Choose the Perfect Solar Panel: 60 vs 72-Cell Complete Guide

72-cell is about a foot taller, and they cost a bit less to mount in large-scale applications. However, both 60-cell and 72-cell solar modules use the same cell technology, and they work out to the same price from a cost-per-watt perspective. Either option can be used in residential or commercial installs – the ideal choice depends on your array layout and space constraints where you will mount your system.

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But when it comes down to choosing your solar modules, the number of cells included in the panel isn’t the most important factor. Cost, aesthetics, warranty, efficiency, and durability should all be taken into account when selecting the right PV panels. In this article, we’ll discuss some differences between 60-cell solar panels and 72-cell solar panels as well as their pros and cons.

Background about solar modules

Solar modules are made from blocks of silicon ingots that are cut into wafers. Those are the squares that you see that make up the modules.

Each solar cell (monocrystalline) produces about 0.55 volt. Multiple cells are wired in series, plus to minus, to make a solar module. Wiring the cells in series increases the PV panel voltage to a usable level. The more cells that are wired in series, the higher the voltage.

12V and 24V nominal solar modules

For example, if 36 cells are wired in series, you get an output of about 19.8 volts. Remember that solar first got its start in the battery-based off-grid world, where PV panels were built to charge battery banks. The 36-cell solar panel that output 19.8V is perfect for charging a 12-volt battery bank. Since you need a higher voltage to charge a battery, a 36-cell solar panel is called a 12-volt nominal panel, it’s designed to charge a 12-volt battery.

Likewise, a solar panel with twice as many cells, 72 cells, outputs about 39.6 volts. And it’s great for charging a 24-volt battery bank. So it’s called a 24-volt nominal solar panel.

If you have a 48-volt battery bank, since there are few companies produce 48-volt solar panels, in that case, you need wire multiple PV panels together in series, either 4 12V nominal panels or 2 24V nominal panels, which will efficiently charge a 48V battery bank even in very hot weather when the voltage of PV panels drops low.

Grid-tied solar photovoltaic system

So all was well and good with figuring out what nominal voltage solar modules to use. Just make them match the nominal voltage of the batteries. But along came two different technologies that added an interesting twist to the next.

The first was grid-tied solar with a grid-tie inverter, you could now convert the DC voltage from the PV panels directly into AC to power your properties, no batteries required. So the restriction of 12V or 24V and 48V went away. This allows solar panel manufacturers to use however many cells they want to.

Today for solar modules up to above 320 watts, the industry settled on 60 cells. Using terminology from the battery world, that’s a 20V nominal panel. With an Open Circuit Voltage or Voc of around 41 volts. Grid-tied solar systems are able to string up to 20 pieces (/41/1.21=20) of 60-cell solar panels in series and stay within the electrical code restriction of staying under VDC, even when considering the cold temperature. If they were using 24V 72-cell solar panels, they would be limited to only 16 pieces (/49.5/1.21=16) in series in cold environments.

PWM & MPPT Charge Controllers

The second change was still in the battery based world, with solar charge controllers that are used to manage to put the power from the PV panels into the batteries. Early on, the pulse width modulated (PWM) charge controllers had to match the nominal voltage between the photovoltaic panels and the battery bank. Maximum power point tracking (MPPT) solar charge controllers came onto the scene and allow you to take a higher voltage input and reduce the charge controller voltage output to correctly charge a battery bank while increasing the output current, eliminating any power loss due to forcing PV panels to operate at whatever voltage the battery bank was actually at.

This opened up the possibility to use any cell count solar modules, as long as the voltage was higher than the battery bank. Although some specialized charge controllers allow you to charge with a lower voltage solar panel, most of them require a higher voltage.

Since 60-cell “grid-tie” solar panels are so common now, their price per watt has dropped much lower than the standard 12V nominal panels, making them an attractive option to charge battery banks. Just remember, you have to use a more expensive MPPT charge controller to do it.

Also, note that you cannot use a single 60-cell solar panel to charge a 24V battery bank. You need at least 1 72-cell solar panel or 2 60-cell panels in series to have a voltage high enough to charge 24V. If you’re in a cold environment, most 150V MPPT solar charge controllers limit you up to only 2 72-cell panels in series, but you can do up to 3 6-cell panels in series and still stay within that 150-volt limitation.

Advantages of higher wattage solar modules

So, what about the 72-cell 24-volt solar modules for grid-tied systems? Well, technology and codes move forward, and newer revision of the electric codes now allow for volts strings for grid-tie commercial and utility-scale systems.

Also, grid-tie inverters are getting bigger and bigger, allowing for extremely high wattages is getting inverted. Since watts equals volts times amps, a way to increase the wattage of a solar panel is to increase the voltage by adding additional cells.

The cost of installing 60-cell vs. 72-cell panels may also vary a bit for your installation. 72-cell solar panels tend to be cheaper to install on a large scale, which is why they’re more common for commercial applications. Because each panel has more solar cells, you can typically install fewer panels to generate the same amount of electricity. Fewer panels mean less racking is necessary, which helps cut down on overall equipment and installation costs.

On the other hand, 60-cell panels are lighter and easier to install which is why they’re more common for residential rooftop installations. This can mean lower labor costs for the installation. For large, commercial installations, the extra size and weight of a 72-cell panel aren’t as much of an obstacle because cranes are often used to lift the equipment to the rooftop.

Exceptions

There’s one scenario where 72-cell solar panels are less common. This exception comes when you build a solar system around micro-inverters.

Micro-inverters work on a 1-to-1/2/4 system, where each inverter is hooked up to an individual PV panel(or 2 panels, sometimes 4 panels). The benefit of this type of system is that it is modular: if one part stops working, it doesn’t affect the rest of your array. This makes it easy to repair and expand your system.

Micro-inverters have a cap on how much AC wattage they can handle. If PV panels produce more power than the micro-inverter can process, the panels would still work, but you’re simply wasting electricity – and by extension, wasting money. You’d essentially pay a higher price for your panels without getting the benefit of additional output.

More factors to consider when choosing solar modules

When it comes down to choosing your solar modules, the number of cells included in the panel isn’t the most important factor. Cost, aesthetics, warranty, efficiency, and durability should all be taken into account when selecting the right PV panels for your home or business.

For the cost, it’s a good idea to compare your 60-cell and 72-cell panel options on a cost-per-watt ($/W) basis. Similar to looking at dollars per square foot when shopping for a home, looking at $/W shows you what the cost of a turnkey solar panel installation is on a per-watt basis. Looking at this factor will allow you to standardize the price of installations using either 60-cell and 72-cell panels, especially if you’re comparing different system sizes.

PV panels come in a variety of cell colors (dark blue, blue, black), cell shapes (pseudo square, full square), backsheet colors (white, black) and frame colors (silver, black). If aesthetics are a concern, make sure to look at an image of the panel before signing the contract, or ask your installer for photos of their past installations with the same equipment to get a feel for how they will look on your roof. If you’re looking for the sleekest appearance possible, there are many black-on-black panel options. You may pay more for these options, but it can be worth it.

Questions to Consider

• Are you building an off-grid or grid-tie solar system?
• If it is off the grid, what voltage battery bank are you trying to charge?
• Do you have a physical size restriction that would limit the size of the solar module?
• What equipment do you want to support the solar modules?
• Will a higher voltage module restrict the number of modules you can use in the solar system?

Frequently Asked Questions

1. What’s the main difference between 60-cell and 72-cell solar panels?

The biggest difference is their size – 72-cell panels are about a foot taller than 60-cell panels. Both types use the same technology and cost about the same per watt of power. 60-cell panels are popular for homes because they’re lighter and easier to install, while 72-cell panels are often used in bigger commercial projects because you need fewer panels to get the same power output.

2. Will 60-cell panels work for my home battery system?

Yes, but you’ll need the right setup! For a 24V battery system, you’ll need either two 60-cell panels connected together or one 72-cell panel. Remember, you’ll also need a special controller called an MPPT charge controller. It costs a bit more, but it helps your panels work efficiently with your batteries.

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3. I’ve heard about micro-inverters – which panels work best with them?

60-cell panels usually work better with micro-inverters. Here’s why: micro-inverters can only handle a certain amount of power, and 72-cell panels might produce more power than the micro-inverter can handle. This means you’d be paying for extra panel power that you can’t use – kind of like buying a super-powerful sports car but never being able to drive it at full speed!

4. Do 72-cell panels really save money?

It depends on your project! For large installations like business buildings, 72-cell panels can save money because you need fewer panels and less mounting equipment. But for home installations, 60-cell panels might be more cost-effective because they’re easier to handle and install, which means lower labor costs. Think about it like buying in bulk – it’s cheaper per item but only if you really need that much!

5. Can I mix different types of panels in my solar system?

While it’s technically possible, it’s usually better to stick with one type. Using the same kind of panels helps your system work better and makes it easier to maintain. It’s like building with Lego blocks – everything fits together better when you use the same type of pieces!

6. What should I consider when choosing panel colors?

Solar panels come in different colors like dark blue, blue, and black. The color doesn’t affect how well they work, so it’s mostly about how you want them to look on your roof. Black-on-black panels are popular because they look sleek, but they might cost a bit more. It’s a good idea to ask your installer to show you pictures of different panels installed on houses similar to yours before making a choice.

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Question:
I got an AC300+B300 set that I currently use as emergency power source.
I also rent 6 rooftop solar panels that are grid connected via a Solis Mini solar inverter.

Manual here: https://www.solar-nu-webshop.nl/data/upload/files/-solis-mini4gseriesinverter700--manual-en.pdf
For safety reasons, when there is a grid power outage, my inverter goes off and I have no solar power.

My questions are:

1. During power outages, can I plug my rooftop solar panels into my AC300?
2. If yes, Which cables do I need to connect my solar panels to my AC300? I need to buy a 10 meter long DC extension cable to connect my solar panels to my AC300.
3. If no, do I need additional hardware or converters before I can plug my rooftop solar panels into my AC300?

It would be nice if I can recharge my AC300 during power outages via my rooftop solar panels.
I don’t know much about the technicals about solar panels installations. Everything was installed for me by the company I rent it from.

First impressions of Bluetti SP120L portable solar panel.
I was very lucky to win this panel in the recent #BLUETTIXASHomeParty competition. Unfortunately the UK winter weather hasn’t been cooperative, but I did manage to unpack the panel indoors and get a good look at it.

This is my first Bluetti panel, but I do have others to compare it to. First impressions are that the panel is sturdy and well made. The design is well thought out and practical.

The leads are contained in a handy, fitted pouch which has extra room for your Bluetti’s solar cable or other small accessories. Importantly, the specs are included inside in an easy to read size.

Being a fan of shiny things, I find the popper type closures for when the panel is folded aesthetically pleasing. They’re also strong.

The panel is IP67 rated, so no panic in a light shower, but is not for permanent installation or leaving out in heavy rain. Nicely thick plastic is used for the handle, and at other crucial points.

The SP120L has 3 study supports. I really like the design.

There are handy angle labels and a simple elasticated hook to select the angle and keep the support in place.

No idea why it only wants to upoload upside down haha, but the pic is to show how flat the panel lays due to the well designed supports.

And most importantly for me - will the SP120L fit in my bike trailer for easy, environmentally friendly transportation. Its a definite yes (although it will be padded and wrapped for its real journey).
All in all I really like this panel and look forward to sunny days when it will be travelling to the allotment and feeding my smaller Bluettis.

Hi @TheQuickFox

Thank you for your questions.

The AC300 does have two MPPTs with each 150V voc. So it would be interesting to know, how the six panels are wired. When you have 2 pairs with each three panels, it should work to connect Pair 1 to MPPT 1 and Pair 2 to MPPT 2. Make sure that the voc of the three panels in series dont exceed the 150V. If you have all six panel wired together, im really sure you over 150V and cant use it.

The AC300 have a MC4 Plug to connect a solar panel, so the same plug the most solarpanels use out of the box. If you use a serial connection, there isnt any additional hardware needed, just a cable pair (or two when have 2 pairs) that connect directly to the AC300.

If all six panels wired together, than the voc of the panels are likely to be more than 150V. Do use the panels with the AC300, you need a voltage step down module (Like the D300S) This would convert up to 500V down to about 120V

How many cable pairs going to your mini inverter? You can measure the voltage with a multimeter.

Hope this answer is going to help you a bit
Erik

@Selfmadestrom Thank you very much for your answers.

There are only two DC cables coming from my solar panels to my inverter. A red one and a black one with MC4 connectors. So that’s probably 6 rigid solar panels in series?

I’s currently winter and very cloudy/misty weather in The Netherlands. I’ll have to wait for a sunny summer day to measure the maximum voltage of my solar panel setup.

So I may need a step down module when the voltage gets over 150V. The Bluetti D300S is very expensive for an occasional use that I need. I hope I won’t have too many power outages that last longer than the usage time of my two B300 batteries. Are there any alternatives for the D300S that are significantly lower priced?

But I will need to do a voltage test first to verify if I really need one. To be continued.

As I have mentioned before, solar panels have a temperature coefficient of around 0.2%. The tested Voc is usually performed at 25 degrees C (77F). For every degree warmer than 25C the Voc will decrease, conversely, for every degree below 25C the Voc will increase. This applies particularly in sunny conditions, but can occur in overcast weather.
The net result is that in a nominal 12V panel with a 25C tested Voc of 24V, at zero degrees C the Voc can be 30V. The effect is per panel, which means in series connected panels the affect is cumulative.
Good v bad weather affects the power output i.e. watts. In bright sun as is in Australia at the moment, the wattage output is very high, however, when it it is 40 degrees C in the shade, the Voc reduces. In winter time at near zero C, or single digit temperatures the Voc is higher, but the wattage output is significantly reduced especially in overcast conditions.

G’day All. I am not an Aussie, but a disillusioned Brit. (Born in Wales, Scottish heritage, brought up in England, but relate to the Irish.)
Presently in our pleasant (or not) island it is pointless to bring out my PV350 panels, as, if by chance there is any sun, I’ll only draw about 70 watts at best. But planning ahead some advice please, if poss.
When the solar power gets a wee bit stronger I’d like to rig up my PV 350 panels so i can leave them out in the elements on a permanent basis. But i remember reading that it is advisable not to leave them out, especially in the rain. Does any one have any suggestions of how I could weatherproof the panels, short of leaving the country for warmer climes.
Would appreciate your help here folks.
Yours. Andy.

Having more wattage and/or current available from the solar panels is not only fine, but can be an effective way to get longer periods of full solar power. What you never want to do is have more voltage (looking at the Voc rating) from the panels than what the power station is rated for. Even more specifically, since solar panels can generate more voltage in cold weather than in warm weather, it may be necessary to remain at or below about 80% of the power station’s maximum solar panel voltage rating.

The reason is that the power station’s solar charge controller will regulate the current used for charging, but it cannot affect the voltage being supplied. Too much voltage will damage the charging circuit.

So on your solar panels you need to find the “open circuit voltage”, referred to as Voc, and use that to determine how many panels can be put in series before the voltage is too high.

I will use my own system as an example. I have an AC300 with 4 B300 batteries, so it can take two solar arrays, up to watts each, and up to 150 volts. I have two arrays, both are identical so I will discuss just one. My 250 watt solar panels have a Voc of 37 volts. So putting 3 in series gets me to 111 volts, but 4 in series is too much voltage because 148 volts is too close to the 150 volt maximum, and where I live it can get well below freezing. So 3 in series is my limit. But that is only 750 watts out of maximum. So I took another three panels in series and put those in parallel with the first three. So the maximum voltage remains at 111 volts (series adds voltage of the panels, parallel add the current), but the maximum current doubles, and the maximum wattage of the array is now watts. My charge controller will limit that to watts, but the array will reach watts for a longer period of time while the sun’s power is not at it’s maximum.

Since I have two such arrays I have watts of solar power for a system that can use up to watts, and it works beautifully.

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