A newbies DIY solar install

beowulf · Mar 7, 2022

orezok said:
Just the opposite here in the desert. Yesterday on my 7530W system I generated 51.6kW for the day with a peak output of 7.1kW about noon. That’s a 94% efficiency and my peak months are still to come in May and November.

My payback will be about 4 years. Absolutely works here.

I recalculated my original payback term (then about 5 years) after the energy costs increased. Now just about 4 years. So, by the end of this year the cost will have been totally recouped.

Roric · Mar 8, 2022

Our 7500-watt grid-tied system was connected in November of 2019.
The output is about 9000 kilowatt hours per year.

The performance and output in the cloud and snow-covered hinterlands of central
Minnesota was a concern before this went online.
It has not been a problem.
The snow and ice cover the panels, but the sun will find a bare black spot on the panels
and unless the windblown snow keeps them covered, they will clear and produce.

As time goes on we have increased efficiencies in the electrical equipment in our home:
Led lamps, newer appliances, newer utility equipment.
(Looking to put in a split A/C unit to replace a through the wall unit this spring.)
We have added a plug-in-hybrid car to our load.

We still use less than we produce. The magic number is about 750kw per month
or 25 kw per day. (We don't have to be careful about it.)

As a result, we are looking at a payback of about 49 months.

A little while ago the Boss of All Things told me that she was wrong about the
'solar thing' and I was right. I marked this on the calendar.

R

Carl_NH · Mar 8, 2022

Roric,

Good Post - that's pretty much what we observe here in NH with 7.2KW system installed in Dec 2014 will generate 8000KWH a year, and that covers 80% of our use.

Question on ROI - our payback is about 8.5 years based on $.22 per KWH, how did you achieve a 4 year ROI?

Did you buy and install yourself, or is it the high cost per KWH generate the savings?

Roric · Mar 8, 2022

I purchased a grid-tied kit (mission solar panels, USA, solar edge inverter and optimizers) and
as I hold a journeyman's license, installed it myself. (Wholesale Solar in California.)
Total cost for materials was about $14,400. Tax rebate reduced the cost to about $9400.
I figured the payback on the Total monthly electric bill not just the KWH price; the fact is the
kw price doesn't accurately reflect the cost of electricity delivered.
Long story short the calculation is based on 3 years of bills before the solar was installed.
This averaged to just short of $2000 per year. The new rate increases would bring this to about $2200
a year. We also get a "solar reward" from our utility of about $630/yr for being a solar producer.
I know the math is a bit fuzzy (4x2200=8800 - 2520=$6280) but we have gotten alot more energy efficient so I adjusted the time as an estimate of payoff. When I was designing it I figured the payoff
would be 4 years and 11 months. It's been better than I figured.

The day the electric bill comes is a happy day for me because while we get a bill some months,
other months we have a credit and for the year we make a few dollars, due to the rewards program

Carl_NH · Mar 8, 2022

Roric,

That explains the ROI, and for our 7.2 KW system in 2014 was $26K installed, with 30% tax credit $7800 and $4500 NH rebates our net cost out of pocket was $14,000. Which for me was why I had it installed and warrantied for 5 years.

So to recoup the $14K we generate $1800 a year or ~ 8 year ROI. Now, one could argue that $14K invested over 7 years would double to $28K. My view is a $14K investment that returns $1800 a year is a 13% return per year for at least 20 years.

Roric · Mar 8, 2022

Carl_NH,

Besides getting a good lift when I open the electric bill I get a kick out of taking one bill off our desk every month. And the plug-in-hybrid goes for 24 miles before the engine is needed and the it is recharged by sunshine power at home. Another bit of savings.
Of course, it's not just about the money, part of it is hoping this does some good.

Best to you,

Ron

jk96 · Jan 17, 2023

Update.....hard to believe it's been over a year already. Here's our year end solar results One pic showing our 2021 electric bills for our all electric home including heat without solar compared to 2022 with solar. 4,400 sq/ft of conditioned space. Also another pic showing production by month. Really happy with the first year results.

Some quick highlights.
1. Savings 2021 to 2022 was $3906.
2.. Total electric bill for 2022 was $751 or $62/month avg. 2021 was $4657 or $388/month avg. (Nov & Dec 2021 bill was changed to the cost without solar as we started it mid Nov 2021)
3. Of the $751 for 2022 $465 was our monthly connection fee so we actually paid $286 on the year for usage.
4. Payback on the system if savings stay the same around 72 months. Less if rates increase.
5. Total system production for 2022 was 37,370 kWh