First time poster with a plan and questions

System · December 2010

This is my first post, so here goes.

The meat and potatoes (my proposed system):

2—135watt 12volt Kyocera panels with MC4 connectors. I have these on hand; I had to start somewhere, and they were on sale from the site sponsor.

To make it complete I plan to add:

A Xantrex C35 charge controller

4—6volt 220 AH batteries wired for 12 volts.

A Xantrex TR1512 1500 Watt, 12 Volt Inverter

Breakers and wiring to support a 1500watt load. This is more than the batteries should have drawn from them, I know, so if I’m way off base on this, I’m open to suggestions.

The site:

Somewhere in PA--41 degrees Lat
House faces south, 45deg roof, no shading.
30 feet—or less--from panels to charge controller.
Equipment will be in the basement. Temp stays between 66-75. Dehumidifier on in the summer.

Proposed loads—so far:
2 freezers: one small, one medium.
Small freezer (data from a Kill-a-watt):
1.1 KWH in 24 hrs
.97 PF
77VA
76 watts
.64 amps

Medium freezer:
1 KWH in 22 hrs
.98 PF
91VA
89 watts
.75 amps

Sump Pump:
I can control the time run, but say 15 min and not every day.
.56 PF
1010 VA
8.5 amps
590 watts—no surge with start up, a surprise for me, but the head pressure is minimal.

Backup: Honda EU2000i.

The rest:

I visit few forums and I have only found one other forum where there is as much friendly discourse as this one. Posters in most forums vie to see who can put as many logical fallacies into one paragraph as possible, granted there is real math and science behind what is discussed here and this no doubt helps. I’ve been kicking this around for a while now. Most of my reading has been online, so when I went to get a book on this, the big bookstore only had Solar Power for Dummies. I don’t recommend buying it, but was something I could put my hands on without ordering it—I read it in an evening. If I did the math right, the above system seemed OK according to his parameters. However, I’ve spent hours reading through this forum; I know I’ve barely brushed the surface, and now I’m not so sure. I have seen some signature lines with systems close to this, so I don’t think I’m too far off base.

I’ve done commercial HVAC, and Uncle Sam has taught me how to do 4th level maintenance on more than a few things—radios, generators, and the like being the most pertinent, so I plan on doing the install myself.

While this may seem a little large for an “experimental” system, I wanted something useful if it panned out. I’ve read in forums about people getting the cheap harbor freight setups, but I want more than just a light and to be able to charge my laptop. Eventual payback isn’t really an issue. Not losing the food in my freezer and having some independent power sources in the face of an extended power outage are. I don’t want to say cost is not an issue, just so long as I do it properly.

Finally, here are a few questions of the hundred I have:

First the usual “Would an mppt charge controller gain enough to be worth it?” Say the Morningstar 15 amp version. My initial plan is to keep this 12 volts from the panels to the charge controller and 12 volts for the battery bank and inverter. That way I could move this to my camper, if I outgrow it at the house. But, with an mppt, if I understand it, I could run 24volts into the charge controller. This would allow me to add at least two more panels (for a total of four) on the roof and not need to resize the wire. The wire that comes with the MC4 connectors is #10awg. I was going to run that to the charge controller.

Next, I’m thinking about going to a Prosine 1800watt PSW inverter or maybe just a 1000watt model as it should run the sump pump. I know I’ll lose the charging function, but I’d have to run a separate circuit to where the inverter is to take advantage of AC charging anyways. I don’t know if the newer appliances (~6 years old) like a MSW as a power source. There is a greater cost here, but more versatility too, since I can charge my cordless tools with a PSW inverter, or run the satellite Internet.

Thanks for your input.

Cariboocoot · December 2010

Re: First time poster with a plan and questions

Hello and welcome to the forum!

It's good that you went to the trouble to get some real data for your loads; 90% of "first timers" skip that essential step.

But (oh you knew there was going to be a "but") let's compare your proposed loads against your proposed system.

First up, you're expecting over 2 kW hours power per day. With four 220 Amp hour 6 Volt batteries you can expect 220 Amp hours @ 12 Volts (approximately) maximum: 2.6 kW hours per day. Looks good so far, if a bit "stretched".

Second, two 135 Watt panels would harvest about 800 Watt hours per day on average. Uh-oh, we're in trouble. You won't be getting back as many Watt hours as you use. Not by a long shot.

Third, those panels will probably produce a peak charge current of around 14 Amps. Like this:
135 W * 2 = 270 W @ 77% efficiency = 207.9 W / 14.2 charge V = 14.6 Amps. Barely enough to meet the recommended 5% minimum charge current for one set of 220 Amp hour batteries. You will have a 440 Amp hour bank, and should "shoot for" this:
44 Amps (10%) @ 14.2 V = 624.8 W / 77% efficiency = 811 Watt array (800 would do).

So as proposed, you've got the all-too-common problem of insufficient panels to properly recharge the battery bank. You would be using the generator daily.

Fourth, the TR series inverter I'm pretty sure is MSW. The motors in those freezers and pump will not "like" that. They will draw more current, run warm and less efficiently, and ultimately have a shorter life span.

I'm going to hazard a guess that you're doing this "to get your feet wet in solar", as it were. In that case you have some options:

1). Reduce/change the loads and use half the batteries
2). Add more solar panel (at least double) and change for a pure sine inverter
3). Save your money for a grid-tie system, which is far more cost effective if the utility is available.

Just a few things to think about.

BB. · December 2010

Re: First time poster with a plan and questions

Everything Marc said--For the most part, people underestimate their loads and overestimate how much the PV system can supply.

To give you a nice way to better estimate your PV System Power. PVWatts website, try Bradford PA, use 0.52 system derating (yes, 50% losses from solar panel rating to AC power output is the BEST you can assume), fixed array, 1 kW (1,000 watts) of solar panels (PV watts' minimum allowed number):

"Station Identification"
"City:","Bradford"
"State:","Pennsylvania"
"Lat (deg N):", 41.80
"Long (deg W):", 78.63
"Elev (m): ", 600
"PV System Specifications"
"DC Rating:"," 1.0 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 0.5 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 41.8"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 9.6 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 2.82, 47, 4.51
2, 3.65, 55, 5.28
3, 4.58, 73, 7.01
4, 4.94, 73, 7.01
5, 5.10, 75, 7.20
6, 5.38, 75, 7.20
7, 5.47, 79, 7.58
8, 5.10, 73, 7.01
9, 4.57, 65, 6.24
10, 3.94, 60, 5.76
11, 2.71, 39, 3.74
12, 2.25, 36, 3.46
"Year", 4.21, 751, 72.10

Lets say that for three months of the year, you don't have enough solar power and a backup genset (for stretches of cloudy weather) makes sense. February would be our "break even month" for solar (note, weather year over year can vary by 10-20% or more--These are just long term averages:

55 kWH per month * 1/30 days per month per 1kW of panels = 1.83 kWH per day = 1,833 WH per day per 1,000 watts of panels in February

Also, note that which inverter you choose and how you operate it (24x7 or only a few hours a day) can have significant costs on your overall power usage... It is not unusual for an 1,800 watt inverter to require 24 watts with zero load:

24 watts * 24 hours per day = 576 WH per day if operated 24x7

Or almost 1/2 the power used by one of your freezers/refrigerators.

Say you want 2.5 kWH per day from solar (about 3.3 kWH per day is a good sized off-grid home that uses a minimal amount of power and uses alternate fuels for heating/cooking/hot water/etc.).

For February:

2.5 kWH per day * 1/1.83 kWH per day per 1,000 watts of panels =1,366 watts of solar panels for a "break even" February

Now--You have choices--power the loads you have (with more panels/batteries/etc.) or look at conservation. ~1kW per day can power a single small fridge/freezer or a full sized energy star rated refrigerator/freezer (there are few small fridge/freezers that are energy efficient).

Here is an example of a (smaller) emergency power system that covers pretty much all of the basic questions about a small solar PV power system (including where to place fusing and how to size the wiring):

Emergency Power

-Bill

dwh · December 2010

Re: First time poster with a plan and questions

Here's a good post that just came up. It's got a link to some real world harvest numbers for a pair of KC-135s (the little flat ones, not the flying bomb ones) with MPPT. Looks like the numbers are from Arizona from about a month ago.

Starts out with the bank about 50ah down, and it takes almost 70ah to get the bank back up to full charge. The modules start seeing some light around 0700, but don't really put out much until about 0900 and don't reach peak output until around 1100. Battery bank doesn't reach full until 1600.

http://forum.solar-electric.com/showpost.php?p=71796&postcount=185

System2 · December 2010

Re: First time poster with a plan and questions

Thanks guys for the responses.

I think the one concept that I need to adjust to is the one of having a minimum (and maximum) amount of wattage to out of your panels to charge your batteries. Ok there's many,

I'll just start with this one. Most articles just make it seem like adding extra batteries for more cloudy days is a good thing (and it is I guess if you can charge them). So just to clarify, I want to stay between 5 and 13% right?

I can see two things here right off from cariboocoot's comments: 1. I have too much load. I'll drain my batteries way below 50%--Ok to nothing. And 2. I'll can see I'll never get enough charge in the batteries in a day. The general consensus is that loads increase over time. I can't see me being much different, other than I don't need the power--at this point. And I'm not afraid to cut breakers and run only one thing at a time as needed. My OCD makes me that way.

So, with the 2 panels and 220 Amp hours of batteries, .5 kW hours should be my limit. Right? I think a 1000 watt Prosine PSW inverter will be the better way to go. I plan on doubling (for now) the panels too. Another question on doing that later. Yep I am trying to get my feet wet--I'm reading the quotes as hesitancy about saying that. I'm OK with it! And I appreciate the help. If you'd see the way some very professional people with serious jobs get their feet wet--you'd cringe.

Bill, the link you provided mirrors what most people want to do with a small scale setup in the other forums I read. And I see that you shouldn't drain a small battery like that using even a small (300 watt) inverter. Taking a charge out of a battery in less than 20 minutes seems bad. I did get some good diagrams from it. Also, if I read the info you provided right, I'd have--let's say--27% of what you mapped out for me. So, in Feb using your example, I would only get 494 watts of power. Right? Even worse than Cariboocoot's figures--reality sucks sometimes, but hey, that's why I'm asking. I do plan on making the panels adjustable for tilt to take advantage of the optimum winter angle--61 deg--or is my OCD getting the best of me?

DWH, thanks for the link. It's really making me reconsider my charge controller.

And to the group; My first question. If I series-parallel Edited I think that's wrong series-series my panels (staying with the 12volt 135 kyocera) how many can I put on a morning star 15amp mppt controller? The website states: "This controller can be used for 12 or 24 volt battery systems, with panel voltages up to 75 volts (3 12-volt panels in series)" Umm, big embarrassment time for me. Isn't 3 24 volt panels 72 volts? Not 3 12 volt panels. So if I wire 2 panels together for 24 volts I could do this three times and hook the three pairs in series and still only have about 72 volts at 7 amps going to the controller--yes? So that would get me the 800+ watts cariboocoot suggested. Not that any one part is more important or critical than another, it seems choosing the right controller will allow me: to go from 4 panels to 6 on the same controller, and keep my wire size down by keeping my amps down.

So the revised system, if I paid attention would be as follows:

135 watt panels X 4 (should be 6 if the charge controller lets me)

Morning Star 15 amp MPPT charge controller

Batteries--the same 440 amp hours.

Prosine 1000 watt PSW inverter (or maybe the Exceltech 1100 watt PSW) any reason for one over the other?

My loads should stay less than 1 kW per day.

Did I learn anything?

BB. · December 2010

Re: First time poster with a plan and questions

Army03CRNA wrote: »

...I'll just start with this one. Most articles just make it seem like adding extra batteries for more cloudy days is a good thing (and it is I guess if you can charge them). So just to clarify, I want to stay between 5 and 13% right?

Yes--Just adding more batteries for cloudy days without considering the amount of charging capabilities (solar, genset, etc.) can be a detriment--Lots of expensive batteries that are "deficit charged" -- basically die from sulphation because of under charging/running dead (and reverse charging "weak cells" which pretty much kills them).

The 5% is a minimum for Flooded Cell Batteries--You could go less with AGM--but realistically, you really want to charge them back in a day or so--not a week after a day's worth of power consumption.

The 13%--You can go above this--but it is expensive (lots of solar panels, oversized genset that runs at reduced load most of the time--wasting fuel if you are much under ~50% loading--and if diesel, they really do not like to run less than ~50-60% of rated load (carbon build up, glazing cylinder walls, oil consumption, etc.).

And--any numbers you deal with in solar--you are looking at a +/- 10-20% range... I.e., 15% rate of charge is not going to kill your battery bank... And 4% will sort of still work... But, in the end, you really need good reasons to go outside of the general rules of thumb.

I can see two things here right off from cariboocoot's comments: 1. I have too much load. I'll drain my batteries way below 50%--Ok to nothing. And 2. I'll can see I'll never get enough charge in the batteries in a day. The general consensus is that loads increase over time. I can't see me being much different, other than I don't need the power--at this point. And I'm not afraid to cut breakers and run only one thing at a time as needed. My OCD makes me that way.

Understand---However, operating loads serially will reduce peak loads--but can you really run your freezer on 5 hours per day vs 10 hours per day long term--and the answer is probably not. You have a choice to fire up the genset, get more solar panels, or empty the freezer(s) and have one heck of a BBQ "the day after".

So, with the 2 panels and 220 Amp hours of batteries, 0.5 kW hours [BB edit: 500 watt*hours -- .5 kWH was easy to miss your decimal point] should be my limit. Right?

Solar is very weather/seasonally dependent... It is not unusal for people to have 1/2 or less average sunlight in winter vs summer... And you can be at 1-10% of summer average power for a week of bad weather. Gensets and/or flexibility of power usage becomes more important for small systems that closely match loads (i.e., if you get an average of 485 WH per day in April from the above tables--Do not plan on pulling 485 WH every day--Some days may be less, a few days may be more---Planning on pulling ~250-350 WH per day (if you don't want to use the genset) "on autopilot" and running the washing machine in sunny weather is probably a better plan.

Also, think about others (if you have spouse/kids)--Your OCD may have you there with spreadsheets and logs planning your next day's power usage---And your spouse may have the divorce lawyer on speed-dial--While the kids left all the lights on and the TV/Radio/XBoxes all turned on with nobody around--blowing all those nice calculations.

Let the solar PV system make your life better--Don't try to get every last usable watt*hour from the system every day with over management. You will drive everyone nuts.

I think a 1000 watt Prosine PSW inverter will be the better way to go. I plan on doubling (for now) the panels too. Another question on doing that later. Yep I am trying to get my feet wet--I'm reading the quotes as hesitancy about saying that. I'm OK with it! And I appreciate the help. If you'd see the way some very professional people with serious jobs get their feet wet--you'd cringe.

Picking the "right inverter" is kind of a toss of the dice... A very rough estimate is 1,200 to 1,500 watt inverter to run a modern frost free 17+ cuft refrigerator/freezer (~400 or so kWH per year). The motor takes something like 120 watts (plus starting loads). The defrost heaters take another 500 watts or so. The ice maker (making ice) actually takes a surprising amount of extra kWH per day. So that 1,500 watt inverter will power the fridge plus a few extra CFL's.

Talking with people who have working off-grid systems and getting their experiences (plus calling Northern Arizona Wind & Sun -- if you are thinking of purchasing from them--for their recommendations) is the only other choice besides the typical SWAG (Scientific Wild A$$ Guess).

Bill, the link you provided mirrors what most people want to do with a small scale setup in the other forums I read. And I see that you shouldn't drain a small battery like that using even a small (300 watt) inverter. Taking a charge out of a battery in less than 20 minutes seems bad. I did get some good diagrams from it.

The right tool for the right job... Yes, you can drain a battery in 20 minutes--At least a few times and if they are AGM (which have very low internal resistance). That is what that UPS you plug your PC into does exactly.

The batteries only last ~2 years before you have to replace them--but they did their job--just enough power to save your files.

Certainly for a day to day Off-Grid model--that is not going to work for anyone.

Also, if I read the info you provided right, I'd have--let's say--27% of what you mapped out for me. So, in Feb using your example, I would only get 494 watts of power. Right? Even worse than Cariboocoot's figures--reality sucks sometimes, but hey, that's why I'm asking.

Yep-- And add +/- 10-20% year over year (those are 20 year average numbers--If you live in the desert, your spread is much less. If you live on the cost with variable marine layers/storm tracks, 20% spread is not unusual at all).

I do plan on making the panels adjustable for tilt to take advantage of the optimum winter angle--61 deg--or is my OCD getting the best of me?

Play with the PVWatts Website. It can make some difference in deep winter and high summer--but not as much as you would think.

A two axis tracker can help a lot (especially in summer at high northern/southern latitudes). And you have a whole bunch of new toys to play with and obsess over.

Here are a couple of threads discussing trackers:

Eletrician Going Off Grid - Sizing / Questions
RedRok Solar Tracker

It is always a tradeoff of more panels vs spending more money on trackers... Dave_Sparks very much likes trackers for his off-grid customers.

In your case, you are starting small... Get some experience before you dump the big bucks into the "next one".

And to the group; My first question. If I series-parallel my panels (staying with the 12volt 135 kyocera) how many can I put on a morning star 15amp mppt controller? The website states: "This controller can be used for 12 or 24 volt battery systems, with panel voltages up to 75 volts (3 12-volt panels in series)" Umm, big embarrassment time for me. Isn't 3 24 volt panels 72 volts? Not 3 12 volt panels. So if I wire 2 panels together for 24 volts I could do this three times and still only have about 72 volts at 7 amps going to the controller. So that would get me the 800+ watts cariboocoot suggested. Not that any one part is more important or critical than another, it seems choosing the right controller will allow me: to go from 4 panels to 6 on the same controller, and keep my wire size down by keeping my amps down.

For MPPT type charge controllers--It is their output current that is (usually) their limiting power factor... For example, the 15 amp output is either at 12 or 24 volts (really 14.5 or 29.0 volts when charging). Throw in a 0.77 derating (solar panels don't usually output their rated power)--and a typical (cost effective) maximum array would be around (remember, I am carrying out 3 digits just so you can confirm my math-- +/- 1 watt is not gong to change anything):

15 amps * 14.5 volts * 1/0.77 derating = 282 Watts Maximum Optimum Array at 12 volts
15 amps * 29.0 volts * 1/0.77 derating = 565 Watts Maximum Optimum Array at 24 volts

There are other limits (maximum array voltage, maximum array current without adding fuses/breaker, etc.)... But it is good start in understanding.

Regarding the solar panel voltage... Vmp and Voc (Vmax-power, Vopen-circuit) rise during cold weather and fall during hot weather....

It works out for most people that a 75 volt maximum controller should not use more than ~50 volt Vmp (at STC rating). That works out to a Voc (cold, open circuit) voltage of near 75 VDC in sub-freezing weather.

So the revised system, if I paid attention would be as follows:
135 watt panels X 4 (should be 6 if the charge controller lets me)

Morning Star 15 amp MPPT charge controller

Batteries--the same 440 amp hours.

Prosine 1000 watt PSW inverter (or maybe the Exceltech 1100 watt PSW) any reason for one over the other?

My loads should stay less than 1 kW per day.

Did I learn anything?

Getting better... You can also look at the Rogue 30 amp MPPT controller for next size up. It cannot take Voc of 75 volts--but is a larger charge controller with good operational results (i.e., happy customers). And it will charge both 12 or 24 volt battery banks.

Need to better understand your loads. A 1,000 watt inverter will still only run 1 hour per day (at 1,000 watt load). And it may not be large enough to power a full sized energy star refrigerator. Perhaps it will run a chest freezer (or chest refrigerator conversion) just fine.

-Bill

niel · December 2010

Re: First time poster with a plan and questions

4 of the pvs will give you, 7.63a x 4 = 30.52a. this is about a 6.9% charge rate. 6 is better and would be 7.63a x 6 = 45.78a for a 10.4% charge rate. you could get away with 5 if all are paralleled. even if you would put some of the pvs into series strings it will still output a high current in the voltage downconversion. for example two kc135s in series with a current of 7.63a will roughly equate to 16 or 17a at 12v. 2 of those will negate the mppt benefits due to being limited in current by the controller's 15a max.
now there would be no way i'd ever recommend the 15a mppt controller when such a large battery bank is involved. the controller may need to be something like this,
http://www.solar-electric.com/motr60ampmps.html
and get the battery temperature sensor.

zeuspaul · December 2010

Re: First time poster with a plan and questions

Most articles just make it seem like adding extra batteries for more cloudy days is a good thing

As I worked through my design I opted for more PV for cloudy days.

I monitor my neighbor's 8.4KW gridtie system. On good days in the summer he harvests between 50 and 60 KWH. In the winter a good day is about 30 KWH.

However I am more concerned about the bad days. A cloudy day in the winter is about 6 KWH.

Using the ratio of 6/8.4 for my 10 x 135 Kyoceras I figure on about 1 KWH per cloudy day. My freezer uses between .7 and 1 KWH per day. Figuring losses the 1350W PV system will almost keep up with the freezer on cloudy days. The 220 AmpHr 24 volt battery can supply the small shortfall for an extended period of time eliminating the need for a generator backup.

Ninety five + percent of the time the PV system will produce more than is needed to run the freezer. The surplus will be used for a pond pump, rock tumbler, security lighting, power tools...

Crown recommends between 10 and 20 percent charge rate. I am maxed out at 20 percent with the Morningstar 45 MPPT. However I doubt the batteries will ever see 20 percent because the pond pump and rock tumbler will be timed to go on during peek PV harvest.

My goal is to minimize the battery bank and eliminate the need for the generator. I can see myself adding more PV to the same controller and keeping the same battery.

Just another viewpoint. Designs can vary a lot depending on individual needs.

Zeuspaul

Ralph Day · December 2010

Re: First time poster with a plan and questions

However I am more concerned about the bad days. A cloudy day in the winter is about 6 KWH.

What I wouldn't give for a 6kwhr cloudy day. Last week my 10kw put in only 741 kwhrs on one day! Mind you it rained, snowed, and then got dark.

Ralph

solar_dave · December 2010

Re: First time poster with a plan and questions

Ralph Day wrote: »

However I am more concerned about the bad days. A cloudy day in the winter is about 6 KWH.

What I wouldn't give for a 6kwhr cloudy day. Last week my 10kw put in only 741 kwhrs on one day! Mind you it rained, snowed, and then got dark.

Ralph

Me wants that array, pretty darn efficent!

On a bad weather day I get about 30-40 kWh out of my 12.5 kW system and the best I ever saw was about 78 kWh. I guess it is all relative, my bad days are still pretty nice

System2 · December 2010

Re: First time poster with a plan and questions

Lots to read through here; I want to read it thoroughly before I ask any more questions. I was on call yesterday, and I had no time to do anything else. I've a bunch on my to do list today as well, but I wanted post a quick Thanks! to everyone to took the time to reply.

drees · December 2010

Re: First time poster with a plan and questions

Ralph Day wrote: »

Last week my 10kw put in only 741 kwhrs on one day! Mind you it rained, snowed, and then got dark.

I suspect you meant 741 Wh, not kWh...

Today looks much better for you as it appears that your system has been pushing out over 10 kW since 10am.

mike95490 · December 2010

Re: First time poster with a plan and questions

What brand of panels are putting out that power on cloudy days?

I've got Evergreens - 3KW array produces about 300W in clouds, 4 hours in winter would give me - 1.2KWh for the day.

Ralph Day · December 2010

Re: First time poster with a plan and questions

Yes, 741 WATThours. Even monkey fall from tree.

Total today 66kilowatthours. Much better. 4 hours at 10300+ watts.

Ralph

System2 · December 2010

Re: First time poster with a plan and questions

I read over everyone suggestions and the whole Rogue thread as well. I'd like to get one these (rogue), but the lack of certification may nix that idea--it's up to the authority with the ultimate veto, no not the govt, the damn insurance co (already switched once cause they gave me headaches). So, I think the morningstar (45amp mppt) is the choice for now. It seems big, but should run 6 panels easily.

I do plan to keep going through areas of the house and garage and adding up different loads to see what will be the best combination of loads. BB you're right about the kids:grr, they understand nothing about conservation, but this won't be wired into the whole house--only loads I deem worthy. And since I'm experimenting with this for now--no divorce lawyer; or least not for this reason:D

I have no problem going with a 1800 watt prosine, but if conditions dictate, or by choice, I run lighter loads, will I get into trouble running one of the freezers by itself on an inverter that big? Is running only a 100 watts going to ruin my inverter (using an 1800 watt in this case)?

Like I said earlier, I need to investigate my loads more thoroughly, so I may readjust what I actually run, but I now have an idea of what my max should be. At least I don't see me having anything really big to start--like an air compressor or AC or something.

Dinner just arrived

thanks guys.

BB. · December 2010

Re: First time poster with a plan and questions

1,200-1,500 watts is normally suggested minimum for running a standard full sized Energy Star Refrigerator... Too large of inverter can swamp the cell phone and laptop loads while charging (larger inverters can be well north of 30 watts with no loading).

If you have other loads, a second 300-600 watt TSW inverter may be really nice to have for charging cell phones, running laptops, etc.

Check the specifications and find out the idling loads for the inverters. Some inverter have a very nice "low power" mode--they turn off most of the time and pop on for a bit looking for 8 watt or larger loads--then turn on full time (sleep mode).

For the non-heavy surge loads--The Morning Star 300 Watt TSW inverter on a 12 volt battery bank is really nice little beast.

Problem is, if you have loads much over 1,200 to 2,000 watts--you really should be looking at a 24 or 48 volt battery bank (keep the inverter currents/battery cables to a reasonable size).

-Bill

First time poster with a plan and questions

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