Investing in a solar power generator today is worthwhile to green energy consumers. Having a backup source of electricity is arguably essential to our productivity in this digital era. Some might even go far as to say that it’s already a basic necessity, like WiFi in a cafe.
The adoption of solar power generators, portable power stations (PPS), and battery energy storage (BES) has risen exponentially in the past decade. Economies of scale, insane cost reduction, and an appealing value proposition all contribute to the growing number of users of this modern technology.
NOTE: In this article, the terms solar generator, solar power generator, and PPS refer to a BES device that can accept solar power from PV panels.
However, not everyone knows how to choose and wire solar panels for their needs. This problem is often frustrating and costly, which can prevent interested green energy users from taking the next step to integration.
This is understandable.
Dealing with solar operating principles and steep learning curves is intimidating—especially when you’re new to solar energy.
In your journey as a green energy consumer, you will inevitably deal with challenges and imperfections when using solar power generators and PV panels like:
“Why is my solar panel not injecting its rated power into the solar generator?”
“Why is my solar generator saying that my solar input is either overvoltage or overcurrent?”
“What do solar panels connected in series and parallel mean?”
We promise to answer all those questions in this article with sample demonstrations. You might also realize why some people prefer to purchase solar power generator bundles rather than buy components separately to save money. Keep reading to know which one works better for you.
How to Select Solar Panels for Solar Power Generators (Criteria)
What you need depends on your lifestyle and what you’ll use it for.
Opinions vary when it comes to selecting solar panels for solar power generators. In our opinion, solar power generators are for on-the-go individuals who need electricity 24/7 in different situations.
With this in mind, we think that aside from price, your top two priorities are portability and compatibility when choosing your solar panel.
Portability
When you invest in solar panel portability, you get convenience. The panels are small and lightweight which makes them easy to transport.
For example, look at the specifications of a standard 200W and a portable high-efficiency solar panel.
|
High Efficiency Panels |
Standard 200W Solar Panel |
|
|
Weight |
10.4kg / 23 lbs |
7kg / 15.5lbs |
|
Dimensions |
55” x 28” x 1.5” |
90” x 21” x 1” (unfolded) 24” x 21” x 1.5” (folded) |
|
Foldable? |
No |
Yes |
|
Output Voltage |
18V |
20V |
|
Output Current |
11A |
9.9A |
Sometimes, the price difference between a standard and a portable solar panel means no drilling on RVs, getting solar power while relaxing under the shade, and easy maintenance - not to mention a grateful lower back.
Solar Panel Compatibility
Solar Panel Compatibility is also something that most beginners overlook when it comes to solar power generators. You can’t just mix and match components from different brands. Much like the accessories of an iPhone are not compatible with Android, there are also components of solar panels which are not compatible with others.
Knowing that this problem exists can help you be more mindful about your purchase, especially when choosing to buy it as a bundle or in separate parts. Don’t worry though, we’ll introduce you to some of the common connectors/terminal types.
MC4
MC4 Terminals are commonly found on traditional unfoldable solar panels. You can distinguish positive terminals by their red color while the negative terminals are black.
Anderson
Anderson terminals are commonly found in solar power generators with solar panel compatibility. Modern PPS with extremely fast charging capabilities need wires that can accommodate high currents, and the Anderson cables address this requirement. A suitable Anderson cable can handle at least 30A of current.
MC4 to Anderson Adapters
Most e-commerce sites offer their own bundles where the solar panels come with Anderson terminals. If you choose to purchase the PPS and solar panels separately, however, you might end up with a PV panel that has MC4 terminals.
This isn’t a big deal since there are MC4-Anderson adapters available for purchase. Oftentimes, PPS developers even include this with your solar generator purchase to avoid the hassle of buying one online.
What Size of Solar Panels Do I need?
What size of solar panels do you need? Standard portable panel ratings fall between 20W and 250W. Choosing the right one depends on your solar power generator.
For example, if you have a PPS that can accept 800W solar panels, we suggest getting four panels rated at least 200W. You could get eight 100W generators, but that can be a handful when setting up your solar system.
How Many Solar Panels Do You Need for Your Solar Power Generator?
Knowing how many solar panels you need for your solar power generator depends on their power and energy ratings.
Determine Solar Power Generator Input Ratings
The limiting factor that will dictate how many solar panels you can have is the power input ratings of your solar power generator.
Let’s stick with our sample Solar Power Generator with a Power Input Rating of 800W. This is the maximum power it can receive from a PV panel.
“So it’s simple. I can buy eight 100W solar panels or four 200W solar panels, then plug and play.”
Unfortunately, it’s a bit more complicated than that.
Recall that Power (P) is a product of Voltage (V) and Current (I) (P=VI)
Aside from power input ratings, your solar power generator has maximum voltage and current input ratings.
The input voltage and current ratings in our sample product are 12-100V and 12A, respectively.
When selecting solar panels and wiring them in parallel/series, these values will be your reference.
“Parallel? Series? What’s that?”
Don’t worry; we’ll cover them in a bit.
Determine Solar Panel Output Ratings
At this point, we will figure out which solar panels can satisfy the Power, Voltage, and Current criteria of our PPS.
|
Solar Power Generator Specifications |
|
|
Maximum Power |
800W |
|
Maximum Voltage |
100V |
|
Maximum Current |
12A |
Now, let’s have a look at some sample 100W and 200W solar panel specifications.
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Sample Solar Panel Specs |
||
|
Description |
100 Watt Panel |
200 Watt Panel |
|
Max. Power Output |
100 W |
200 W |
|
Open Circuit Voltage |
24 V |
24V |
|
Short Circuit Voltage |
5.23 A |
10.46 A |
|
Maximum Power Voltage |
20 V |
20V |
|
Maximum Power Current |
5 A |
10A |
Based on the table above, we can begin speculating how to connect solar panels to produce 800W while meeting the solar power generator’s voltage and current limits.
How to Wire Solar Panels for Your Solar Power Generator
At this point, some of you might be making a face.
“Ew. What’s with all the nerdy stuff? These people are just showing off!”
Nope, not exactly.
To appreciate those figures we gave you, let’s look at some of the basics regarding wiring solar panels.
Solar Panel Terminals
Solar panels all come with wire terminals, as we mentioned earlier. The most common e-commerce sites nowadays are the MC4 terminal types. Positive terminals have red line markings (see the left cable in the figure above). Negative terminals, on the other hand, are pure black.
How to Wire Solar Panels in Series
Wiring solar panels in series involve connecting the first PV panel’s negative terminal to the second panel’s positive terminal. Then you connect the second panel’s negative terminal to the next. Keep repeating this process until you have a “string” of solar panels connected. There’s only one path for the current to pass through and if one-panel malfunctions, the other panels/terminals also turn off.
Wiring solar panels in a series string involve connecting one panel's negative terminal to another's the positive terminal.
Wiring solar panels in series add the solar panels' voltages, but the current rating is the same.
WARNING: Don’t connect solar panels in series if they have different current output ratings.
So, if we take our sample panels and connect them to form an 800W system, we will have the following results:
|
Solar Panel Size |
Quantity |
Total System Voltage |
Total System Current |
Total System Power |
|
100 W |
8 |
8 x 20V = 160V |
5A |
800 Watts |
|
200 W |
4 |
4 x 20V = 80 V |
10A |
800 Watts |
Based on the table, we can conclude that connecting four 200W solar panels in series will satisfy all the conditions of our PPS. On the other hand, eight 100W solar panels in series will satisfy current and power limits but exceeds the PPS voltage ratings (160V>100V).
Table: 100W Solar System will cause overvoltage
|
Specifications |
200W Solar System |
100W Solar System |
|
Power Input |
800W = 800W |
800W = 800W |
|
Voltage Input |
80V < 100V |
160V > 100V |
|
Current Input |
10A < 12A |
5A < 12A |
So does this mean we are limited to the 200W panels? Not exactly; we’ll show you how to connect eight 100W panels later correctly.
How to Wire Solar Panels in Parallel
Wiring solar panels in Parallel is easier to remember since you will be connecting the same terminals (both positive and negative). In actual practice, this is usually done with an MC4 branch connector (see the right image below).
And how do wiring solar panels in parallel affect voltage, current, and power?
A system with parallel-connected panels will have the same voltage, but all current ratings are added.
WARNING: Don’t connect solar panels in parallel if they have different voltage output ratings.
Using our sample panels in a parallel connection, we will have the following results:
|
Solar Panel Size |
Quantity |
Total System Voltage |
Total System Current |
Total System Power |
|
100 W |
8 |
20V |
5A x 8 = 40A |
800 Watts |
|
200 W |
4 |
20V |
10A x 4 = 40A |
800 Watts |
Table: Parallel configuration will cause overcurrent for both 200W and 100W solar systems.
|
Specifications |
200W Solar System |
100W Solar System |
|
Power Input |
800W = 800W |
800W = 800W |
|
Voltage Input |
20V < 100V |
20V < 100V |
|
Current Input |
40A > 12A |
40A > 12A |
Checking the solar system outputs above, we can see that connecting 200W and 100W panels in Parallel will cause an overcurrent in our solar power generator. Therefore, there will be compatibility issues in our setup if we use a pure parallel connection.
Series and Parallel Wiring Combination
So far, we’ve only introduced pure solar panel series vs. pure parallel case studies. In reality, solar installers use a combination of both to meet the system requirement of either the energy storage system or the inverter.
100W Panels
For example, if we want to meet the PPS requirements using eight 100W solar panels, we recommend making two groups, each with four 100W solar panels in wired series:
|
400W PV System: Four 100W Panels in Series |
||||
|
Solar Panel Size |
Quantity |
System Voltage |
System Current |
System Power |
|
100 W |
4 |
20V x 4 = 80V |
5A |
400 Watts |
Next, you connect these two 400W PV Systems in parallel to get the following output:
|
800W PV System: 2 Groups of Series-Connected 100W Panels wired in Parallel |
||||
|
Solar System Size |
Quantity |
System Voltage |
System Current |
System Power |
|
400 W |
2 |
80V |
5A x 2 = 10A |
800 Watts |
Eight 100W solar panels in a series-parallel wiring configuration to meet the solar power generator input requirements.
200W Panels
Earlier, we concluded that connecting four 200W panels in series will already satisfy the operating conditions of our PPS.
Let’s do a little thought experiment to see if we can implement a series-parallel configuration using 200W panels that will satisfy the operating criteria of our solar power generator.
Before you read further, challenge yourself and imagine how many solar panels you will connect in series before merging the series string PV systems in Parallel.
The only option, in this case, is a 2-by-2 setup wherein you connect two 200W panels in series before connecting the 400W systems in Parallel. The resulting 800W system will have 40V and 20A output.
This setup isn’t compatible with our solar power generator since it exceeds the current limit.
Four 200W solar panels wired in a 2x2 series-parallel configuration will exceed the current limits of the solar power generator.
Therefore, while it may be cool to do series-parallel combinations, it is not always the solution to solar compatibility problems.
Conclusion
Hopefully, that blew your mind—in a good way. There are endless possibilities when wiring solar panels, especially now that you know how to combine series and parallel setups. From here, your choices depend on your goals, like low current or low voltage systems.
Can I Use Different Solar Brands on One Solar Power Generator?
Yes, you can use different solar brands with some exceptions. You cannot connect solar panels with varying voltages in Parallel. You also cannot connect solar panels with different currents in series.
Remember, dealing with electricity introduces a lot of safety hazards. Consult an expert if you are planning to DIY. This is also a reason why some choose to go with solar generator bundles.
Final Thoughts
There you have it! The basics on choosing and wiring solar panels for your solar generator. By now, you should have more confidence in your solar generator decisions. After all, a well-planned purchase doesn’t only feel empowering; it also saves you time and money.
