All about stand alone Solar power system for homes.

Off grid power system for homes.

Off grid power system using solar as an alternative source is becoming an increasingly popular choice for American homes. This is mainly due to the fact that many people now are looking to reduce their carbon footprint and are in favor of avoiding reliance on fossil fuels for eco-friendly living. Moreover, such a changeover would help them to assert their independence, as stand alone solar power system is totally independent of utility grids.

The off grid power systems are the perfect choice for remote rural areas or villages to provide continuous reliable power. They are most often used in faraway places where electricity is not easily accessible or where the connection fees of the grid power are higher than the cost of an alternative energy system.

In this post, I am going to give an overview of an off grid power system for homes using solar power.

What is an off grid power system?

‘Off the grid’ simply means that you’re no longer connected to the utility power grid supplied by power plants. Off grid power system is any setup that takes an alternative power source and converts it into usable electricity. These systems allow you to stay off the main power system that almost everyone connects to. Unlike a grid-connected power system, off grid power system fulfills the power needs of homes or business appliances without tapping into any networked power grids. The most common alternative power sources for off-grid power solutions are,

1. Batteries;

2. Generator;

3. Solar;

How off grid power system with solar power work?

Off grid power system with solar power or a stand alone solar power system consists of an array of solar panels, which absorbs sunlight and convert it into electricity which is then stored in a battery bank. A stand alone solar power system for homes operates using the stored energy in the battery bank via an inverter that pulls the DC power stored in the batteries and converts it into AC power for use in homes and other structures. At night, and during overcast days without the sun shining, all necessary power is provided by the batteries. The off grid solar panels keep the battery bank charged on a daily basis. The number and area of the panels depend on the amount of electricity required to be produced each day. For people with little or no access to the grid, such off grid power system helps in continuous and uninterrupted power supply.

Stand alone solar power system design –  major points to consider

1. How much power do you need each day

The most important step towards planning an off grid power system is to figure out how much power you will need per day from your system. Solar panels are only capable of producing power during the day when there is the sun. It is, therefore, paramount to understand that your power requirement for 24-hour use has to be covered by the average amount of energy that the solar panels collect from the sun during the day. The most important challenge in off grid power system design is to balance your energy consumption with the supply of energy by the system and you cannot do that without first knowing how much energy you need each day. The easiest way to know your energy consumption is to look at your monthly energy bill and estimate your daily consumption. You could also calculate your energy consumption by knowing the average watts of each device you use and for how many hours you will be using them on average.

2. How big battery bank you will need

Once you know how much power is required per day you are to work out the size of the battery bank (a battery bank is essentially a group of batteries wired together) needed for an off grid solar system to store this necessary power. The stand alone solar power system for homes is limited by the power generated by the solar panels throughout the day unless you have a backup generator or a secondary power source. But putting in a system of batteries to store the required output of the sun involves more than meets the eye. Before installing a battery bank, much thought, care, and calculation will be necessary to ensure that the system chosen will fully meet your energy needs in a cost-effective manner. You are to consider how many days you will want to power your home if there is no sun. The days of storage you desire, multiplied by the power (in watts) you need per day, will give you the required capacity of your battery system. You can calculate the size of the battery bank in amp-hours from the amount of power you will need.

3. The number of solar panels you will need for stand alone solar power system

The peak sunlight hours of your particular area will have a direct impact on the energy you can expect from your stand alone solar power system. Peak sunlight hours describe the intensity of sunlight in a specific area. Peak sun hours occur when the sun is highest in the sky. Your average daily energy usage is your target daily average to calculate your solar panel needs. Each solar panel generates a limited amount of electricity. The number of panels you will need in your solar array depends on how much power you need to generate. Once you know your average power requirements per day you can calculate the number of off grid solar panels needed from the daily peak sunlight hours for your area (A peak sunlight hour is typically defined as an hour of sunlight that offers 1,000 watts of photovoltaic power per square meter)

You may also like to read: How solar panels work step by step

4. Selecting a Solar Charge Controller 

Good solar charge controllers are crucial for keeping the batteries healthy and ensuring the long life of your battery bank. The solar charge controllers (also known as battery regulators) limit the rate of current being delivered to the battery bank to control the pace at which the batteries are to be recharged. Solar charge controllers protect the batteries from overcharging. If you have a battery-based inverter, chances are that the charge controller is integrated with it.

5. Selecting a solar Inverter

Another crucial piece of electronic equipment in your stand alone solar power system for homes is the DC-AC solar inverter. If you are running only DC loads straight off your battery bank, there`s no need for an inverter. However, nearly all indoor electrical home appliances run on alternating current or AC. If you are powering AC loads, you will need an off-grid inverter to convert the Direct Current from the batteries into an Alternating Current for your appliances. Electrical current flows from the solar panels through the solar charge controller and the battery bank before it is finally converted into alternating current by the off-grid-inverter. Unlike standard models, off-grid inverters are also capable of converting AC power to DC power. This is good for effectively managing solar panel energy output and battery storage. How big your inverter should be will depend on how many watts of power you need per day.

6. Backup Generator 

Even though a backup generator is not always required, it is a good idea to have a secondary power source as it would increase the reliability of the power supply. By installing the generator you are making sure that you are not solely dependent upon a stand alone solar power system for your power requirements. Without a backup generator, it would require a lot of storage capacity and a very large solar panel system involving a significant financial investment in order to prevent total power loss in the event of a winter snowstorm or an extended period of overcast days without the sun shining. Modern generators can be configured to start automatically when the solar array and /or battery bank doesn’t provide sufficient power. The typical output of the backup generators is AC, which can be sent through the inverter for direct use, or it can be converted into DC for battery storage.

You may also like to read this related post: Grid tied solar system – why it is homeowners’ popular choice

Frequently asked questions

Before I conclude let me also address some of the queries related to the off grid power system for homes.

How many solar panels do I need to power my house off-grid?

The number of solar panels you will need in your solar array depends on how much power you need to generate. Once you know your average power requirements per day you can calculate the number of off grid solar panels needed from the daily peak sunlight hours for your area (A peak sunlight hour is typically defined as an hour of sunlight that offers 1,000 watts of photovoltaic power per square meter)

What is the best off-grid power source?

Solar power is the most popular available option when it comes to the off grid power system.

How much does it cost to build an off grid power system?

The prices of off-grid solar kits that can power an entire home range from $12,000 to $50,000.

What are the biggest disadvantages of Solar power?

Here’re the major disadvantages:

1. The initial cost of a solar system is quite high;

2. Solar power is Weather-dependent. During cloudy and rainy days, the efficiency of the solar system drops;

3. Storage of Solar Energy is expensive;

4. Solar panels use a lot of space;

You may also like to read this related post: Solar Residential System – an easy guide for home solar system planning

Conclusion

The idea of going for stand alone solar power system independent from any electric utility grid is no doubt an attractive one. Many homeowners have chosen this route in search of eco-friendly living, independence, sustainability, and cost savings. If energy independence, stopping blackouts, or eliminating electricity bills is the main reason for your going for an off grid power system, your decision may be right. However, one should keep in mind the following important points before deciding to quit the grid:

a. Costs & payback

Before you go for off grid solar system you should judge whether going off the grid is worth it financially. While quitting the grid may mean that you are going to be free of electricity bills and associated price fluctuations but that doesn’t mean your energy will be ‘free’ of cost. This is because you have already incurred substantial capital costs associated with installing the new stand alone solar power system. Therefore, investing in a stand alone solar power system for your home may only be worth it if you plan to stay in your home for long enough to offset the capital costs over the years with your monthly costs which are much lower than the power company’s electricity bills.

 b. Availability of roof space to mount solar panels

For most homes, especially those in an urban or semi-urban area, perhaps the biggest limiting factor on whether a solar system for a home can go off-grid, is the amount of available roof space (or yard space) on which to mount the solar panels. If your roof is small you may only be able to fit a modestly-sized solar panel array. Therefore, before going for off grid solar power systems it needs to be ensured that sufficient roof space is available in your home to mount the full array of solar panels, unless your home’s energy consumption is extremely low, or you’re willing to sacrifice some comforts by going for a smaller system.

c. Running costs of the system

In addition to the initial capital investment for the stand alone solar power system, there will also be occasional maintenance costs that are necessary to ensure that the system operates optimally.

Normally solar panels come with a 25-year standard warranty. But batteries and inverters may have to be replaced every 5-10 years depending on the warranty of the devices. Additionally, if you have a backup generator, you will also have to pay for its fuel. Besides this, when you go for off grid power system, maintaining your power supply becomes your responsibility. Regular service from a professional person is, therefore, essential because, in case of something goes wrong with your home solar power system and you face difficulties in running your backup generator, you may be left without electricity until it gets fixed.

d. The value of your property

Should you decide to sell your home after going off the grid, your prospects will be markedly different than if you had maintained a grid connection. While an off-grid home may have more appeal to some buyers, there are many buyers who may not share the same view, and hence it may take a longer time to sell your property. There’s also the question of the age of the solar system at the time of sale. The potential buyers moving into an off-grid home solar power system would expect many years of maintenance-free operation ahead of them as opposed to ending up with a system that they know they’ll need to replace a great deal in the next few years.

You may also like the post: Facts about Solar Energy