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Catdean6
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# Posted: 3 Oct 2017 18:50
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Hello!
Planning a new build with an off-grid solar system. 800 sq ft home. Electric needs consist of fridge, freezer, few led lights, flat screen, chargers, laptop. I was thinking about an 800w to 1200w system. Would like to hear your story, what you have in your system. I'm a little leery of the "kits" and want to put together my own system with a back-up generator. I'm building in the southern part of Colorado. What would you put together? Thanks for your input.
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ICC
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# Posted: 3 Oct 2017 19:29
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Quoting: Catdean6 Electric needs consist of fridge, freezer, few led lights, flat screen, .........
You need to be a little more specific. Power consumption of fridges varies with size and design. Same with the flatscreen; size matters. The EPA has a list of projected consumption online. You can design a system that does not need a generator. Ours only gets used whenever I do a lot of electric welding.
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Ontario lakeside
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# Posted: 3 Oct 2017 21:00
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That may be slightly small for your needs. we built a 1000w system and run a small fridge, lighting water pump etc with about 1.5 KW usage per day.
Have a look at our build video if your interested.
https://www.youtube.com/watch?v=ZfilBtej3t4
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Catdean6
Member
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# Posted: 3 Oct 2017 21:48
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Nice setup! Love the video. It's good to see how other folk are not only getting by, but thriving in an off grid setting. Thank you for sharing and continued success in your endeavors!
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Steve_S
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# Posted: 4 Oct 2017 07:54
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@Catdean, more information is required as ICC says so that you can get a better answer / opinion.
What is your current Power Usage on your power bill, is a good start. Amount of Kwh used per month... etc depending on how it's broken down on your bill.
As for appliances... Solar works well BUT it cannot deliver to some things unless you go really big and that translates into big bucks to insane bucks too...
For example, Electric Stove, Hot Water Tank, Electric Dryer, any heating with an element (baseboard etc) Toaster Ovens are all NOT Solar Friendly - these are the Big Power Items that power companies so love.... * IF you presently use any of those in your current place let us know as that will be reflected in your power usage on power bill. NOTE that most Air Conditioners are Energy Hogs and in Southern Colorado that's likely a Wanted Item... That's a side topic but should be addressed too... there are ways to make your home cooler & more efficient reducing the need for AC use and some AC options that will work..
Many of the Kits are good value with good components that will work together nicely and they vary in pricing quite a lot. Don't discount using them but like with all things, one must be careful and so do shop around once you have an idea of what you "need" as a minimum and design closer to what you "want" giving you room to grow. That's another point too... Don't think of it as "I use X amount of power so that's what I need" because it is solar... cloudy days, storm fronts, winter solar shift ALL affect how much you will generate. So consider the "X Amount" you use as the baseline for what you need to build and then build bigger than that to compensate for the above conditions and more... even dusty panels reduce the amount generated by them.
Off Grid means stand-alone, no grid connection at all and also means a sizeable Battery Pack to store the power... You mention a Backup Generator, of course this is wise and is a must because Stuff Happens and you always need a backup when fending for yourself... I would very strongly urge the use a Propane Fueled Backup Generator... yes they are a bit more expensive but very well worth the extra... Propane will not sour or go bad so it will store for ages, unlike Gasoline. You can have a couple of spare tanks which will give you lot's of juice if needed. IF you have propane on site for appliances (the bigger tanks like 100 Gallon+ (not 100 lb portables) then the Genny could be tapped into that.
Best Bang for Bucks Backup Gennies come from Champion Power Equipment. Good products, tough, work as designed & intended and their tech support is pretty good tool... I have some of their equipment and haven' had any issues over the years.
REF: https://www.championpowerequipment.com/products/generators/home-standby-generators/
Alternately, you can get a smaller unit which is dual-fuel Gas/Propane and keep portability while getting the benefits of LPG as well.. Handy for construction mode but will generate less power than the stand-by gennies... BUT as you would be charging your Solar Batteries with it to run your cabin, that works too, as long as you have the right combo of Inverter/Charger or standalone charger for your battery bank.
REF: https://www.championpowerequipment.com/products/generators/portable-generators/?fwp_p ortable_generator_filter_fuel_type=289c20eacde24057172b76f1aa777f75
BTW: These are NOT Honda's or other top brand label expensive units BUT they do work very well and are a good dollar value - like with all things mechanical, good maintenance, oil changes and filters etc are a must regardless of brands.
The more detail you can provide the better...
Is your cabin built or still planning ?
Do you have good southern solar exposure ?
Do you intend to Roof Mount, Ground Mount, Fixed Mount or Tracking ? (affects how many panels needed & costs !)
Have you considered Tesla Powerwall & Solar Shingles ? I think there is lot's of improvement there, yet...)
Are there kids ? Kids can certainly add to power usage as they grow up all from different things, so have to account for such... It's the Munchkin Costs that people sometimes forget about...
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Mike 870
Member
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# Posted: 4 Oct 2017 09:36
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How do you like the Victron stuff Ontario? (my apologies if you addressed it in the video, my browser here doesn't support sound!)
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Ontario lakeside
Member
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# Posted: 4 Oct 2017 12:34
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Hey Mike
I very happy with the victron parts. the bluetooth monitoring is great. the inverter is quite I've never had the fan come on yet. they seem very solid.
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KabinKat
Member
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# Posted: 5 Oct 2017 11:23
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Great stuff here! I really like that solar set-up!
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Scott G
Member
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# Posted: 5 Oct 2017 13:02
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Watching this thread as I'm in the same boat.
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Catdean6
Member
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# Posted: 5 Oct 2017 14:05
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Okay so I have been doing my homework assignments! Here is what I think I know...
Based on my calculations and needs consisting of usage of: coffee maker 800w, tv 150w x 3hrs, laptop 30w x 3hrs, DVD player 40w x 3hrs, microwave 800w, energy eff chest freezer 1080w, energy eff fridge 1200w, 4 led lights 10w x 4hrs....i come to around 4692w per day.
An assumption of 4 hours of sunlight, in sunny southern colorado, puts me at 1173w per hour.
Sooo... a 1200 watt system should account for my needs. Back-up gen would cover a once a week washing machine (Natural air dry, of course) And any power tools used.
Hot water will come from wood stove/fp. So will heating. Water is from gravity fed cistern.
So that's where I'm at...a 1200w system.
I found 300w panels reasonably priced for pick up.
4 of them should do the trick.
Any thoughts on what charge controller is best? What about the best inverter? And the the battery bank??
I was looking at the samlex pst1500-24 pure since inverter, the 1500 mppt Midnite charge controller 45a, and 6 Costco golf cart batteries. Topping off with a Honda gen
Any opinions, thoughts??
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NorthRick
Member
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# Posted: 5 Oct 2017 17:23
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1200w of panels will rarely produce 1200w. Panels heat up and don't make rated power, the sun is rarely hitting the panels perfectly, clouds happen, etc. Also, you will have losses along the way - in the wire connecting things, in the charge controller, inefficiencies in battery charging/discharging, and in the inverter.
In addition, I have found that actual use always seems to exceed what you calculate out beforehand. Also, watts are what something is drawing at any given moment, watt/hours is the power used over a period of time.
Bottom line is, I think you will be disappointed in the performance of the system you are proposing.
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creeky
Member
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# Posted: 5 Oct 2017 17:25
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You could have a look at my website. bobolinksolar dot com. It has Lakesides system. Now called the "Great Grey Owl"
smile.
Prices have come down on the parts with the improvement in $C. But batteries have gone up.
Two notes:
1) do not buy lead acid batteries. Please. You will be sorry.
2) Try to go as high voltage as possible. 48v is more efficient and you will save money all the way through most of the process. There will be the odd thing a bit pricier. But ...
Good luck.
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Steve_S
Member
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# Posted: 5 Oct 2017 18:11
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Ohh My... I have to agree with NorthRick... based on your info, that won't cut it.
BUT !
Somewhere you calculations went sideways.
Coffee Maker (perk with no "warming" element) will run 1000-1200 W while perking. Thermos type carafe keeps coffee hot all day and it won't get burnt and no ongoing power used.
TV @ 150 Watts ? WHAT ?? Is this an old Picture Tube dealio ?
an LED TV would use at MAX 1/3rd of that...
EXAMPLE: I have an LG 47" LED TV (used as computer screen) a Satellite Modem (25w) and my HP EliteDesk i7 Computer and with all cores running on PC I'm using 91 Watts.... See pic below from the UPS it's attached to.
Fridge: 1200W is energy efficient ? what is it, a double door with icemaker etc ? My fridge uses a grand total of 540kw (5400w) for a whole year... Energy Star rated and verified.
I STRONGLY suggest you run over to HomeDespot and buy a Kill-A-Watt meter... That will tell you what your are really using on your devices, does not do 240V but that's not a part of your equation anyways.
REF: http://www.homedepot.com/p/Kill-A-Watt-Electricity-Monitor-P4400/202196386
A General Rule is to plan for your base level need and add 25% (for your regional area, it's higher further North you go) which should just about cover it.
IF your numbers are correct - consider changing up devices, even a new 55" LED TV will use about 50 watts (without extras like surround sound bar etc)
Conservation is FAR Cheaper than building capacity to support your toys. That is just one of the little facts of life which is more true today than ever before.
With your basics as they are, I would consider nothing less than 2Kw to 2400kw (8x300w panels) to a 24 Volt Battery Bank. Even better for more oomph would be 48VDC battery bank but this is getting more $$$...
Golf Cart Batteries are so 1990 and won't serve for a longtime, they are not made as well as they used to be and deep discharge will murder them quickly. Deep Cycle Batteries from Trojan, Rolls Surette will give you 5-7 years (because it's your first run & you WILL abuse them, everyone does when they start, not realizing the maintenance religion). Ideally for best bang for buck, longest lifespan and pretty much user proof, Lithium which will let you discharge to 97%, unlike Lead Acid which will allow 55% discharge at max, lower and your damaging the batteries.
Charge Controllers these days are all pretty darn good compared to even 5 years ago... some folks have favourites, I like my Midnight Classic and it does everything it should. Even the cheaper Chinese ones like EP Solar's 60A is a very nice unit with heaps of features.... As mentioned above Victron is a Top Brand and also loaded with goodies to make life easier... Outback has had some problems with quality & support recently and they have had some roller coaster issues around that...
Inverters... Samlex is OK but... also another one that has ups & downs, too pricey for what they are IMO. Magnum Energy you see a LOT of Refurbs on the market, never ever a good sign. I myself used a Marine Grade Inverter / Charger combo which signals gen to start and takes "shore power" and allows bypass to cabin + charge the batteries... It IS Chinese and bought it through a Marine Specialist who had it drop shipped from factory to me, twas a deal which I could not pass up being the first to buy that model...
I do NOT mean to sound harsh or to upset you BUT I would prefer to tick you off a little now and educate you a bit, rather than lead you up the Gum Tree and have you seriously "put out" after spending a pile of hard to come by cash... Sometimes a reality check is like a hard knock on the pumpkin.
I cannot suggest any vendors to you as I am not American and don't know who is who down there, others here will likely be better at making such suggestions based on their own experience with them.
A Very good site which will teach you more and help you understand what your getting into and potential solutions is here: http://www.freesunpower.com/index.php
They have calculators, configuration aids and planners. Fairly straight forward and minimal techno-alphabet soup babble.
Another with excellent info and quite helpful is here:
https://www.homepower.com/articles/solar-electricity/basics/what-solar-electricity
Again, I will reiterate that Conservation is worth far more than building capacity and the payback is there right away. Best way to manage a crisis is to prevent it in the first place...
Power used for TV, Puter, Sat Modem
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Catdean6
Member
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# Posted: 5 Oct 2017 20:05
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It's okay, I can take it! Haha
I very much appreciate the honesty and criticism it exactly what I need to hear. Especially at this point...nothing has been purchased yet!
With that being said.... I got those numbers from a list not from the actual appliances. Guesds I should have looked a little deeper.
I will be buying new appliances. So if my numbers are off on the wattage> then I may be okay.
Not sure if I can go the 2kw to start though. $
Thanks!
Good info on the batteries and inverter.
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ICC
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# Posted: 6 Oct 2017 10:28 - Edited by: ICC
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catdean, you have intermixed the terms watts and watt/hours and at the same time toss in things like "30w x 3hrs". "30w x 3hrs" is equal to 90 watt/hours. The watt and watt/hr numbers can look the same or similar but are different.
When talking about how much energy is used in a day, a week or a year we use the term watt/hours or kilowatt/hours. When talking about the power rating of something, that is watts, or amps x volts. A 50 watt TV used for 4 hours consumes 200 watt/hours.
When sizing the inverter remember that standard refrigerators have a large start up surge. It is a short duration event but the inverter must be able to supply that to get the fridge compressor started. If it can't the fridge could be damaged or the inverter could be damaged. If it is a good inverter it should trip off when the load supercedes what it can deliver. That will likely require a manual reset. Some newer fridges with inverter technology use soft start technology and avoid surge.
Also keep in mind that the watts referred to in microwave info is the cooking power. The actual consumption of the oven will be more in the order of 1100 watts, like my small microwave. My big one rated at 1100 watts cook power consumes 1600 watts operating.
If the microwave was being used and the fridge started that would overload a 1500 watt inverter and the inverter would shut down. Same thing if your freezer was running and the fridge started. An inverter that can handle all the possible power uses at the same time makes it easier to live there. No thinking about where or not you can operate the microwave at that moment in time (is the fridge already running? will it start while I heat my dinner?)
No mention so far on modified sine wave vs pure sine wave inverter. Pure sine wave is better, much better when electronics are involved. Electronics last longer on pure sine wave. Also microwave performance is abysmal on modified sine wave. Some hardly work at all and all make a lot of noise on mod sine wave.
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