Sunday, September 24, 2023

# How Many Batteries For A 400 Watt Solar System

DIY 400 Watt 12 volt Solar Power System Beginner Tutorial: Great for RV’s and Vans! *Part 1*

To figure out what type and how many batteries you need, you must first understand some details about home batteries themselves. There are 3 main factors that will influence the solar panel owners decision about a home battery:

CapacityThe capacity is the total amount of electricity that the battery can store. This is measured in kilowatt hours and represents how big the battery is. For example, Tesla Powerwall 2 has a 13.2 kWh capacity. Check this video to know more about kilowatt hours.

Power RatingThe power rating for a solar battery is the amount of electricity that can be delivered at once. This is measured in kilowatts and directly impacts that quantity of electricity that can be drawn from the battery. So, if you want a battery that can power many of your household appliances and devices at once, you will need a high power rating. Depth of Discharge The DoD is simply the amount of charge that was used by a battery. For example, if the battery has a 30% charge left, then the DoD is 70%. The reason why the DoD is important is that due to the chemical composition of some home batteries, you must ensure the DoD never gets to 100%. This means that for most home batteries, you will need the capacity to be slightly larger than the maximum amount actually needed.

## Will A 400 Watt Solar Panel Run A Refrigerator

A 400 watt solar panel will run a fridge

A 400 watt rated panel will run a medium size refrigerator, combined with a 120Ah lithium iron phosphate battery and a 500 to 600 watt inverter . If a 400 watt solar panel produces about 584kWh/year and a refrigerator needs between 2ookWh to 400kWh/year, then it seems a comfortable match.

Lets take a closer look assume the fridge in question consumes 400kWh/year.

A fridge runs continuously day an night, but solar panels only produce power during the day. This means some kind of battery is needed to power the refrigerator during the night equivalent to about 200kWh/year or 50% of the energ needed.

In daylight hours the solar panel has to generate 200kWh per year to power the refrigerator and an additional 200kWh to charge the battery back up for running during the night.

If there are not too many cloudy days a 400 watt panel should generate enough energy to run a medium sized fridge.

## What Can I Power With A 400

You can power a refrigerator for 24 hours with a 400w solar panel!

Lets see how:

A 400 watt solar panel can power most of our common household appliances. Ranging from a light bulb to a TV or computer.

Their lifespan will largely depend on the battery associated with your 400-watt solar panel.

The sun is a natural source of energy its power greatly fluctuates depending on the weather conditions and the time of the day.

Solar panels are usually paired with batteries. They will store your energy and act as a buffer in case of a cloud passing by or any reduction of power output.

The batteries together with an inverter will provide the clean and stable power that is needed for our appliances.

Weve seen that a 400w panel can produce 2 kWh/day storing your energy in batteries is a must for a stable power output over time. During battery storage and inverting, you will lose some of the produced energy. However, you can still hope to use at least 85% of what you initially produced.

A medium-size refrigerator with a freezer will consume around 1.4 kWh/day, still less than what your 400w panel can produce in one day.

But remember, we are working with natural elements here. So on a cloudy and/or windy day, the output of your solar panel wont be enough for the refrigerator to run for the entire day.

Below, you can find examples of appliance running times. They are running on a 400w solar system paired with a 1 kWh battery pack

 Appliance

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## What Is The Difference Between Series And Parallel Solar Panels

Connecting 400 watt solar panels in series or parallel determines voltage and current

If you want to use two 4oo watt solar panels to double your power output, be careful how you connect the two together.

In parallel youll double the output current to 19.72 amps, so you might want to upgrade to a solar charge controller with a higher current rating.

In series the current stays the same, but the voltage doubles to 98.6V, so youll have to upgrade to a solar charger model that will accept a higher voltage.

## Why The Upgrade To 400 Watts

We found that 200 watts of solar power was not quite enough to power a few of our larger electronic devices like for instance Annes 21 iMac computer or our 43 LCD TV. Both can draw anywhere from 50 to over 100 watts each. This is fine and dandy when the sun is strong and high in the sky, but as soon as it is gone we are dependent on our battery bank and whatever suns energy was stored in there. The large computer and TV can be easily run off my Champion Generator, but it sure would be less of a hassle and quieter to have the solar panels and 12-volt batteries power them instead.

Two other reasons for the upgrade are cloudy days and short winter days. Doubling our solar power might allow us to get by with just solar energy where last year the generator had to be fired up. Also, with these issues in mind I upgraded my battery bank from two big 6-volt golf cart style batteries to a bank of four.

Boondocking almost exclusively from December to May on 200 watts of solar and 232 ampere hours of battery capacity was learning experience for me. It showed me that around 400 watts of solar and 464 AH of battery capacity should be the sweet spot for our particular energy needs. Rather than conserving power like mad, we can be a little more liberal with things and maybe run some just for fun stuff.

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## How Many Batteries Do I Need For A 400 Watt Solar Panel

It depends on how much power you need to use when the sun goes down. If you are off the grid or on a mobile home, your backup power supply should be enough to cover up for the solar panel in case of cloudy or rainy days.

A 100ah 12V battery is equal to 1200 watts. Even if the battery is lead acid with a depth discharge of 50%, that is still 600 watts. A fully charged 100ah battery can cover up for your 400W solar system in case of a cloudy day.

Ideally you should let the solar panels charge the battery all day. Run your appliances from the battery , and since it is being charged, it will not run out of power. At sunset you still have a full powered battery available for use.

If a 400 watt solar panel system is sufficient for you during the day, it will be too for the night as well. So a 100ah battery should be good enough for a typical RV.

Keep in mind that most RV solar setups have additional power sources such as a generator or offshore power. If you have one, you donât need to rely solely on the battery. However it is still a good idea to have at least as much power as the solar panels in case of emergency needs.

## What Can A 400

The standard setup for a 400-watt solar panel includes the following:

· 400-watt solar panel

· Proper wirings for the connections

· Standard wall outlet for your appliances

However, to know if this system is suitable for your application, you need to write down your needs and see if a 400-watt solar panel is enough to keep everything running.

Each off-grid solar system application will use utility-specific appliances with differing wattage specifications. So, before you start buying parts for your solar panel system, make sure you list out on paper exactly what you will be plugging into your electrical source.

Once youve determined that your 400-watt solar panel and battery system will support your applications, you can be confident about spending the money. Remember that planning saves money!

Contents

• 13 The bottom line
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## What Size Inverter For A 400 Watt Solar Panel

As a general rule, an inverter should be sized closely to the actual power rating of the solar panels. This is because inverters are most efficient when fully loaded. Most inverters have a continuous load rating and a surge power rating. A 500 watt pure sine-wave inverter would be a good choice.

Your first thought might be that its obviously 400 watts, but a good ruel-of-thumb is to over-estimate the inverter rating.

A fridge or freezer with a running watts between 40 to 100 watts might run in full sunshine, but the power drawn by this type of appliance is not constant.

Motor surge current can be 3 times more than its running current, and as a fridge compressor stops and starts in normal operation the power demand will fluctuate.

The 400 watt solar panel may well supply this load, but perhaps not if the panel isnt operating at maximum output solar panels dont output their maximum power for much of the time.

Power output reduces due to a host of factors time of day, cloud coverage, seasonal changes, temerature and dirt.

A battery is essential to supply power if the solar panel power drops

How big should inverter be for 400 watt solar panel?

#### Solar system PV losses

Its a sad fact that every part of a solar circuit loses some power. In total, a domestic solar power installation loses up to 23% of the rated power output!

## How To Calculate Solar Battery Bank Size

DIY 400 Watt Solar Power System Beginner Tutorial *Part 2*

Our solar battery bank calculator helps you determine the ideal battery bank size, watts per solar panel, and the suitable solar charge controller. If you choose to build an off-grid system, it’s important to size your system based on the month with the least amount of sunlight. That way, you will have access to a sufficient amount of energy at all times. There are several steps to follow when calculating your solar battery bank. Let’s review them below:

## How Long Will It Take A 400 Watt Solar Panel To Charge My Battery

A full charge takes a couple of hours with a lithium battery but up to 12 hours for lead-acid batteries.

Forget about AGM, deep cycle, valve regulated, or other types of lead-acid batteries, they are all based on the same outdated technology and are definitely not the best for solar charging.

Lithium batteries are your best choice. Lead-acid batteries might require 12 hours or more to reach full charge due to technological limitations, whereas lithium batteries can be charged in just a few hours.

They also exhibit a high tolerance towards sharp power input variations, e.g. when a cloud suddenly shadows your panels.

A long lifespan, lighter weight, and higher power output make these the game-changer that we have been waiting for

They might require a bigger investment at first, but their durability and ease of use largely surpass the lead-acid technology you wont regret it.

Dont forget that your charging abilities depend on the instant power output of your 400 watt panel.

Maximize the circuit current and voltage by optimizing the exposition of your solar panel to direct sunlight.

Charging will be faster around noon when the solar irradiance is at its maximum.

## How To Calculate The Energy Requirement Of Your Refrigerator

The first step in determining how much solar power youll need to run your refrigerator is to figure out how much energy it consumes.

#### Direct method

You may pay less attention to the provided information, but practically every manufacturer places an energy rating sticker on a sign. The sign is usually placed on the refrigerators door.

#### What is the size of a solar panel for a refrigerator?

This information is expressed in kWh and ranges between 200 and 600 kWh. Depending on this figure, you will get the running watts of your refrigerator in any unit.

If the annual energy rating is 365 kWh, for example, you can divide 365 days by the watts. The outcome is 1-kilowatt hour each day. Also, if you want to calculate the watt per hour, divide 1 kWh by 24 hours to get 0.042 kW/h.

#### Indirect method:

If you cant discover the above-mentioned indicator, look for the quoted power rating instead. This message is normally placed next to the serial number of the product. Watts are used to measure it.

Another option is to multiply the voltage by the number of required amperes for the refrigerator. As a result, youll get the power figure, which could range from 100 to 400 watts or more. Then youll need to know how many hours per day you want your appliance to run and multiply that by the power to get the final value.

This number will decide how big a refrigerator youll need and the battery bank size youll need for your solar system.

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## How To Calculate Battery Capacity For Solar System Off

 Last year during holiday period with some friends we planned to go to 5 days trekking in the wilderness. No food or water was available during the trip. So we had to figure out how much we had to carry with us. Not carrying enough food and water could be risky because we could run out of supplies. Carrying too much food and water would put too much weight in our backpack. It was not an easy decision. Finally, we decided to take high energy bars that would help us to have enough food with less weight. Maria and Paul decided to take canned food because they only planned to stay with us for 3 days.

A similar problem can arise when you design a solar system. Your battery must be big enough to supply your power needs but also small enough to reduce the total cost of the system.

How to calculate battery capacity for your solar system? You need two key pieces of information: energy consumption and days of autonomy

Follow these procedures when calculating the required battery capacity of your solar system.

## Watt Solar Panel How Many Amps

The maximum currents of a 400 watt solar panel is known as Imp and is indicated on the specification sheet by the supplier. Average current is 9.5 amps DC for a 400 watt solar panel with Voc 49 volts. The equivalent current to run AC appliances is about 3.3 amps.

When converting to AC current, inverter losses of at least 10% should be deducted.

If Vmp is 42 volts, we should reduce the DC current valuer by the ratio of the DC to AC voltage. A simple looks like this:

AC current = DC current x 42/120 = 9.5 x o.35 = 3.325 amps AC

Inverters are not very efficient if not loaded to 100% and drops sharply as the load decreases. Lets assume 95% if fully loaded. This depends on the inverter size and in practice, the load wont remain constant so the efficiency will change dynamically.

Final AC load current =3.325 = 3.16 amps AC

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## How Long Will It Take A 400

A standard 400-watt solar panel will charge a single 200 amp-hour deep cycle solar battery in 4 to 6 hours. This is dependent on the hours of direct sunlight.

If there are fewer hours of direct sunlight, the battery will take longer to charge. These values apply to Gel type, AGM, and flooded batteries. Because the power depletion is only 50%, you only charge 50% of the battery in 4-6 hours.

For lithium-ion batteries, you can safely discharge the battery by 80% of the total charge. These batteries will take all day to recharge on a single 400-watt solar panel.

## What Is The Difference Between Mppt And Pwm Solar Charge Controllers

The cheapest and most basic type of solar charge controller is called Pulse Width Modulation .

Basically, it chops up DC current into square-shaped packets and adjusts to voltage level by changing the width of the pulses.

PWM controller varies the length of output voltage pulses to match voltage required by the load

An MPPT controller is more expensive and operates in an entirely different way.

I previous said that the Maximum Power Point of any solar panel is when the loads internal resistance matches that of the panel this is how the MPPT controller works.

The controller searches for and matches the impedance that will give the maximum power output for the prevailing sola rpanel conditions.

It always delivers the maximum charge current that the solar panel can produce.

My own tests have shown that an MPPT charge controller can deliver up to 40% more power than PWM I recommend using them in general.

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## Is It Necessary To Use A Battery To Run The Refrigerator

Solar panels can only work when there is sunlight, which means that they can power your refrigerator during the day. But how will it be powered when it gets dark? To solve this problem, youll need to install a battery that stores the energy so that the refrigerator can run all night.

So, how do you pick a battery? Is the battery powerful enough to operate the refrigerator at night?

You should verify that your battery capacity is sufficient to power your refrigerator for the entire night. For diverse uses, batteries with voltages of 12v, 24v, and 48v are usually available. You may use a 12V battery to power your refrigerator.

Then well need to know how many amp-hours the battery has. It displays the battery capacity, or how many amperes the battery can give for your refrigerator and how long the supply will last.

We can assume that the battery can give electricity for a whole day to ensure that your refrigerator runs smoothly on solar power.

For example, if your refrigerators running watts are 200, you may compute the total watts per day by multiplying 200 by 24 hours. As a result, the overall wattage is 4800 Wh .

The total amperes can then be calculated using the following formula: 400Ah = 4800Wh x 12V. So youll need a 12V, 400Ah battery in theory. However, you can double it to account for battery tolerance and power backup: 400Ah multiplied by two equals 800Ah.

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