This is the final part of our series to help Home Owners go Solar. Click here to read Part 1, Part 2 or Part 3.
Consumers in the USA have enormous choice for almost everything and Solar Panels and Inverters are no exception. Here, we will make some recommendations and help you make a selection that focuses on quality, efficiency, value and longevity.
1) Solar Panels : Choose a Solar Panel with panel efficiency of 20% or more. This narrows the field down to mostly mono crystalline solar panels manufactured by companies like Sunpower, LG, REC, QCell, Silfab, Trina, Longi, Canadian Solar and Panasonic.
2) Inverters : The choice is between Enphase Micro inverters and Solar Edge Optimizers. These two solutions are the most effective for Home installations where shade, orientation and space constraints require every effort be made to harvest the maximum power from your solar panels.
Regular Inverters are almost never the best choice for a home. They work much better for commercial installations where you have no space or shade limitations.
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1. What is the best Solar Panel to buy?
Here are the most important factors to consider while choosing a Solar Panel for your home.
The black on black Solar Panels on the right are the preferred look, sleeker are and more unobtrusive.
Looks | price | EFFICIENCY | Brand |
|---|---|---|---|
For Solar Panels on your front roof, their curb appeal is important. All black panels with no visible lines or borders are the best looking. Industry jargon for these panels is "Black on Black" | Look for value. Many Solar manufacturers with superb quality and efficiency have great value pricing. Most expensive is not necessarily the best. | Higher efficiency panels are usually the latest design with feature innovations designed to get the most power out of the panels. As of early 2020, 19% or more efficiency is a good target to aim for. | Certain brands like LG and Panasonic have brand appeal across products and they tend to charge a premium. SunPower which has the most efficient panels also charges more. Other brands like REC, Silfab, Hanwha, Trina etc make outstanding panels as well. |
COMPANY | warranty | SIZE | Type |
|---|---|---|---|
Tier I Solar Panel manufacturers referred to in this article are all huge companies with global foot prints and long history Anyone of them is a good choice. Beware of companies and solar panels that are not certified and rated by top labs. | All the top Solar Panels come with 25 year product warranties. Some have production guarantees which give them a slight edge. For example Panasonic, LG and Sunpower guarantee 90% or more production after 25 years. Compare that with 84% for the others. | Solar Panels usually come in two sizes, the smaller 60 cell panels and the larger 72 cell variety. Most residential solar panels are the smaller 60 cell variety. Half cell and smaller cell panels from Panasonic, Hanhwha etc are similar in size to the smaller 60 cell variety. Size matter when you have limited roof area. | Most high efficiency (20% or more) solar panels will be Monocrystalline. Polycrystalline and Thin film are much less efficient and they should be avoided for home installations. |
There are other Solar Vendors with high efficiency panels which you could consider. Brands like Baywa, Recom and more.
If your Solar Vendor is offering a solar panels with panel efficiency of 20% or more, you have made a good choice, even if they are not in my list.
Just makes sure the solar panel efficiency rating provided is by independent third party agencies like Edif ERA,DNV GL,Black,TUV etc.
There are a few web sites which show the so called Tier 1 solar panel listings. But they are mostly highly unreliable. The best source of information would be your solar company providing you with a certification or data sheet. The brands I have mentioned here in this article are all legitimate and make outstanding solar panels.
Once you have made a shortlist of manufacturers, start evaluating the panels on the other parameters such as look, size, price etc as mentioned above to make your final selection.
The good news is that any high efficiency solar panel from these top tier vendors will work very well. There is very little to choose between them. It 's like buying a car from GM or Chrysler or Toyota - you will get a quality product backed by a solid warranty.
1a. How do I check Solar panel efficiency?
Ask your Solar vendor for the Data Sheet for the Solar panel. It will be a 2 or 3 page PDF file, which will have a lot of information. Look for the following in the file :
The 20% efficiency threshold I have advised is as on date today, which is early 2022. It you are reading this a couple of years from now, it would be a good idea to check for the most efficient solar panels available.
Panel efficiencies are constantly increasing and you might have something better available. However, there is no point waiting for the next big innovation. Moving from 20% to 21% will not give you a huge performance bump and the price differential is usually very large, just not worth the extra investment.
As on date today, the pricing for 20% plus efficiency solar panels is competitive and you are likely to get the best value along with top efficiency.
1a. Should I buy a higher watt panel?
Solar Panels are rated for the maximum power they can output. For example a 380 watt REC panel or a 350 watt QCELL panel etc will output a max of 380 watts or 350 watts in perfect conditions.
The panel watt rating of 360 or 315 or 385 etc is certified by a leading rating agency. The higher the watts, the more power they output. But, many higher watt panels are larger in size.
That where efficiency comes in. Two panels with the same panel watts, might have different module efficiencies. The panel with the higher efficiency will be smaller.
Thus, if you select a high efficiency panel, you are likely to get a smaller sized panel that has great output.
Go for the higher watt panel only if it is more efficient than the lower watt competitor panel. If the panel efficiency of a lower watt panel is higher than the module efficiency of a higher watt panel, choose the lower watt panel.
You will get the same or more power from the lower panels over less area on your roof because they are more efficient.
2. What is the best Inverter to buy?
Residential Solar Buyers have three choices for the Inverter - String Inverter, Micro Inverter and Solar Optimizer.
The String Inverter is usually a poor choice for roof top solar because of the constraints of different shapes of arrays ( 5 panels on one roof, 7 on another etc etc).
The second problem is with overhanging trees, chimneys and vent shafts producing shade. And, this is a major problem. Panel output can reduce by 20% or more even with the introduction of a minor amount of shadow, like that of a vent stack, Yes Solar Panel are rather temperamental when you consider shade.
String Inverters will produce the lowest output amongst the 3 choices because of these two major constraints. Hence, we will limit ourselves to Micro Inverters and Solar Optimizer which have solved these tow problem with different designs.
2b. Comparing Enphase Micro Inverters with Solar Edge Optimizers
| | |
|---|---|---|
Overall System Efficiency | This is the efficiency of the combined Optimizers and the Solar Edge String Inverter. | This is the Micro Inverter efficiency. There is no additional string inverter in this design. |
Overal System Efficiency | 97.5%
Fill Counter
| 97%
Fill Counter
|
String Inverter | One or Two are required. | Not Required |
Power Output from the Panels | DC power that is routed to the String Inverter in your garage downstairs | Panel output is converted to AC on the roof and you have AC coming down. No requirement of additional string inverters or high voltage DC wiring. |
System Architecture | DC based and closed. Any problem will have to be taken care of by Solar Edge, no body else can help | AC based and open. A regular electrician can trouble shoot most problems. And you are not locked in to Enphase, you could choose other micro inverters in the future |
Expandability | Possible, but problematic. You will have to add new array string and a new string inverter. New panels would have to similar to the existing panels : a big issue as panels keep going obsolete in a few years. | Very easy. You can add 1, 2 or any number of panels. You can even add different panel types and not worry about matching. |
* The monthly payments assume your solar system costs $15,540 after the tax credit of 26%
While both, Solar Edge Optimizer and Enphase Micro Inverters do an excellent job of maximizing the power output from your solar panels, we like the Enphase Micro Inverters better because they give you more choices and greater flexibility.
After getting your panels, you might have service issues in 10 or 15 years. If all is well, the warranty support will take care of you. However, in case someone goes bankrupt, you will be in big trouble with the Solar Edge Solution.
Solar Edge Optimizers only work with Solar Edge String Inverters. If they are not around, you are going to be stuck. This is not a problem with Enphase's micro inverters. The produce standard AC power that is easily worked on by regular electricians.
You could even replace an Enphase Micro Inverter with another brand ( cabling will be an issue, but not insurmountable). Adding more Solar Panels to expand your system is infinitely easier with Micro Inverters.
5. Conclusion : Which Solar Panels and Inverters are the best?
A top notch Solar System with high efficiency Solar Panels, 20% and upwards from well known manufacturers such as REC, QCell, Sunpower, LG, Silfab, Trina, Longi, Canadian Solar and Panasonic is your best choice.
Solar Edge Optimizers or Enphase Micro Inverters are both excellent choices for the Inverter. We are little partial toward Enphase because of their design and future flexibility. String Inverters are a No No for most residential install.