Which Inverter? Which Charger To Buy?

pabloesguapo

Hope this is in the right forum. If not, I guess a moderator will redirect me.

Inching slowly ever closer to purchasing the equipment necessary for my off-grid homestead project. It's a huge double house; A 4 bedroom for me, my wife and three kids on one side, and a "mother in law suite" that is really an entirely self-contained house on it's own for my M.I.L. on the other side. Both houses will be connected by a big sunroom in between. In total, about 5,000 square feet. I'm thinking I'll need about a 5KW system on generator backup. That may be enough, maybe not, maybe it's too much. But it's a good place to start, I think. If it's not enough, we can run a generator once in a while for a while until we can afford to add more panels and/or batteries. If it's too much? Well, I'd rather have it and not need it than need it and not have it. If it turns out to be too much, I am also building a third house next year. I can take a few panels and batteries from the first house and incoporate them into the new off-grid house I'm going to build later. I am not here to discuss the size of the system, merely the components of it.

I was planning on purchasing a ready made 5.25Kw package from a company in Phoenix. I'm beginning to not like their customer service. I also have noticed that our host, NAWS has really good prices on comparable and better equipment. I have recently purchased a grundfos deep well pump from them, and am quickly getting comfy with their "bedside manner".

So, what are your thoughts on the following?

For charge controllers, I'm torn between these two:

http://www.solar-electric.com/mnclassic.html

http://www.solar-electric.com/xaxwmp60amps.html

I like the price of the Xantrex, but for only a few dollars more I get so many other sexy features with the Midnite.

For an inverter/charger, I kinda like this one, but am not "sold" on it:
http://www.solar-electric.com/xaxwmp60amps.html

If anyone has any other suggestions, I'd really like to hear them.

Thanks,
Paul

solar_dave

Re: Which Inverter? Which Charger To Buy?

Have you done a load estimate on that 5000 sq ft monster? That is really the place to start.

BB.

Re: Which Inverter? Which Charger To Buy?

Hi Paul,

I think the last link is in error--Just points to the XW solar charge controller again.

Have you made a spread sheet/estimate of power power needs?

Usage is highly personal--While one family might do well with 100 kWH per month, yours might be looking at a 300-500 kWH per month for your double home (and a lot more if you include AC/Heat Pump heating in the mix).

While peak power is important--The average load drives much of the system costs (solar panels, battery bank size, generator fuel usage in poor weather, etc.).

I have mixed opinions about Inverter/Chargers vs getting separate units. I like the Inverter/Chargers because there is a good selection of Power Factor Corrected/Programmable AC battery chargers as part of the inverter (there seem to be few "full featured" PFC/Programmable AC stand-alone battery chargers). On the other hand, if either the charger or inverter fails--You typically have lost both functions.

-Bill

westbranch

Re: Which Inverter? Which Charger To Buy?

I concur with Dave, I was put back on my heels when I added it all up...what i thought would be a 'too big' battery became a 'very close fit'. I recommend the load analysis even if it is just a WAG it will get the juices going.

solar_dave

Re: Which Inverter? Which Charger To Buy?

You can even ask here for estimates of certain appliances, like Energy Star fridge & freezer, AC units, TVs, computers ....

pabloesguapo

Re: Which Inverter? Which Charger To Buy?

Yes, gentlemen, I have worked through many different calculators. It's impossible to get an accurate assessment when we are building something completely new. We do not yet know what HVAC units we will buy (but it'll be a swamp cooler, not an AC unit, I can guarantee you that) , we don't yet know what major appliances we will be bringing with us vs. leaving behind. All I know for sure is that I will be living with two women and two teenage girls who like to leave the lights, TVs, radios, fans and computers on, who always think it's too hot in the summer and too cold in the winter, all the while leaving the doors and windows wide open, as well as take long, hot baths and showers. And my son? Well, he likes to get his clothes dirty and stare into the open refridgerator for "inspiration". Like I said, I do not wish to discuss my decision to go with the size system I have. Part of my calculation on that was based on what we can afford to build (vs. the cost of having APS run us a line all the way out there and then give us the "privilege" of paying them more money every month). Let's just stay with a 5k system and talk about equipment, OK?

Link to the inverter/charger. A Xantrex 4548:
http://www.solar-electric.com/xaxw12hyin.html

or perhaps this one:
http://www.solar-electric.com/vfx3524.html

BB.

Re: Which Inverter? Which Charger To Buy?

How many Watt*Hour or kWH per day (seasonal variations?)? That drives the battery bank sizing--which then drives the panel/AC backup charging/etc. part of the design.

-Bill

Vic

Re: Which Inverter? Which Charger To Buy?

Hi pabloesguapo,

Well, your loads really DO dictate ALL else. With teens in the household it can become very difficult to manage the consumption side. And this is a huge living space for off-grid.

The second inverter link, above, may well be a typo -- it is a 24 volter, which is not appropriate for a system of your size.

Probably you will need to soon consider that you could have a lot of generator run-time, but again, you will need to take a cut at your LOADS.

Evap coolers would probably work well for you, altho do not know the nature of your weather -- Monsoon season and so on.

There is no comparison between the XW SCC and the Midnite Charge Controller. The XW is stunted and very expensive for the small number of things that it can do (IMHO). However, if you have an XW inverter, some of the extra-cost items could be shared with the XW SCC, but, still, the XW SCC is a poor performer IMHO. The Midnite Classic CCs are new, and on the leading edge of function, flexibility and connectivity. Many innoative functions are built-in, which are extra cost or not available on the XW (or most other CCs). It is a great value, and the Midnite crew is continually extending the performance of this CC.


The XW Inverters are very capable, but programming seems to be an ongoing issue, and the Xantrex/Schneider customer "support" is viewed by many to be poor at the best (this has been my experience).

looking at your existing power bill, plus that for the in-law that will also be sharing the new residence will help you come up with yur baseline useage. Realize that the configuration of the new residences could be much different. And, as BB noted, Heating and Cooling loads could be a significant load, as well as possible water pumping, if a well is required.

When first going off-grid, I had a similar quandry, as the nature of the new location was going to be quite a bit different than the old one. Had to guess, and built a system on the largish size. This can be expensive, but it was the best choice in my case. I can understand that this could be a difficult issue to address. Vic

stephendv

Re: Which Inverter? Which Charger To Buy?

The Xantrex 6048 is only slightly more expensive than the 4548, so would give you a nice bit of future proofing. As far as charge controller go, I think the midnite unit is the one to get. So many features, and most importantly easy access to the people who built it on the midnite forums.

westbranch

Re: Which Inverter? Which Charger To Buy?

Pablo, have a look at my analysis, it is for a house hold of 2 adults and very few large appliances. Biggest is the fridge, and we are at 6000Wh. The graphs show distribution over the day... Just for reference as to your predicament, hope it helps.

http://forum.solar-electric.com/showthread.php?14904-Evaluation-of-Usage-vs-PV-vs-Battery-needed

solar_dave

Re: Which Inverter? Which Charger To Buy?

Sorry I think you are underestimating your loads, 5000 sq ft is going to require at least 2 coolers, you have 2 women and 2 teenagers, you will have hair dryers, kitchen appliances, a well pump, TVs and on and on. If your family expects grid type electric service then you have a problem.

pabloesguapo

Re: Which Inverter? Which Charger To Buy?

Thanks for the input, guys. It looks like our power usage in the spring/fall, when we are not running the air conditioner CONSTANTLY here in southern NV, is about 18kw a day. That's in a wood frame, chicken wire and stucco house with old windows, with 30-ish year old heater, old style incandescent bulbs, older style washer and dryer, a swimming pool filter running a few hours a day, all sorts of electrical appliances on all day...

We're moving to a climate that is consistently 10-15, oftentimes 20 degrees cooler. We're building a log home from a kit, with modern windows, a wood burning furnace, getting mostly all new energy star appliances, installing high efficiency light bulbs, ditching all but one desktop PC, switching the rest over to laptops, no swimming pool, ditching the TV (for the time being. We'll see when football season starts up again.) We'll be living in camping trailers for a few months down there during construction. Everyone will be getting a crash course in energy conservation. 8)

I'm happy to hear that Midnite has good customer service. This being my first PV install, I have a lot of questions. (In case you couldn't already tell) It's nice to know I can actually get ahold of someone, hopefully on the phone.

Vic

Re: Which Inverter? Which Charger To Buy?

Hi Pablo,

Thanks for the added info.

Yes, Midnite has teriffic customer support via phone, internet and at their Forum:
http://midnitesolar.com/smf_forum/index.php

Xantrex had a Forum, but for reasons on their own, they took it down three, or so years ago, and unfortunately, the historic posts are gone.

Good luck with the system design. Will note that if there was any way to get Grid power extended to this new location, it could be a good thing. Off grid systems are very expensive to built and take time to maintain. The grid is the best and least expensive (by far) battery that you will ever find. You have been a member here for a while, so you know this.

I love to hate my in-town power utility, PG&E, But, at the least expensive power tier, where all of my useage is, the rate is less than $0.15/kwh. This is dirt cheap (do not tell them this). Have Fun, Vic

westbranch

Re: Which Inverter? Which Charger To Buy?

If at all possible, move the cooking out of the campers, you will have a happy wife for doing that,ask me , that is what we did last ear from July to Nov 19... and have started again last weekend... SWMBO loves it, even cooking outdoors at 10 below, though the experience is starting to wear thin. It will be over as soon as we get the chimney and a few windows in.

Enjoy the build and don't rush anything.

Attachment not found.

ps that is the framers truck that did not want to start!!

Vic

Re: Which Inverter? Which Charger To Buy?

WOW Eric,

That is a beautiful building! Have Fun, Vic

vtmaps

Re: Which Inverter? Which Charger To Buy?

pabloesguapo wrote: »

It looks like our power usage in the spring/fall is about 18kw a day.

Paul, In the long term it will help you to think more clearly and communicate with us if you are less loose with the terms "power" and "energy". Power is measured in watts or kilowatts. Energy is measured in wattHours or kilowattHours.

"Power usage of 18 kw a day" doesn't make any sense. If that is your average power usage it means you are using 18x24 or 432 kwh of energy per day. I think (hope) that your average power usage is 750 watts which is 0.75x24 or 18 kwh of energy per day.
--vtMaps

Blackcherry04

Re: Which Inverter? Which Charger To Buy?

Please post back with your progress on the build, it will be interesting to follow. I am glad it's your MIL and not mine. Every time my wife tell's her mother about something I am doing, it is a " I'll believe it when I see it " from her .........lol. She's 90 now and after 40 years she ought to get a clue.