeration.
• WATER — You have municipal water (instead of a well) and/or have water saved up so that a power outage does not impact your water supply. You don’t mind bathing with non-heated water.

In a minimal power scenario, your primary use of solar and battery would be for some LED lighting, smartphone use, local radio, and perhaps some limited computer usage.

MEDIUM POWER NEEDS — Medium power needs would be similar to those listed above, with exceptions for your own unique situation. Here are some examples.

• CLIMATE — If it is summer and you need to have some fans running to cool your home this could increase your power needs. You can use small 5-watt USB fans to keep yourself cool at lower power without trying to circulate air in the entire room.
• FOOD — A small dorm-style low-power refrigerator can help keep some foods or medicines cold. Without using extra power for a defrost heating cycle, these smaller refrigerators might use 300 kWh per year. So, about 800 watts per day.

Whatever small exceptions you make to the “Minimal Needs” list, your power requirements will slightly increase the demand for solar panels and batteries. You may want to purchase properly-sized dedicated power packs for each appliance and device you plan to be using. This way, with each additional purchase of a power pack, you are planning accordingly and bringing additional appliances and devices online. A portable pack could be carried from one room to another to power a TV, fan, or other temporary devices in that room.

HIGH POWER NEEDS — For power intensive needs, a bigger investment would be needed. Depending on the situation, you may need several thousand watts of power per day. Some larger appliances can require bursts of energy that require very powerful generators or battery systems. For people wanting to deliver high power to their entire home, a transfer switch and critical loads panel would probably be needed. This requires an electrician and extra materials. For this level of power, usually a home generator is installed. [Learn More] Here are some examples of high power needs.

• CLIMATE — In extreme heat or cold, and air conditioner or heater may be required. These systems use a lot of electricity. Air conditioners might use 700 watts to 2,000 watts. Heaters use a similar amount of electricity. These usually do not need to be running constantly, but during a given day they may use several kWh by the end of the day.
• COOKING — A typical electric stove will use 1,200 to 3,000 watts when in use. If you cook 20 minutes three times a day, then that’s 1.2 to 3 kWh per day.
• FLOOD — If you’re experiencing a power outage due to a thunderstorm and excessive rain, you may have flooding and need a sump pump. These pumps require 1,000 to 3,000 watts when starting and then 800 to 1,000 watts to continue running. So, this is a very energy intensive requirement.
• FOOD — If you don’t want to have your refrigerated foods go bad, you will need a battery pack that can handle the energy requirements of a larger refrigerator that may use up to 2,000 watts per day.
• HUMIDITY — If you are in an area with excessive humidity, you will probably need a dehumidifier that could require 400 to 500 watts of power, and generally will keep running during the day. So, about 12,000 watts per day.
• WATER — If you have an on-demand hot water heating system, you’ll need many watts of power while using hot water. If you have a traditional tank system, you’ll need to keep the water hot throughout the day by periodically using a lot of electricity to heat the water in the tank. Heating with electricity is very demanding. If you have your own water pump, you will need signifiant power to run the pump.

These are a few examples. Looking at the full list of considerations, you can think through other options to fit your own needs.

Determining Power Supply Need

Based on the Power Demand Scenarios described above, you would want to determine what the maximum power requirement could be if your most demanding devices and appliances were running at the same time. Even if only for a short time, a microwave oven and stove might require several thousand watts. So, your battery pack or generator should be rated as able to handle that demand. This information about peak load (short-term) and sustained load is usually included when the specifications.

In addition to having a battery system to meet your peak load needs, you’ll want one with enough reserve long-term power to meet your ongoing needs.

Think through your average day, and how you use electricity. Here is an example.

MORNING — In the morning, you use the microwave oven, or stove, to prepare breakfast. If the stove is on for 30 minutes and uses 1,000 watts while it’s running, that would equate to 500Wh of electricity. If that’s the only electricity you use in the morning, you’d need a battery power pack capable of a 1,000 watt sustained load and able to provided 500Wh of electricity. Write that number down. Note that the 1,000 watt sustained load is different than the peak load is usually higher than the sustained load rating.

A battery pack that would meet those needs would be the ECOFLOW 1260Wh system with 1800 watt sustained output and 3300 watt surge capacity for about $1,100 to $1,400. [View] That power pack could handle the sustained load of 1000 watts. Since you use about 500Wh each time (every 30 minutes), and the capacity is 1260Wh, you could easily get two sessions of cooking from that battery pack. So, that could provide two days of breakfast preparation. You could purchase a high capacity battery power pack with similar specs and have that as your kitchen power supply.

You can quickly see how shelf-stable foods are an economical way to have food during a power outage, since they require no cooking.

DAYTIME — Let’s say you use your laptop computer for 8 hours each day, and it uses 50 watts while in use. That’s 400 watt-hours (Wh) of energy. The math here is fairly simple. We multiple 8 x 50 to calculate the watt hours of use over the 8 hour time period. We can use the same calculation for other devices you use during the day. Let’s say you use another 200 watt hours accumulated throughout the daytime hours with your other smaller devices. A battery power system like the BLUETTI Power Station EB705 for about $570 would provide 716 watt hours. [View] You could even consider two smaller portable power packs if you want the option of continually charging one while using another. The cost for power systems is usually about $1 per watt hour. The EB705 mentioned here is an exception and offers a bit more capacity than usually expected for the price.

EVENING — Your evening may include cooking another meal, and possibly watching TV. These tasks could require another ECOFLOW 1260Wh system with 1800 watt sustained output and 3300 watt surge capacity for about $1,100 to $1,400. [View]

BACKGROUND — You can calculate separately the background power usage. The background power usage is typically very high and very costly to maintain. This includes your furnace, air conditioning, hot water heater, sump pump, fans, lighting, and other items. Built-in ceiling lights would need to be powered through your home’s electrical system. In the winter, you may need heat tape for pipes that would otherwise freeze.

If you take a more sparse approach, and are able to adapt to a simpler life for a few days during a wide-spread outage, then a few power systems and a generator or solar panels may be sufficient. It’s convenient to purchase double the capacity of what you need. That way, some batteries can be charging (outside near the solar panels) while others are in use.

The Importance of Batteries

If you have a small generator or are using solar panels, it is important to have some way to store the power you are generating so you can accumulate power in a reserve.

Also, you will likely have appliances or electronics that need short bursts of much electricity. A microwave oven may need 1,600 watts of power for a few minutes. Instead of purchasing a 1,600 watt generator or 20 to 30 solar panels, having batteries to store the energy would allow you to have fewer solar panels or a smaller generator.

Full-Home Power Systems

A full-home power solution with solar and/or wind energy with long-term battery backup might cost $20,000 to $30,000 or more depending on capacity and what appliances are used. A 3-fuel generator could also be used for greater flexibility.

If a home home uses mostly gas for the stove, water heater, clothes dryer, refrigerator, and furnace, then much less electricity would be required. A full-home power system might cost $10,000 or less depending on capacity and what appliances are used.

If energy efficient appliances, electronics, and lighting are used, there can be a considerable reduction in overall cost.

Some people choose renewable energy for long-term savings of money. Others make the choice to reduce pollution or to gain energy independence. The specific needs and goals will determine what system is designed.

Benefits of Small Capacity Power Packs

A small capacity power system, like the Jackery Explorer 300 can be fully charged in 2 hours with a dual feed charging system. With a solar panel attached, the system serves as a continuous power reserve.

The cost of all-in-one battery packs (like the Jackery) will be about $100 per 100 Wh (or $1 per watt hour). So, the Explorer 300 (with 293Wh power) will cost about $300. With the 100W solar panel the cost is about $600 as shown below. [View Product Page]

A battery pack with about 1,000 Wh capacity will cost about $1,000. With two solar panels, the cost would be about $1,650. [View] Additional solar panels help reduce the charging time with larger capacity battery pack systems.

DIY Solutions

To make your own battery storage system, you would need a charger, an inverter, and the batteries. As explained above, portable all-in-one battery packs cost about $1,000 for 1,000 Wh of power storage. People reading this will immediately wonder why the cost is so high since high quality batteries might cost $1000 for 1,344 Wh [View Example] or sometimes $700 on sale at Costco. The portable all-in-one power systems include the charger, inverter, and some other nice features like power meters and adapters.

Small portable travel battery chargers will have a much higher cost per kWh. For example, the Anker PowerHouse 100 provides 97.2Wh for $200. [View]

Examples of Power Usage and Calculating Your Electric Needs

A traditional 100-watt light bulb would use 100 watts in an hour (100Wh), and could run for about 3 hours using the Jackery Explorer 300 power pack shown above. Modern LED light bulbs can produce the equivalent light output to a 100-watt bulb using only about 15 watts of power. [View Examples] So, an LED bulb could run for about 20 hours with an Explorer 300 power pack.

Energy efficient devices are ideally suited for using battery power. A typical smartphone charger might use about that same amount of power as the LED bulb mentioned above. If your phone can go from a 10% charge to an 80% charge very quickly, then you can expect many recharges.

A laptop computer might use 15 watts to 30 watts depending in the charging state. A more power hungry laptop computer might use 60 watts or more. A desktop computer during low power demand might use 100 watts or 400 watts under peak load.

Some devices need a lot of power for short periods of time. A toaster, water kettle, or microwave oven might use 1,000 to 1,500 watts when on.

Some devices need to stay plugged in and running almost non-stop. A dehumidifier may use 400 to 500 watts when running, and if it’s running all the time, that will accumulate a lot of electric usage in a day. At 500 watts, that’s 12,000 watts per day.

A refrigerator might use 100 to 200 watts while running, but will cycle on only infrequently when the temperature goes above a certain setting. So, while it’s “on” all day, the cumulative power used in a day would be much less than a light bulb left on all day.

A person can create a spreadsheet to calculate their overall power needs. Power meters can help more precisely measure power usage for each device. These typically plug into an outlet, and the device you are measuring plugs into the meter. [View]

Distributed Power

In a home, instead of having a single large battery pack, units could be placed throughout the home to provide sufficient power for the needs of each room.

For the same cost per watt-hour of power, a person could purchase three Explorer 300 systems rather than a single Explorer 1000. The benefit of three small systems is that you get three times the number of power outlets.

For rooms with large appliances, larger capacity systems would be required. For example, a refrigerator will demand more power. A 2,000 watt-hour (Wh) system would be needed to keep a small refrigerator running for several days.

Power Pack Manufacturers

The examples mentioned above are from Jackery, a California company. However, good options also exist from other manufacturers. Here’s a short list of some popular brands.

• Anker [On Amazon | Main Website]
• BLUETTI [On Amazon | Main Website]
• ECO FLOW [On Amazon | Main Website]
• GoalZero [On Amazon | Main Website]
• Jackery [On Amazon | Main Website]

Customer Service

Of the companies mentioned above, across their product line, you may find products with 85% or higher number of 5-star reviews, and tapering down to hopefully a small number of 1-star negative reviews. The negative reviews reflect that some people have had a bad experience with the product and/or the customer service.

These days “customer service” basically involves hiring an overseas call center of inexpensive people who answer calls or text chat. They have a card deck of possible questions and the boilerplate canned responses they will give. If you really get into trouble with a faulty product, or need help, you may end up being frustrated by the support available. Unfortunately it isn’t very different from other industries.

If it’s discovered that one of the companies above offers exceptional customer service, that information will be added to this report in the future. Until then, you can assume that the customer service will be average or poor.

There are some stories among the 1-star reviews that describe defective products being received, or products failing after a short time, and no assistance from the manufacturer being provided.

You may be able to get an extended warranty from the vendor where you purchase the item. Stores like Costco offer better customer service and easier returns. However, the Costco selection is primarily the Massimo brand which has horrible ratings for some of their products. [View Products]

DIY Home-Made Power Systems

If you choose to build your own DIY backup power system, it’s possible to find better quality higher capacity batteries, lower cost solar panels, more efficient faster charging systems, and more robust inverters. Those components would likely come with warranties from the manufacturers. You may be able to produce a lower cost per kWh system, but it would require some time and skill to create.

Factors Driving Demand

Here are some factors driving demand for portable power systems.

• The Van Life movement and the tiny house movement
• Wide-spread power outages due to natural disasters have prompted an increased interest in backup power systems.
• There have also been some grid failures due to technical problems or excessive demand.

Low-Tech or No-Tech Devices

If you need to operate for extended periods on limited power, think of ways to accomplish tasks without using electronic devices. For example, for task lists and notes consider using a pen or pencil and paper. Combine tasks that require electricity. Plan a time during the day to spend an hour on the computer and complete the tasks that require the computer. Prioritize tasks that require electricity and only do the essential ones. This is similar to driving an electric car very reservedly to extend the driving range.

Special Considerations — Cooling Under Heavy Load

Battery power packs generally have built-in fans for cooling under heavy loads. The active cooling fans use electricity which places more of a demand on your power reserve. So, instead of charging many devices at one time, it may be better to charge devices individually. As an example, the Jackery 240 system is rated at 200W maximum load. At about 100W the fans turn on to keep the power pack cooled. The fans are probably enabled automatically based on temperature. The AC plug on the battery packs will require an inverter that can generate extra heat. Charging the battery pack can also create heat. The most efficient use of the battery pack would be with the USB-A and USB-C ports which are DC power.

Laptop Computer Use

A laptop computer using USB-C might pull 30W to 60W power depending on the size of the computer. This is better than using an inverter to convert from DC power to AC 110V household power, then using a laptop power cord to go from AC 110V back to DC power. A laptop with USB-C PD (power delivery) will be the most efficient power connection.

More Resources and Reading

Here are some helpful resources.

• Global Solar Map [View]
• Learning Center at Northern Arizona Wind and Sun [View]
• Off Grid Solar Load Calculator at Northern Arizona Wind and Sun [View]
• Map of Solar Potential Energy — based on location with rooftop analysis [View]
• Rooftop Potential for Solar Energy [View]
• Solar Energy Resources — U.S. Department of Energy [View]
• Where Solar is Found and Used — U.S. Energy and Information Administration [View]