Just to be clear... Our host (renamed to NAZ) founded the forum and provides money and support to keep this forum running.

The forum is open to all (you do not need to be a NAZ customer) and is operated independently of NAZ (i.e., me, the "moderator")--I am a volunteer here and just help keep the forum running and spam free.

If you are new to solar/power systems--Please feel free to ask any questions you may have. No such thing as "dumb questions". Even if you plan on hiring somebody to design and install your system (not a bad idea if you have never done this before), learning about the basics (sizing, paper design, trade-offs, available equipment, different options, etc.), you will be in a much better position to communicate with a designer/installer.

NAZ is a wholesaler/retailer for solar/on and off grid systems and such. They also have engineers there for detailed support and can even "pre-build and test" complete systems for turn-key units (pretty nice for remote installations--No driving 100 miles to a hardware store or PO Box for missing parts).

https://www.solar-electric.com/

Regarding figuring out how much power you will "need"... The things that you listed (heating, fridge, sump pump, etc.) can all be pretty energy intensive (motors, moving air and liquids, etc.). So you have two things to worry about... Peak (Starting/Surge) Wattage (for a few seconds), and Watt*Hours per day (average running Watts * Hours of operation of each appliance).

For the "small stuff", a Kill-a-Watt type meter can help you a lot.. Cheap and you can move it from corded appliance to appliance (links are just for your research--Not any specific recommendation):

https://www.amazon.com/kill-a-watt/s?k=kill-a-watt

For larger homes/permanently installed equipment (furnace, well pump, etc.), you can get "whole home monitoring systems. Fairly simple to install, and can give you the ability to measure your loads for the whole home.

https://www.amazon.com/s?k=whole+home+energy+monitor

More or less, you can start with these rules of thumbs:

500 WH per day (0.5 kWH per day or 15 kWH per month)--Cabin lightning, cell phone charging, etc.
1,000 WH per day (1.0 kWH per day, or 30 kWH per month)--Cabin/emergency home backup (RV style water pump, laptop computer)
3,300 WH per day (3.3 kWH per day, or 100 kWH per month)--Very energy efficient home. Full size Energy Star Fridge, Clothes Washer, solar friendly well pump. Close to a "normal" electrical life
10,000 WH per day (10 kWH per day, or 300 kWH per month)--Energy efficient home, less conservation needed. Electrical power for cooking, (gas/propane) central heat, etc.
33,000 WH per day (33 kWH per day, or 1,000 kWH per month--Typical North American home is 500-1,000 kWH per month. Lots of electrical usage (water heating, electric stove, some A/C)

What usually drives the sizing of a battery bank/solar power system is the appliances that run 24x7... A refrigerator which may take 120 Watts running 24 hours per day may use 1,000-2,000+ Watt*Hours per day.

A microwave that takes 1,200 Watts may only run for 20 minutes per day or use around (1,200 Watts * 1/3 rd hour per day) 400 WH per day--Much less than a refrigerator.

A full blown solar+battery backup system with "days" of backup power, as folks said above is generally not cost effective. If you have a week of power outage per year (random winter failures)--The cost of batteries and replacements (every 5-10 years) for a large battery backup system, is usually just not economically justifiable... A solar+battery power system can make economic sense if used 9+ months a year.

However, there are other options... You are concerned about generator noise. A good compromise is to have a few things run from a solar+battery system (some LED lightning in the kitchen, living room, bathrooms, bedrooms, a laptop computer, cell phone charger, etc.) and build out a small (say 1,000 Watt*Hour per day system) for quiet evening/night time power. And run the genset during the day/peak power times (breakfast/mid day/dinner as needed) to run your larger loads, recharge the battery bank, keep the fridge/freezers cold.

Usually not a bad way to go (it is what I do--I have Grid Tied solar, no backup power, a smaller genset like a Honda eu2200i or eu3000i or other equivalent, enough fuel for 1+ weeks--Around 1-2 gallons per day, and a small battery+AC inverter like Jackery or similar).

-Bill

More or less--I suggest a 3,300 WH per day system is on the order of a "larger' off grid power system (cost, complexity, etc.)--Costs are highly variable--Much depending on your choices (quality of batteries, Amp*Hour of bank, low cost or high cost solar hardware, possible costs for design/installation....

For an emergency/backup system (days/couple of weeks)--Looking the minimum amount of power you need (solar/battery)--Sort of a camping experience using propane/natural gas/wood for heating/hot water/etc...

Regarding your furnace system--Choices of running central heat (air?) vs wall/floor mounted natural gas/propane (that don't need AC power) for "backup heating" may be a cost effective issue (again--Depends on what you have locally, size/configuration of home--Your personal choices). In a moderate climate (no freezing weather, no A/C needed). I grew up in a 4 bedroom home with one wall natural gas furnace (no fans, etc.) and we were happy.

If you want to monitor your Furnance electrical usage using a simple kWH meter--You don't really need to check it at (for example) 8am every day and log... Just write down the meter reading at the start of cold weather, and write down the reading a week (or a month) later... The "per day" of energy usage is usually as close as we need to get for accurate loads/system design.

kWH per day = kWH over period * number of hours of measurement period * 1/ 24 hours per day = Average kWH per day
kWH per day * 1,000 WH per kWH = WH per day

I am big on measurements and modeling to better understand your loads. Off Grid Solar power is not cheap (on a system running 9-12 months a year, $1=$2+ per kWH is a good starting estimate--For solar/battery power system that run days/weeks a year--The $/kWH price does not really make economic sense--With solar/battery power, you can only harvest per day and use power per day (or over several days)... Any power not used (i.e., 11 months of the year), has zero economic value to the system owners--And the batteries are still aging (you have aging due to time/temperature and cycling based wear--Both are important factors in eventual battery bank failure).

At least with gensets--More or less, if taken care of, generators will last for decades (I "pickle" gensets after use--Run out of fuel, put a teaspoon of oil in the spark plug hole, crank a few times, and pull rope to stop on compression stroke--1 cylinder, valves closed). Have done this with my Honda eu2000i gensets and others for years--no problems so for (knock on wood).

Fuel wise, use a fuel stabilizer in 5 gallon gas cans--And recycle to car once a year... No "extra fuel costs" as fuel is eventually used (either in genset, or most often in cars). I like to use smaller fuel efficient gensets. An eu2000i runs around 4 per gallon at full load (1,600 Watts) or around 9+ hours at 25% load (400 Watts) per gallon. I use, very roughly, 2.5 gallons per day to run some lights, a couple refrigerator/freezers (in this example, running 24 hours per day for elderly in-laws' home during the last major fire season)... So keeping a week of use (3-4x 5 gallon gas cans) is not difficult (watch fire codes, storage conditions, etc.).

You see lots of ads for Generac and similar gensets--Typically around 9+ kWatt (9,000 Watt) units... Most homes use much less power (no electric stoves, hot water, HVAC usage)--And they can use 0.5 to 1.0 (estimate) gallons of gasoline per hour (can convert to propane, natural gas, if needed)... These large gensets can give you a nice backup power... But the fuel usage can be a huge issue. If gasoline, you are looking at 12-24 gallons per day of gasoline, or at $5 per gallon (ugh, my California price for regular fuel in last week or two)--I would be looking at $60 to $120 per day to run that 9kW genset (let alone upwards of 2.5-5x gas cans per day of fuel). If it "worth it" to you... That is great. If not, again modeling your usage and energy generation system cost/usage can be a great help to make your plans/decisions.

For me (again personal choices)--I can live with 2 gallons per day to keep food cold/frozen and run some lights, battery based AC inverter (TV, laptop, cell phone charging, random lights in home, etc.). 24 Gallons per day vs 2 gallons per day, 1 day of stored fuel vs 12 days of stored fuel.

Regarding Amp*Hour and Watt*Hour clamp meters... AC "current clamp transformers" are very accurate and do not need calibration/re-calibration due to drift.

For DC power systems, you can use Shunts (precision power resistors), which do not drift:

https://www.solar-electric.com/search/?q=shunt


And there are (typically) AC and AC+DC current clamp DMMs (digital multi-meters). The AC only meters--Very accurate and do not drift. The AC+DC DMMs do drift (on DC only, as I recall) and can need to re-zeroed after a few minutes (+/-).

https://www.amazon.com/UNI-T-Digital-Handheld-Resistance-Capacitance/dp/B0188WD1NE (example of "inexpensive" good enough meter)
https://www.amazon.com/Auto-Ranging-Resistance-Klein-Tools-CL800/dp/B019CY4FB4 (mid-cost AC+DC clamp meter)

These meters are great for debugging and understanding power systems--But these are not a great choice for measuring energy usage (Amp*Hours @ xx Volts, Watt*Hours, etc.). A refrigerator typically runs at something like 50% on and 50% off (with higher power for an hour or so per day to defrost). You want a power meter (kill-a-watt, or other energy meter--i.e., AH/WH over time for AC or DC power measurements). I have not researched, but there are DC energy meters that do not need to be recalibrated in normal usage when using a current clamp (Hall/magnetic effect Transistor have zero point drift).

There are also "issues" with AC power--Something called Power Factor (and other terms)... To get accurate AC energy measurements, you need a Watt*Hour meter that measures both current and voltage (and phase angle). Another post (if needed).

The options out there these days are amazing for measuring AC and DC power--At very low prices (for entry level devices) to at least get started....

next post....

As you can see, lots of information that we can do "back of the envelope" with... Are these correct for your needs? At this point, I cannot say. But they give you some tools to size the system--And then you can start costing components, making choices (Lead Acid vs Lithium Ion batteries and such).

In general, we use rules of thumbs here that should give you a working system without major surprises. And you can do "what if" questions (genset vs more solar, battery types with "cheap" lead acid batteries last 3-5 years, and "good Lead Acid / Li Ion" can last 7-15 years}.

Lithium Ion are great for hot climates... Lead Acid are difficult to beat for sub freezing applications.

Posting photos and such... We are supposed to be able to do "drag and drop"--But that usually does not work for me (I typically use a cheap ChromeBook computer). You can attach files (data, PDF, etc.) with the "Attach File" (black paper Icon). Or you can do inline photos/drawings/etc. with the "Attach Image" sun/mountain icon (from image file on computer, or from Internet--I sometimes have to "open image" in browser to get "clean" image for use here). This is what I do (mostly) to upload screen shot files here:


Sorry for the long answers... Normally I/we try to go through step by step (energy needs, then math, and finally hardware choices)...

Please feel free to ask for clarifications to the above Q&A... I try to "show my work"--But I do make the occational mistakes (ask my wife).

Have fun Rusty,
-Bill