Sizing a Grid Tie System?

[jbinpa]

Looking at Putting a Grid Tied Roof Mount with IQ8+ Micro Inverters on 455 W 144 split cell 1Mx2M panels
on my smallish house in Cambria County Pa
NEC2017 is in place here
Local AJH is down on DIY roof Solar

My Electric supplier is Penn Elec, no TOU or other tiered usage here
upto 10 DC KW ipanels nstalled their review is fairly simple / with a $100 review charge
NEM is: 10.39 monthly customer charge / use grid as no cost "battery" until annual true up
then if I underproce vs my consumption I owe them $0.17/KWH grid power used same as If I didnt have PV
If I overproduce they pay at the "cost to compare" rate of $0.10 /KWH so a 7 cent spead per KWH
so not a totally horrible NEM

local grid is quite stable iirc one 4hr outage in the 9yr we've been here and a few shorter outages
so while I'd like a furnace battery UPS to keep the furby's happy its not cost effective,
and If I'm home my F150 is the Powerboost varient with 7.2KW of 120/230VAC available at the tailgate plus we have a 2KW 120VAC Yamaha Inverte Genset

Local installer that did a 19.6KW 3 small arrays ground mount for a former neighbor gave me a 3 tiered qoute
YES i know this is a DIY foruom, I'd Love to DIY this but its not feasibable to do so here and now as a grid tie roof mount
I "might " be able to DIY a small off grid ground mount later for power/yard tools batttery recharging

The per watts $ are net after Fed Rebate and are for a Fully Permited Utility Approved TurnKey Install, cash or non inIstaller Finacing, I keep the SREC 's
I'm planning on a cash purchase

A) 13 panels 5900 DC watts $2.33 / DC Watt estimated annual production on my site 6200KWH's
B) 17 panels 7735 DC Watts $2.09 / DC Watt estimated annual production on my site 8130 KWH's
C) 20 panels 9100 DC Watts $1.97 / DC Watt estimated annual production on my site 9560 KWH's
production estimate is lower than PV Watts estimates but thats installers "gaurenteed " production levels so he's going to lowball it a bit

Trying to decide the best sizing for us as its cheaper to over build for current usage than add more later
but self consumption has a better ROI than selling to grid

My current electrical consumpsion is right at 5MW per year with Wife off being a Granny Nanny, all heating loads are Nat Gas, cooking is gas/microwave
We're planning on adding AirConditioning either as Mini Splits or Central so I'm thinking that will add at least 2MW per yr
even if it does reduce the dehumidifier usage somewhat

Also figuringing that once we're retired and she's back home our consumption will go up as rght now I mostly charge small electronics at work
and rarely watch TV(actually unpluged right now), Wife does watch quite a bit and surf the Net when she can so Maybe add another 500-1000KWH per year?

We may go to a Plug in Hybrid for wifes next car but I have no Idea how much usage that would add

I'm planning on choice C) 20 panels barring compelling reasons otherwise
thats the max number I can fit on the roof with the larger format panels and I'd have to drop down to 60cell /120 splits to fit a higher covrage level but then between lower wattage per panel and the additional inverters needed, $ / installed DC Watt goes up

 

[Mike 134]

I'm guessing your 20 panel system will generate about 140 recs over 15 years based on your 9.5MWH/year. That about what they told you? How much you getting per rec?
What have been the prices from 2 other contractors?

 

[jbinpa]

is I'm guessing your 20 panel system will generate about 140 recs over 15 years based on your 9.5MWH/year. That about what they told you? How much you getting per rec?
What have been the prices from 2 other contractors?

Currently SRECs in PA are at $40@, installer will register system with SREC trade and monitor output
Installer is quoting a bit low on output compared to PV Watts estimate because he's gaurenteeing that output as a minimun
if it doesnt make that min for first 2 years I get a prorated refund on system install so he has a vested interest in specing output low

Of the 3 National California based companies I talked to were all $8-10K higher for a 7KDCWatt system and 2 were pushing financing AND
how they used the best Panasonisc 300w Panels, and bad talked locals that wouldnt be around for repair work, basicly cookie cutter installs

3rd national co I actually talked to a rep who knew the engineering and was willing to discuss system specs and didn't bad talk the locals,
wasn't just a salesperson, and was closest to the local companies estimate

two of the localish companies that used to serve this area don't anymore as they have enough work closer to home,
the fourth came did a on site drone survey on Oct 4 and no response since, did tell me what they would be using for system componets during the site survey Silfab panels / IQ micro's / UniRack so should not of taken much to spec out the job, but they also knew I had a competeing estimate and from whom

Local Company that did quote me and I'm planning on going with has been in business 14years and is based 45 min away
Company Owner was told upfront during site survey that I was getting multiple estimates but not who from
and that I wouldn't finance or lease a system, wanted a cash sale only
He suggested that although he would buy out the SREC rights as a credit against system price that I was better off if I could afford the upfront cost to keep the SRECs

20 panels should produce 2MW more per year than I expect to need unless we get a plug in hybrid
thats the only reason I was considering the 17 panel qoute,
the 13 panel quote was the installers minimun size job that he'll do but that if I could afford it bigger would be cheaper per DCWatt

 

[Solarisium]

What did you ended up doing?
if you have any update, let us know.

 

[jbinpa]

What did you ended up doing?
if you have any update, let us know.

asked for a revised contract for the increased panel count and they never got back to me, even after several voice mails left and emails sent
they did have the 3 varied estimates available but, the only one actual contract they had in hand when doing the site eval was for the 13 panel minimum job,
i was willing to put the 35% deposit down at signing even tho it will be spring before I can reroof, which needs to be done b4 a PV install
maybe they want to wait and re quote the job in the spring, or maybe they dont want the job after all and are ghosting me,

 

[Solarisium]

Keep in mind when sizing your system:
You still will be pay a flat rate to the utility company.
You will not get paid back in cash for over production You only get credit to be used during the months of low production (winter). Unused credits will not roll over!
You’re going to pay a lot of money to generate free power for the utility company.

If you’re planning on doing a diy off grid later, then start with a small system fit for your current consumption now. You’ll learn process, your roi will be more favorable, and gets done faster. Future consumption increase will be covered by your future diy off grid system.
My two cents

 

[Mike 134]

Keep in mind when sizing your system:
You still will be pay a flat rate to the utility company.
You will not get paid back for over production.
You’re going to pay a lot of money to generate free power for the utility company.

If you’re planning on doing a diy off grid later, then start with a small system fit for your current consumption now. You’ll learn process, your roi will be more favorable, and gets done faster. Future consumption increase will be covered by your future diy off grid system.
My two cents

Depends on your power company.
In Illinois I do have the flat rate of $15 to be connected to the grid.
If I over produce the utility pays the same price to me as they charge to buy back my excess generation. The utility gets no free power from me. Some months I have a credit on my bill for the excess production.

 

[Solarisium]

Under NEM2.0 SoCal Edison gives credits when over producing to be used in the same year. It’s credit, not an actual check!

Is that the same in Illinois?

 

[Mike 134]

Under NEM2.0 SoCal Edison gives credits when over producing to be used in the same year. It’s credit, not an actual check!

Is that the same in Illinois?

yes. My calendar "year" starts in April, credits can be used in those 12 months. Anything leftover the following April goes Poof!! But mine get used up over the snowy months.