When you’re starting out to either build or expand your off-grid solar system, how do you know what panels to buy? You read customer reviews and Amazon ratings till you’re blue in the face, but the fact is many of those reviews are from 1st time buyers who have nothing else to really compare the product to. I have experienced this very same dilemma over the past 10 months and decided to share my results with you.
I started my system by buying a prepackaged 200 Watt system from Renogy. (Read the review here.) The system came with two 100 watt monocrystalline panels which seemed to work well (again nothing to compare them to) so when I went to expand I simply bought two more for $139 each. The Renogy panels had a 4.7 star Amazon rating and good customer reviews. As I continued to expand, and of course so did the cost, I began to explore other manufacturers. My next purchase was two 100 watt polycrystalline panels from WindyNation for $112 each. They had a 4.4 star Amazon Rating with good customer reviews. About a month later I purchased two 100 watt polycrystalline panels from Newpowa for $100 each. They had a 4.6 star Amazon rating also with good reviews. The last purchase I made was two 100 watt monocrytalline panels from ECO-WORTHY for $115 each. They too were rated very well with a 4.5 star Amazon rating and again, good customer reviews.
So all in all I purchased panels from four different manufacturers (so far) priced between $100 and $139 with Amazon customer ratings ranging from 4.4 to 4.7. So is there really any difference?
Since I will be purchasing another 5 panels over the next couple of months, I decided it was time to do some real world testing on these panels. I waited for a nice, clear sunny day so the panels would be operating at their optimal output. I began the testing at about 1 pm when the sun is directly overhead at this time of year. Each panel would be tested for 10 minutes wired directly to the charge controller through a 15 foot 10 gauge wire with it’s average output taken as the final rating. I then repeated this process using one of the other panels from the same manufacturer to be as thorough and fair as possible. Note: I actually conducted a third test on the Renogy panel as I was suspect of the two previous readings.
- The results: WindyNation polycrystalline panel:
- Amazon rating of 4.4 stars cost of $112 output of 80.4 watts
- Newpowa polycrystalline panel:
- Amazon rating of 4.6 stars cost of $100 output of 92.92 watts
- Renogy monocrystalline panel:
- Amazon rating of 4.7 stars cost of $139 output of 85.26 watts
- ECO-WORTHY monocrystalline panel;
- Amazon rating of 4.5 stars cost of $115 output of 94.5 watts
To put this all in perspective, if I were to buy the 5 panels I need for my system, the following would be the cost per watt generated:
- WindyNation: $560, 402 watts = $1.39 per watt
- Newpowa: $500, 464.6 watts = $1.08 per watt
- Renogy: $695, 426.3 watts = $1.63 per watt
- ECO-WORTHY: $575, 472.5 watts = $1.22 per watt
And as always, your results may vary.
I should note that the build quality of all the panels is very similar with the Newpowa and WindyNation panels barely distinguishable from one another. I have spoken to Renogy’s customer service and found it to be very good, but I have not had opportunity or need to contact any of the others. Considering the results I will most likely purchase 2 more ECO-WORTHY Mono panels and 3 of the Newpowa Poly panels, but as with anything the price maybe different by the time I decide to make the purchase.
Disclaimer: I personally purchased all products through Amazon; none of the items were provided to me for testing.
Hope for the best, prepare for the worst.