Can I Combine Mono and Poly Solar Panels?

The two most popular solar panel types are monocrystalline and polycrystalline, or mono and poly for short. A question that beginners often ask is, can you combine the two? Can you install them in one solar array? The answer yes it is possible, but you should not do it.

You can combine mono and poly solar panels in an array, but they have to be in separate strings. Installing the panels in the same string could cause problems because their specifications are not the same.

What Happens When You Mix Monocrystalline and Polycrystalline Solar Panels?

Monocrystalline solar panels – including the Renogy 100W Panel – are more efficient than polycrystalline. If you put both in the same string, solar power output and performance will suffer.

Monocrystalline solar panels produce higher current and voltage than polycrystalline. If you put a polycrystalline and monocrystalline panel in a single string, the system will use the lowest voltage.

A string is the number of solar panels connected in a series. Suppose you have a 200W monocrystalline panel at 25V and a 20V 200W polycrystalline pane. The system will use 20 volts to produce power.

Amps x volts = watts, so the lower the voltage the less watts produced.

The same applies to the amps or current. If you have an 8A monocrystalline panel and a 5A polycrystalline panel and install them on the same string, the system will use 5A.

Again, amps x volts = watts, so the lower the amps the less watts produced.

Efficiency Comparison

Monocrystalline solar panels are also more efficient than polycrystalline. If you combine the two in a string, performance and solar production takes a hit.

Efficiency determines how much sunlight a solar panel can turn into electricity. Because of the way solar power works, not all sunlight is converted.

The best solar panels have an efficiency rating of 20% to 23%, though it is getting better all the time. 23% does not sound high, but back then it was only 15%. The HQST 100W Solar Panels are examples of high powered PV modules.

Monocrystalline solar panels have a higher efficiency rating than polycrystalline. If you combine a 23% rated mono with an 18% poly, the array will not reach maximum output.

The best results comes from combining similarly ranked solar panels. Pairing it with a low efficiency solar panel might drag the entire array down.

Do not confuse efficiency rating with output. Wattage output is determined by the weather, environment, design etc. A 100W solar panel might not reach the maximum 100W output due to any of the factors mentioned. But its efficiency rating is just one aspect.

The higher the efficiency rating, the more sunlight the solar panel can convert. Whether the panel reaches its maximum rated output depends on numerous variables.

The point is, monocrystalline solar panels have a higher efficiency rating. Pairing it with a low rated polycrystalline panel is going to waste its potential.

How to Properly Use Monocrystalline and Polycrystalline Solar Panels Together

You can use monocrystalline and polycrystalline solar panels at the same time, but they have to be in separate strings. Each string must have its own MPPT charge controller.

You can set up a solar array so there are two strings, one with polycrystalline solar panels, and the other with monocrystalline. When their respective charge controllers are ready, the system can run.

Under this set up the solar array is going to work. There are some reasons you may want to do this:

• Compare polycrystalline and monocrystalline solar panels and determine the difference in performance.
• You already have one panel type and do not want to get rid of them.
• Want to test the two types for efficiency.

While this configuration is going to work, there are some things you need to keep in mind.

• The solar panels on the same string must have similar parameters and specifications. The LSC, VOC, VMP, LMP etc. have to be an exact match.
• If you have 3 monocrystalline solar panels in a string but their LSC (short circuit current) are dissimilar, the output will be restricted to the lowest current. The same applies with polycrystalline.

This is another reason why you should avoid mixing solar panels with different watts. Varying solar panel sizes have different specifications that affects the output.

To summarize the main points.

• You can only use polycrystalline and monocrystalline solar panels if they are in separate strings.
• All the panels in the same string must have the same electrical specifications.
• Each solar string must have its own MPPT controller. Do not use the same controller for each string because it is going to use the lowest parameters in the system.

Differences between Polycrystalline and Monocrystalline Solar Panels

Monocrystalline and polycrystalline solar panels share some properties, but there are distinct differences between the two.

Both are comprised of solar cells and convert sunlight into electricity. The difference is how polycrystalline and monocrystalline solar panels transform sunlight into direct current.

Monocrystalline solar panels are comprised of one silicon crystal. This is what gives mono panels their black hue. The single silicon crystal results in higher efficiency and greater reliability.

Polycrystalline solar panels consist of different silicon which gives it a bluish tint. Due to the various silicon used, the cells are not as effective as monocrystalline solar panels.

Head to Head Comparison

Monocrystalline solar panels are superior to polycrystalline. They are more expensive, but it is more effective and converts solar energy at a higher rate.

The following is a direct head to head comparison of monocrystalline and polycrystalline solar panels.

Lifespan. Solar panels are good for many many years depending on the warranty, but monocrystalline is more durable. Majority of solar panels have a 25 year warranty. After 25 years the efficiency drops by 10% to 20%. Monocrystalline lasts longer and with a lower efficiency drop.

Performance. As mentioned above, monocrystalline solar panels are more effective when it comes to producing solar energy. This is important if you have limited space on your house or RV. You want to maximize performance and this is one instance when monocrystalline solar panels are ideal.

Reliability. A lot of this comes down to the manufacturer. But monocrystalline solar panels use superior technology. This makes a huge difference in terms of results and output. Polycrystalline are also good but not on the same level.

Practicality. Solar panels weigh 40 lbs. each and measure 5.4 x 3.2 feet. Unless you have a large house or RV, space will be at a premium. This is another advantage for efficient solar panels. In these cases, a high rating, high wattage monocrystalline solar array is the best option.

Durability. Solar panels are exposed to heat, cold, rain, snow and other environmental elements. Both monocrystalline and polycrystalline solar panels are built to withstand these. But just like with almost everything, you get what you pay for. The more expensive panels are usually the most durable.

So Which is Better?

So which should you choose? All things considered monocrystalline is the better choice. It is a good long term investment and pays for itself with reliable performance.

Monocrystalline solar panels are ideal for homes and RVs. They are the best option for large off grid systems and if you plan on going solar for the long term.

Polycrystalline panels are acceptable for small loads. They are also ideal if you are on a budget. Make sure though that the panels you buy are made by a reputable manufacturer and has a good efficiency rating.

Tips For Using Monocrystalline and Polycrystalline Solar Panels

• If you are new to solar power, plan ahead. What will you use solar power for? For how long? What is your budget?
• If you are going to use solar to power small loads, polycrystalline solar panels will be sufficient.
• Think of the long term. If you are going to use solar power to run most of your appliances, consider investing in high quality monocrystalline solar panels.
• Use a high quality MPPT charge controller for each solar string. This is to ensure the right amount of power goes into the battery bank.

Conclusion

So to summarize the main points, you can use monocrystalline and polycrystalline solar panels if their specifications are similar. But usually they are not, and it is just more practical to use one type. if you have to combine these solar panels, make sure they are on separate strings.