Choosing solar PV system in 2023

[scrambler]

What's the best and simplest way to perform a detailed electrical load calculation in absence of a smart panel?

Make a list of all the equipment in the house, and use their spec to calculate their continuous load and eventually their peak startup load if relevant.
If specs dont provide the info, you can use a Power meter for small appliances, or use an amp clamp on the wire coming out of the breaker for single appliance breakers.

Create an excel sheet with all the data.
Here is an example
Electrical loads table.xlsx

[oregon_phil]

rmk9785e , the all loads spreadsheet is a good place to start. Everybody has a different way to capture loads, but here's how I did it.

Buy a Kill a Wall.

Go to your electrical panel. The large pieces of equipment will have a dedicated breaker. i.e. AC condenser electric range, electric dryer, well pump, etc, there will be a name plate with volts & amps listed. List start amps (locked rotor) and running amps.

Then room by room determine what is plugged into the wall. Use the killawatt to figure out amps & watts. Do the same for outside devices: pool pump, water fountain, etc.

This will take some time for a large house, but it is a rewarding exercise.

What is the size of the electrical panel and electrical service into the house?

[bcroe]

What's the best and simplest way to perform a detailed
electrical load calculation in absence of a smart panel?

Perhaps simplest and best are not the same. If you want to
use standby power, you will need to determine starting current
peaks for your system. If you want to reduce PoCo bills or
figure battery capacity needed, you will want to find KWh used
per month or other interval.

Oregon_Phil has sent you in the right direction. Appliances draw
one level of energy starting, another running, and another (often
not zero) off, for variable periods of time. Almost none of those
numbers will be found on the nameplate.

If you want to know KWh, best run the appliance energy through
a KWh meter for a month or so, to get a good average. A clamp
on ammeter will not account for power factor or variable line volts,
and I have not seen one that integrates over a long interval of on-
off cycles. The Kill-A-Watt meter does a great job of this for 120V
appliances. I have a couple to use on 240V stuff, accurate and
neither is very expensive. Bruce Roe

120and240.jpgENEmeter.png

[J.P.M.]

Perhaps simplest and best are not the same. If you want to
use standby power, you will need to determine starting current
peaks for your system. If you want to reduce PoCo bills or
figure battery capacity needed, you will want to find KWh used
per month or other interval.

Oregon_Phil has sent you in the right direction. Appliances draw
one level of energy starting, another running, and another (often
not zero) off, for variable periods of time. Almost none of those
numbers will be found on the nameplate.

If you want to know KWh, best run the appliance energy through
a KWh meter for a month or so, to get a good average. A clamp
on ammeter will not account for power factor or variable line volts,
and I have not seen one that integrates over a long interval of on-
off cycles. The Kill-A-Watt meter does a great job of this for 120V
appliances. I have a couple to use on 240V stuff, accurate and
neither is very expensive. Bruce Roe

120and240.jpgENEmeter.png

+1 to that.
Also, after that and as Scrambler notes, spreadsheets can be very useful, but do the Kill-a-Watt meter chores as Phil notes.
A bit of work and organization will pay dividends.

[Calsun]

After getting a free ride from rooftop solar owners the utility monopolies in California now want property owners to pay for battery banks for the grid. This is something that the utility companies should be funding but with the CPUC in their employ the NEM 3.0 that they drafted penalizes new systems without a $10k or greater investment in batteries.

I replaced my failed inverter with one from Solis that has provision for charging batteries so I would have that as an option in the future. The Solis inverters are the best engineered and they have Wifi so they can be diagnosed from anywhere on the web. I use it to monitor my inverter with my smartphone. Most inverters are still using RS-485 ports that originated in the 1980s. When my Sunpower inverter failed in September of 2022 I tried for 6 months to get a replacement from Sunpower. That was when I researched other manufacturers (Sunpower actually rebadges Sonny Boy products) and decided Solis produced the best inverters. Turns out they provide a superior level of post sale customer support as well.

LG recently bailed on their panel customers as it was not a significant growth area for them. LG paid their customers a small amount to go away and use a different company to replace failed panels. Safer to go with a company like Sunpower where panels are key aspects of their business.

[rmk9785e]

{SNIP}
The most important beside finding someone with reasonable prices, is to find a reputable installer that will be there for the initial years of the system, when problems are most likely to arise. that is of course easier said than done, given the high percentage of charlatans out there....

I had chosen a reputable installer from this forum back in October 2016. They are still in business and have now started installing their own branded solar panels however their service and support has been sub-par. Specifically,

1. They do not have a monitoring system that would even alert them of a communication outage between the SolarEdge portal and the inverter. Every time it happened, I had to call them to fix it.
2. They did not register our installed panels with the manufacturer (LG).
3. There is no way for them to monitor if the array is performing as advertised and degradation is not more than what is stated in the contract. Requests for them to look into it are simply ignored with no follow up.
4. Their 'departments' don't talk to each other in that the service department has no idea what sales sold a customer. Every time they have to go digging.

Is this too much to expect?

in 2016, we chose LG panels hoping this large company will be around to honor their warranty. Well, the company is still around but apparently has gotten out of solar panel business. Wonder how and if they will honor the 25 year warranty.

[rmk9785e]

{SNIP}
LG recently bailed on their panel customers as it was not a significant growth area for them. LG paid their customers a small amount to go away and use a different company to replace failed panels. Safer to go with a company like Sunpower where panels are key aspects of their business.

I didn't get the memo from LG. Which company is to be used if our LG panels ever fail?

[rmk9785e]

Perhaps simplest and best are not the same. If you want to use standby power, you will need to determine starting current peaks for your system. If you want to reduce PoCo bills or figure battery capacity needed, you will want to find KWh used per month or other interval.

We have the PGE power data download to calculate KWh used per day/month. Would that not give us an accurate picture of the total power used?

We want to figure the battery capacity needed since there are many power outages in this area.

Oregon_Phil has sent you in the right direction. Appliances draw one level of energy starting, another running, and another (often not zero) off, for variable periods of time. Almost none of those numbers will be found on the nameplate.

If you want to know KWh, best run the appliance energy through a KWh meter for a month or so, to get a good average. A clamp on ammeter will not account for power factor or variable line volts, and I have not seen one that integrates over a long interval of on-off cycles. The Kill-A-Watt meter does a great job of this for 120V
appliances. I have a couple to use on 240V stuff, accurate and neither is very expensive. Bruce Roe

How did you put together your own 240V meter? Can you share details of parts/schematics?

[bcroe]

That spinning disc 240VAC meter is just 2 wires in, 2 wires out. Super
accurate and reliable, available on the internet for less than the price
of the box it mounts in.

The digital meter is just a DROK AC Meter, AC 80-300V 100A for a
couple dozen bucks. Mine reads 6 things, including KWh. The only
wiring needed for the portable version is a plug and socket to give
access with straight feed thru. I am set up with a 4 wire 50A range
cable, and the matching socket. Several appliances here use this. A
single meter has the 2 wires going to the 240 leads, one conductor
goes thru the meter current transformer.

My particular version has 2 meters, one for each 120V side of a 240V
load. That because my unvented clothes dryer has an unbalanced
loading. The switch allows going to a single meter at 240V. I will need
to scan in the schematic from another computer here.

I continue to believe the simplest system is the least trouble, after
reading about one communication or monitoring problem after another.
There is no internet connection to my system. There is no individual
panel monitoring. Panels are more reliable than any monitoring system.
I detect any problem with an occasional glance, looking for a near match,
at the pair of inverters. If a problem IS detected, someone will need to
deal with it in person, regardless. After over 1000 panel years, the only
faults have been with wiring, something never monitored. Bruce Roe

[Mike 134]

. The Solis inverters are the best engineered and they have Wifi so they can be diagnosed from anywhere on the web.

. Safer to go with a company like Sunpower where panels are key aspects of their business.

Just curious How are the Solis inverters built differently from other brands to make them the best?

Sunpower like LG was/is currently a major player in the solar market. They very well could go the route of LG.

[bcroe]

How did you put together your own 240V meter? Can you share details of parts/schematics?

Here is the Dual DROK energy monitor schematic. The 240V
50A range cord just runs straight to the corresponding pins on
the outlet. Run the BLACK or the RED lead thru the current
transformer that comes attached to the DROK. For a single
balanced 240V load, the small DROK voltage wire connect to
the BLACK and RED. The convenient place to do that is at
the load socket. HOWEVER there is a minor problem, the
DROK draws a bit of power for itself. To keep this power from
showing up in the readouts, run the voltage wire back thru the
current transformer so it cancels out.

I built a Dual DROK unit, for each side of unbalanced loads. One
has its voltage wire passing thru its current transformer on the
BLACK lead, the other DROK has its voltage wire passing thru
its current transformer on the RED lead. The voltage leads are
tied together to a switch. When the switch is connected to the
WHITE neutral, each DROK measures one 120V side of the load.
When the switch is connected to the RED lead, the DROK wired
to BLACK sees the full 240V load, the DROK wired to RED sees
0V and turns off. Bruce Roe

DualDROK.jpg

[rmk9785e]

Now we have three proposals that I'm trying to compare. Please see the attached template and help me make sense out of it.
The first vendor did not include a storage solution because according to them "A battery is not required for NEM 3.0 customers. A battery may provide more bill savings and pay for itself if operated correctly, but even a 100% energy offset solar-only system will bring value to a customer."
The vendor with Panasonic panels doesn't see a need for Module Level Monitoring.

Am I wasting my time with unnecessary analysis? Most vendors don't provide a lot of detail. Getting itemized proposals is like pulling teeth.
Where can I read more on NEM3.0 in plain English?