Need advice and critique of our future solar system

sunshinemosunshinemo Registered Users Posts: 9 ✭✭
Hi all! We are fixing to buy equipment for a small off grid system and need some guidance. We live in northern missouri.

We have 3 goals. 1. Ability to prevent food loss in case of outage 2. Be as independent as possible of the grid 3. Ability for petite woman to move the system if needed.

Here goes: The only things that will be plugged in constantly are a 7.1 cf chest freezer turned into a fridge, and a future 3.1 cf chest freezer used as a freezer. The other stuff will be occasionally used, such as several aa/aaa battery chargers, curling iron, microwave, phone, tablet, task light and sewing machine.

The 7.1 cf "fridge"  is 115v 1.7amp (195w then ?). It only runs about 5 minutes an hour. As we don't have the small freezer yet I don't know it's power consumption.

The aa/aaa battery charges are 5v, 2amp. Possibly will have up to 3 at once for about 4 hours daily. Phone and tablet are probably 5v and 2amp as well.

Curling iron is used approx 5 minutes daily and is 120v and 90w.

Microwave will be used approx. 5 days weekly for less than 5 minutes each day.

Task light is 12w, 110v and may be used approx. 12 hours monthly.

Sewing machine is 120v and .5 amp. Used about once a month less than an hour.

Lighting, except the task light mentioned above, is already taken care of and won't be on this system.

We want quality components that will last a long time. Thinking about battleborn lifepo4 battery(ies). Don't want a 12v system. Maybe Renogy 160w flexible panels (very lightweight). Can't easily forge ahead on other components till we get some advice.

Because of neighbors from hell, plus occasional bad weather we will be building an enclosure with glass southern wall for the panels. I'm aware the panels won't charge as efficiently this way but this seems to be our lot in life at the moment.

So, can anybody help me along on this journey? Not sure of which brand or size of charge controller or inverter, etc.

Thank you so much, in advance!


Comments

  • Dave AngeliniDave Angelini Solar Expert Posts: 5,910 ✭✭✭✭✭
    More info might help others. Where in Northern Missouri, when, how (permitted system? The why you have answered. Also include what appliances you use from the grid now. Do you need a 120/240 inverter or is 120 only good enough? Will there be future growth? Budget?
    Since you have the grid the cost of a back-up genset will be far cheaper than solar, Right? 

    My advice is to stick with one brand of equipment so that is can all be networked to make it easy to see and adjust. That pretty much is Outback power systems, or Schneider Solar. I guess you could add the company I always forget, because I have never used them in over 300 offgrid homes. They are up in Washington state. If you are going to do this for a long time I would use 48vdc and not 24vdc battery.
    Stay away from flexible solar panels.Two ladies can easily move/install the common 300+ watt panels these days. Consider building a pergola or an awning in the yard. You will need 1KW of solar to start. Plan for more and where would you install it.

    Good Luck! It can be a fine project if you do the costing and have the room.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • PhotowhitPhotowhit Solar Expert Posts: 5,576 ✭✭✭✭✭
    You might want to get a Kill-A-Watt meter to figure out your loads, it's a simple device that you plug the loads into then it will monitor the loads over an hour, day or week, so you can get a good idea of the power usage. Amazon link, but cheaper at Harbor freight or ship to store WalMart;

    https://www.amazon.com/P3-P4400-Electricity-Usage-Monitor/dp/B00009MDBU

    Flexible panels don't work well with longevity, I'd skip them. Since you would like things portable, you might give some idea of what you can handle weight and size wise. I think mounting them inside under a glass ceiling/wall will make the larger 12 volt nominal panels a good option. 

    Amazon has some good deals with shipping companies and may be your best deal per watt, here's an example 80 cents a watt delivered;

    https://www.amazon.com/Pieces-HQST-Monocrystalline-Solar-Panel/dp/B018BN5P66/ref=zg_bs_2236628011_30

    In a room with a glass 'wall' panels will have very minimal output, likely a East or west wall would be better during summer. panels NEED direct sunlight to put out meaningful current. During the summer the sun is over head during the day, but might get direct exposure in the morning or evening (East or west). With out direct sunlight figure 5% output likely best....

    As to poor weather solar panels are very durable. 3 years ago hail cracked 4 of 6 windshields between my neighbor and myself, 1 1/2" minimum. My array survived just fine;


    Here's 16" of wet snow on my array;


    It would be hard to venture a guess, but I'd think you may want a pretty huge array, if it must be inside. Maybe 4000 watts in east and west facing windows... Just a shot in the dark. Sorry you have crappy neighbors...
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • PhotowhitPhotowhit Solar Expert Posts: 5,576 ✭✭✭✭✭
    I'm in Missouri as well, You might make a visit to the Dancing Rabbit, if you are nearby. They are in the North Eastern part of the state. They might be able to offer suggestions;

    https://www.dancingrabbit.org/


    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • softdownsoftdown Solar Expert Posts: 3,504 ✭✭✭✭
    Your system doesn't need much power in my opinion. Chest freezer converted to fridge? Very economical.

    I'm thinking an ~ 1500 watt inverter and ~1200 watts of panels. Though I don't know how that glass in front of the panels will work out. Got a bad feeling about that. Panels are more efficient at cooler temps.

    Panels are indeed tough. Got a goat from hell, they all are, that likes to walk on some roof panels. Hasn't killed them yet. Has even launched from them to another roof. What a surprise - finding a goat on a 10' roof.

    I'd buy golf cart batteries the first time. Everybody kills their first set. You probably know somebody with a Sams Club or Costco membership -$90/battery. In fact - I may try them next time. Life serves up a lot of changes so why invest in 15 year products when 5 years may be more than enough?

    Want to trade neighbors? Mine has done:
    Robbed precious metals in some likelihood
    Flattened, exploded many, many tires
    Shot windows with BB gun
    Taken logging chains
    Siphoned gas many times
    Hatchet/axe through steel siding
    Scratched wet cement a lot
    Broken fence insulator which triggered alarm for day. Ruined end of vacation and battery.
    Poisoned dog the day fence went online
    Removed what is readily removable
    Wolf dog attacked alpaca - trip to vet and fence upgrade followed
    Wolf dog killed alpaca
    Could all be coincidence. Or not.
    Yea- neighbors can be bad. Been looking for 40 acres and three separate electric fence lines. Too expensive right now.

    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • sunshinemosunshinemo Registered Users Posts: 9 ✭✭
    Dave Angelini, We are near Hannibal Mo. Ideally this system would be up and running before November. We don't need any permits here. This system is only the beginning. Ultimate goal is to be 100% offgrid but that can't happen at this location. Looking for greener pastures. 

    The only things I'm concerned about powering with this system right now is what I listed. I've figured out either how to comfortably do without other stuff or how to work around it if I need to, so no worries. Future growth of the system is definitely in my plans, but only for powering similar stuff that's listed. For ex, we may add a small flat screen tv and DVD player someday, etc. Nothing high powered such as an electric stove, etc.

    Our budget sux lol! We aren't rich by any stretch of the imagination. That being said, we've been around long enough to know that you get what you pay for. If we can't afford quality stuff we'll save up till we can.

    Actually thought 48v would be the way to go but wasn't sure.

    Couldn't find the answer online: since the lifepo4 batteries are 12v, would I need more if it's a 48v system? If so, we'd need to go with different batteries cause those are 1000.00 each.

    Since you suggest to plan for 1kw, that sounds like an awful lot. I am able to charge the small devices and all the batteries with solar already, so maybe I should just start with a system that only powers the "fridge" and small freezer and then expand the system as we can afford it?

    Thanks so much for your help!
  • sunshinemosunshinemo Registered Users Posts: 9 ✭✭
    Photowhit, I have a device similar to killawatt lol! We recently did a bunch of projects in the house and it's missing in here somewhere. Still have to complete a few of the projects and will probably eventually find it.

    Based on advice so far, we will forget about enclosing the panels and concentrate on figuring a way to prevent theft and vandalism instead. That will be extra expenses, such as alarms and cameras. Maybe a huge German shepherd  or a rottie too lol!

    Thanks for the tip about the dancing rabbit. Heard of them but never visited. Looked on their site and looks like they've cancelled events for this year, probably covid related. I'll email them.

    Where are you located, if you don't mind saying? We are near Hannibal Mo.
  • sunshinemosunshinemo Registered Users Posts: 9 ✭✭
    Photowhit, I have 
  • sunshinemosunshinemo Registered Users Posts: 9 ✭✭
    Softdown, that sounds encouraging. So far, we've shaved 25% off our electric bill as compared to last year at this time. If I could get my husband convinced of certain things, we could save even more.

    You win the crappiest neighbor award for sure. I'm so sorry! How could people be so heartless as to kill or hurt innocent animals??! Not to mention all the other stuff they've done. Someday they'll get it back cause what goes around comes around. I've seen it happen. Just gotta be patient and wait for it.

    Ours have mainly stolen stuff and vandalized, with a heavy mix of terrorism thrown in. I could write several volumes on what they've done but they aren't worth the paper or the ink.

    We want to move, but everything is paid for and times are pretty scary right now. We are stuck with them for now sigh...
  • sunshinemosunshinemo Registered Users Posts: 9 ✭✭
    Ok, so I think we will:

    1. Do without the enclosure for the panels
    2. Only try to power the "fridge" and small chest freezer on this system
    3. Make it a 48v system 
    4. Go with regular momocrystalline panels instead of flexible ones
    5. Acquire a huge German shepherd or a rottie and maybe a cannon. Lol just kidding about #5

    I will study some more tonight and see if I can figure out what will work for this and get back on here later and see what you all think.

    Thanks very much so far!

  • softdownsoftdown Solar Expert Posts: 3,504 ✭✭✭✭
    See my thread on electric fence with alarm. I think he has actually stayed out for awhile now. No flat tires since going online. Flat tires were killing me.

    Terrible neighbors are interesting. There is literally almost nothing the victim can legally do.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • PhotowhitPhotowhit Solar Expert Posts: 5,576 ✭✭✭✭✭
    Dave Angelini, We are near Hannibal Mo. Ideally this system would be up and running before November. We don't need any permits here. This system is only the beginning. Ultimate goal is to be 100% offgrid but that can't happen at this location. Looking for greener pastures. 
    So 'Why' do you want to be off grid?
    I get the "prevent food spoilage" and "Be'ing' as independent as possible". I just want you to understand that saving money is really rare in off grid situations.

    Not sure why you couldn't go 100% off grid where you are, if you wanted to? There is a power line right-of-way that crosses my property, and my place was on the grid before I bought it 9 years ago. If this isn't going to remain home, I don't think I would invest in a lithium battery bank. Beginners often make mistakes and that is a VERY expensive battery bank to ruin. The also are required to be inside, in 17+ years of living off grid, I've yet to share my home with a battery bank. I also heat with wood, have pex plumbing and regularly leave the home during winter unheated. (This worked fine even with single digits here a couple times, but I broke manifolds and even the PEX in 2 places when I left for a week and came back 10 weeks later, FWIW - when I came back I took a couple hotpockets out of the freezer and popped them in the microwave, the solar electric system had no issues. I COULD NOT DO THIS with a lithium battery bank, lithium must stay above freezing to be charged)

    I would suggest that this is an experimental system, do it cheap. Golf cart batteries work well and have a good bang for the buck. but you need to know your total loads. I agree a 48 volt system is the way to go! When I thought I was setting up my 'forever system' back in 2005, I had a small cabin and small loads to go with it. I figured I would be fine with a 24 volt system and a 2000 - 2400 watt array. I had a fridge and a window air conditioner as major loads. Here's a photo of the cabin, array and battery box/power center.

    With trees behind the array a simple cantilever design was cheap and simple. I replaced 1 of the PT 2x4's for the new owner (friends) in 2013 when I sold it, it had warped a good bit. I did a slightly different design between the 2, originally figuring I'd seasonally adjust the panels in pair to catch the higher summer sun, but eventually went to PVWatts and saw there was just nominal difference.

    Where are you located, if you don't mind saying? We are near Hannibal Mo.
    I live 7 miles south of the tall water tower on I-70, just down the road from the guy who does chainsaw repair... Near Williamsburg, MO (Cranes Store), I was in Troy today!

    Math with unknown loads is very tricky, particularly with people new to solar, but you won't be living on solar and will have the grid available.

    So... I know this guy, who brought home 1800-1900 watts of solar panels, 310-320 watt panels. Heck they were cheap, from a guy who installs community solar projects. They were new, but 2 were panels that they damaged slightly on installation. 1 a slightly twisted piece of aluminum, when they mounted and suspended from 1 bolt, and 1 that the mounting nut galled and torn an eraser sized piece of the backing (I have since applied tool dip/ liquid electrical tape to patch. The other 4 were never mounted. I've not done more than a continuity check, but suspect they are all fine. He had assorted other panels from leftover jobs, even gave me a solar shingle that I've enjoyed playing with... I even have the quicky built rack I used to bring them home.



    As I recall these are 72 cell panels, One of the tricky things about not knowing where you are going with things is you may end up with un-matching panels. Another is 72 cell panels, often, don't 'play nice' with 48 volt system. They would be fine with a cheap PWM charge controller, but the high VOC sizes them out of many MPPT type charge controllers. I have a Schneider 60-150, but I think 150 volts is a max VOC so these wouldn't work in strings of 3, and strings of 2 would be too low a voltage. I've yet to check out the CC, but hear they are pretty bomb proof. Also all the MorningStar controllers won't work with either strings of 2 or 3.

     I was thinking about what else I might have to build a system around, I have a 24 volt exeltech xp1100(true sine inverter), I've run my 20 year old fridge off it without an issue, it would likely run 2 fridge/freezers until the oddity of both starting at the same time. It's really only less than a second with the high demands (locked rotor amps). It wouldn't damage the inverter, it would just shut down, but I don't now and would have to check to see if it restarts on it's own.

    With a chest freezer and your chest freezer conversion, you may only use around 1 kWh a day (just those items), You could likely get by with 4 of those panels and 4 golfcart batteries. The tricky time will be during the long cloudy spells in the fall.

    Anywho think about it, I think I can find some mounts for the panels. I made some extra from aluminum angle the last time around. Work well with wood. You could use 4 panels and a 60 amp PWM charge controller (cheap) and likely have a usable system for Under $2000 and some hard work, that would last 4-5 years until needing the batteries changed out.

    Expenses, would look something like this;

    $400 panels delivered,
    $440 for 4-GC batteries Costco or Sams club, maybe Rural King...
    A PWM charge controller, Epever has one at $75. 
    A section of Din rail and 4 breakers a comb and a bus bar $120-$150(if you convert a "Baby Box" )
    Inverter 24 volt Samlex EVO 1200 watt inverter/charger, $600 Not sure why Northern Arizona Wind and Sun doesn't sell this, but it has a 3x surge rating so likely would be no issue if both started at once, and it's an inverter/charger, so you can hook up the AC output from your generator to charge the batteries in need.
    A main breaker, breakers ahead and behind the CC, wiring, PT wood, aluminum angle to make mounts, another $4-500.



    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • softdownsoftdown Solar Expert Posts: 3,504 ✭✭✭✭
    I'm unclear as to whether this augments grid power for power outages or what. Solar power costs at least twice what grid power does. A bitter pill for most dreamers to swallow.

    If it still makes sense I'd take advantage of Photowhit's very considerable experience.

    If you do go 48V that requires 8 six volt batteries with each replacement cycle. Your current design would do fine with four such batteries.
    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • sunshinemosunshinemo Registered Users Posts: 9 ✭✭
    Photowhit, Money savings isn't my ultimate goal with solar. I want to be as independent as possible and I don't like wasting food. It's irrelevant that solar electricity costs more than grid power; I don't care. That being said, I still want the most bang for my buck.

    My desire is to have as portable of a system as I can, kind of like a system that could even be used in an rv if I  wanted. The way I do things now, that's exactly what we have, but on a much smaller scale. I want a system that will power my "fridge" and freezer that I can move by myself if I want. 

    I was hoping for a "plug and play" setup, as I'm not very mechanically inclined. Mind you, I'm not an idiot; I can learn, so I have no doubt that I can handle this, with advice like I'm receiving.

    My goal for batteries is to have lithium because there is no memory effect, no maintenance, and they're lightweight. I now understand that I should go for less expensive batteries than I had chosen to buy, because I'm inexperienced and there is a good chance that I'll make mistakes and fry them lol!  So, I still have to research batteries. I'm gonna give the golf cart batteries a good looking over soon. 

    I had already figured on the lifepo4 batteries being in the house, so temperature and weather weren't an issue. I was gonna run wires through the wall from the solar panels to the battery bank inside a closet in the house. It's my understanding that lithium batteries are safe to be in the house and take no maintenance, which is exactly what I wanted.

    There are several reasons we can't go totally off grid here. We have very little space. Our home is 100% electric, even our heat. House isn't set up well at all to add wood heat. We don't have enough money to build on a room to put a wood stove in, and we don't want to go into debt to do that. Our roof is not oriented correctly to put panels up there, even if we wanted to, which we don't because then it wouldn't be a portable system. Think Goal zero portable power stations. Plug a panel in and you can recharge your portable power station, and you have a system you can move around wherever you want. 

    I LOVE your cabin setup! You really know your stuff! And it's so cute.

    I've changed my way of thinking and will treat my first *real* system as an experiment and buy cheaper stuff and gain some (cheaper) experience with it, and I'll use my fridge and small freezer as my loads. Sounds like I would've made some really big mistakes if I hadn't come to this forum first. Can hardly wait to get started! I'm interested in the setup you illustrated with the panels you bought. I'll talk to my husband. This is exciting!

    Thanks for your advice, I really appreciate it!
  • sunshinemosunshinemo Registered Users Posts: 9 ✭✭
    Softdown, This system is meant to be a totally off grid stand alone system to power my fridge and freezer. Portability would be a bonus. Once I have it set up, I'm planning on not ever plugging my fridge or freezer back into the grid again. That's the way I want to live. Eventually, we want to find a place that is better suited to off grid life and go totally off grid. I love the thought of being in total control of our power needs. I've learned so much about doing without, and doing stuff without grid power that I know we'll be ok. I regularly already do many of those things without grid power.  I know it won't be all sunshine and unicorns, but that's ok. I don't care.

    It's irrevelant that solar power costs more than grid power, but I also want the best bang for my buck. 

    Thank you very much for the info about the batteries. I couldn't get that answer anywhere I looked online, and very few people really know about solar. Even electricians that I've come across are somewhat clueless. So, thanks!
  • PhotowhitPhotowhit Solar Expert Posts: 5,576 ✭✭✭✭✭
    The 100 watt panels I linked to are about 22 pounds, and should be easy enough to manage. There will be a trade off for smaller panels, as each string of panels will need a fuse or breaker. So if you used 2 of the 100 watt panels for a 24 volt system, then you would need a breaker on each pair. I think a string of 5 would work for a 48 volt system, and if you did 2 strings for 1000 watts you wouldn't need individual breakers. A lot more connections (which EE's would call points of failure) but with 2 strings of equally wattage (power) one string couldn't over power another so there is no additional fire risk.

    You could mount them in a ladder configuration on a pair of 2x4's but it would make a very tall/long frame, but at 40 degrees should be within reach at the high end even for a shorter person. I suspect you could devise a method of mounting so that it would be less work to move. If you feel you can handle 55 pounds or so you could do the panels in pairs and a 1000 watt array is substantial, and won't be simple to move.

    I've seen, and used a system with larger panels where I cut aluminum 'spikes' and mounted them to the panel to push the panel into the ground, and then a back rest board. It would be fine for know weather conditions, I'd trust up to about 20 mph wind with a 40 degree angle, but above that it would be suspect.

    To give you an idea of a 1000 watt array, that is about the size of the 8 panels in the cabin system above (120 watt). They are mounted on 12 foot long PT boards. When I helped the new owners move the system, we were able to detach the front panel and move as a group on a trailer. It took a couple strong people to move them in this manner. No solar panels were harmed in the move, but we made 2 trips. This was not a setup and take down setup, but you could do something like this. 
    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • BB.BB. Super Moderators, Administrators Posts: 31,684 admin
    OK... I will do some quick suggestions and math to at least try and get you approximatly configured.

    First, I suggest that you plan on your batteries, especially if some sort of Li Ion / LiFePO4 type, that they be in a separate shed/building. Li Batteries when they catch fire/burn can release Hydrofluoric Acid. This stuff is highly toxic (scary toxic to human/life) and the standard method to deal with the contamination is to haul everything away that has been contaminated.

    Will you have a fire, will your location get contaminated with Hydrofluoric Acid--The risk for a properly designed and installed system is low--But not zero.

    Next, divide your loads into too types.. Base loads (those loads you must run every day like fridge, freezer, some lights, possibly a computer for work, etc.). And the optional loads that can be postponed in cloudy weather (water pumping, clothes washing, ironing, cooking with electricity, etc.). And I would suggest that your system solar array be ~2x larger than your base load needs to allow for bad weather and reduce any generator power needed.

    Inverter size--If you are using standard refrigerator and freezers on 120 VAC power--A 1,200 to 1,500 Watt minimum AC inverter is suggested.

    It sounds like you have headed down the first road correctly. Energy Conservation--It is almost always cheaper to conserve energy than to generate it.

    Next, measuring your loads--Pretty easy right now because you are living in the home, and have the appliances. A kill-a-Watt type meter is the place to start--And measure your WH/kWH usage over at least one day... And probably over a week for "energy hogs" like a refrigerator.

    With solar power systems, you have to plan for both the average energy usage, and surge power usage... For example, a typical full size refrigerator may use 120 Watts running, >600 Watts starting, and ~500-600 Watts defrosting (for a frost free fridge).

    Your refrigerator numbers of 195 Watts for 5 minutes a day would work out to:
    • 195 Watts * 24 hours per day * 5 minutes * 1/60 minutes per hour = 390 WH per day
    Does not sound "typical"... A standard (very efficient Energy Star) fridge runs around 100-120 Watts for 20-30 minutes per day:
    • 120 Watts * 24 hours per day * 20 minutes * 1/60 minutes per hour = 960 WH per day
    Typically I would be suggesting around 1,000 to 1,500 WH per day for a "full size fridge". 390 WH per day is pretty low.

    Also, while a microwave may take 1,200 Watts, it is only for 5min per day (large power drain for short period of time):
    • 1,200 Watts * 5min * 1/60 minutes per hour = 100 WH per day (1/10th that of a standard fridge)
    But your 12 Watts of Lighting 12 hours per day:
    • 12 Watts * 12 hours = 144 WH per day
    Or more "energy" (Watt*Hours) per day than your microwave usage...

    You can look at appliances and make choices... Do you want Frost Free, or is manual defrosting OK with you and your spouse? Are you going to want larger than a 7 cuft fridge down the road? Some folks have used converted freezers to refrigerators (change the freezer thermostat to a refrigerator type) and gotten down to ~250 WH per day. So, low energy use for a refrigerator is certainly possible.

    As an aside, there are some 12/24 VDC fridges and freezers that are pretty energy efficient--But they are not cheap. Sometimes a tradeoff between a smaller solar system and $$$ refrigerator.

    https://www.homedepot.com/p/Unique-10-3-cu-ft-290-l-Solar-DC-Top-Freezer-Refrigerator-Danfoss-Secop-Compressor-in-Black-UGP-290L-B/308537092

    524 WH per day for 10 cuft fridge/freezer @ 12/24 VDC--For a smaller solar power system, may be a good reason to stay at 24 VDC.

    A freezer is going to be closer to 1,000 WH per day (if you are going for the 0F or lower range).

    Anyway lets start with 2,000 WH per day, and an 1,800 Watt minimum AC inverter/load. On a 24 volt battery bank (48 volt is find too, just 1/2 the 24 volt AH capacity). Assume 2 days of storage and 50% maximium discharge (for Lead Acid/AGM type systems... Close enough for Li Ion too at first pass):
    • 2,000 WH per day * 1/0.85 AC inverter eff * 1/24 volt battery bank * 2 days storage * 1/0.50 max discharge = 392 AH @ 24 volts
    That would be 4x 6 volt @ 200 AH "golf cart" batteries (typically flooded cell) in series for 24 volts, times 2 parallel strings for 400 AH (@ 24 volts).

    And a sanity check... More or less, you can run a 500 Watt AC inverter per 100 AH of 24 volt FLA batteries... An 1,800 Watt inverter would need:
    • 1,800 Watt AC inverter * 1/500 Watts * 100 AH (at 24 volts) = 360 AH (at 24 volts) minimum battery bank
    So--400 AH @ 24 volts looks to be "workable".

    To size the solar array, we have two calculations. First is based on charging current to the battery bank. The second based on hours of sun and your daily loads.

    To charge your battery bank, 5% to 13% rate of charge is typical... 5% for weekend/summer system. 10%+ for full time off grid highly suggested.
    • 400 AH * 29.0 volts charging * 1/0.77 solar panel+controller deratings * 0.05 rate of charge = 753 Watt array minimum
    • 400 AH * 29.0 volts charging * 1/0.77 solar panel+controller deratings * 0.10 rate of charge = 1,506 Watt array nominal
    • 400 AH * 29.0 volts charging * 1/0.77 solar panel+controller deratings * 0.13 rate of charge = 1,958 Watt array "typical" cost effective maximum
    And the second array sizing is based on loads and hours of sun per day. Using a simple solar irradiance calculator, fixed array, facing south, for Springfield Ill (closest major city I could quickly find):
    http://www.solarelectricityhandbook.com/solar-irradiance.html

    Springfield illinois
    Average Solar Insolation figures

    Measured in kWh/m2/day onto a solar panel set at a 50° angle from vertical:
    (For best year-round performance)

    JanFebMarAprMayJun
    3.08
     
    3.48
     
    4.28
     
    4.80
     
    5.01
     
    5.23
     
    JulAugSepOctNovDec
    5.52
     
    5.29
     
    5.24
     
    4.53
     
    3.22
     
    2.90
     

    So, you now have a decision, do you want to use a genset during part of winter, or design for solar only during winter? I will pick December at 2.90 hours of sun per average day (not that bad):
    • 2,000 WH per day * 1/0.52 off grid AC end to end efficiency * 1/2.90 hours of sun per day (Dec) = 1,326 Watt array "December" break even
    A typical solar array would be around 1,326 to 1,506 to 1,958 Watts... And 1,506 Watt array minimum would not be a bad place to start.

    And you have the choice of, for example, using less power in a cool house... Say just a few lights and fridge/freezer at 1,500 Watt*hours per day. Suggest 50% to 65% of predicted average harvest for base load usage (turn off optional loads for bad weather and less genset usage):
    • 1,500 WH per day base load * 1/0.50 base load fudge factor * 1/0.52 off grid eff * 1/2.90 hours of sun =1,989 Watt array 50% fudge factor
    • 1,500 WH per day base load * 1/0.65 base load fudge factor * 1/0.52 off grid eff * 1/2.90 hours of sun =1,535 Watt array 50% fudge factor
    So depending on how much or how little you want to run the genset--1,535 to 1,989 Watt array could certainly be justified to ride through some bad weather.

    Suggest more solar panels (and backup genset), rather than "oversizing" the battery bank (solar panels last 20+ years, batteries last 3-5-8 years for "typical batteries").

    Anyway, some math to hang your questions and answers on based on my guesses.

    For a "near normal" electrical existence off grid (and using propane/wood/etc. for heat, cooking, hot water, etc.)--I suggest you start at 3,300 WH per day (or ~100 kWH per month). A 2,000 WH per day system (2 kWH per day * 30 days per month=60 kWH per month) is a pretty small system--But if it fits your needs--Great.

    See how low of power bill you can get your home down to... 500 to 1,000 kWH per month is typical in North America. Under 200 kWH per month is pretty conservation heavy. Getting to 100 or 60 kWH per month--That is really minimal/highly conservation minded usage.

    Your thoughts?

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • softdownsoftdown Solar Expert Posts: 3,504 ✭✭✭✭
    edited July 2020 #18
    Awesome analysis but I may point out:
    1) 5-7 cu. ft Chest freezers have numbers like 350 kWh on their yellow tags - as I recall.
    2) Chest freezer converted to fridge. No yellow tags but something like 150 kWh seems normal from here - assuming common opening/closing for getting food. My 18 cu. ft. upright commercial freezer was on track for about 120 kWh until I started using it as a freezer. I didn't open the door a lot but cold air stays in a chest - for the most part. Their big advantage. 


    First Bank:16 180 watt Grape Solar with  FM80 controller and 3648 Inverter....Fullriver 8D AGM solar batteries. Second Bank/MacGyver Special: 10 165(?) watt BP Solar with Renogy MPPT 40A controller/ and Xantrex C-35 PWM controller/ and Morningstar PWM controller...Cotek 24V PSW inverter....forklift and diesel locomotive batteries
  • sunshinemosunshinemo Registered Users Posts: 9 ✭✭
    Photowhit, my husband and I would like to look at the setup you suggested. Are you around on saturdays?
  • PhotowhitPhotowhit Solar Expert Posts: 5,576 ✭✭✭✭✭
    I'm not sure about the protocol here, @sunshinemo , I'll send you a message and perhaps you can reply to it. 

    If not post again here.

    My earlier system (4 panels on a couple 2x4s braced and mounted, has move to Williamsburg proper, I'm still "Facebook Friends" with the husband, his wife passed a couple years ago. I haven't seen it since it moved. I can message him if that is the system you would like to see. 

    The other panels which were on the roof of my Scion XB are the 310-330 watt panels. They are just sitting at my place, but the bridge is out on the way here. That isn't a euphemism! This bridge is being replaced as part of an ongoing social distancing program  a bridge renewal program. Making getting to my place a pain. Also makes bringing home ice cream a pain! I do live 8 miles south of the tall water tower, by I-70, Please note, there are no on/off ramps here, you have to do that 2-3 miles either side. and adds 3-4 miles of gravel road to the trip.





    Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Magnum MS4024, Prosine 1800(now backup) and Exeltech 1100(former backup...lol), 660 ah 24v Forklift battery(now 10 years old). Off grid for 20 years (if I include 8 months on a bicycle).
    - Assorted other systems, pieces and to many panels in the closet to not do more projects.
  • sunshinemo2sunshinemo2 Registered Users Posts: 5
    Hey, I am sunshinemo. Lost password and email address, so I had to register again.  For some reason, I am unable to receive the confirmation email, so I can't complete the registration. 

    Anyway,, about two months ago, the electricity went off and on in rapid succession a few times and managed to fry the compressor in our one year old chest freezer-converted'p-to-fridge. We should've gone ahead and set up our off grid system and we'd still have a fridge. Sigh...

    So, I looked our electric bill today and it says we used a little over 3000kw in February. Wow. Keep in mind that our house is all electric, including heat. We have solar lighting though, and we don't have hardly anything plugged in and running 24/7, except the little freezer. 

    The bill for last month states that we used 11.7% MORE electricity this year than last year, and we've been doing without a refrigerator even. This is one reason I HATE being on the grid. How can I prove they are ripping me off??? We keep the temperature at atound 65. We got new windows last fall. What is going on??

    Any advice would be greatly appreciated

    We are getting ready to put up a large arbor and the roof of the arbor will be where the solar panels will reside. I no longer care about making this a portable system.
  • sunshinemo2sunshinemo2 Registered Users Posts: 5
    I'm unable to complete registration, and "you need to confirm your email address. Click here to resend, etc" keeps filling my screen til I can't see anything but that. 

    No matter how many times I click on that or refresh my email, it keeps happening. Gonna have to leave the site (tried leaving and coming back but it did no good) and try again tomorrow.
  • sunshinemo2sunshinemo2 Registered Users Posts: 5
    Ps: we are planning to install a wood stove this year. That should help considerably with electric usage and the bill.
  • BB.BB. Super Moderators, Administrators Posts: 31,684 admin
    Sunsinemo(2)--You are using two proton mail addresses for the two accounts... Please feel free to send me a private message I an get you connected back to your preferred email account and original user ID (we do not spam or email from the forum email database).

    The way even a utilty lineman will (for a first pass) test your meter... Turn off all branch circuit breakers except one (to a room, garage, etc.). Make sure the meter is not moving. Then connect an electric heater (1,500 to 1,800 Watts typically--You can use a Kill-a-Watt type meter to confirm wattage) and see if your meter detects the heater and see if your utility meter logs the load correctly (1,500 Watts for 1 hour is 1.5 kWH of load).

    https://www.amazon.com/s?k=kill+a+watt+meter&ref=nb_sb_noss (kill-a-Watt type meters)

    You can also get "whole house" power monitors... Both simple ones that only monitor your mains power usage, and those that have multiple ports (heating, cooking, hot water, etc.):

    https://www.theenergydetective.com/ (one of many brands)

    Over the years, I have seen and read about many issues with billing (in multi unit buildings, wiring from one unit on the wrong meter; heater+A/C units running at the same time; Hot vs Neutral reversed and leaking power through the ground rod, etc.)...

    You can get an AC current clamp DMM (digital multimeter) or even AC+DC Current clamp DMM (nice for battery/solar system debugging):

    https://www.amazon.com/UNI-T-Digital-Handheld-Resistance-Capacitance/dp/B0188WD1NE (inexpensive AC+DC CC meter)
    https://www.amazon.com/gp/product/B019CY4FB4 (mid priced AC+DC CC meter)

    And you can measure the load on each breaker (clamp wire from breaker to measure current). Note that while power = voltage * current... (i.e., 120 VAC * 10 amps = 1,200 Watts)--The actual power/energy measurements are more complex and a simple clamp meter cannot "accurately" measure power.

    Even though 3,000 kWH per month is a lot of energy--If you had an "unknown" load that was pulling 1,000 kWH per month (well pump pulling energy--but not using well pump anymore):
    • 1,000,000 WH * 1/30 days per month * 1/24 hours per day = 1,389 Watt load (running 24 hours per day, 30 days per month)
    Just one electric heater running 24x7 forgotten somewhere can be 1/3rd of your bill.

    Generally, if the house was reasonably efficient, I would have guessed at 1,000+ kWH per month spring/fall... And 3,000 kWH per month if you were in Texas in the middle of summer running A/C at max power.

    Doing things like running your home with "normal loads" and see what your power meter shows (modern utilty meters generally show the actual Wattage used as that moment in time--Very nice). And turn off one breaker at a time and make sure you understand all your loads.

    You may just need to look at conservation (insulation, checking filters, make sure you don't have a lot of "phantom loads" like entertainment system in "standby" drawing power, etc.)...

    A full size desktop computer running 24x7, monitor, modem, router, printer can easily run upwards of 300-500 Watts with nobody using it (on, not on low power standby). Have a couple of folks with their own desktop computers/servers--And you could be looking at 1/3rd of your energy bill right there... The Kill-a-Watt type meter on each of your plugin loads can help you find these energy "hogs"... In the summer, the heat from those desktops also adds to the A/C load for cooling too... (I use small/cheap laptops for most day to day use these days--Closer to 10-30 Watts while used, near zero on sleep--The router may still use 25 watts or so 24x7).

    At this point, you are are looking for the "big loads"... Moderate loads running 24x7. Or large loads a few hours a day (water heater wasting energy, electric room heater, etc.). Don't drive people nuts unplugging cell phone and laptop chargers (at least not yet).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • BB.BB. Super Moderators, Administrators Posts: 31,684 admin
    I cannot change your old ID to your existing mo****@protonmail.com email address (forum is set up for 1 email address = 1 forum ID). If want to use the original account--PM me and we can work something out (temporary email address, kill account #2, etc.).

    My humble suggestion--Unless you are wealthy enough to not worry about a 3,000 kWH per month power bill (which you probably are not--And by the way, that would be upwards of a $1,200 per month power bill in Kalifornia)--I would humbly suggest that you look at getting down to below 500 kWH per month... And for a "cheaper" solar system down towards 300 to 100 kWH per month... Of course, if you can get you could get down to 300 kWH per month (possibly looking at propane water, cooking, heating and stove/dryer if really going to to "solar")--Then your "new" electric bill would be quite cheap (much cheaper than solar costs to install and maintain).

    Something does not sound right on your home... a 3,000 kWH per month bill, is the equivalent of:
    • 3,000 kWH per month = 3,000,000 WH per month * 1/30 days per month * 1/24 hours per day = 4,167 Watt load running 24x7
    • 4,167 Watts * 1/120 VAC = 34.7 Amps @ 120 VAC load
    • 4,167 Watts * 1/240 VAC = 17.4 Amp @ 240 VAC continuous load
    • 4,167 Watts ~ 3-4 HP motor running 24 hours per day

    If you have a digital utility meter... The typically run through several values (line voltage, current Watts, etc.)... Good place to start.

    Figure out what your meter is telling you, and then start turning of breakers and check (such as a drop from 4,000 Watts to 1,000 Watts, etc.).

    Other things to check... My utilty offers a web page connected to my electronic meter... For residential meters, it gives me 1 hour chunks per day... I can check there and find if I have times were I am using way more energy that I thought:



    This is not my usage--But shows you what our utility can do (daily usage above).


    And hourly usage (above).... (natural gas appliances, couple of fridge/freezers/600 Watt fish pond pump/etc.).

    Don't know if your utility offers "live" meter views... But worth checking. Saves running back and forth from panel to meter, or using a pair of walkie-talkies with two people.

    For the US, the energy detective store is here (~$190 for mid-priced model):

    https://www.globaltestsupply.com/category/spyder-packages

    I don't know anything about store and have never used their product... Just an example.

    Other options does include Amazon:

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

    When looking at house monitors--You have the option of one or two current coils (all power usage--Just like your utility meter)--Or getting a 1/2 dozen current sensors (on A/C, electric heat, electric hot water, etc. multiple major loads/branch circuits).

    If you were using 500-700 kWH per month (before "conservation")--That is a "typical North American" home (500-1,000 kWH per month)--That would be what I would expect.

    Right now--You are using the equivalent of two electric room heaters (1,500-1,800 Watt) on full power 24x7 (on all the time).  And if you load is variable (like 6 hours per day), that would be 4x more load or ~16,000 Watt load for 6 hours per day...

    A typical water heater is ~4,800 Watts. A drier also around 4,800 Watts too. The microwave--I would not even worry about its cost/Watt load right now (5 minutes per day ~ less than 0.3 kWH per day). 

    Anyway... I am pretty sure you are using (or paying) 4x more for electricity than you should be using... Unless you something different (water your garden with hot water, etc.). Or are in sub freezing weather with a 1950s home and all electric heat... Don't know where your energy is going. You do not have a 3 HP sump pump running 24 hours per day...

    You might find something like a stuck sump pump water level switch running the pump 24x7, or other stuff you are not paying attention too.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • sunshinemo2sunshinemo2 Registered Users Posts: 5
    BB, can you kill both accounts and then allow me to register with this one? 

    We have walkie talkies and this weekend I'll get my husband to help me with looking at the meter, etc. Like you, I think something is very wrong.

    In missouri, we do get freezing weather for much of the winter, and our home is all electric. There's no reason we should be using MORE electricity than at this time last year though, especially since we don't even have a fridge this time.

    Found a whole house energy monitor for around $100. Gonna look at a few more and then get us one.

    Thanks so much for your help.
  • BB.BB. Super Moderators, Administrators Posts: 31,684 admin
    edited April 19 #28
    Just keep using this *^2 account--I think it is configured correctly.

    I can rename the old account "-old" and take the "2" off this account if you wish.

    Usually, you can look at the meter and watch the display and figure out how your meter/utility programming is displaying data on the LCD screen. Generally, the main display is in kWH (i.e., 00001 to 00002 is +1 kWH). The display on the meters around here typically have a small number set that alternates between line voltage (like 245) and Watts or kWatts... 1.230 kWatt or 1230 Watts.

    A typical modern refrigerator is on the order of 1-2 kWH per day (30-60 kWH per month)--A fair amount of power for a solar power system... But not the big issue you are looking for at the moment.

    A 20 year old refrigerator may use 4-5+ kWH per day (120-200 kWH per month)--Still not 3,000 kWH per month class of power hog.

    Let us know what your find... Always nice to understand what was going wrong and how it was fixed.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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