-
CS6P-260P/SE3000 - http://tiny.cc/ed5ozx -
So a quick price check I just did shows $145 for M250s vs. $125 for M215's.
That's a 16% higher cost.
For 280w panels, I'm sure you won't get 16% more production...
BUT if you look at the total system, it's likely less than 5% additional cost - and it's plausible the performance improvement would justify it. With ~300W panels, IMO it's very likely that it makes economic sense. (Just got an email offering $.97/w for 300W panels... Sad I didn't get that - but OTOH I would have been up on the roof in august instead of Feb. And my production is already going - 6 months earlier than if I had waited)Comment
-
I would stick with marginal cost analysis for something like this. A $500 "upgrade" that doesn't deliver $500 of value is the same whether you are talking about a $5000 system or a $25000 system. Scaling it to the total cost is how car salespeople attempt to get us to buy all kinds of ridiculous extras ("Just $5 / month more for the designer floor mats" ... no offense to floor mat aficionados intended).CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
-
To be clear, that 5% increase (or $20/panel) *IS* the marginal cost. So if you're talking 20 panels, it's a question of whether that extra $400 is going to have a reasonable ROI or not. And IMO at that price differential it likely will. If it were a $40/panel difference, I think it likely won't. But there are a lot of items involved in that analysis.
FWIW, when I did the analysis of using an enphase system vs. solaredge, solaredge came out ahead. But that was mostly ignoring labor costs.Comment
-
Whether done by individual panel/micro or by entire system, I'd think one way to do the analysis would be to first get an estimate of the difference in annual generation from one inverter to another. Then, get the net present value (or worth) of the difference in the cost of that annual production difference. If the net present worth of the (estimated) greater production from the larger inverter(s) is deemed greater than the initial cost of the larger micro inverter(s), the larger inverter would be the choice.
If, say, 150 kWh is the diff. in annual system prod. on a system with 20 micro inverters, and one is on T.O.U., the extra production may well be mostly at peak hrs. and carry a value of, say, $0.45/kWh --->>> ~ $67.50/yr.
OR, if on tiered rates, those savings will be lower assuming < 100% offset but high enough to be entirely in tier one so that the savings are say, $0.20/kWh, or, ~ $30/yr. marginal savings.
If the cost diff. is $20/micro, the task is to determine if ($20 X 20) = $400 is more or less than the net present value of the annual savings.
Most folks brain hits the wall about 2 sentences into a discussion about net present value of anything, and they usually wind up dividing initial cost by initial annual savings for something that is loosely defined as "payback".
In this back of envelope, incomplete and simplistic example, that # is $400/$67.50 = 5.9 yrs. if on T.O.U., or $400/$30 = 13.3 yrs. if on tiered rates.Comment
-
One more consideration that may still be appropriate for the back of the envelope is that some degradation may be expected in the panels, and the amount that is "clipped" would decrease each year (assuming irradiance and temperature are unchanged). For example, if a panel starts at 275 W out of the box, it might be reasonable to think of it as a 265 W panel in year 5. This will tend to stretch out the time it takes to achieve NPV equivalence, sometimes significantly.CS6P-260P/SE3000 - http://tiny.cc/ed5ozxComment
-
Noted and generally agreed.
Also noted: That would be one of the several considerations (or many as deemed important for the analysis) of any thorough life cycle cost estimate in determining the net present value of the savings.
I'd suggest most of the simple "payback" nonsense usually used is not sophisticated enough to need or even make practical use of decreased annual savings from expected panel production decrease as f(time).
Even if known, I'm not real confident the significance or use of such a # would be applied in a meaningful way.Comment
-
I ended going with the CP bid (original: 4675w. $19,685.00 ($4.21/w). 17 Suniva OPT275 + Enphase M215). The sales guy I worked with was very detailed in what he initially provided me and with all of his responses. In the end, he sweetened the deal by dropping the price by $500 and doing the attic install in that cost. I was sort of leaning towards SolarEdge but given the cost savings, I just couldn't pass it up. I tried doing some long term projections for SunPower using SAM (for kWh produced over 25 years) to get a lifetime $/kWh price but it was working out to be a couple of cents higher. So that cost premium wasn't worth it and kept me under my planned budget.
Now to hopefully get things installed and running before all the prime generation time is gone. I just want a taste...
Comment
-
congrats
i am nervous going with chinese panels right now.
who knows where those companies will be in 10 years.
sticking with known US based vendors who atleast will honor the warranty via local installers.Comment
Tweet
Comment