Newbie needs advice on off grid system

carcus27 · September 2014

Hi any advice appreciated,

Been wanting to go off grid for a while now, but just waiting for the prices to become affordable, and that time is now...;)

This electrical jargon is very confusing. Anyhow I've found a package that seems good for my needs.... I'm wanting to start with 1.5kw system and possibly adding to it if needed, but hopefully that won't be required as we are using 7.7kw/h per day average in winter. which we can get down when the time comes to cut ties with the grid.

The system I'm looking at is:

PANELS
Max Power: 250W
Rated Voltage: 30.4V
Open Circuit Voltage: 37.9V
Rated Current: 8.24A
Short Circuit Current: 8.65A
Max System Voltage: 1000V
Dimension: 1640 x 992 x 35 mm
Weight: 17.4 kg
CE Certificate
Type of Junction Box: TUV, IP65
Cable Type. Diameter: 4mm2
Connector: compatible to Type 4 (MC 4)
Tempered Glass: 3.2mm, high transmission, low iron

$249 incl gst

INVERTER/CHARGE CONTROLLER 48V 4000w 8000w max
· Adjustable AC input voltage 90~280VAC
· 4KW pure sine wave output with up to 2X surge max 5 seconds 8000w
· Built-in 3-stage high efficiency battery charger 30A
· Built-in SOLAR charger max PWM 50A – MPPT charger optional upgrade
· Total system charging current = AC + SOLAR = MAX 50A
· Dual priority operation selectable: AC vs. DC mode
· Free monitoring software
· Works with 48V battery system only (Not 24v)
· Transformer less, light weight design
· RJ45 comm port
· Transfer time <10ms
· Programmable LCD with menu
· 24 hour operation (Built for lots of use)
· Intelligent battery charging control for all battery types
· Built-in alarms and protections
· Suitable for wall mount
· Optional remote display and power switchremote 289x300 Inverters
· CE, EMC certified

$1269 incl gst

BATTERIES

Undecided exactly, but thinking AGM 4x12V

I read somewhere that for a 48V system to work efficiently you need a minimum system size of 2kw, not sure if this is true?

Thanks in advance
Marcus

zoneblue · September 2014

Re: Newbie needs advice on off grid system

Welcome to the forum.

carcus27 wrote: »

Hi any advice appreciated,Been wanting to go off grid for a while now, but just waiting for the prices to become affordable, and that time is now...;)

If you are moving somewhere with no grid, then read on. If you just want to unhook, you should think long and hard about the numbers. You are unlikely to save any money ... yet.

This electrical jargon is very confusing. Anyhow I've found a package that seems good for my needs....

Well my advice is this. If you are wanting to design and install this system yourself, do not buy anything, until most of that jargon makes sense. And "packages" are unlikely to meet you needs, and will be more expensive.

I'm wanting to start with 1.5kw system and possibly adding to it if needed, but hopefully that won't be required as we are using 7.7kw/h per day average in winter. which we can get down when the time comes to cut ties with the grid.

Out of curiosity how did you arrive at this number? You ideally want a design target demand. For a small house for two people 3kWh/day is quite doable without much hardship. Start from there and add or subtract key loads as required. Or do a proper load analysis.

The system I'm looking at is:

PANELS
Max Power: 250W
Rated Voltage: 30.4V
Open Circuit Voltage: 37.9V
Rated Current: 8.24A
Short Circuit Current: 8.65A
Max System Voltage: 1000V
Dimension: 1640 x 992 x 35 mm
Weight: 17.4 kg
CE Certificate
Type of Junction Box: TUV, IP65
Cable Type. Diameter: 4mm2
Connector: compatible to Type 4 (MC 4)
Tempered Glass: 3.2mm, high transmission, low iron

$249 incl gst

Looks like a 30 cell panel. But try to get something tier one with UL listing. Brand name is your only real guarantee. "gst" puts you in the south pacific i guess. Tier one chinese panels that are readily available here are suntech, csun etc.

INVERTER/CHARGE CONTROLLER 48V 4000w 8000w max
· Adjustable AC input voltage 90~280VAC
· 4KW pure sine wave output with up to 2X surge max 5 seconds 8000w
· Built-in 3-stage high efficiency battery charger 30A
· Built-in SOLAR charger max PWM 50A – MPPT charger optional upgrade
· Total system charging current = AC + SOLAR = MAX 50A
· Dual priority operation selectable: AC vs. DC mode
· Free monitoring software
· Works with 48V battery system only (Not 24v)
· Transformer less, light weight design
· RJ45 comm port
· Transfer time <10ms
· Programmable LCD with menu
· 24 hour operation (Built for lots of use)
· Intelligent battery charging control for all battery types
· Built-in alarms and protections
· Suitable for wall mount
· Optional remote display and power switchremote 289x300 Inverters
· CE, EMC certified

$1269 incl gst

An inverter without a brand name is worth nothing in this industry. Your inverter is the cornerstone of your system, and is the single most likely failure point. Many of us learned that the hard way. For permanent wiring in homes, you want one of the big four brands. CE is basically worthless. You need UL.

BATTERIES

Undecided exactly, but thinking AGM 4x12V

Yeah well thats a big topic. Theres no one right answer and all i can suggest is lots of reading. You should consider budget, your aptitude for maintenace, and how conservative you are. Tried and true is FLA, GC2/L16. Modern in AGM, try to geta decent brand, and learn to charge them properly. Post modern: LiFePo4, should definately get a look in, were about breakeven point on cost there.

I read somewhere that for a 48V system to work efficiently you need a minimum system size of 2kw, not sure if this is true?

Id rephrase that by saying that generally a system 3kWp and over should always be 48V. In the twighlight zone between 2 and 3kWp it would be optional so long as you were never going to grow. The downsides to 48V are few. Higher array voltages= slightly elevated shock risk. Thats about it. All the std gear, breakers and such is 48v compatible. For the odd 12v thing 48-12c converters. The upsides are many.

BB. · September 2014

Re: Newbie needs advice on off grid system

I believe the original poster is out of New Zealand.

As ZoneBlue says--You need to get a bit of the math speak down first. It is not difficult, but unless you have a good handle on your power needs--Your chances that you will have a cost effective system that meets your needs are slim.

Volts, Amps--the basics
Power = Volts * Amps = Watts == This is equivalent to Miles per Hour (a rate). 1.5kWatts is a rate

But you also need to know time (Hours) to figure out the amount. I.e., if you drive 55 MPH for 10 hours, you went 550 Miles. For electrical:

Energy = Power * Time = Volts * Amps * Hours = Watts * Hour = Watt*Hour = WH

So, if you had a 1.5 kWatt load for 5 hours per night:

1,500 Watt * 5 hours = 7,500 Watt*Hours per night

That is a lot of energy, but doable for a larger off grid power system. This would not be a small/starter system.

Lastly--Don't get confused with Amps and Amp*Hours when sizing your system. Many times people think they are using 2 amps for 2 hours = 4 amp*hours of use... And that is true, but missing the working voltage. For example, if you have a 2 amp load @ 230 VAC:

2 amp * 230 VAC = 460 Watts
460 Watts / 12 VDC battery bank = 38.3 amps

A 20x increase in current at the lower working voltage for the same power... So a load:

2 Amps * 10 hours = 20 AH (at 230 VAC)
38.3 Amps * 10 Hours = 380 AH (at 12 VDC)

You can get a Kill-a-Watt type meter for measuring your AC loads (UK Amazon site)--This will really help you understand and measure your power needs. There are similar devices for measuring DC loads too (Amp*Hour/Watt*Hour meters).

-Bill

carcus27 · September 2014

Re: Newbie needs advice on off grid system

Thanks guys for the reply's

I might have the money, but this shows I still have no where near the knowledge to do this myself.

I am in NZ. The reason I want to cut ties to the grid are not financial. The reason is self sufficiency. In the 3yrs I've been back in NZ the price of energy has exactly doubled. Every installer over here is pushing grid tied systems which are getting real cheap (about $6K), but when you ask about off grid the same companies want to run a mile and give outrages quotes like $30,000 for a 1.2kw system, which even I know with my limited knowledge is incorrect.

In my opinion and call me a pessimist, grid tied systems are good at the moment, but I've seen in aussie them cut the tariff's from .66cents a kw down to .22cents and eventually you'll be paying 'them' once they work out a way to tax you for using the sun. You know it's coming!

Perhaps what I need if someone has the time to help (would be so appreciated), would be for someone to tell me exactly what I need to buy, brands etc. I've got about $10K NZD and I'd like to start off with a system that I can just run the lights (led) and water pump (650w, would maybe run for an hour a day max, i should time it sometime) off for now and be able to add a fridge (i'm willing to purchase a small DC fridge)

Looking forward to any help...
Thx

BB. · September 2014

Re: Newbie needs advice on off grid system

Don't buy anything yet!

Lots to talk about. On my phone at the moment and cannot type long posts.

Without losing my mind.

-Bill

carcus27 · September 2014

Re: Newbie needs advice on off grid system

OK, I'll put the wallet away.... ha ha

This is apparantly the best supplier in NZ, his online store. http://www.trademe.co.nz/Members/Listings.aspx?member=3073130

Photowhit · September 2014

Re: Newbie needs advice on off grid system

Like most everyone else here, I'll let you know it's hard to beat the grid for cheap reliable electric! If you have to pipe it in and have a great costs involved, you might be able to, if you live where there is very high electric costs, you might be able to, but even these places typically also have higher costs involved in solar. Hawaii, for instance may have 45 to 70 cents a Kwh electric, but they also have to import every thing solar including batteries! so the costs go up...

If you're bound and determined, and you understand the costs will be greater, first consider reducing your demand. Most people living off grid, are very energy frugal. Most of us could tell you exactly what is running at any given time! So first reduce your loads! your first 'solar' project might be to make a low energy use fridge out of a chest freezer. Here is a blog of someone who details the adventure pretty well.

carcus27 · September 2014

Re: Newbie needs advice on off grid system

Thanks, I'm determined for off-grid... also we live in the country and get a lot of power cuts, which being grid tied isn't going to help with so as my understanding.

Photowhit wrote: »

Most of us could tell you exactly what is running at any given time!

My wife prowls the house turning everything off at the wall constantly, to the point she's become obsessive about it!!

westbranch · September 2014

Re: Newbie needs advice on off grid system

for minor appliances, tv, cd player, internet, etc you need a power bar with a lighted switch to really know it is OFF....

add ... look here at our hosts site for some ideas as to what you might need, http://www.solar-electric.com/solar-panels-mounts-kits-accessories/prsy.html

zoneblue · September 2014

Re: Newbie needs advice on off grid system

carcus27 wrote: »

Thanks guys for the reply's
I might have the money, but this shows I still have no where near the knowledge to do this myself.

Off grid you have two choices. Either reach for the yellowpages and stump up the cash, or spend an inordinate amount of time learning and researching. I have an old engineering qual, and yet it still took me about 2 weeks full time to research our system. It was suprisingly complex.

I am in NZ. The reason I want to cut ties to the grid are not financial. The reason is self sufficiency. In the 3yrs I've been back in NZ the price of energy has exactly doubled.

Interesting when i last studied the grid prices on powerswitch (18 months ago), prices had risen on average 4.5% pa over the previous 5 years. Sounds like the pace is picking up!

Every installer over here is pushing grid tied systems which are getting real cheap (about $6K), but when you ask about off grid the same companies want to run a mile and give outrages quotes like $30,000 for a 1.2kw system, which even I know with my limited knowledge is incorrect.

Its a numbers game, there are relatively few off grid systems. And they are more complicated. Batterys will do that to you.

In my opinion and call me a pessimist, grid tied systems are good at the moment, but I've seen in aussie them cut the tariff's from .66cents a kw down to .22cents and eventually you'll be paying 'them' once they work out a way to tax you for using the sun. You know it's coming!

I understood from talking to some townie friends that the good old days of meridians net meter program are done. After you cross the new threshold the buy back rate drops off dramatically. Lots of people got a little burned by that having invest tens of K looking for a return. The original NEM program was specifically never guaranteed to last. And it didnt. Turns out.

Perhaps what I need if someone has the time to help (would be so appreciated), would be for someone to tell me exactly what I need to buy, brands etc.

This is almost the diametric opposite of what you want. Try to hear this. If you want to install and maintain it yourself its CRITICAL that you understand it. Electric systems are dangerous, doesnt matter, on grid, off grid, (with batterys, off grid is probably MORE dangerous). Hence you do need a bit a math head and be able to muster up some basic electrical nouse.

Have we scared you off yet? (initiation test

I've got about $10K NZD and I'd like to start off with a system that I can just run the lights (led) and water pump (650w, would maybe run for an hour a day max, i should time it sometime) off for now and be able to add a fridge (i'm willing to purchase a small DC fridge)
Thx

We spent almost exactly NZD10K for a 1.8kWp peak system (see sig) that will deliver 4kW/day reliably, with another 4kWh/day about 2/3 the year. So your budget isnt unrealistic.

This is apparantly the best supplier in NZ, his online store. http://www.trademe.co.nz/Members/Lis...member=3073130

AAsolar are a prominant supplier, but the thing to do is to first understand the brands. Once you get the likes of Midnite and Outback under your skin, then you can deal direct with the importer Independent power, or import direct from the US, right here from NAWs. They have the best price, service, and just use Youshop to bring them in. It will save you, yeah, quite a bit.

carcus27 · September 2014

Re: Newbie needs advice on off grid system

zoneblue wrote: »

Have we scared you off yet? (initiation test

Yep! Maybe I'll just live without electricity, that would be easier than this I think...

Photowhit · September 2014

Re: Newbie needs advice on off grid system

carcus27 wrote: »

Yep! Maybe I'll just live without electricity, that would be easier than this I think...

Sorry, there is lots to understand! It can be done. But rarely does a "buy this" advice ever work out... Do you know what you use in Kwh on a monthly basis?

In very general terms, It requires 3x the array size, and sometimes even more! for an off grid system, compared to a grid tied system to provide the same amount of usable electric! Storing and using the electric is about half as efficient and to store enough and produce enough to recharge in short days (Do you call June-August Winter?) requires a larger array.

CDN_VT · September 2014

Re: Newbie needs advice on off grid system

Carcus27 , do a small solar setup with grid till you get it all down.
Get on the Kill-a-watt , & start recording as you read ..
This is not as easy a plugging in a cord , but I find this as well as life is great with awards .

VT

Surfpath · September 2014

Re: Newbie needs advice on off grid system

carcus27 wrote: »

Yep! Maybe I'll just live without electricity, that would be easier than this I think...

Carcus,
I noticed that the proposed inverter/charger you list is a whopper (4kw/8kw surge). It seems to be your largest single expense, and one that might use a lot of power just sitting there.

No need my friend. When/If you do go solar consider one of the many inverter fridges now available in New Zealand (search google.com and you will see). From the experiences of a poster on this forum, this type of appliance can be run on a 300 watt Suresine inverter (with a 0.055 amp standby mode). A generator could take care of your larger but temporary loads.

Yes, an inverter fridge still will be a big daily draw but if you intend to save $$ on gear this may be a good approach to take. -SP

BB. · September 2014

Re: Newbie needs advice on off grid system

1 kWH per day (1,000 Watt*Hours or 30 kWH per month) will light your home, run a laptop computer, and a small water pump pretty easily.

3.3 kWH per day (100 kWH per month) will run a full off grid/very energy efficient home with above loads, plus a full size refrigerator, washing machine, well pump, etc.

10 kWH per day (300 kWH per month)--A very efficient home (natural gas/propane for heating/cooking/hot water) will give you quite a bit of power--But is not cheap. Solar hot water and microwave/possible hot plate usage (not too much).

Look at the kits so you can see what major components and "minor stuff" (wiring, racking, breakers, etc.) are needed too.

If you currently have grid power--It is a good chance to look at conservation first. You can reduce your power needs and just look at the meter/monthly bill to see where you are at (average power usage).

Do you know how much power you use per month now (you have to look at 12 month history--if you have significant winter/summer swings).

Near any of these cities?

Christchurch
Dunedin
Hamilton
Lower Hutt
Manukau City
North Shore
Tauranga
Waitakere
Wellington

Figure out how much sun you get over the year.

-Bill

carcus27 · September 2014

Re: Newbie needs advice on off grid system

Surfpath wrote: »

Carcus,
I noticed that the proposed inverter/charger you list is a whopper (4kw/8kw surge). It seems to be your largest single expense, and one that might use a lot of power just sitting there.

Thx, I've gone off that combo, it was just a starting point I guess

carcus27 · September 2014

Re: Newbie needs advice on off grid system

We are in winter and last month we used avg 7.7kw/h per day, so that means a whopper system required.

How about I just start small by powering my water pump 650w, which is required out here for when the power is out.

I'll buy a meter to measure the consumption of the pump and then I'll get back to you guys to see what I'll need for that project.

I'm nearest Hamilton, will check out how much sun I get....

Thanks for all the replies, even though it wasn't what I wanted to hear ha ha.... but at least I spoke to your before splashing out the cash:-)

carcus27 · September 2014

Re: Newbie needs advice on off grid system

CDN_VT wrote: »

Carcus27 , do a small solar setup with grid till you get it all down.
Get on the Kill-a-watt , & start recording as you read ..
This is not as easy a plugging in a cord , but I find this as well as life is great with awards .

VT

Wanting to be a bit covert about this operation, so grid tied is really out of the question, thx anyhow.

BB. · September 2014

Re: Newbie needs advice on off grid system

ore 8 kWH per day--That is a fair size system alright... Especially in winter. Certainly you are using less electricty than the vast majority of North Americans (~1,000 kWH per month).

Using the Solar Electricity Handbook for Hamilton, fixed array, facing "north" (note, software needs your array to "point south" even though you are in the other hemisphere--go figure):

Hamilton
Average Solar Insolation figures

Measured in kWh/m²/day onto a solar panel set at a 52° angle (from vertical):
(For best year-round performance)

Jan
Feb
Mar
Apr
May
Jun

5.35
5.08
4.72
4.02
3.29
2.94

Jul
Aug
Sep
Oct
Nov
Dec

3.17
3.47
4.09
4.48
4.91
5.12

So--Just to give you some very rough ideas... Say your generator fuel costs are very high, and you want to use ~3 hours a day of "noon time equivalent sun" for 8 kWH per day system.

8,000 WH per day * 1/0.52 system end to end AC efficiency * 1/3 hours of sun = 5,128 Watt array minimum

And if you aim for 2 days of storage and 50% maximum discharge (good cost effective optimum for most people), a 48 volt battery bank would be:

8,000 WH per day * 1/0.85 inverter eff * 2 days storage * 1/0.50 max discharge * 1/48 volt battery bank = 784 AH @ 48 volt battery bank

And to double check--We suggest a 5% to 13% rate of charge for your battery bank--With 10% to 13%+ being desirable (if you have the room and the money for the panels). 5% rate of charge can work, but mostly if you charge during the day and use the power at night (and typically for weekend/seasonal cabin):

784 AH * 59 volts charging * 1/0.77 panel+controller losses * 0.05 rate of charge= 3,004 Watt minimum array
784 AH * 59 volts charging * 1/0.77 panel+controller losses * 0.10 rate of charge= 6,007 Watt nominal array
784 AH * 59 volts charging * 1/0.77 panel+controller losses * 0.13 rate of charge= 7,809 Watt maximum "cost effective" array

So, based on some quick rule of thumbs design--A 5,128 to 7,809 Watt array would be a good range, with 6,007 Watt or larger array being recommended for a full time off grid home.

Battery bank capabilities--You could justify a 7-8 kWatt maximum AC inverter (another rule of thumb ~1kWatt inverter per 100 AH @ 48 volt flooded cell battery bank).

The system is certainly doable--But not small and you would want to get some knowledgeable help if this was your first system--Especially if you have not had much experience wiring a house or large boat/DC power system before.

Also, remember that while your solar array should last 25 years, the batteries may last 7-10 years (you can get 15+ years from Forklift batteries), and the major electronics will have a good life if they last 10+ years between replacements (may need repairs at 5+ years for charge controllers/AC inverters).

And a genset--More or less a 10% rate of charge on the above battery bank would be ~80 amps @ 59 VDC:

80 amps * 59 volts * 1/0.80 charger eff * 1/0.80 genset derating = 7,375 Watt genset minimum

Still interested? Lots of questions? Not a system design--Just a back of the envelope design to start the discussion based on what we know so far.

-Bill

CDN_VT · September 2014

Re: Newbie needs advice on off grid system

carcus27 wrote: »

Quote Originally Posted by CDN_VT View Post
Carcus27 , do a small solar setup with grid till you get it all down.
Get on the Kill-a-watt , & start recording as you read ..
This is not as easy a plugging in a cord , but I find this as well as life is great with awards .

VT
Wanting to be a bit covert about this operation, so grid tied is really out of the question, thx anyhow. .

KiWI , Nada . Do a small system / pump , to learn But keep the grid tie till YOU LEARN !

You need to start on a small project , and learn , then you won't go crazy & broke in the dark , hungry & smelly

..

Alright M8

VT

mike95490 · September 2014

Re: Newbie needs advice on off grid system

And if you can stand to run a generator in the winter, you can downsize the PV a bit. Don't try to add enough PV to power the place in cloudy weather, that takes 10x as much PV as normal would.

gww1 · October 2014

Re: Newbie needs advice on off grid system

coot

•8,000 WH per day * 1/0.52 system end to end AC efficiency * 1/3 hours of sun = 5,128 Watt array minimum

And if you aim for 2 days of storage and 50% maximum discharge (good cost effective optimum for most people), a 48 volt battery bank would be:

•8,000 WH per day * 1/0.85 inverter eff * 2 days storage * 1/0.50 max discharge * 1/48 volt battery bank = 784 AH @ 48 volt battery bank

And to double check--We suggest a 5% to 13% rate of charge for your battery bank--With 10% to 13%+ being desirable (if you have the room and the money for the panels). 5% rate of charge can work, but mostly if you charge during the day and use the power at night (and typically for weekend/seasonal cabin):
•784 AH * 59 volts charging * 1/0.77 panel+controller losses * 0.05 rate of charge= 3,004 Watt minimum array
•784 AH * 59 volts charging * 1/0.77 panel+controller losses * 0.10 rate of charge= 6,007 Watt nominal array
•784 AH * 59 volts charging * 1/0.77 panel+controller losses * 0.13 rate of charge= 7,809 Watt maximum "cost effective" array

So, based on some quick rule of thumbs design--A 5,128 to 7,809 Watt array would be a good range, with 6,007 Watt or larger array being recommended for a full time off grid home.

Battery bank capabilities--You could justify a 7-8 kWatt maximum AC inverter (another rule of thumb ~1kWatt inverter per 100 AH @ 48 volt flooded cell battery bank).

The system is certainly doable--But not small and you would want to get some knowledgeable help if this was your first system--Especially if you have not had much experience wiring a house or large boat/DC power system before.

Also, remember that while your solar array should last 25 years, the batteries may last 7-10 years (you can get 15+ years from Forklift batteries), and the major electronics will have a good life if they last 10+ years between replacements (may need repairs at 5+ years for charge controllers/AC inverters).

You just described my system, it was self install. 800 ah forktruck battery, 5600 watts solar.

I did all the work. bought the inverters used but if I take the turbine expence off probly close to new money.

$17500 after taxes. The solar was less then one dollar a watt but not much.

The nine year old inverter had circuit boards replaced and 9 year old cc has internal fan out and am using a fan from a computer power supply.

I am sure that I didn't overpay on much but a system that big cost. I did pay 5 grand for battery.

I am not bragging or complaining, just trying to put stuff in perspective.

Could have went grid tie and not did the work for lots cheeper. The battey cost and electric company rebate. The electric company has change the rebate now but maby yours still has one.

Good luck
gww

Newbie needs advice on off grid system

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