10 Best Design Of Off Grid Solar System Guide 2021

10 Best Design of Off-grid Solar System Guide 2021


What is an off-grid solar power system?


Off-grid solar power system is a system that uses solar energy (green and clean energy) to provide stable power to AC devices when there is no grid or grid is only used as a backup.


Building an off-grid solar power system is a difficult task that many people want to but don't know how to start. It is common for us to design and build a complete off-grid solar power system in areas where there is a shortage of electricity or for the concept of environmentally friendly, but how to build it reasonably? This article will use the simplest language to help you answer various doubts about building off-grid solar power system. Rico Chen, founder of CNBOU, engaged in the off-grid solar power business for ten years, we have collected a lot of information in the sales of about 15000 inverters each year, and finally presented a set of relatively reasonable off-grid solar power system solutions.

Note: This guide mainly describes solar panel, Mppt solar charge controller, off-grid power inverter and battery, does not include cables, connectors, brackets and some auxiliary materials. 

Our guide is divided into the following two types of off-grid solar power system:
Small off-grid solar power system (300W-3000W)
medium and large off-grid solar power system (5000W-45000W)

Small off-grid solar power system (300W-3000W)

If you want to build a low-cost off-grid solar  power system to meet the daily electrical appliances, such as monitoring device, LED lights, electric fans, rice cookers and refrigerator, this program will be suitable for you. It is popular in some areas with shortcomings or unstable power in Asia, the Middle East, Africa and South America, or in some Tiny houses in North America and Europe. 

1. Design guide for 300W small off-grid solar system (12V battery system)


A. 1*300W Mono/ Polycrystalline solar panel.
B. 1*30A Mppt solar charge controller.
C. 1*100AH 12V Gel or 1*50AH LiFePO4 battery.
D. 1*300W pure sine wave inverter.

How much power does a 300 watt solar panel produce?

With an average daily sunshine of 5 hours at full load, this system can generate approximately 1.5kWh, calculate the power generation of this solar panel according to the local sunshine situation. Without using the load, the 12V 100AH battery can be fully charged in about 4 hours. Assuming that our system is used for outdoor monitoring, usually a set of monitoring power is 20W, which also means that the power consumption for 24 hours  is 0.48kWh. Because the inverter has a conversion efficiency, we calculate it at 88%, the 20W monitoring consumes about 0.55kWh per day. If you are in a place where there are 10 hours of daytime, this system will fully meet the daily monitoring work and even can support more than 48 hours in  the absence of any sunlight. If you need a longer time or larger load, you can increase the battery capacity. And the cost of this system is very low, suitable for off-grid solar power system with only low-cost budgets.


2. Design guide for 600W off-grid solar power system (12V battery system)


A. 2*200W Mono/ Polycrystalline solar panel.
B. 1*40A Mppt solar charge controller.
C. 4*100AH 12V Gel or 1*100AH LiFePO4 battery.
D. 1*600W power inverter.

How many batteries do I need for a 600 watt solar system?

In a 12V system, if the solar panel is 400W, the maximum current is 40A when charging the battery, so we choose 40A Mppt solar charger controller in this configuration. If you use GEL or AGM battery with 0.1C charge and discharge current, to make the battery have a better service life, that means you need to use the battery larger than 12V 400AH. And the maximum continuous output current of 12V 600W power inverter is 60A, it needs 12V 600AH battery based on the 0.1C calculation. Under normal circumstances, it is impossible to use a 600W inverter to run at full load for a long time. The occasional high current output has little effect on the battery, so the service life of the lead-acid battery used in the system can reach 5 years. But if you use battery with 100AH or 200AH, it will shorten the service life of the battery, which is normally less than 2 years.

For lithium battery, the charge and discharge current is normally 0.5C-1C, which can match the system with 12V 40AH-100AH lithium battery.  Although the price of lithium battery is more expensive than lead-acid battery, the cost of lithium battery is even lower for long term use, because lithium battery usually has a build-in protection board or BMS, LiFePO4 battery can be cycled more than 2000 times, even if it is cycled once a day, it can reach more than 80% of the power after 6 years of use.


  


3. Design guide for 1kw off-grid solar power system (12V or 24V battery system).


A. 2*300W Mono/ Polycrystalline solar panel.
B. 1*60A @12V battery or 1* 30A @24V battery Mppt solar charge controller.
C. 6*100AH 12V ( 3*100AH 24V) Gel or 1*100AH (2*50AH) LiFePO4 battery.
D. 1*1000W inverter.

What can a 1 kW solar system run?

1 kW off-grid solar power system is very popular in the market, CNBOU configures more than 10000 units of 1kW pure sine wave inverter for 1kW system, which has good value, and the system is also very simple.  1000W pure sine wave inverter can run two fans with 75W, five LED lights with 20W, one television with 75W, and one more rice cooker with 600W, which you meet the need of a small family. If you have a refrigerator with lower than 100W, BP series of  1000W inverter can run normally. The peak power of the refrigerator is between 400W-800W, it can run easily for BP series 1000W inverter. And the 1kW off-grid solar power system is the most popular for the off-grid solar power system enthusiasts.


    

4. Design guide for 2kw off-grid solar power system with batteries (12V or 24V battery system).


A. 3*300W Mono/ Polycrystalline solar panel.
B. 10*100A @12V battery or 1* 50A @24V battery Mppt solar charge controller.
C. 10*100AH 12V ( 5*100AH 24V) Gel or 1*200AH (2*100AH) LiFePO4 battery.
D. 1*2000W pure sine wave inverter.

How many solar panels do I need for a 2kW system?

It depends on whether your system is running at a full load for a long time or  using it occasionally, just like: induction cooker or kettle, etc. Because if we only use several minutes or less than half an hour, we don't need to match with solar panel with same power. Solar panel with 900W can generate electricity 4.5kWh in 5 hours, the electricity consumption of 2kW pure sine wave inverter in an hour is 2kWh, if just use occasionally, it will be enough. Of course, you may say I have many LED lights used in the off-grid solar power system of the farm, that you may need configurative 6*300W Mono/polycrystalline solar panel. Meanwhile, you need to replace the Mppt solar charge controller that is twice as large. Here we highly recommend Mppt solar charge controller. Although PWM is cheap, its efficiency is 20%-30% less than that of Mppt, which will lead a waste of your solar panel.


    


5. Design guide for 3kw solar system with battery (24V or 48V battery system).


A. 6*300W Mono/ Polycrystalline solar panel.
B. 1*80A @24V battery or 1* 40A @48V battery Mppt solar charge controller.
C. 8*100AH 24V ( 4*100AH 48V) Gel or 1*300AH (3*100AH) LiFePO4 battery.
D. 1*3000W pure sine wave inverter.

How many batteries do I need for a 3kW solar system?

1.Lead-acid battery for 3kW solar system, in the statement of 24V, 3000W/24V=125A, if it needs to stay in the best condition, and run at full load for a long time, we suggest you to use 125A*10H=1250AH, 13 batteries in parallel. If  itis 48V, it needs 14 batteries, 7 in parallel and 2 in series. Such configuration can satisfy the running of this system, and is good for the service life of the battery. If you occasionally use with 3000W load, just 1000W in normal, that will be fine to configure  according to 1000W system. It has little effect on the service live of battery when in a short time use. Why we need such large battery system? If the charge and discharge current of the lead-acid battery is 0.1C, (most charge and discharge current of lead-acid battery is 0.1C on the market), the charge and discharge time is 10 hours, it is its own original design. We have tested, if charge the 100AH battery with 40A Mppt solar charge controller, the battery is exhausted and unusable in less than 45 days.

2.LiFePO4 battery for 3kw solar system, LiFePO4 is different from lead-acid battery, it is designed with charge and discharge current 1C, (also have charge and discharge current 0.2C-0.5C on the market). If you don't need to run at 3KW for a long time, LiFePO4 battery is very suitable for the system. Its weight and volume is much smaller than lead-acid battery. 1C to charge or discharge battery for one hour  will not effect the service life of the battery. LiFePO4 battery can cycle more than 2000 times, even if it is cycled once a day, it can also be used for more than 6 years and keep its attenuation less than 20%. In this system, we just need 150AH 24V (75AH 48V) LiFePO4 battery, which will save space and lower the cost.


  

It depends on how long you require your system to run on batteries without any assistance? There are many types of 5KW off grid solar inverters on the market, what we see are usually  two types:

1. Solar panel input is less than 5000W
2. Solar panel input is greater than 5000W.


1. Off-grid solar power system with solar panel input less than 5000W (48V battery system)

Assuming your solar panel is 3000W, the electricity generated is 3kWh per hour, which means that you need 48V60AH battery to store. If your location has 5 hours of sunshine, the electricity generated every day needs 48V300AH battery to store, that is 15kWh, when the off-grid solar power system you design runs for a day, when the battery is full, the energy obtained from the solar energy will be directly converted into AC power for the load. The battery is always in a full state and is used at night when there is no solar energy. 15kWh, supplying 1000W load can be used for 15 hours. The cost of this system is low and practical. If it is a configured lithium iron phosphate battery, the life will be very long.

2. Off-grid solar power system with solar panel input greater than or equal to 5000W (48V battery system)

This kind of design is generally for commercial or industrial use, which uses a lot of electricity during the day and basically does not need to be used at night. We designed 5000W solar panel input, which can generate 5kWh per hour, and most of the power is directly converted to the load, and a small part is stored in the battery. Calculated on a daily basis for 5 hours of sunshine, it can generate 25kWh of power a day, and what capacity of the battery you need depends on the load usage at night, but it produces 5kWh of electricity per hour, even if you use a 1C lithium iron phosphate battery, it needs at least 48V120AH.

Summary: what capacity the battery needed for an 5kw off-grid system? In addition to calculating the usage of the load when there is no solar or no grid, it also needs to calculate the power to charge the battery per hour to achieve the best state of the battery. If the capacity of the battery is too small, it will be damaged very quickly.

When you need to install off-grid solar system on your boat dock, I think it is a professional work. Boat dock is usually built without grid, if we need to apply for a transformer to power a separate boat dock, it will be very expensive to achieve. Therefore, choosing an off-grid solar system for free, eliminating the need to build a transformer to provide grid (about $20,000) and not having to pay for the usual grid, is a good solution for your boat dock.

Off-grid solar system on boat dock from a solar energy system can power the following:

●Boat lifts
●Lighting fixtures
●Air conditioner
●Washing machine, microwave oven
●Charge to Mobile phone, laptops, tablets
●Power tools
●Party accessories like speakers, TVs

Many owners of boat docks wonder if off-grid solar system will cover all their use cases or not. The answer is yes. This off-grid solar system can work all year round.


How much power can you generate on your dock with off-grid solar system?


It depends on how many Watt of solar panels you need to build. Boat dock owners usually only go to enjoy the boat dock life on the rest days, and hardly use electricity on weekdays, only to power some Camera or LEDs, and this can be hardly calculated, because only a small amount of electricity is needed. If we can use off-grid solar system to generate 2kWh per day, we can store 10kWh from Monday to Friday, and 10kWh is enough for two days of electricity, and of course off-grid solar system can also generate 4kWh on every Saturday and Sunday.

Assuming 5 hours of sunshine per day in your local area, it would only take 400W of solar panels to generate 2kWh of power and store 10kWh of power, need 200AH of batteries for a 48V battery system, providing a large enough inverter to run most electrical equipment, like a 5000W pure sine wave inverter. The following list mentioned (because to ensure that there is enough power generation and the whole solar system will have some conversion loss, we will design a larger device):

●300W MONO or Poly solar panel *2
●20A Mppt solar charge controller (12V/24V/48VDC Auto)
●51.2VDC 200AH LiFePO4 battery
5kw pure sine wave inverter

Such a system configuration takes low cost and can be used for more than 6 years. The service life of solar panel, Mppt solar charge controller and pure sine wave inverter can reach more than 10 years.

CNBOU's Mppt solar charge controller and 5kw pure sine wave inverter combination has been in operation for more than 50 off-grid solar systems on boat dock in the US for more than 3 years.



If you need to set up an off-grid solar system, you need to understand your needs first. How much load do you need to power, and how long do you need this system to work for you when there is no external environment (no grid and no solar) to provide power? Only when you understand your needs can you design an off-grid solar system that meets your expectations, and we present here two options to choose from.

1. Separate off-grid solar system
A. Solar Panel
B. MPPT solar charge controller
C. Battery
D. DC to AC power inverter

Separate off-grid solar system consists of solar panel, MPPT Solar charge controller, battery and pure sine wave inverter. The cost is low and the combination is flexible.

This is a very flexible composition and your off-grid solar system will be very flexible and ready for future expansion. If you increase the load, then you need to increase the solar panels, at this time if the MPPT solar charge controller is not enough, you just need to replace a MPPT Solar charge controller. of course, if you feel that the pure sine wave inverter is not enough, you can also directly replace the pure sine wave inverter, no need to replace the whole system, or you add a MPPT solar controller so that it is connected in parallel It is also feasible, although not very recommended, but in order to save costs, is a way to balance. Of course if you add a load that can have independent lines, you can also add a pure sine wave inverter directly, but it requires independent lines and cannot be used in parallel.

2. All-in-one off-grid solar system
A. Solar Panel
B. Off grid solar inverter
C. Battery

An integrated off-grid solar system consists of solar panels, an integrated off-grid solar inverter and batteries. The cost will be higher, but easy to install.

Off grid solar inverter is a combination of MPPT solar charge controller and pure sine wave inverter into a stand-alone solution, which is very easy to install and will have more functions. The downside is that it will be less scalable and cannot be expanded, and if your system changes, the entire off-grid solar inverter will need to be replaced.


If you live in a city, building a completely self-contained off-grid solar system may not seem particularly appropriate, either for economic reasons or for environmental reasons.  Maybe you don't have enough roof space to build a solar panel for your entire home, and since the electricity supply in cities is stable and relatively inexpensive, building such an off-grid system may not seem to meet the goal of cost savings.

If you are in a rural area, or in a less developed area, it is possible to build a stand-alone off-grid system to meet the electricity needs of your house. We first need to calculate the electricity consumption of your whole house, if it is a new house then you need to calculate the power and average time of use of all the electrics, if it is an old house then you can check your electricity bill to see how much electricity you use each month. Considering that the electricity comsumption is relatively high in summer and winter (mainly air conditioning), we recommend you to ask a professional EPC to do the calculation while spring and fall are relatively less. To create a stand-alone off-grid solar system to meet the year-round electricity consumption of your entire house requires accurate calculations. In addition to calculating electricity consumption, we also need to consider the weather and climate of your location. The sunshine is different in each region, and the energy produced by the solar panel will be very different. Although we know that the electricity generation in summer is always greater than that in winter, we have to calculate according to the sunshine situation and install enough solar panels to supply the electricity demand of the entire house. Once we have the exact amount, we can measure if you have enough space on your roof. When considering the installation of solar panels, it is very important to install them in a south-facing direction, as the sun shines much more often in the south than in the north.

After we confirm the size of the solar panel to be used and the installation space, we select the appropriate MPPT solar controller and sine wave inverter. We suggest to use an MPPT solar controller that 20% larger to facilitate the use of later expansion. The inverter needs to be larger than the peak power, for example, you have air conditioner, refrigerator, these are inductive loads, instant start power is very large, choose the right power inverter will make the system more stable operation.

A house runs on solar power alone is completely achievable. After we understand the most basic calculation, it is still recommended to hire a professional installation company to build the independent off-grid solar system.

It depends on how big an off-grid solar system you are going to build, usually an off-grid solar system consists of the following parts:

· Off-grid solar inverter
· Battery
· Solar Panel
· Solar panel bracket
· DC and AC circuit breakers
· Connectors and cables

Of course, this is only the cost of hardware, if you need to ask the installation company, it may also needs to spend some fees.

If you need to build a small off-grid solar system, you only need 1000W inverter, and our latest Hestia series 1000W off-grid solar system kit will be very suitable. It integrateds with a 40A MPPT solar charge controller, 1000W pure sine wave inverter and 12.8V 100Ah LiFePO4 Battery. The 40A MPPT solar charge controller can support a maximum of 600W solar panel input in the state of a 12VDC system, and our unique design will allow you to additionally expant 3 sets of the 12.8V 100Ah LiFePO4 battery. The total battery capacity will reach 5.12KWh.

Hestia series off-grid solar system is currently the most suitable system for DIY, the build-in 40A MPPT can support 12VDC/24VDC/48VDC battery system, and the maximum power of the inverter can be matched with a 2000W pure sine wave inverter. If you have enough hand-on ability, we can configure a 48VDC 2000W pure sine wave inverter, so that the entire system will become a 48VDC system, the build-in 40A MPPT solar charge controller will support the largest solar panel input to 2000W. And for the build-in 12.8V 100Ah LiFePO4 battery, we have reserved an interface, which can connect 3 BL-1280 battery in series externally to make the whole system achieve 48VDC. BL-1280 battery can support a maximum charging current of 1C, if you have a 2000W solar panel, it will fully charge the battery in 2.5 hours. 2000W pure sine wave inverter can meet most loads, this is completely a DIY design, and teh combination you like will give full play to its perfromance. Even if you need to upgrade in the future, you just need to repurchase the inverter module.

We will end here with 300W-5000W small off-grid solar power system, these come for a large number of actual customer cases we have collected and then recommend. If you want to know more about the information, please contact us. Also if you have batter suggestion, please let us know, and let's contribute to the development of off-grid solar power system.


Author: Rico Chen By CNBOU



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