New learner- Is this the right palce for me?

RustyWrench

Random searching on power backup led me here. I'm not solar oriented but do recognize intelligent dialogue when I see it. 

I live in NE Ohio; not ideal for solar. We have infrequent, but becoming more frequent, power outs. I'd like to move beyond my little 3500w genset mostly because the noise is bothersome. Also I've just learned I need to replace the main panel.

My idea is to have a whole house battery(s) that can power a relatively light load- gas furnace blower, fridge, sump pump, tv and a couple lights.
For up to 3-4 days. And that the battery can be be charged from grid, generator, and potentially solar.

My hope is to have someone else install such a system but to learn enough what a good install would be.

I started this last year but had to put it aside. At the time I was settled on a kilovault 7.5kwh and schneider xw inv/chartger. But more to the point I'd feel more comfortable with a plan set of diagrams and specs. When I watch YT it seems as if folks buy stuff and just bolt it together. Maybe I'm wrong. And I hear about so many problems...

So still reading. Hoping to learn more about the consultant design/build side of things. Was also hoping to connect with individual/small shop sort rather than the "big company we'll have somebody get back to you" sort. Nothing against them. 

Advice, comments?
Thank you

littleharbor2

For any meaningful battery backup You will need more than 7.5 kwh worth of battery. Take your utility bill for the months you feel the need to cover and locate the kwh. usage for the month divide it by 10 and you will get an idea of 3 days worth of typical usage. This will give you a realistic idea of your back up needs.

SumPower

RustyWrench said:

Random searching on power backup led me here. I'm not solar oriented but do recognize intelligent dialogue when I see it. 

I live in NE Ohio; not ideal for solar. We have infrequent, but becoming more frequent, power outs. I'd like to move beyond my little 3500w genset mostly because the noise is bothersome. Also I've just learned I need to replace the main panel.

My idea is to have a whole house battery(s) that can power a relatively light load- gas furnace blower, fridge, sump pump, tv and a couple lights.
For up to 3-4 days. And that the battery can be be charged from grid, generator, and potentially solar.

My hope is to have someone else install such a system but to learn enough what a good install would be.

I started this last year but had to put it aside. At the time I was settled on a kilovault 7.5kwh and schneider xw inv/chartger. But more to the point I'd feel more comfortable with a plan set of diagrams and specs. When I watch YT it seems as if folks buy stuff and just bolt it together. Maybe I'm wrong. And I hear about so many problems...

So still reading. Hoping to learn more about the consultant design/build side of things. Was also hoping to connect with individual/small shop sort rather than the "big company we'll have somebody get back to you" sort. Nothing against them. 

Advice, comments?
Thank you

The store here does a great job in consulting and system design. They would get you to a system with the least amount of time spent in research. I would suggest giving them a call or fill out there online system design and consulting form.

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

I have purchased equipment from them and there advise and support has been good.

I will agree with @littleharbor2 on the battery backup sizing. you will need more battery than just the 7.5kwh.

SumPower

SteveK

The knowledge base here is impeccable. You might not get all the advice you seek but you will not get bad advice. There's a limit on what can be passed online versus what you truly want to hear.

If you can do solar my advice is don't do a backup in the traditional sense where it only works when the grid is down. Don't try to fit a "solar generator" to your home and only use it like a generator after a hurricane. Try to incorporate the grid down mentality in your everyday life. Pick and chose your critical loads battles and actively support those daily. This way you get financial benefit from your outlay in the form of reduced electric bills every month...outage or not. This way you will actually use your outlay and "wear it out" instead of succumbing to "calendar aging" while it sits there basically collecting dust.

Calendar aging is the nemesis of big battery backup solutions. The bang for buck just isn't there compared to a generator. If you aren't going with cheaper off-shore battery types or DIY kludges the outlay is massive compared to what you can get a whole house generator with large buried LP tank for. And it works "where the Sun don't shine." 

You might be surprised at your home's location and it's ability to harvest enough solar to make the rather small investment expense of adding solar to your plan cost effective. Panels are cheap enough. More "quality" battery isn't. I have a location that all solar companies balked at. They said it didn't make sense and it didn't when I added their contribution of the cost to the analysis. If you live in an area with a cool AHJ magic is possible.

RustyWrench

littleharbor2- thanks. I have the ability to measure individual loads. Making some estimates I see how quickly a 7.5 gets depleted.
SumPower - thanks. I had not realized availability of service here

SteveK- Had not heard the term calendar aging before. Those middle two paragraphs are a fantastic point of view for me. Probably some of the best advice I've come to consider in my brief foray into this field. I'll be back after a bit more pondering. Thanks much! 

BB.

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

RustyWrench

BB- Thank you for the careful read of my first post and responding in context. Now mulling over your advice on a 'good compromise'.

By now I have a fair understanding of the parts but not a lot of clarity on the system. That will come in time, I'm sure.

Last year about this time,  I started to collect usage data but other priorities became paramount. Most runtime stuff is easily measured over a short period, I think. But the furnace is different. I had put in a panel meter but wasn't good about recording the data. I'd like to have a good sample of cold weather runtimes before I make a statement of needs.

I like those energy monitor systems. From DC auto diagnostics, I know the low current amp clamps, in that use, can drift and need to be zero'd for every new measurement. Any similar concerns on AC higher current? Or is that an overthink. I have that tendency.

Recently learned the house main panel was faulty. Voltage (one leg, It seems) was getting past the main circuit breaker when turned off. I found this out when connecting gen to power inlet box <eek>. A moment of scare but nothing bad happened. 

My questions of the day are:
Anything specific to instruct electrician do during new panel install. There will be some kind of secondary load center for critical circuits?
My genset now powers the panel fully though obviously limited. Is that not a good construct for grid tied solar - genset arrangement?

On the solar supply side: How do I measure availability for my particular spot? In plant science we talk about photon flux density. Does that apply here? Can I set up a single small panel and gear then extrapolate to what a larger array would generate?

How do I post an image? Tool wants an image URL. I don't know that a jpeg in my laptop folder has an URL. Just a path?

Thanks

BB.

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....

BB.

Regarding AC panel... Typically you can replace a bad breaker. Depending on brand/model/age, there are some that have been discontinued due to safety issues (out of the 1960's and 1970's at least). Have a house with "Federal" breakers.. They stopped making (out of business) due to breakers failing to trip in over-current conditions--Took out the utility's pole transformer when the internal distributions panel caught fire (next to coast, salt air, fog, humidity). Need to redo the electrical system for the home.

What should you do next? Today, the standard seems to be 200 Amp panels (120/240 VAC split phase power for North America). If you go with a larger panel, you may need the power company to do an engineering study to see if they can support (a larger?) 200 amp panel with their existing network. I have a 125 amp service in my home (no "shop", no A/C). That is your choice/future value of home. Some folks with electric vehicles are installing 400 Amp or even dual service panels to charge their vehicles...

Another option--If you are looking into a (smallish) solar power/backup power system, you may want to have a second sub-panel installed as you suggest.

The sub-panel would power your "backup power needs" (LED lighting, some random outlets in the home (kitchen, TV/Computer, bathroom/hall lighting, bedroom backup AC power)... You can then connect your backup sub-panel to your battery backed AC inverter to give you backup power when the mains are down--And not have to flip breakers, run extension cords, etc. around the home. This does get into the genset/backup solar / refrigerator / central heat / etc. questions (one "genset backup", a second "low power" battery backup, run the main home on the "big genset", and the overnight battery loads on second panel, etc.).

There are retrofit "generator transferswitch retrofit sub-panels" too. You wire into your existing main panel and pull off various circuits to be powered by the genset transfer switch (manual, automatic, etc.):

https://www.homedepot.com/s/generator transfer switch?NCNI-5

As you can guess, there are lots of options out there....

Regarding generators--I lean towards the manual systems (manual start, transfer switch, etc.). The "fully automatic" with weakly auto tests and such--There seem to be a lot of things that can go wrong over time (need debugging, fixing, etc.).

There are some things regarding adding Grid Tied solar to a home... More or less, you can add 20% over sub-panel capacity (say 100 Amp main breaker and up to 20 Amps more for GT solar for 120 Amps of "power to the panel"). And the GT solar breakers are installed "opposite end of the bus bars" to the main main breakers (so you don't have 100+20 amps on one end of the 100 amp rated bus bar).

Solar energy... Everything (planning wise) is based on averages... You may have 3.0 hours average sun per day in December, but you could have a sunny December or a cloudy/stormy December. I have seen my GT solar generate 30% of "typical power" on a "winter day", or even 5% of predicted power during stormy weather. For solar, our deratings (for real life) run like:

• Grid Tied Solar: Solar array power name plate rating * 0.77 for panel and inverter derating/losses (panel lose Wattage output in hot sun)
• Off Grid Solar (lead acid batteries, AC power system) Solar array * 0.52 panel+charger+battery+inverter losses
• Predicted OG solar output * 0.65 to 0.50 of "predicted" solar harvest "usable" (bad weather, etc.)

So your 100 Watt panel * 4 hours of sun = 400 Watt*Hours in "real life":

• 400 Watt*Hours of Sun * 0.52 off grid AC solar system eff = 208 WH per day (long term average) usable harvest
• 208 WH per day usable * 0.65 solar fudge factor = 135.2 WH per day planned harvest (minimize genset usage, keep batteries happy, etc.)

A good place to start for solar information:

https://pvwatts.nrel.gov/pvwatts.php

I will use 1 kWatt (1,000 Watt) array (minimum PVWatts supports) as an example. Location Mentor Ohio, 1 kWatt array, (defaults), system losses 48%, 42 degree tilt (typically year round optimum). (note: I use my own numbers here--Seems to work well for predictions):

RESULTS

Print Results

System output may range from 2,798 to 2,953 kWh per year near this location.
Click HERE for more information.

Month	Solar Radiation ( kWh / m2 / day )	AC Energy ( 1 kWatt array / kWh per month)
January	2.35	147
February	3.64	205
March	4.54	274
April	4.85	274
May	5.43	305
June	5.45	289
July	5.85	317
August	5.85	318
September	5.04	271
October	3.76	219
November	2.70	156
December	1.80	111
Annual	4.27	2,886

Say you want 3,300 WH per day... In December, and you may lose power for 1+ months (long term outage, avoid genset usage). Normally 3+ Hours of sun per day is "good enough" for Solar... Less than that is not really "solar friendly". Yes, you are over sizing the system--That is typical for off grid solar.

Sizing battery bank for 2 days of storage and 50% max planned discharge (for longer battery life + 1 day of "emergency backup energy"

3,300 WH per day * 1/0.85 AC inverter eff * 2 days storage * 0.50 max planned battery usage * 1/48 volt battery bank = 324 AH @ 48 volt battery bank

Normally charge battery bank at 10% / 13% / 20% / 25% rate of charge (10% minimum suggested for off grid system)

324 AH battery bank * 58 volts charging * 0.10 rate of charge * 1/0.77 panel+charger derating = 2,441 Watt minimum array size (suggested)

Then there is array sizing based on hours of sun per day:

3,300 WH per day * 1/0.52 off grid AC system eff * 1/1.80 hours of sun per day (December average) = 3,526 Watt array December Average Break even array

And then the solar "fudge factor" of 0.65 to 0.50 (bad weather, minimize genset usage, etc.:

3,526 Watt array (average production for December) * 1/0.65 solar fudge factor = 5,425 Watt array with some backup genset usage
3,526 Watt array (average December) * 1/0.50 solar fudge factor = 7,052 Watt array (less genset usage)

next post...

BB.

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

RustyWrench

Wow! That was astonishingly thoughtful and detailed. I printed it out.   

I will be back. Perhaps not soon with all this study. 

Thanks again.
Best regards.

SteveK

RustyWrench said:

Wow! That was astonishingly thoughtful and detailed. I printed it out.   

I will be back. Perhaps not soon with all this study. 

Thanks again.
Best regards.

Did I mention impeccable?