September 2022 State of the solar art and installation on a home...

All the following are my personal opinions. If you have questions/see things differently--We are all here to learn.

First. I do not call GT Solar an "investment". If you have $60,000 floating around looking for someplace to go--Can be nice.

HOWEVER, get the documents from the supplier/installer... Warranty, loan paperwork, who is responsible for repairs, what happens if system does not produce expected amount (either shading, electrical issues, failing panel(s), failing GT inverter, etc.).

You may have 10-20+ year warranty, but you may have to cover labor after 5+ years (yes, will get new panel, but you pay to diagnose/labor to R&R).

Be aware--Things (in general) churn in the electronics/solar/etc. market... 5 years down the road, may not be able to find same/similar replacement panels, GT inverter, micro inverter(s) may no longer be available (same brand/model)...

In general, for electronics (all electronics) past ~5 years can be difficult to impossible have repaired/get parts. In California we have a 10 year warranty on solar purchased with CA credits... Probably most suppliers are 10 years now(?). Again check for labor/etc. costs if covered by warranty or not.

Check how your utility charges/credits for GT Solar Energy. When GT solar started 10+ years ago--The billing plans were pretty nice for the GT Solar owner (basically full credit off my bill for every 1 kWH generated--At the end of one year, have "trueup" if I generated enough or "extra power", I did not owe any money for power other than a $5-$10 per month connection fee).

Now, GT solar is very popular. And the State PUC and the Utility have been "adjusting" rate plans. They are now making peak and off peak charging into 8-9pm at night... Solar does not generate during late evening or in the dark. Solar billing is no longer (in many places)as it used to be (I can argue--Less subsidies from "regular" customers to GT solar customers--Fair or not fair?).

In California, they will only guarantee "rate plan" basics for 10 years (grandfather)--After that, who knows where things will go.

Note that standard GT Solar systems do not produce power if there is a power failure (no backup power). Storms, car hits pole, etc.... No power for you until the grid is restored.

Note there are a few GT Solar systems that can generate 1,000+ Watts in the middle of the day (i.e., you can plug your freezer into the "secure power" outlet of the GT solar system and run the freezer in the middle of a sunny day).

Personally, I don't believe that GT Solar adds the value of the home. At best, maybe a little added value... Or you may run into buyers that think the panels detract from the looks of the property, or are afraid of all the wires and panels on roof/side of home. If you got 10%+ from the $60,000--I would be very surprised (who pays off loans/leases if you move...).

If you have neighbors--What if they build an addition that blocks sun... Or trees/landscaping that grows over time (you have to hire tree trimmers, you cannot control grown on neighbors/open land).

Personally, I highly suggest going through and look at Energy Conservation first. It is almost always cheaper to conserve energy than to generate it....

• Ceiling insulation
• Energy Star rated HVAC
• Weather Stripping
• HVAC Duct insulation (i.e., piling insulation over ducts, etc.)
• Possibly looking at mini-split heat pumps (more efficient A/C vs older systems, Modern heat pumps can use 1/3 to 1/2 the amount of electricity vs resistance electric heaters even down to freezing or below).
• LED lighting
• Turning off stuff not in use (entertainment systems, desktop computers and such can take a fair amount of power if "not being used")
• etc.

For a home that has never really looked at energy conservation, it is very possible to save 25% to 50% of energy usage (gas, electricity, etc.).

Getting a Kill-a-Watt meter to measure individual appliances (refrigerator, computer, and such)... It is sometimes surprising, a microwave using 1,200 Watts for 15 minutes (1/4 hour) per day uses 300 WH per day. A desktop computer running at 150 Watts (not in "sleep") 24 hours per day can take 3,600 Watt*Hours per day... (3.6 kWH per day)

If your system is sized to produce 12 kWH or 12,000 WH per day (or 360 kWH / 360,000 WH per month)... You may be paying around $0.15 to $0.50 per kWH--California is now around $0.40 to $0.50 per month--More than Hawaii now).... Measuring your energy usage and figuring out where to spend your money...

1,200 Watt microwave---0.3 kWH per day * $0.20 per kWH = $0.06 per day
Desk Top computer "left on"---3.6 kWH per day * $0.20 per kWH = $0.72 per day

The (mythical) desktop computer (networking, router, cable modem, printer, etc.) can use 10x as much energy per day vs a microwave in random use.

Also, if you use A/C in the summer--Inefficient appliances (refrigerators, freezers, desktop computers, etc.)--Basically all of the energy they use ends up as heat (i.e., your 150 Watt computer is the same as plugging in a 150 Watt heater)--So in this case, you are paying to "heat" your home (old computer, old fridge, filament lamps, etc.) and then paying for the A/C to remove the heat from your home.

Another way of looking at whole home energy usage... Something like one of these:

https://www.theenergydetective.com/

They can measure the whole home energy usage, and you can purchase versions that let you measure major loads (electric stove, water heater, dryer, well pump, etc.)...

Other things to look at... If you have an "older roof", you may need to include the price of a new roof (array mounted over homes roof). 25 Year panel "life" and 20 year old roof--Not a good mix.

And if you have a "more difficult roof" (metal, tile, etc.)--Mounting the array standoffs and preventing/fixing leaks can be an issue...

A roofer I have used over the years--He was looking into installing GT Solar--Much of his work was fixing leaky roofs after a roof top solar array was installed (poor weather proofing around array anchors).

Also look at roof top wiring--If have little animals that like to chew/nest--The array and array wiring can attract those little guys.

There can be other issues too... Depending on local electrical codes--There are access issues for roof (so firefighters can access roof to ventilate--Walking space). And there are issues with array power cutoff (shorts, arcs on roof top, new codes can require "remote shutdown" devices or micro-inverters (one inverter per panel) vs central inverter(s) (one inverter for whole array).

You don't really need to worry about code issues (your installer should be doing this work)--However, down the road issues can cause you headaches/extra costs (replace bad panels, replaced failed micro inverter on roof X years down the road)...

Your estimated harvest is 14,953 kWH per year and covers 90% of your usage:

• 14,953 keH per year / 12 months per year = 1,246 kWH per month solar
• 1,246 kWH per month / 0.9 total home load = 1,384 kWH per month total
• 14,953 keH per year / 365 days per year = 41 kWH per day solar
  
• 41 kWH per day / 0.90 total home load = 45.5 kWH per day total

https://www.eia.gov/energyexplained/use-of-energy/electricity-use-in-homes.php

Your home, presently, uses a fair amount of electricity... If only have electricity (no natural gas), and A/C--That is not unusual... Lots to think about. But my first choice would be Conservation (measure existing energy usage) and replace energy hogs... 

-Bill