Cost vs Efficiency for same size panel

The blog states:

For Example, a high efficiency 360W+ panel could cost $300 or more while a common 300W panel will typically cost closer to $150. This equates to roughly $0.50 per Watt compared to $0.90 per Watt. Although in the case the leading manufacturers such as LG, Sunpower and REC the more expensive panels have higher performance, lower degradation rates and generally come with a longer ‘manufacturer’ warranty period, so it is often a wise investment.

If I have enough roof space…
And I spend $300, I can get either:
1 of the high efficiency 360W panels, for a total of 360W output, or
2 of the standard efficiency 300W panels, for a total of 600W output

After 25 years, the 360W panel may output 330W, while the 300W panels may output just 240W for a total of 480W for the two.

So, it would seem it is a better deal to buy the cheaper (less efficient panels)…
For the same $$ amount, I generate more output power even after 25yrs.

I am thinking the panel companies are heavily discounting their older production panels and charging a premium for the newer more efficient panels.

Unless I do not have the roof space, it would seem the “lower $/W panel” is a better choice as long as I still generate more power out of them at the 25 year mark… That is, premium is only justified when roof space is not enough.

Am I doing the math wrong somewhere? Any other costs to take into account (I figure I need to buy extra micro-inverters, if that is the setup I am going for)…


1 Like

Hi Humberto

You’re not doing the maths wrong, and I think it is a good way to look at it.

However, another way to look at it is that for a 6.6kW system, you can pay $2500 extra and get the latest and greatest panel technology with a lower degradation rate and longer warranty. People are often very happy to pay that premium for a product that is going to be on their roof for hopefully 25 + years.

There is no right or wrong answer when choosing solar products, just as there isn’t when choosing a phone, or car. It comes down to personal preference, budget, risk appetite etc etc.

Thanks for adding to the conversation. Some good thoughts.


why does sunpower offer me a 10kwp system at 87% of my power with 30 panels and rec offers a 10 kw system with 100% of my power with 27 panels