What to Look for In Off Grid Solar System Packages
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If you have contemplated installing an off-grid solar power system, you have probably searched online for information. It’s likely left you feeling utterly confused at the ridiculously large variety of everything sold under the name of solar power kits.
On the one hand are basic $1000 kits that include a solar panel or two, a tiny inverter, and some cables and connectors. On the other hand are complex, full-fledged systems with dozens of big and small components and a price tag of tens of thousands.
While it is easy to get lost in the sea of options, a slightly technical understanding of your own requirements and a basic understanding of solar power packages and their components and specifications can help you feel confident in making a perfect choice.
Steps in Picking the Right Off-Grid Solar System Package
1. Understanding Specifications
If you were about to buy a car, it would help to spend some time familiarizing yourself with specifications, such as engine capacity, brake horsepower, and fuel economy, to help you understand which model is more suited to your needs.
Similarly, different components of a solar power system have different specifications, and it is essential to understand what they mean if you want to choose the right solar system package for your off-grid requirements. Let’s take a look at these specs:
a) Power (W)
In physics, power is simply the rate at which work is done. So, an athlete running faster is consuming more power than someone slower than they are.
Power is measured in watts and tells us how much energy something is consuming or generating per hour. For example, a solar panel with a 200W power rating produces 200W (every hour), while a TV set with a 200W power rating consumes 200W of power (every hour).
Different electrical appliances have different power ratings, and your solar panels and batteries must be capable of providing the total power consumed by all the appliances you will run at any point.
b) Energy (Wh)
Often confused with power and used interchangeably (wrongly), energy is the total power consumed over a certain period, such as in a day, month, or year.
Energy is an important factor in load calculations because getting only power consumption is incomplete information when designing a solar power system. Since energy is a product of power and time, its unit is watt-hours (Wh). Most batteries available in the market today specify their energy capacity in Wh.
c) Current (A)
Electric current is the flow of electrons from point A to B or in a circuit that facilitates the transmission of power. Current rating is important in solar system specifications since it helps select the correct size of cables, correct charge controller, etc.
d) Voltage (V)
To define voltage in simpler terms, one can say that it is the force with which current travels or power is transmitted.
All electrical devices have a specified voltage rating, and when connecting things, it is important to match their voltage ratings. For example, when connecting solar panels and batteries to a 24V inverter, the panel array rating and batteries rating should also be 24V.
2. Understanding Your Requirements
Getting an off-grid solar system package should be as easy as buying a TV. Unfortunately, that is not the case, and you have to spend some time learning how to choose wisely.
When it comes to solar kits, there is no one-size-fits-all. The first and most important selection criterion is how much power you need from your system and when you need it.
One way to calculate this is to find the power rating (W) of every appliance you have and the hours (h) of operation of each, then find the energy consumption (W x h) for every appliance, and sum it up for the total energy consumed.
Here’s an example:
|Sr. No.||Appliance||Watts (Power)||Duration of Use (hours)||Energy (watts x hours)|
Another option is to use an online load calculator, which has the power consumption values of several appliances pre-fed into it.
Example of Online Load Calculator
Once you have the total energy consumption in Wh, divide by the number of sunshine hours per day at your location, and you will have your required solar panel rating.
For example, if your location receives an average of 5 hours of sunshine daily and your total Wh consumption per day is 5000, then you will need
5000 Wh ÷ 5 h = 1000 W solar panels
Next is a simple calculation for batteries. Since you’re building an off-grid system, you will need batteries, but, the battery does not need to store every Wh of energy produced by the panels. A considerable amount of the energy generated by panels is consumed instantaneously during the day, while the consumption during darker hours varies from person to person. For instance, if you need about 60% of your energy overnight, you can choose a battery with an energy capacity that is around 60% of your calculated daily consumption value. In our example,
60% x 5000 Wh = 3000 Wh battery capacity
Similarly, when selecting an inverter, choose a power rating that is slightly higher than the size of your solar panel, such as a 1200 W inverter in this example.
Lastly, you will need a charge controller, which optimizes the charging of the battery. Based on your inverter’s voltage rating, choose a controller that has a similar voltage rating (12V/24V) and a current rating that is slightly larger than your system’s current rating (total amperage of your solar panels)
Another way of ensuring that the system is right for you is looking for a section in the product description that says something like, “What can you power with this?” This section usually appears on the seller’s website and often outlines the types and quantity of devices that you can run using that particular solar kit. Here’s an example from a well-built solar kit:
What Can Your Solar Kit Power?
3. Comparing Parameters
Calculating the size of your solar power system is only half the battle. Once you have noted the specs, you still need to choose among the myriad options available in the market today. Not all solar power systems of the same capacity are the same. Some might produce significantly less power if the component efficiencies are low. Some might have poor build quality, or some might have too few features for the cost.
Here’s a quick list to help you decide what to look for in an off-grid solar power system from the features point-of-view:
Monocrystalline solar panels
Solar panel efficiency has constantly improved since its invention, but the last two decades saw large technological leaps that took the efficiencies of panels from less than 15% to well over 20%.
The more efficient a solar panel is, the less space it will occupy. Among the major types of panels in the market, monocrystalline silicon panels are rapidly gaining popularity because of their higher efficiencies compared to multi-crystalline panels.
Just a few years ago, bulky lead-acid batteries were the norm for off-grid solar systems. They were not only difficult to handle but also required regular maintenance.
In recent years, lithium-ion batteries have become mainstream, thanks to their notably higher energy density, which makes them much lighter than lead-acid batteries.
But the advantages of Li-ion batteries are beyond just weight. Most of them are highly efficient, meaning you lose very little energy when charging or discharging the battery.
Even in Li-ion batteries, we recommended going for Lithium Iron Phosphate (LiFePo4) or LFP batteries, which offer strikingly long life (thousands of lifecycles), much better fire resistance, and higher current rating.
Suppose you have narrowed it down to a few contenders with similar price points, one of which gets to become your off-grid solar power system. All the specs and major features such as panel type and battery type are similar, how do you choose one?
At this stage, we look at what a component can provide above and beyond its basic role. Many inverters/generators come with several useful ports, such as an RV plug, wireless charging pads, etc.
Some companies offer solar panels that have integrated mounting stands, saving you the hassle of fabrication and mounting structures.
Other things to look for are the weight of the inverter/battery, the build quality of components, etc. Last but not least, you should receive a wiring schematic and even an installation guide that guides you step-by-step in the entire connection and installation process of the solar system package you have purchased.
4. Optimizing Consumption to Optimize Size of Solar System
Prices for solar equipment have plummeted over the past few years, and going solar is easier than ever. Despite that, off-grid solar power systems still require a sizable investment. A wise way of minimizing the cost of a solar power system is to optimize power consumption.
For example, replacing a 300 W air conditioner with a 50 W fan reduces energy consumption by a factor of 6. For an operating time of 5 hours, the AC would use a staggering 1500 Wh, and a fan will use 250 Wh. This approach not only reduces the size of solar panels required but also the battery capacity. It is one of the most decisive factors in the pricing of the system.
Other tweaks include using LED lights and as much natural lighting as possible.
Off-grid solar system packages are becoming wildly popular, thanks to how much financial and ecological sense they make, plus their ability to power virtually anything anywhere. As a result, many companies have launched off-grid solar power kits, and it is more difficult than ever to choose the perfect kit per your needs.
The main steps to choosing the right kit for yourself include understanding the basics of a solar PV system, calculating your energy requirements, and understanding and comparing key features.