Solar production. Panel ratings/claim vs reality

[MAX-24-Dean]

What does your 10kw system produce through out the year? What's January production? May? And maybe July to give me an idea

What latitude?

December and January output is about 25% of system total here.
February and November are about 46%.
March, October are about 83 %.
April, September are about 90%
May, June, July, and August are about 99% production months.
Latitude 46N
Unique conditions here in that I live in a box canyon with a hill that has 300 foot higher elevation in the sunrise direction and a 200 foot mountain to the west (sunset). This has quite a negative effect on my December and January production.
Panels are at 37 degrees, reason being the cost benefit ratio of the extra cost for a foundation at a greater angle would not pencil out for the small solar production gain with the higher angle. Basically you have to account for solar panels being sails that catch the wind. So the higher the angle placement for the panels the more you have to spend on the foundation (ballast of a sail boat) to overcome the forces of the wind.
My new location had to account for 100 lb snow load per square foot and the 100 lb wind loading.
PVWatts is very accurate for production potential for any location, you can rely on the numbers with a few exceptions. One local condition for an installtion was fog. For about 3 months each year during the winter the location is fogged in until the later part of the day. Take everything into account and write it down so you can review it and make a good decsion based on the knowledge for your location.

 

[MAX-24-Dean]

The company at the link has regular sales events throughout the year.
Currently 6% off sale for the 4th of July.
I have used thier services for more than 15 years and I would reccommend the free consultation they provide.

NAZ Solar Electric | Off Grid & Grid-Tied Solar Power Systems

Solar power equipment for homes, businesses boats and RVs. Backed by industry experts ready to help get your solar system up and running.

www.solar-electric.com

 

[techman]

If you have 10KW of panels, you will never produce 10 KW. The standard ratings are at 1 kw/m^2 illumination. So unless you live on the equator and it is high noon, you will never see the rated output. I have a 9.2 KW rated system on a ground array, located in PA at 40.4N I average 1+ MWH per month in the peak months and as low as 550 KWH per month in the winter. Annually I generate around 11.5~12 MWH for the year. That covers about 40% of my total usage.

A typical day looks like:

The dips are passing clouds, and you can see the start, peak and tail off in the late afternoon.

Paul

 

[LD1]

If you have 10KW of panels, you will never produce 10 KW. The standard ratings are at 1 kw/m^2 illumination. So unless you live on the equator and it is high noon, you will never see the rated output. I have a 9.2 KW rated system on a ground array, located in PA at 40.4N I average 1+ MWH per month in the peak months and as low as 550 KWH per month in the winter. Annually I generate around 11.5~12 MWH for the year. That covers about 40% of my total usage.

A typical day looks like:
View attachment 878454

The dips are passing clouds, and you can see the start, peak and tail off in the late afternoon.

Paul

Good info.

I think 10kw is what I am gonna need and based on your data....the PVwatts calculator and numbers I showed seem pretty realistic expectations

 

[LD1]

If the utility allows you to "over-size" production it is to your advantage.
(We were limited to 120% of historical use).
Make hay while the sun shines is the old saying.

NAZ lists a 11,200 system with Enphase inverters for $14,000.
Depending on your utility rules and regulations it may prove a faster payback. There is a value in taking a bill off the table every month.

best of luck,

R

Oversizing dont help me. It actually hurts the ROI because even going over a 10kw system...there isnt much dropping in price in terms of cost per kw

Its all my rural coop electric company.

Basically as long as I dont produce more than I use in a given month, every kwh I can make will save me 12.5 cents.

IF I make more than I consume in a given month....anything over what I use is only saving me 7.5cents.

So no benefit to going too big as it will delay the payback. And still never gonna take the bill off the table because we have a $57 meter charge.

Only way to wipe that clean would be to produce 760kwh MORE than I use every month. Id need a system that could make ~2200kwh in the summer. Pushing a 18kw array. Then that system is only gonna make ~1200 kwh per month in the winter and ID still have a ~900kwh bill and the $57 meter charge. So I'd still be paying ~$170 for about 3 months out of the year.

But I dont think they will allow oversizing that much anyway.

Given the net metering policy as I have already explained....the sweet spot is to never make more than I use. That way I know for certain that every kwh I make directly saves me 12.5cents rather than 7.5 cents

 

[newbury]

Given the net metering policy as I have already explained

But didn't that policy just change?
What guarantee is there it won't change again?

 

[LD1]

But didn't that policy just change?
What guarantee is there it won't change again?

Yes It recently changed for the better.

Who knows if it will change again. I can't make a decision based on speculation about what may or may not happen in the future

 

[ning]

December & January suck.

I'm at approximately 39°N.

Here's 2023.

On a dark day there's very little production.
I have a small amount of production clipping because the system is fairly new so the panels can produce slightly more power than the microinverters can handle. The math was something like bigger microinverters would've cost another $1000+ and the clipping is likely worth about $200 over 20 years.

 

[LD1]

Still in research mode at the moment looking at the various options for inverters, mounts, and panels.

I think I am leaning towards the hoymiles HMS2000 inverters. They are a 4-into-1 but still have individual panel optimization....and a fraction of the cost of a complete enphase system. And looks like they can handle the output from some of the larger panels better than anything enphase has either.

Also been looking into Aptos and APsystems....both have a 2:1 inverter but currently leaning toward the hoymiles....and read some good things.

Basically I can get enough inverter/cabling/connectors/DTU, etc to do 20 panels for about $3000 or 24 panels at about $3300. Which only leaves buying panels and mounting.

NAZ has a 9.6kw kit that actually has 6x of the hoymiles inverters. Its a $9000 kit but I dont like the choice of REC400w panels at a price of $225ea when I see so many other panels (including bifacials) at far cheaper cost per watt. So I basically selected everything included in that kit minus the panels to come up with those above prices.

As for mounting....I am leaning currently toward the EG4 mount. For $279 to mount 4 panels....and 25-30-35 degree adjustable....looks hard to beat. All I need is the concrete footing or piers....which I can easily handle.

For panels, I can find 400w bifacials for ~$130 per panel and 545w bifacials for ~$200 per panel.

So....for a 10kw system....and keeping things in multiples of 4 (to work both with the racking and the 4-to-1 inverters.....

6 EG4 mounts..................$1674
24 panels @$130..............$3120
inverters and cabling.........$3340
Total................................$8134 for 9.6kw

OR

5 EG4 mounts..................$1395
20 panels @$200..............$4000
Inverters and cabling.........$2964
TOTAL.............................$8359 for 10.9kw

Obviously will have more in it than that with having to run power from the array to house, and concrete footings, and some other odds and ends. But I am thinking I can get this done for ~$10k

The question....and waiting on some follow up emails to different companies....is how well the hoymiles work with the 545 watt panels and/or if I will experience any clipping or want to overheat the inverters or anything. Even though the components for going with the second option and 20 x 545w panels is a few hundred $$$ more, its one less rack to mount (less concrete)....a little less wiring....and about 1.3kw larger system. So total cost will probably be the same for a little larger system.

As much as everyone raves about enphase....they are just too dang expensive and pushes the ROI out too far for my liking given the alternatives out there. And they dont handle the larger panels. So 24 micro inverters, their combiner/monitering stuff, cabling.....Im at nearly $7k for just enphase stuff. About $4000 more than hoymiles.

Again, still just penciling out and researching what is out there to find the most cost effective way to get to 10kw. But things are looking good and this may become a reality sooner rather than later.

 

[tradosaurus]

If you're not getting the solar panels and installation for free you have to factor in that cost.
We looked at solar and minimum cost would be about $30K which would buy a LOT of electricity over the years.
Most solar companies, IMO, are scammers.