I think we're going solar

Say, that is a snazzy site.

I'll have a bit of play with it. One thing we haven't locked in yet is the tilt for the panels. Since this is ground-mounted, I have some flexibility in whether I optimize for winter, summer or split the difference.

Currently thinking to optimize for summer because there will be early morning winter shade from a neighbor's trees that I can't do anything about. Rest of day & year would be fine.

Site says 30° would get us ~20,000kWh/year, and we bought just over 18,000kWh last year. Digging this.

 

Wow, I just got summits quote, $60,000. Before credits.
50%higher than the other four

 

Another thought, if I invest the 20k at 5% over 20 years, should I subtract that from the potential savings?

 

The spread I've seen is from about $2.65-3.40 per installed watt, with my preferred* contractor coming in at $3.16

*the guy I prefer is an electrician who specializes in solar. No funny business financing. I gives him the moneys and he builds me the system. No snazzy marketing. Much (but not all) made in usa. Consistently comes back with good answers to every question I ask, no slippery sales BS.

 

PVWatts can be configured to compute for multiple roof segments with different orientations.

 

i would love someone like that. all i'm getting are companies with good and bad reviews, and all the same price except todays

 

"Optimum" tilt angle depends on one's goals.

The old most simplistic rule was to have the tilt match the geographic latitude, which intuitively gives square-on orientation at the Spring and Autumn equinoxes, and equal reduction at summer and winter solstice. But this doesn't account for seasonal differences in day length and cloud cover.

An off-grid system will want to tilt higher for winter production, then will be throwing away considerable summer excess. An on-grid system aiming for maximum annual production and carbon offset will want to tilt lower for better production on long clear summer days, at the expense of short cloudy winter days that have lower production anyway. While the day length is easily computable from geometry or astronomical almanacs, the weather and cloud cover are empirical things that vary enormously by location, and must be measured. NREL has access to decades of solar and weather data for very many locations, and now good models to interpolate for other areas.

For my system, I ran the old-version PVWatts calculator with tilts covering the full range. My 5:12-pitch roof is slightly less steep than the 'best' angle for my location, losing just a few percent of theoretical production. This is so close that the complications of using a different angle weren't worth the effort and wind-loading risks:


Other locations will get a different curve. Even at the same latitude, different locations will get different curves due to different seasonal cloud coverage.

A system mounted on a frame in the yard isn't constrained by roof pitch. It could even be somewhat easily built for adjustable pitch to adjust for different seasons, if anyone wanted to put that much effort into it.

 

i have a company coming tuesday to see if a heat pump will work with our high speed a/c

 

I was wondering about this exact thing this afternoon. Made me wonder if there's a trick bracket kit or something that would let me tip them another 10-15° twice a year.

Though if the curve in your graph is typical, might not be worth it since I'm quite close to 40°N anyway.

Thanks again for another informative post!

EDIT, adding:

Also going to see what I get out of clocking the array to 190°... This would give me more late-day, and minimize the penalty of my neighbor's trees uphill to the ESE of the planned array site.

 

I just tripped over suncalc, another really cool solar related website.

Of note, this thing is letting me trace out a prediction of shadows cast throughout the day for any date I enter. I just centered the map on the objects that would cast the shadows, enter a height differential, and scrub the timeline to see the shade arc. Super cool!

I'm hoping this helps me fine-tune my array site.

 

A company in town solved the azimuth problem with one of these systems a "solbot"- years ago This system may be outdated by now, I believe the Company went out of business but an out of the box solution to a problem that plagues solar installations.

Robots pivot solar panels to face the sun - YouTube

 

azimuth tracking would get me a good 20% boost, according to the NREL calculator @fuzzy1 helpfully gave.

The downside is that it would add a few thousand in up-front costs. I can see why they were used when panels were much more expensive.

Panel prices have dropped by more than 99% in my lifetime. Pretty reasonable to just buy a few more and then use cheap static mounts.

 

One of the guys I used to work with figured out a way to point mirrors at his array to increase his panel's output. First thought was the manufacture might void a warranty if panels are forced to overproduce year after year.
.

 

Rule of thumb for the Netherlands is "0.8", as in a 10kW system will net you around 8MWh a year. You're at a comfortable "2". Go Florida!
My first 2001 556Wp system did only 0.7 in the first years.

Just looked it up, Netherlands is way above Vancouver or Montreal...

I've read about a system that was passive and worked with evaporation of ammonia in the frame by the sun: if it evaporates, it is all over the sealed hollow frame, if it condenses, it sinks to the lowest part and the weight can tilt the frame.
I've mentioned this before on a site and no one could find anything about it either, so they suggested I might have dreamt it and might be on to something

 

just had a guy out to look at my unico high velocity a/c, he says bosch makes the only allowed heat pump system approved for the tax credits, and will work efficiently down to 9 degrees f. but i have to contact mass save first for an energy audit.

who new trying to save energy could be so taxing

 

anyone use solarinsure, or think it might be worthwhile? an extra $1,200. for 30 years

 

$1200 for an extended service contract warranty? or extra initial cost. Never heard of them

 

WE HAVE BEEN TRYING TO CONTACT YOU ABOUT THE EXTENDED WARRANTY ON YOUR SOLAR PANEL.

Don't feed the beast.

 

it is part of the offer. it covers everything, including roof links. (i haven't read the fine print) and i haven't read the details of the manufacturers or installers warranties.
are parts and labor usually covered for 20-25 years?