New here and need some advice

BB.

Re: New here and need some advice

Yep... Sounds about right:

0.5 kWH per day * 365 days per year = 183 kWH per year

When the weather gets warmer and/or you start putting in warm drinks and making ice, you probably will see the power usage go up to around 0.8 kWH per day...

-Bill

westbranch

Re: New here and need some advice

and it did not have to cool those cans down first, they were already cooled... and the dogs were frozen too.

solarpowernovice

Re: New here and need some advice

K so i added the .5 KWH my fridge takes (im just gonna unhook from home and bring with me to the cabin its only a 20 minute drive) I also figured out a fan on medium for 8 hours (on a hot summer day) is .8 KWH. My pump takes .1 KWH for 38 minutes of use which i HIGHLY doubt i will ever use it that long in 1 day... So when i add 2 or 3 LED lights for the small cabin at night i should be right at 1.6 or 1.7 KWH. So if i buy Four 6v batteries in series (24volts) @ 232AmpHours, thats 24x232 = 5.568KWH. Divided by 3.333 for the 30% DOD gives me 1.670KWH. This would be all i need to fit my needs. Heres the parts list i came up with so far: Three 260 watt Solar panels, Four 6v batteries, A 1000Watt Pure sine inverter, and a 45 amp morningstar MPPT controller. Can anyone list the remaining parts I will need to order to wire this all together? Will I just need fuses between each component or a DC Disconnect box(e-panel)? Thanks.

EDIT: here are the panels i plan on ordering http://www.affordable-solar.com/Hyundai-HiS-260MG-260w-Mono-Black-Frame - are these panels compatible with the 150Volt charge controller? (Vmpp) : 31.0 (Voc) : 37.5

I can always buy a lower wattage fan / pump /chest freezer and convert it if i find i need to. Am i on the right track?

jcheil

Re: New here and need some advice

BB. wrote: »

When the weather gets warmer and/or you start putting in warm drinks and making ice, you probably will see the power usage go up to around 0.8 kWH per day...

My neighbor has a mini fridge and in the (Florida) summer the usage is close to 2kwh per day, which is more than my full-sized 18cf (2 year old) fridge. He is finally going to switch it out with a "real" fridge this week. Mostly because when his mini fridge is FULL, it takes a lot more to cool it because it has so little insulation and the "room" temp can be in the low 80's most of the time which doesn't help it either. My opinion is that in the long run, it's better off getting a new energy efficient full-size fridge which will ultimately use less energy overall.

Cariboocoot

Re: New here and need some advice

jcheil; your opinion is correct on this. http://forum.solar-electric.com/showthread.php?12272-Just-how-bad-a-small-frige-is

solarpowernovice

Re: New here and need some advice

I've been looking around and i found this kit http://www.wholesalesolar.com/solarpowersystems/medium-dc-off-grid-solar-power-system.html
Like I said in earlier posts all i need is a few LED lights a 12 volt pump and a fridge. I found some portable 12volt fridges online like this one: http://store.arbusa.com/ARB-Fridge-Freezer-50-Qt-10800472-P3626.aspx the specs are: Average DC power consumption: 0.7 to 2.3 amp hr. Ive been reading comments on these portable fridge/freezers and people say they run no more than half of the day, and people use them off of their vehicles battery. So theoretically I could power the fridge for 3+ days with the LED lights and a 12 volt pump(for 30 minutes a day max) and i wouldn't even need an inverter? I dont see one listed in the kits parts list. Would this kit run all this for 3+ days without going past 50% DOD? What types of batteries would you recommend if so?

I have a local Trojan battery and interstate battery store.

BB.

Re: New here and need some advice

You really need to "do the math" even for kit systems.

Loads? Say:

2.3 amps * 12 h * 12 volts = 331 WH for fridge
2*13 watt * 6 hours = 156 WH for lights
5 amps * 1 hour * 12 volts = 60 WH for pumping
==================================
Total = 547 WH per day

I am going to round up to 1,000 WH per day--Since that is closer to what I think you may run (cell phone, laptop, etc.).

Battery size (1-3 days, 2 days typical, with 50% maximum discharge)--Use 3 days for you:

• 1,000 Watt*Hours per day * 1/0.85 inverter eff * 1/12 volts * 3 days no sun * 1/0.50 max discharge = 588 Amp*Hours @ 12 volt battery bank

Sun wise, say you want to run this into the winter, Richmond VA using PV Watts, fixed array, tilted to Latitude:

Month    Solar Radiation (kWh/m 2/day)
1      3.99     
2      4.37     
3      4.96     
4      5.32     
5      5.49     
6      5.54     
7      5.55     
8      5.31     
9      5.30     
10      4.65     
11      3.95     
12      3.51     
Year      4.83      

3.51 typical sun in December:

• 1,000 WH * 1/0.52 system eff * 1/3.51 hours of sun = 348 Watt solar array minimum

And based on battery bank size (note, larger battery banks need larger solar arrays for proper charging current):

• 588 AH * 14.5 volts charging * 1/0.77 panel+controller deratings * 0.05 rate of charge = 554 Watt minimum array
• 588 AH * 14.5 volts charging * 1/0.77 panel+controller deratings * 0.10 rate of charge = 1,197 Watt array nominal
• 588 AH * 14.5 volts charging * 1/0.77 panel+controller deratings * 0.13 rate of charge = 1,439 Watt array "cost effective maximum"

So, with a 3 day bank (we normally recommend a 2 day bank as being a bit more cost effective), you are looking at a 554 to 14,39 Watt solar array (over the minimum array of 348 Watt array because of the larger than average battery bank).

If I guessed wrong on your 1,000 WH per day, and you want something smaller--Then plug in your WH per day numbers.

If you want a 2 day battery storage (plus 50% max discharge), you can play with that value too and reduce the battery bank AH capacity.

A ~588 AH @ 12 volt battery bank is getting to about the maximum AH capacity at 12 volts... You might also look at a 24 volt battery bank--especially if you decide you need a larger battery bank (more than ~600-800 AH, you should go 24 volt battery bank for various reasons).

-Bill

solarpowernovice

Re: New here and need some advice

Thanks Bill. Two days of backup is good seeing how it's just a weekend cabin. If I use 2 days instead of 3 in your equation I get 392 amp hours. How does 4 Trojan T-105-RE's sound? (12v @ 450 amp hours) this should give me plenty of backup for 2 days at least. Maybe 4 208 amp hour Interstate golf car batteries would be a better choice seeing it's closer to 392? I personally would rather have the trojan batteries, IF it's a good match that is...

BB.

Re: New here and need some advice

I think that would be fine... 2 days of storage (plus 50% maximum discharge) is usually just fine. Just plug in 12 volts @ ~440 AH (depending on exact battery type you choose) and run the rest of the math.

Since it is weekend use and you do a 5% rate of charge until you figure out your actual power usage--And you can add more panel later, if needed.

10% rate of charge is actually a very nice balance for charging and support a full year round residence.

On the other hand, I was very conservative... If your power usage is truly closer to 500-600 WH per day and you will not be there much in the "winter", you could really cut back on the system size. You could get away with a pair of 6 volt @ 220 AH "golf cart" type batteries very easily.

Over sizing the system costs you extra money, more batteries to replace 3-5 years down the road, and more risk (if theft/vandalism) is an issue.

Power usage is a highly personal set of choices--And my guesses may not be "right" for you.

As you can see, just a "slight" variation in assumptions (3 days of storage, 1,000 WH per day vs 2 days and 550 WH per day) can change the system sizing dramatically.

A Honda eu2000i or even eu1000i (or similar Yamaha, etc.) "suit case" sized genset can always be used when needed for a extra power (working on cabin, guests in winter, etc.). If you ever go "full time", you should consider using a backup genset+battery charger anyway. The genset+10-20 gallons of gasoline can be very useful at home for emergency backup power too (around 1-2 gallons of fuel per day to run a fridge and a few lights).

-Bill

solarpowernovice

Re: New here and need some advice

Okay heres what I've got so far (this is the list of parts in that kit) and then I'll buy the Four 225AH trojan T-105's

4 Kyocera KD140SX-UFBS 140 watt solar module

1 Morningstar Tristar TS-45, 45 amp Charge Controller

1 Morningstar TriStar TS-M-2 Digital Meter Face for TS controllers

1 MidNite 6 Position Combiner Box 150V (MNPV-6)

4 MNEPV-15 15 amp DC Breaker 150VDC DIN, 13mm

60' 10/2 Sunlight Resistant Tray Cable 10/2 per foot

4 1/2" Strain Relief for #10 or #12 wire

Could someone recommend an inverter for this system, and whatever else I may need? I have a 6000 running watts/7000peak starting watts generator and a 10amp 12 volt battery charger already. I'd like to order all of this together then get the batteries when it all arrives. I was also under the impression that you can bypass the inverter using 12 volt appliances which would mean no loss of efficiency when using an inverter, is this possible?

BB.

Re: New here and need some advice

Based on 4x 6 volt @ 225 AH Batteries (wired at 12 volt)--The "reasonable maximum" inverter size would range around:

• 4 * batteries * 6 volts * 225 AH * C/8 rate of discharge * 0.85 inverter eff = 574 Watt "balanced" AC inverter for batt bank
• 4 * batteries * 6 volts * 225 AH * C/2.5 rate of discharge * 0.85 inverter eff = 1,836 Watt "max surge" AC inverter for batt bank
• 1,836 Watt max surge / 2 for "typical" max surge capability inverter = 918 Watt "max rated" inverter continuous

If your AC power usage is "smaller"--The Morningstar 12 volt 300 Watt (600 watt ten minute surge) TSW AC inverter would be really nice.

Otherwise, you are looking at a "Maximum" AC inverter in the range of 600-1,000-1,200 Watt range for this battery bank. What size do you think you would like/need.

Yes, you can connect DC loads directly to the battery bank and save the 0.85 losses of the AC inverter... But given the issues of wiring 12 volt loads (and battery banks that can run >15 volts when charging/equalizing, which some "12 volt" car based devices don't really seem to like--I suggest that 120 VAC loads (if you have a lot of them--such as laptop/cell charger/tool battery charger/electronics) are sometimes better to run off of 120 VAC and that leaves you with just the AC Inverter + battery chargers 12 volt wiring issues.

A 6 kWatt generator--The maximum AC power "typical" battery charger I would suggest (based on Generator capacity):

• 6,000 watts * 0.80 max cont. generator * 0.80 charger eff * 0.65 PF * 1/14.5 volts charging = 172 Amps @ 12 volts maximum

That is obviously way larger than you would need to charge the battery bank (20% rate of charge would be 450a*0.2=90 amps)...

So, working the other way, the generator would be around--pick 20% rate of charge, but 5% to 13% to even 25% rate of charge is doable:

• 450 AH * 14.5 volts charging * 0.20 rate of charge * 1/0.80 gen derating * 1/0.80 charger eff * 1/0.65 PF = 3,137 VA genset @ 90 amps and 12 volt battery bank

If you dump the current down to 10% (~45 amps), you can then use a Honda eu2000i (1,600 watt class) genset and keep the system relatively small (and not too expensive or fuel hungry).

Lots of choices--Depending on your needs, then we can start looking at hardware to support those needs.

-Bill

solarpowernovice

Re: New here and need some advice

I'm thinking this inverter http://www.solar-electric.com/samlex-pure-sine-wave-inverter-pst-600-12.html .... are you saying after i hook up my system I should run all of my loads through the inverter and not directly from the battery?(Sorry you kinda lost me there) are you also saying it would be better for me to sell my generator and to get a smaller generator like the Honda eu2000i, and buy a higher amp battery charger too? Because if so I will it takes too much gas anyway. I see lots of people have this generator as their backup and it seems to be highly recommended. If you OK this inverter it looks like I am ready to start ordering

BB.

Re: New here and need some advice

solarpowernovice wrote: »

I'm thinking this inverter http://www.solar-electric.com/samlex-pure-sine-wave-inverter-pst-600-12.html .... are you saying after i hook up my system I should run all of my loads through the inverter and not directly from the battery?(Sorry you kinda lost me there)

It depends on how many 12 volt loads you have and if you already have 12 volt items to run or if you will have to purchase 12 volt adapters/appliances to operate.

Yes, the inverter is something like 85% efficient and will "waste" ~6 watts while running. However, once you have committed to running some 120 VAC loads anyway, the inverter is already operating so adding a few more loads won't burn an extra 6 watt tare load.

More or less, running 12 volt devices can be a pain. If your system/cabin/needs are small--Yes you can simply put some 12 volt plugs on your battery bank and run the devices (cigarette lighter plugs, or HAM radio folks use a lot of Anderson Connectors as a 12 volt bus standard).

But if you have a lot of different loads and/or need to send the power more than 5-10 feet or so, setting up the plugs/cabling/adapters is a pain. It is easier just to plug the AC version of the appliance into a power strip.

If you don't have many 12 volt power needs, or the power usage is small (few LED lights, 12 volt radio, etc.)--Yes, using 12 volt power directly can save you some energy (you only need to turn on the inverter when you have AC loads to power).

The Samulex inverter looks nice--That it has a remote power switch is nice too. Saves you having to add a heavy 12 VDC switch (or breaker) to turn the inverter on/off.

You are still planning on running a small refrigerator too? A 600 Watt inverter may or may not start that refrigerator (usually a 1kW to 1.2 kW inverter in a recommended minimum). I simply do not know if this will start the fridge or not.

Remember, my inverter sizing guesses are working "sideways" from your battery bank size (and I am guessing on the battery capacity--is it ~200 AH per battery?).

Before you buy anything--I would like to see a basic hardware list... Something like:

1. 600 Watt average loads, 1,000 WH per day
2. 500 watts of Vmp 30 volt panels
3. MS MPPT TS 45 charge controller
4. Samulex 600 watt 12 vdc inverter
5. 4x 6 volt @ 200 AH batteries
6. X kW brand Y genset
7. Z brand/model of XX amp 12 volt AC battery charger
8. System located near Richmond VA
9. etc...

My goal is for you to have a "Balanced System Design"... Getting this all on paper first, before you purchase anything will help avoid issues later (something too big/too small, or system will not power your needed loads).

It will also help you size wiring (gauge, lengths) and pick fuses/breakers appropriate for your system (the "small stuff" is, in my opinion) is really the pain. Making the connections is a critical part of building out your system and were forgetting a couple crimp connectors/etc. leaves you in the dark and miles from a hardware store to buy them).

Some folks will take a 4x4 piece of plywood and mount everything to it and get it wired/operating at home--Then take the whole pre-wired assembly to the cabin.

By the way, said plywood--But I recommend fire safety. Mounting in the cabin on sheet rock or concrete board, and having a non flammable metal shelf below the electrical or on the floor can keep flaming bits from setting the cabin/off grid home on fire. Yes, I am paranoid about fire and Battery Banks--But design for safety assumes that anything can fail. Fusing/breakers/fire resistant installation helps prevent those failures from causing further damage/harm to people nearby.

are you also saying it would be better for me to sell my generator and to get a smaller generator like the Honda eu2000i, and buy a higher amp battery charger too? Because if so I will it takes too much gas anyway. I see lots of people have this generator as their backup and it seems to be highly recommended.

I don't know what battery charger you have today... A 12 volt automotive charger is not usually very good for the job. And you are talking about some very high currents during charging (~40 amps or more). Clipping a 12 volt battery charger onto the bank is not the correct/reliable method for a permanent off grid installation.

Regarding what to do with your present genset and charger... I don't know what you have (and I guessed at the battery bank). So, I cannot tell you what you have will or will not work for you.

But--Just taking some typical rules of thumb/guesses... A 6 kW genset should draw ~1 gallon per hour at 6 kWatt output And below ~3 kW will drink around 1/2 gallon of fuel per hour (even with zero load, it will probably take from 1/4 to 1/2 gallon per hour).

If your battery charging charging+AC loads will keep the genset loaded to 3+ kW most of the time--Your genset will be pretty fuel efficient.

If, however, your average loads are something like ~1 kW or less--Then the big genny will be drinking 2-3x as much fuel as you really need to use (i.e., 2 kWH per gallon of fuel or worse).

A Honda eu2000i will use about 1/4 gallon per hour at 1,600 watts and about 1/10 gallon per hour at 400 watts:

• 1.6 kW * 4 hours * 1/1.1 gallon fuel tank =5.8 kWH per gallon
• 0.4kW * 9.6 hours * 1/1.1 gallon fuel tank = 3.5 kWH per gallon

Say you buy the Honda for ~$1,000 --- And you pay $4 per gallon for gasoline. And lets say your genset runs 0.5 gph at 1,000 watts and the Honda runs at 0.2 gallons per hour at 1,000 watts.

And you need 1,000 Watt load * 2 hours per day of generator run time 30 days per year:

6kW genset:

• 0.5 gph * 2 hour per day * 30 days = 30 gallons of gas per year
• 30 gallons * $4 per gallon = $120 worth of gasoline

Honda eu2000i:

• 0.2 gph * 2 hours per day * 30 days = 12 gallons of gas per year
• 12 gallons * $4 per gallon = $48 worth of fuel

At $1,000 for the Honda, it would take you:
$1,000 / [$120-$48]per year = 13.8 years pay back

So--While you will save money on fuel and need to haul/store less fuel--If you do not use the generator very much--It is difficult to justify the extra $1,000 for a new genset if your generator is perfectly OK...

If your present genset is reliable and the noise is not a problem (as well as fuel storage)--I would go ahead and build out your off grid power system and starting using it. And see how much you use the genset and make the decision to keep/replace down the road.

You probably will need to get a "better" AC battery charger that matches your battery bank and can be hardwired. You will have to keep in the back of your mind if you are going to keep the 6kW genset or replace it with a 1.6 kW genset (or other size) down the road... (smaller genset, smaller AC supply).

If you OK this inverter it looks like I am ready to start ordering

Since I don't get one dime from any of your purchases (I don't work for NAWS or any other supplier), I am not in a big rush for you to purchase equipment. I am pretty cheap and want you to have a good paper design to make sure the system will meet your needs and not just empty your wallet.

At this point, I really am not sure what your needs/present shopping list/owned equipment is. I have made lots of guesses about what you will be purchasing and your power needs... But those are pure guesses on my part.

Energy usage is a highly personal set of choices. What would work for me (who does not live off grid), may or may not work for you. Please make sure you have a solid set of needs and equipment list on paper first before you start purchasing. I think you will be much happier down the road.

-Bill

solarpowernovice

Re: New here and need some advice

Loads:
I'd like to convert a chest freezer to a fridge because its more cost effective than an ENGEL or ARB 12v fridge/freezer. I've looked around and the consensus is they take no more than 300 to 400 watt hours per day. I need to use Two 13 watt LED lights for 6 hours, A 26watt laptop charger for 4 hours and a 5 watt cellphone charger for 4 hours. I think i need to replace my A/C transfer pump (more about it below) with a 12 volt pump like this one http://www.northerntool.com/shop/tools/product_527_527?cm_ven=natural&cm_cat=netconcepts&cm_pla=&cm_ite= which would only be used half an hour a day max. I am not sure of the power consumption on these pumps? So lets just say FRIDGE: 360 watt hours LIGHTS: 156 watt hours LAPTOP: 104 watt hours CELLPHONE CHARGER: 20 watt hours PUMP: 100 watt hours? complete guess... all of this would be 740 watt hours per day.

Here is a list of the products I have already, and the ones I plan on ordering. First the ones I plan on ordering:

4 Kyocera KD140SX-UFBS 140 watt solar module Maximum Power Voltage (Vmpp) 17.7V

1 Morningstar Tristar TS-45, 45 amp Charge Controller

1 Morningstar TriStar TS-M-2 Digital Meter Face for TS controllers

1 MidNite 6 Position Combiner Box 150V (MNPV-6)

4 MNEPV-15 15 amp DC Breaker 150VDC DIN, 13mm

60' 10/2 Sunlight Resistant Tray Cable 10/2 per foot

4 1/2" Strain Relief for #10 or #12 wire

4 Trojan 225 amphour T-105-RE batteries

1 Samulex 600watt inverter (if it will run a Chest freezer to fridge conversion) if not then a 1000 watt inverter. Here's the freezer I would like to convert into a fridge, it seems to be the best on energy consumption per cubit foot.http://www.walmart.com/ip/Danby-8.7-cu-ft-Chest-Freezer-White/21854529 @ 262KWH/yr. I plan on selling my extra side by side fridge/freezer to pay for it. If what I've heard about chest freezer conversions are true and it runs half the time or less than it would as a freezer thats .36 KWH or less per day. 262KWH yr./365days = .71KWH/2 = .358KWH

As for what i have already:

A 1/10th HorsePower A/C transfer pump that takes 160 watts while running (170 at startup) on the kill a watt meter. But I think I may need to buy a 12 volt pump??? I need the pump to get the water down a very low slope (but it is down hill all the way) from a 5 foot deep cistern about 50 feet down hill to my "cabin".

A Champion 6000 running watts/7000 starting watts Electric start generator (it is very loud). link here: http://www.championpowerequipment.com/generators/41311/

And a 12 volt 10 amp automotive battery charger. link here: http://www.bestbuy.com/site/schumacher-battery-charger/1305644180.p?id=mp1305644180&skuId=1305644180 (which would not work)

Thanks for all the help bill! You are a life saver.

Oh i almost forgot the location... I just found this site http://solarelectricityhandbook.com/solar-irradiance.html and entered the closest city to me (Harrisonburg, Virginia) I dont know if this helps.

jcheil

Re: New here and need some advice

I am sure one of the experts here will give you a detailed overall analysis but I would recommend abandoning the freezer conversion. You can get an 18cf fridge/freezer combination that has an EPA usage estimate of around 300kwh per year for around $450. That is less than 1kwh per day. Your estimate of 360w per day (.36kwh), I would venture to guess is low, especially if you are in a warmer climate.

There are tons of other threads going on now regarding fridges. They all end up in the same place, you need a bigger inverter to start them (1000+) and a lot more power to run them than most people realize. And please don't even consider the small 5-6cf fridges as they use as much if not more power than the big 18cf ones.

solarpowernovice

Re: New here and need some advice

Would i be able to run this fridge/freezer you speak of on this system i have proposed tho? If so could you send me a link of this fridge/freezer? I don't want to splurge on a big system if i can keep it small and pair it with very efficient appliances. Maybe an Engel or ARB would be the best choice???

BB.

Re: New here and need some advice

I think you can get below a 0.5 kWH per day (even in warm weather) with a chest freezer to refrigerator conversion. The bigger issue is how much starting current they draw... For the most part, you will probably need that minimum 1,000 Watt inverter.

Unfortunately, the minimum inverter to run the freezer may need some experimentation (you could ask whomever you purchase the inverter from what their customer's experiences may be).

Loads:

• FRIDGE: 360 watt hours
• LIGHTS: 156 watt hours LAPTOP: 104 watt hours
• CELLPHONE CHARGER: 20 watt hours
• PUMP: 100 watt hours? complete guess...
• all of this would be 740 watt hours per day.

Looks reasonable--I would round up to 1,000 WH per day.

The pump... DC Pump will be more efficient--But sending the 12 VDC power 50' (call it 7 amps) with 1/2 volt drop... Using a generic voltage drop calculator and one-way run (some use round trip length):

• 6 awg @ 50' and 8 amps -> 0.4 volt drop

It is a tradeoff... If a 100'+ feet of 6 awg is in your budget + a 12 volt pump--It probably would be pretty nice setup. And avoid another load on the inverter (plus DC Pump efficiency). But a 100 WH of AC power is not a huge deal either--And you can use much smaller gauge wire for the run. In any case, if you bury the cable--I always suggest using a large conduit so you can easily pull wire (and more stuff later if needed) of any reasonable gauge.

Here is a list of the products I have already, and the ones I plan on ordering. First the ones I plan on ordering:

• 4 Kyocera KD140SX-UFBS 140 watt solar module Maximum Power Voltage (Vmpp) 17.7V
• 1 Morningstar Tristar TS-45, 45 amp Charge Controller
• 1 Morningstar TriStar TS-M-2 Digital Meter Face for TS controllers
• 1 MidNite 6 Position Combiner Box 150V (MNPV-6)
• 4 MNEPV-15 15 amp DC Breaker 150VDC DIN, 13mm
• 60' 10/2 Sunlight Resistant Tray Cable 10/2 per foot
• 4 1/2" Strain Relief for #10 or #12 wire
• 4 Trojan 225 amphour T-105-RE batteries
• 1 Samulex 600watt inverter (if it will run a Chest freezer to fridge conversion) if not then a 1000 watt inverter.

The MorningStar TS-45 comes in two flavors--A PWM version (less expensive) and a MPPT version.

The 4 Kyocera panels will work fine with either controller. A major reason for picking MPPT type controller would be if the solar array run to controller/battery shed was a "longer distance"... If you have more than 10-20 feet of wiring run, you may wish to think about the MPPT version. This will keep the copper wire diameter smaller for this run.

Using the website you provided for solar calculations... The minimum would be 2.99 hours per day in winter, and if you toss the bottom three months, you are looking at 3.75 hours of sun per day (December vs February, array tilted ~52 degrees from vertical for year round best average).

So, running the calculations. For a 1,000 Watt*Hour per day load:

• 1,000 WH per day * 1/0.52 end to end system eff * 1/2.99 hours of sun = 643 Watt array (December "break even")
• 1,000 WH per day * 1/0.52 end to end system eff * 1/3.75 hours of sun = 513 Watt array (February "break even")

And 4x 6 volt @ 220 AH batteries with 5-13% rate of charge array calculation:

• 4 batts * 6 volts * 220 AH * 1/0.77 panel+controller derating * 0.05 rate of charge = 343 Watt array minimum
• 4 batts * 6 volts * 220 AH * 1/0.77 panel+controller derating * 0.10 rate of charge = 686 Watt array nominal
• 4 batts * 6 volts * 220 AH * 1/0.77 panel+controller derating * 0.13 rate of charge = 891 Watt array "max cost effective"

And you presently have 4 * 140 Watt panels = 560 Watts

Which is not a bad choice. Especially if this is not a full time home at this time. You could add one or two more panels later if your power needs are larger than you expected (running that fridge).

If you have a TS-45 PWM controller--You can add one, possibly two more panels (you need to check the manual).

If you have a TS-45 MPPT controller, you could have as much as:

• 45 amps * 14.5 volts charging * 1/0.77 panel+controller derating = 847 Watts "cost effective maximum"

MPPT controllers can safely/reliably limit their maximum output current. PWM controllers cannot--they need to be limited by the array design.

Here's the freezer I would like to convert into a fridge, it seems to be the best on energy consumption per cubit foot.http://www.walmart.com/ip/Danby-8.7-...White/21854529 @ 262KWH/yr. I plan on selling my extra side by side fridge/freezer to pay for it. If what I've heard about chest freezer conversions are true and it runs half the time or less than it would as a freezer thats .36 KWH or less per day. 262KWH yr./365days = .71KWH/2 = .358KWH

Freezer to fridge conversions are so much cheaper than purchasing a "designed for off grid 12/24 volt" refrigerator, you can usually throw in a bit larger inverter and solar panels and still come out spending a whole lot less money.

As for what i have already:
A 1/10th HorsePower A/C transfer pump that takes 160 watts while running (170 at startup) on the kill a watt meter. But I think I may need to buy a 12 volt pump??? I need the pump to get the water down a very low slope (but it is down hill all the way) from a 5 foot deep cistern about 50 feet down hill to my "cabin".

If you already have the AC pump--Try it... You will not lose anything for trying (extension cord, a few plumbing fittings, etc.).

A Champion 6000 running watts/7000 starting watts Electric start generator (it is very loud). link here: http://www.championpowerequipment.com/generators/41311/

I have read some pretty good things about the mid-range Champion Generators (Costco is selling the next size up).

Looking at the specs, notice that it is rated to run at 50% power for 10 hours on 6.5 gallon fuel tank... Or ~0.65 gallons an hour (close enough to the 1/2 gallon per hour I guessed at).

More or less--Your choice, you can certainly build out your off grid system and start running it (and learning how to manage your power usage)... And if this genset is too loud and/or fuel thirsty, you can then look at the smaller Honda/Yamaha gensets (I really like the inverter-generator sets--when running at lower power levels, they can throttle back save you some more fuel).

Quite a few folks have several genests--A smaller Honda eu2000i or eu1000i (1,600 watt or 900 watt rated power)--And a larger genset to run larger loads (shop tools) and as a backup for your backup genset.

And a 12 volt 10 amp automotive battery charger.

Yea--Running a 12 volt * 10 amp (120 Watt) battery charger from a 6kW genset is going to really drink fuel.

We can run the similar calculations for 5-13% rate of charge (same as solar) or even 20-25% rate of charge (you need to watch battery bank temperatures >~13% rate of charge--Some inverter-chargers and off grid chargers will have a remote battery temperature sensor option--And most solar chargers have that option--highly recommended to get a RBTS for optimal battery charging). To same typing, lets look at a 10% and 20% rate of charge on your genset. Note, I am assuming you will run the genset at ~80% of rated power during battery charging:

• 12 volt @ 450 AH battery bank * 10% rate of charge = 45 amp @ 12 volt charger
• 14.5 volts charging * 450 AH bank * 10% rate of charge * 1/0.80 charger eff * 1/0.65 Power Factor * 1/0.80 of generator rated power = 1,569 VA rated genset
• 12 volt @ 450 AH battery bank * 20% rate of charge = 90 amp @ 12 volt charger
• 14.5 volts charging * 450 AH bank * 20% rate of charge * 1/0.80 charger eff * 1/0.65 Power Factor * 1/0.80 of generator rated power = 3,137 VA rated genset

So, if you were going to think about getting a Honda eu2000i in the future, I would stick with the 40-45 Amp 12 volt charger...

If you think you will stay with the Champion, you might think about using an ~90 amp charger (12 volt) and load up the genset closer to 50% of capacity (more fuel efficient).

Our host likes the Iota chargers--Very simple and reliable. And will charge at rated power. They are not particularly efficient--But will fit nicely in your current system design. For off grid, you really do not need the IQ-4 module. And there is a ten turn pot inside the chargers (as I understand) so you can tweak them to fit your needs.

What are your thoughts?

-Bill

solarpowernovice

Re: New here and need some advice

I looked at Samlex's manual for both the 1000 watt and the 1500 watt inverters, the 1000 doesn't say fridge/freezer but the 1500 does. I dont want to fry the inverter and then be out all of that money. So heres the new inverter for the list http://www.chargingchargers.com/inverters/s1500-112b2.html I would need to add the DC-2000 Inverter Installation Kit - 200 Amp Fuse thats under the picture to my list too right? As for a PWM or MPPT Charge controller I was thinking about mounting it on a pole because you can adjust the angle for the season, but then I'd need a MPPT controller. I could mount them on the metal roof which would mean less than a 20 foot wire run for sure. Is it really worth getting a pole mount and paying more for an MPPT CC seeing I can adjust the pole mount for the seasons, or should I just settle for roof mounts? The top of pole mount for the 4 panels is $400 vs. $250 for roof mounting (on iron-ridges mounting calculator on their website).

So now my list has changed from the 600 watt Samlex inverter to the 1500. I think sticking with my current generator and buying that 90 amp charger is the best way to go. I also will stick with my A/C pump until i find the need to change. Can you think of anything else I need to add to my list? all i need now is the "small stuff" like wires / fuses right ? (and of course the 4x4 plywood and slate slab)

UPDATED LIST:

4 Kyocera KD140SX-UFBS 140 watt solar module Maximum Power Voltage (Vmpp) 17.7V

1 Morningstar Tristar TS-45, 45 amp Charge Controller (or the MPPT version)

1 Morningstar TriStar TS-M-2 Digital Meter Face for TS controllers^

1 MidNite 6 Position Combiner Box 150V (MNPV-6)

4 MNEPV-15 15 amp DC Breaker 150VDC DIN, 13mm

60' 10/2 Sunlight Resistant Tray Cable 10/2 per foot

4 1/2" Strain Relief for #10 or #12 wire


^ kit from wholesalesolar ^

---

4 Trojan 225 amphour T-105-RE batteries

1 1500Watt Pure sine Inverter w/ 200 amp fuse install kit

1 Iota DLS-90 Battery Charger, 90 Amp, 12 Volt

BB.

Re: New here and need some advice

solarpowernovice wrote: »

I looked at Samlex's manual for both the 1000 watt and the 1500 watt inverters, the 1000 doesn't say fridge/freezer but the 1500 does. I dont want to fry the inverter and then be out all of that money.

Looks like it should run a converted freezer/fridge very nicely. Read the manual very closely and understand how much power it draws when 120 VAC is "on"... From the website:

This 1500 Watt Pure Sine Power Inverter is a switch mode (microprocessor controlled), highly efficient inverter, providing a continuous 1500 watts of pure sine 115 VAC power with a 2000 watt surge, from a 12 volt battery or battery pack. This unit has a low 1.5 watt no-load current draw, RS 232 interface, a low battery alarm set at 10.2 volts DC and a low battery shut down set at 9.5 volts DC to protect the battery pack. It also features meters for battery voltage and watt output, so observation of residual battery voltage and current watt consumption can be maintained.

If the specifications are correct/true--That is a really nice inverter. Larger inverter with very low Tare Losses is tremendous for use in smaller off grid power systems.

Personally, I think those minimum battery voltages are too low for Lead Acid batteries... Running a bank much below ~11.5 volts is going to risk permanent damage. Running to 10.5 or lower voltage, looking at new batteries.

Also check the maximum voltage. Many inverters will alarm/shut down at 15.0 volts--If you can find an inverter that will run at 15.5-16.0 volts--That is better (battery equalization).

Assuming this all works as planned, you could be our new poster child for small off grid solar with a converted freezer to fridge. That is a good thing. Let us know how everything goes and the performance of your system.

Check too that you can turn off the inverter and see what its "off load" would be. More than a few people have put their system away for the winter--And left the inverter on (to run alarm, forgot to turn off, etc.)... The Charge Controller hickups and shuts down (needs manual reset/service). The owner comes back after a couple of months and fines a dead battery bank.

So heres the new inverter for the list http://www.chargingchargers.com/inverters/s1500-112b2.html I would need to add the DC-2000 Inverter Installation Kit - 200 Amp Fuse thats under the picture to my list too right?

Should be fine. Get extra fuses, or think about a 200 Amp Breaker instead (over-current+On/Off switch).

Looks good--If you get the fused protection (and in general), get some extra fuses to keep on the shelf. Nothing like popping a fuse and losing power on your day off. Sometimes, that is a "good enough" reason to use a circuit breaker. Replace a couple fuses, and you paid for a breaker--Plus sometimes it is really nice to simply have an on/off switch.

Also, look at Battery Monitors (Victron is another good brand). Especially if you have a spouse, kids, guests and you want simple instructions. I.e., "call me if you get below 50% state of charge, turn off loads, start genset).

As for a PWM or MPPT Charge controller I was thinking about mounting it on a pole because you can adjust the angle for the season, but then I'd need a MPPT controller.

Pole mounts are a lot of work and concrete. Mounting on the roof can be a little bit more theft resistant. And I found my home's attic is a lot cooler from the simple shading by the panels.

Large arrays on poles require a lot of engineering, metal, and concrete. A personal choice to a large degree.

I could mount them on the metal roof which would mean less than a 20 foot wire run for sure. Is it really worth getting a pole mount and paying more for an MPPT CC seeing I can adjust the pole mount for the seasons, or should I just settle for roof mounts? The top of pole mount for the 4 panels is $400 vs. $250 for roof mounting (on iron-ridges mounting calculator on their website).

The whole PWM/MPPT/Vmp~17.5 volt vs GT solar panels/advanced logging/more options for charging/etc... Lots of choices. And lots of shades of grey.

A PWM controller (cheap) + Vmp~17.5 volt panels (expensive) vs MPPT controller (expensive) and GT Panels (Vmp~30-40 volts--cheap).

Add a stand alone Battery Monitor (not cheap) vs a Midnite Classic with their (soon to be released--hope, hope) Battery Monitor option (not cheap MPPT controller plus hopefully cheap external battery shunt)....

So now my list has changed from the 600 watt Samlex inverter to the 1500. I think sticking with my current generator and buying that 90 amp charger is the best way to go. I also will stick with my A/C pump until i find the need to change. Can you think of anything else I need to add to my list? all i need now is the "small stuff" like wires / fuses right ? (and of course the 4x4 plywood and slate slab)

Not sure about slate slab--For a floor--that is fine. For a wall, either sheet rock or concrete backer board (sometimes called "Wonder Board") for a bit better fire resistance (vs mounting on wood stud wall/plywood shear wall).

For a first time person (and somebody doing a remote install and no local hardware/electrical store)--You might look at some version of an E-Panel:

MidNite Solar E-Panels and Accessories

Can make a very clean installation and less hunting for compatible parts/connection hardware.

Also, I would look at the Samulex Remote panels (may be included with your inverter--I am not sure). If they let you monitor your inverter's output and ability to turn on/off without needing a breaker/knife switch--Can be very nice.

Note sure which converter box you will be getting--but you may need to get some male/female MC4 cables you can cut in half. Connector to your panel lead, cut end you wire into the balance of system (many vendors will try and void warranties if you cut the MC4 connectors off).

MC4 Interconnect Cables and Adaptors for Solar Electric Panels

UPDATED LIST:

• 4 Kyocera KD140SX-UFBS 140 watt solar module Maximum Power Voltage (Vmpp) 17.7V
• 1 Morningstar Tristar TS-45, 45 amp Charge Controller (or the MPPT version)
• 1 Morningstar TriStar TS-M-2 Digital Meter Face for TS controllers^
• 1 MidNite 6 Position Combiner Box 150V (MNPV-6)
• 4 MNEPV-15 15 amp DC Breaker 150VDC DIN, 13mm
• 60' 10/2 Sunlight Resistant Tray Cable 10/2 per foot
• 4 1/2" Strain Relief for #10 or #12 wire
• ^ kit from wholesalesolar ^

• ---

• 4 Trojan 225 amphour T-105-RE batteries
• 1 1500Watt Pure sine Inverter w/ 200 amp fuse install kit
• 1 Iota DLS-90 Battery Charger, 90 Amp, 12 Volt

I am sure others here can give you some more details from their installation experiences.

-Bill

solar_dave

Re: New here and need some advice

The Samlex line 1000 watt will do 16.5 V high cutoff. That is why I bought a pair of 1000 watt models for the Volts to use during an outage, the DC to DC converter in them tend to run into the mid to upper 15 volt range.
http://www.solar-electric.com/samlex-pure-sine-wave-inverter-pst-1500-12.html
http://www.solar-electric.com/samlex-pure-sine-wave-inverter-pst-1000-12.html

Rybren

Re: New here and need some advice

Be sure to check the model and specs if you get a Samlex. Some models have the 16.5V cutoff and others only have a 15V cutoff.

The PST series has 16.5V, but I believe that the SA line only has 15V

solarpowernovice

Re: New here and need some advice

Ok but will the PST run a freezer? I dont see anything about it in the manual, but in the SA manual I do... It should seeing its 1500 watts I'm guessing. Looks like the PST is the way to go, with a 200 amp breaker right? Would I need a breaker between the charge controller and the batteries too?

BB.

Re: New here and need some advice

In general, a good quality 1,200 to 1,500 Watt inverter should run a refrigerator. And, you need short/heavy cable from the battery to the inverter. At 1,500 watts, the worst running current would be:

• 1,500 watts * 1/0.85 inverter eff * 1/10.5 volts minimum batt cutoff = 168 amps.

Add a 1.25 NEC derating for fusing/wiring:

• 168 * 1.25 NEC derating = 210 Amp fuse/breaker/wiring (200 amps is close enough)

The 16.5 volt operating peak battery voltage--Yea, it is worth it. Some industrial batteries need >15.0 volts charging--And if you live in very cold regions, cold batteries need higher charging voltages too.

Note that the rules of thumbs and recommendations I and other suggests here are "engineering based" opinion--I.e., we want to see the system work as you expect in all operating conditions (hot/cold/full charge/less than 50% charge/suggesting to follow National Electrical Code when you can/work well on days with less than ideal sun, etc.).

It is a bit on the "over kill" side--And if you are very price sensitive, may not be the best opinion/option for you. We are making some assumptions on how you will use the system and I (and others) prefer to error on the side of caution when making suggestions for your system.

-Bill

BB.

Re: New here and need some advice

Also, regarding the question of circuit protection. I suggest that each major load (especially heavy loads) should have their own branch circuit and protective device.

For example, I would suggest not sharing the Inverter cabling/breaker with the Charge controller. Both the 200 amp circuit is too large for the 45 amp charge controller (not safe if the charge controller shorts internally) and electrical noise/interference from the switching power supply and PWM/MPPT charge controllers can confuse each other. If you "home run" back to the battery bank, the batteries act like a large filter--reducing noise in the power system components.

Each positive circuit that leaves the + battery bus should have a fuse/breaker/wire sized to the maximum sustained current expected.

For example, a 45 amp charge controller * 1.25 NEC derating = 50 amps. Round up to the next standard value of breaker/wiring.

Each branch circuit should have the same calculations.

Negative/Return (assuming negative ground battery bank) leads should never have fuses/switches in them. Only the "hot" leads have fusing/switches/breakers.

-Bill

solarpowernovice

Re: New here and need some advice

Lets just say i ordered all the parts in this kit from another website... Can you use 24 volt panels in a 12 volt system? I found 3 250 watt Hyundai panels for cheaper than 4 140 watt kyocera panels, whats so special about kyocera's panel?

hyundai panel: http://www.affordable-solar.com/store/solar-panels/Hyundai-HiS-255MG-255w-Mono-Black-Frame


I think these are the last questions I have until I order all the parts and start putting them together. Thank you all.

BB.

Re: New here and need some advice

Kyocera has made good quality panels over these many decades... And when they did have problems a decade ago, they stood by their warranty.

However, good panels from a good company--Shopping on a $$$/Watt (based on price delivered to your front door) is the way most people buy panels (I am not in the business, so I cannot really tell you which panels have the lowest return rate). And things change over time (Sanyo make very reliable panels, but now they are gone and Panasonic is taking over).

If you buy panels with Vmp>>17.5 to 18.6 volts or so, then you will need a MPPT type charge controller to efficienty take high voltage/low current from the array and down convert to low voltage/high current used by the battery bank.

If you put "24 volt panels" on a PWM controller and 12 volt battery bank, you will lose ~1/2 of the wattage of the solar array.

This is the paper design part where you compare the price of 4 * "12 volt panels" and a PWM controller vs 3 * "24 volt panels" panels and MPPT controller. You should be happy with either configuration.

If you have very hot weather, the "high" Vmp array + MPPT controller will give you more power in hot weather (and cold batteries).

-Bill

solarpowernovice

Re: New here and need some advice

I'm back! Lol ... I have just one question for you. All I need to know now is what kind of E-Panel you recommend for this list. My new list has a 60 amp MPPT charge controller because in the manual for the 45 amp it says 600 watts max PV input @ 12v, and its 800 on the 60 amp version. It's Basicly the same list just with 3 24 volt panels, the 60 amp Charge controller, and an MNPV3 combiner box seeing I'll have 3 panels. I am ordering 90% of the parts on the list from the same website (it has the best prices for all the parts i need) so here we go:

3 Suniva OPT265-60-4-100 > 265 Watt Solar Panel (795 watts) - Max Power Voltage (VMPP) 30.70 V

1 Morningstar TS-MPPT-60 > TriStar 60 Amp w/ battery temp. sensor

1 Morningstar TS-M-2 > TriStar Digital Meter

1 Midnite Solar MNPV3 Combiner Box

3 MidNite Solar MNEPV15 > 15 AMP 150 VDC DIN Breaker

1 1500watt PST-Samlex Inverter w/ remote control

1 Iota DLS-90 Battery Charger, 90 Amp, 12 Volt

4 Trojan 225 amphour T-105-RE batteries

(I have a hardware store right down the street where I can buy all the wires etc. )

Heres the link for the E-panels they sell... http://www.ecodirect.com/AC-DC-Enclosures-s/348.htm
If you dont see the one I need on here could you please link me to the one I need?
I just want to make wiring this all as easy as possible, seeing I'm a beginner. Sorry for all the confusion.

This is what I was thinking http://www.ecodirect.com/Midnite-Solar-MNDC250-250A-Mini-DC-Disconnect-p/midnite-mndc250.htm With an 80 amp breaker(for CC) and a 60 amp breaker (for solar panels)..

niel

Re: New here and need some advice

spn,
is there a reason why you can't put the pvs in series and save yourself the cost of a combiner and several breakers, not to mention a savings on wire size?

BB.

Re: New here and need some advice

You can try calling the retailer and see what they recommend.

There are reasons that you may pay a bit more/or not (at NAWS for example) as they can provide more pre-sale/tech support.

I don't work in this business--So I am of limited help here.

You can also go to the Midnite Solar Forum if you want some more information on e-panels and other Midnite products:

http://midniteforum.com/

-Bill

And as Niel says, you can put the three Vmp~30 volt panels in series with the MorningStar MPPT controller--Will save a lot on wiring and you don't need a combiner box for the solar.

solarpowernovice

Re: New here and need some advice

Ok thanks Bill, I will do that. Niel - if I wired all 3 in series without a combiner box, would I need a fuse on the PV+ or just put the PV+ directly into the charge controller? Also how would that save me on wire size?

sorry I think I just figured it out on this link im reading says you don't need a fuse when in series only parallel.