Need HELP!! New system. I don't know how much power?? KW??

LemonChipsLemonChips Registered Users Posts: 8
Ok I'm having trouble understanding how much power my system will be taking in. Can you help me understand this?

If I'm using (there would be more than one solar panel battery):

- Solar Panel
Helios Solar Works 300W Mono Solar Panel, 7T2 Series, 7T2 300

- Charger/Inverter
Outback Radian Gs8048 8000Watt inverter-charger 48vdc

- Communication Manager
Hub 10 coms Manager

- System Display & Controller
Outback Mate 3 Display & Controller
Flexnet DC System Moniter

- Sensor
RTS Temperature Sensor

- Battery
Deka 8A22NF 12V 55AH Sealed AGM Solar Battery

- Charger
Outback FM-80 FlexMax MPPT Charge Controller - FM80-150vdc
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Comments

  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    Ok I'm having trouble understanding how much power my system will be taking in. Can you help me understand this?

    If I'm using:

    - Solar Panel
    Helios Solar Works 300W Mono Solar Panel, 7T2 Series, 7T2 300

    - Charger/Inverter
    Outback Radian Gs8048 8000Watt inverter-charger 48vdc

    - Battery
    Deka 8A22NF 12V 55AH Sealed AGM Solar Battery

    You are connecting a single 300W module to an 8000W inverter? A huge 48V charge controller to a very small 12V battery?

    Methinks there is information being omitted here.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Welcome to the forum.

    What you have described there is an incomplete system that won't do anything.
    To start with, the inverter is 48 Volts. You have listed one very small 12 Volt battery. You need to put four of those in series for 48 Volts before the inverter will even turn on. After that it will shut down fairly quickly because the Radian is an 8kW inverter and needs a lot more than 55 Amp hour on it to function properly. In fact it needs roughly 800 Amp hours @ 48 Volts.

    When you get a properly sized battery bank you'll run in to another problem: you have listed one 300 Watt panel. That won't provide enough power to recharge the battery bank, much less supply any surplus for grid-tie sell-back (if that is the goal). You actually need about 5000 Watts of panel, up to 8000 if you plan on running the GT capacity of the Radian to its utmost.

    But the size of the array is also irrelevant, because there's no charge controller on your list. Absolutely essential to have a charge controller between the array and the batteries. If everything were sized right, you'd be looking at an Outback FM80 controller here. I know it says "inverter-charger" for the Radian but the "charger" part of that is from an AC feed such as the utility or a generator; it is not for connecting to solar panels.

    So shall we re-evaluate from the beginning? What is your goal? Are you trying to get a grid-tie system, emergency power, or a totally off-grid set-up?
  • LemonChipsLemonChips Registered Users Posts: 8
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Well yes there would be several more solar panels and batteries (but I don't the maximum amount of solar panels I can connect to that system; would it just be up to 8000w of solar panels?) and for the batteries would you recommend I get a 48V deep cycle (is that compatible with 120/240 systems)? I was told 12v. Oh and the charge controller is bellow

    - Charger
    Outback FM-80 FlexMax MPPT Charge Controller - FM80-150vdc
  • BB.BB. Super Moderators, Administrators Posts: 29,747 admin
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Backing up a moment... What are your loads and what do you want to do? Save money, go off grid, emergency backup power, etc.? How large are your loads (watts, watts*hours per day)? Where will the be installed (roughly for amount of sun in your location).

    It is very difficult to "grow" a solar power system... For the most part, you need to match/balance components for size, voltage, expected loads, etc...

    Large inverters need large battery bank, which need a large solar array, and a large charge controller.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    Well yes there would be several more solar panels and batteries (but I don't the maximum amount of solar panels I can connect to that system; would it just be up to 8000w of solar panels?) and for the batteries would you recommend I get a 48V deep cycle (is that compatible with 120/240 systems)? I was told 12v. Oh and the charge controller is bellow

    - Charger
    Outback FM-80 FlexMax MPPT Charge Controller - FM80-150vdc

    You need a 48 Volt battery bank to run a 48 Volt inverter. The AC output side is not relevant to that fact. The size of the battery bank in Amp hours is determined by the amount of power you need it to supply, as per Bill's post. If you don't have a handle on that number you are lost in the solar woods and spending money unwisely. Usually a 48 Volt battery bank is made up of several lower Voltage batteries connected in series.

    The charge controller is the right one for the rest of the equipment.

    Before we go any further (and you spend any more money) it is absolutely vital to know what the purpose of the system will be. That is one very impressive and expensive inverter you've got there, and I hope you haven't just spent a lot of dollars on something that does not suit your intent.
  • LemonChipsLemonChips Registered Users Posts: 8
    Re: Need HELP!! New system. I don't know how much power?? KW??

    My main goal is to be self sustainable (Off-Grid). last month I pulled about 3100KW! I figure if I'm going to pay a large bill I'd rather put it into this so I won't pay that for ever. I haven't made any of these purchases yet; that's the system I was heading towards. Is it really that difficult to grow the system?
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    My main goal is to be self sustainable (Off-Grid). last month I pulled about 3100KW! I figure if I'm going to pay a large bill I'd rather put it into this so I won't pay that for ever. I haven't made any of these purchases yet; that's the system I was heading towards. Is it really that difficult to grow the system?

    Darn near impossible.
    Good that you haven't spent any money yet, as an Outback Radian is probably not the choice for strictly off-grid (it has grid-tie ability, and if you aren't going to use that why pay for it?)

    So last month you used 3100 kW hours (the "hours" part is important). That is a lot of electricity. Time for Forum Lecture #1: conservation, conservation, conservation! If you spend money reducing that number you'll be further ahead than spending it any other way. Trying to make that much power (100+ kW hours per day) off-grid comes at a big price.

    That brings us to the second consideration; grid-tie. If your utility allows it, investing in a GT system can be more beneficial than disconnecting entirely. Look in to this option before buying anything too.

    Off-grid would be a last resort. It may sound strange, but it costs anywhere from $0.75 to $1.50 per kW hour to generate electricity off-grid. That would be the equivalent of a $2,325 monthly electric bill. You probably aren't getting charged that much, are you?
  • LemonChipsLemonChips Registered Users Posts: 8
    Re: Need HELP!! New system. I don't know how much power?? KW??

    I'm actually being charged near that amount per month!! But ok I see what you're talking about with the Outback. Ok I'm looking at my bill and it's actually around 2900KWH. And as for conservation. I live in house that is nearly 30-35% glass - 6200sq.ft. There is an orchard that consumes 70% of the electricity to warm the grapes during the winter and any cold day when it drops below a certain degree (it's on a regulator so it powers itself on whenever it needs to) but it has a 65 acres of land so there is most definitely space for solar panels. Those outdoor heater draw an insane amount of heat and the 2900KWH a month was only because I manually shut them off when I saw it was almost warm enough.
  • BB.BB. Super Moderators, Administrators Posts: 29,747 admin
    Re: Need HELP!! New system. I don't know how much power?? KW??

    If you have grid, and your utility supports a 1 year net meter billing plan (or similar), then a pure Grid Tied system (solar panels to GT inverter to your AC Mains Panel) is the best solution.

    Depending on where you live, your power costs with GT solar can be at pariaty with the grid, or even cheaper.

    However, if you go with a Battery Based system (or even a "hybrid" GT/Off-Grid capable system), usually they will end up costing you more in $$/kWH than the grid...

    For example (very rough numbers):
    • $0.10 to $0.30 per kWH for Grid/utility Power
    • $0.10 to $0.30 per kWH for Grid Tied Solar (no batteries, no backup power)
    • $0.45 to $0.75 per kWH for Hybrid (GT+Battery Backup) power
    • $1-$2+ per kWH for Off Grid power

    The above numbers both capital costs (20 year life), battery replacement (5-10 year life), and replacement electronics (about every 10+ years).

    So--we here like to emphases conservation first. It is almost always cheaper to conserve a watt than to generate a watt...

    And there has been a lot of new technologies in this area... Besides the low E/double pane windows, figuring out that adding a lot of insulation in the ceiling/walls, and the energy star appliances (plus using less power to get the job done--like laptop vs desktop computers to use 1/10th the power)---There are now heat pumps which can heat and cool your home much more efficiently, and do things like heat pump based water heaters (about 2x as efficient as a normal electric water heater--Perhaps even more cost effective than natural gas or solar hot water in some cases).

    Power use is a highly personal choice... And we can make comparisons (your monthly usage is about 10x mine, and there are people here where their usage is 1/10th my one usage).

    So--I like to be very straight forward about the whole conservation issue. Basically, figure out where you can cost effectively use less energy... Then after all that is done, figure out the whole alternative energy system setup...

    The problem is that 3,000 WH per month is a lot of energy... And would be a very huge and hugely expensive solar PV system to implement.

    For example, PV Watts can estimate the amount of sun and power you will get from a solar array/PV system. Assuming you are somewhere near Long Beach Ca (fixed array tilted at 34 degrees from horizontal):
    Month    Solar Radiation (kWh/m 2/day)
    1      4.43     
    2      5.00     
    3      5.52     
    4      6.21     
    5      6.12     
    6      6.09     
    7      6.63     
    8      6.79     
    9      6.18     
    10      5.46     
    11      4.81     
    12      4.34
    Year      5.63      
    
    So, lets say you average 5.63 "hours of sun" per day over the year, a 3,100 kWH per month system * 12 months a year would look like:
    • 3,100,000 WH per month 1/30 days per month * 1/0.77 solar sys derating * 1/5.63 hours of sun per day = 23,836 Watt solar array..

    More or less, even with today's prices, that is somewhere around $50,000-$100,000 install for Grid Tied...

    If you where going to do this with a battery based system (and backup generator)--Probably a 2x larger array and 4x the expense.

    Again--Just really rough first pass guesses at what a system might look like. There are still a lot of details to discuss--But trying to get the idea across that if you can cut your power usage by 1/2 for $25,000 to $50,000 -- It would probably be a good deal.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Egad. Electric heat. Might as well pile up your money in cash and set fire to it.
    You should look into alternatives for keeping the grapes warm. Propane or natural gas. Or ice wine. :D

    Under the circumstances, having a large GT system would benefit you most in terms of solar-electric as any surplus produced when you don't need it is sold to the grid; no "waste".

    Even so I'd be going over that house with a really good energy audit ... and a Kill-A-Watt meter.

    To produce 100 kW hours AC per day would require a massive array of panels. We're talking 38kW or possibly even larger (depending on the amount of sun you get).
  • LemonChipsLemonChips Registered Users Posts: 8
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Ok I did a quick estimate on things I can cut out/use less/replace to conserve and it'll still come out to 2200 (approximation) probably less. Do you have any suggestions. I understand what you're talking about with the high cost of going so large, but I don't understand this part

    However, if you go with a Battery Based system (or even a "hybrid" GT/Off-Grid capable system), usually they will end up costing you more in $$/kWH than the grid...

    For example (very rough numbers):

    $0.10 to $0.30 per kWH for Grid/utility Power
    $0.10 to $0.30 per kWH for Grid Tied Solar (no batteries, no backup power)
    $0.45 to $0.75 per kWH for Hybrid (GT+Battery Backup) power
    $1-$2+ per kWH for Off Grid power

    Mainly the off Grid power. I don't understand how would still be paying for this if It's self generating?
  • solar_davesolar_dave Solar Expert Posts: 2,346 ✭✭✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    For example (very rough numbers):

    $0.10 to $0.30 per kWH for Grid/utility Power
    $0.10 to $0.30 per kWH for Grid Tied Solar (no batteries, no backup power)
    $0.45 to $0.75 per kWH for Hybrid (GT+Battery Backup) power
    $1-$2+ per kWH for Off Grid power

    Mainly the off Grid power. I don't understand how would still be paying for this if It's self generating?

    You have to amortize your systems costs over the life over the number of kWh you generate. When you take into account battery life, charging loses and the like you have to have a much larger off gird system, it has to meet you maximum consumption sometimes for several days when the sun doesn't shine.

    My 12.5 Kw Grid Tie system can squeeze out about 70 kWh a day mid summer. I do use much more than that mid summer (100-120 kWh) but I have credits from the non-cooling months that I apply to the bill. That is the beauty of Grid Tie, unlimited "battery" in the grid with long term "storage". None of the watts I generate ever go to waste, I get paid for my excess at year end as a credit for the following year.

    FYI my electric utility bill last month was $24.80 of that $5 was for off peak generation the rest was fees and taxes. I run three 3 ton AC units, a swimming pool and have 2 plug-in electric cars. Before my solar system, my annual costs were $4000-$5000. We did the conservation deal first to get the loads down, then did the solar.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Let's shift down to the fundamentals and explain the three different basic types of solar-electric power systems:

    1). Straight Grid-Tie. Solar panels feed a GT inverter directly, its output is connected to conventional household wiring with utility service. Any power produced by the panels is used, either by household loads or by being sold back to the utility company.

    2). Off-grid solar. Batteries run an inverter which supplies power needs. These batteries are recharged by solar panels through a charge controller. There is no utility involved.

    3). Hybrid Grid-Tie. Functions like the straight GT system, except that the inverter runs from batteries recharged by solar panels as with the off-grid system. Surplus panel production (what is produced after the batteries are charged) is used the same as a straight grid-tie system. If the utility power fails, batteries will provide power for household needs.

    The last two systems requires batteries and charge controller(s) which add significantly to the initial cost as well as on-going maintenance and future replacement costs. So any system that utilizes batteries as part of its make up produces power at a higher cost per kW hour over the lifespan of the system.
  • LemonChipsLemonChips Registered Users Posts: 8
    Re: Need HELP!! New system. I don't know how much power?? KW??
    Let's shift down to the fundamentals and explain the three different basic types of solar-electric power systems:

    1). Straight Grid-Tie. Solar panels feed a GT inverter directly, its output is connected to conventional household wiring with utility service. Any power produced by the panels is used, either by household loads or by being sold back to the utility company.

    2). Off-grid solar. Batteries run an inverter which supplies power needs. These batteries are recharged by solar panels through a charge controller. There is no utility involved.

    3). Hybrid Grid-Tie. Functions like the straight GT system, except that the inverter runs from batteries recharged by solar panels as with the off-grid system. Surplus panel production (what is produced after the batteries are charged) is used the same as a straight grid-tie system. If the utility power fails, batteries will provide power for household needs.

    The last two systems requires batteries and charge controller(s) which add significantly to the initial cost as well as on-going maintenance and future replacement costs. So any system that utilizes batteries as part of its make up produces power at a higher cost per kW hour over the lifespan of the system.

    Yes I understand the difference between the three. I want Off-Grid
  • solar_davesolar_dave Solar Expert Posts: 2,346 ✭✭✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    Yes I understand the difference between the three. I want Off-Grid

    You do understand the time it will take to amortize the costs against the kWh produced? And that the costs is about 200-500% more for the power you consume? And that off grid tosses lots of power into the bit bucket because of the max sizing required to make sure you don't run out? And that most off grid systems have a generator to back them up, and they also have a limited life? And battery maintenance is a PITA.

    You need to make sure your not cutting off your nose to spite your face on this and there should be a good reason to go off grid. Financial it makes no sense when the grid is there to act as your battery.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    Yes I understand the difference between the three. I want Off-Grid

    That is the most expensive. High initial investment, no return from sales of "surplus" power to the utility, more maintenance and replacement costs.

    Example:
    You spend $20,000 on a system. It can produce 'X' kW hours per day, 365X kw hours per year. It lasts 'Y' years: 365X * Y = total kW hours produced over its lifespan. Divide the initial capital cost by the total kW hours and you have the price per kW hour. This is the amortization. And that is hoping that nothing fails prematurely. Panels can be expected to last 20 years. Most inverters & charge controllers will last 10, possibly 15, 20 if you're lucky. Batteries? If they make 10 years it's practically a miracle, and along the way they will go down in capacity. These things can not be avoided.

    With a straight GT system you have only the longest-lasting components (panels and inverter) and a lower initial cost. Plus any "surplus" power gets sold to the grid, which helps offset the cost per kW hour. In some cases (especially if government or utility incentives are available) you can actually profit.

    Off-grid is not the cost-free Nirvana some people would have you believe it to be. I know; I do it. $8,000 initial cost to get slightly less than 3kW hours a day, and that not all year round. If it rains, the generator starts burning fuel @ $1.26 per litre. There is no alternative at the site because there is no utility available (at ten cents per kW hour I might add).
  • solar_davesolar_dave Solar Expert Posts: 2,346 ✭✭✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??

    FYI I get great sun, my 12.5 KW system in May produced 2214 kWh. I consumed 1800 kWh of on peak solar production and bought 170 kWh of off peak from the utility. I credited my on peak account with 220 kWh. I don't know where you are but I suspect your sun is no where near to mine. If you need to generate 3100 kWh a month to break even then you have an expensive problem even for a Grid tie system. To hit those kinds of numbers here would require about a 18Kw solar farm, you could probably double that for an off grid system to get enough production/storage.

    Ah but this is where net metering a grid tie system steps in, I can consume 3500 kWh during a couple of the summer months from my credits combined with my production.
  • BB.BB. Super Moderators, Administrators Posts: 29,747 admin
    Re: Need HELP!! New system. I don't know how much power?? KW??

    There can be an issue with Grid Tied and Commercial billing...

    Net Metering plans (user power, meter turns forward--generate power, meter turns backwards) may not be available for business users.

    At least in Northern California, commercial/agricultural billing can be so complex that some folks have to hire a "billing engineer" to figure out the best option to move forward.

    Also, "going off grid" is not always an option for Californians... The fact that "small solar" PV systems (typically 10kW and smaller) are exempt from "stranded utility infrastructure" payments may not be available for larger/non-residential systems. Basically, the utility has made long term loans and investments based on you "being a customer" and you have to pay the utility back for stranded assets if you leave the grid and generate your own power.

    This can be as complex a "regulatory" issue as it is a Solar PV system technical issue.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Eric LEric L Solar Expert Posts: 262 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    Ok I did a quick estimate on things I can cut out/use less/replace to conserve and it'll still come out to 2200 (approximation) probably less

    Like dave, BB, and Cariboocoot said you'd be looking at a massive off-grid system. So you'd be using around 73.3 kWh/day on average. As a very rough-guideline, off-grid systems typically need a panel capacity of about 2x the average daily use (this is a rough guideline than can vary greatly with location, etc). So you'd need to be generating about 150 kWh/day. If you had 4.3 sun hours in Dec (lowest month from BB's post #10 at your approximate location from your ISP), that's 150/4.3 = 34.8 KW of array: a 34,800 watt array, minimum. Battery bank? I don't want to think about it.

    Anyway, even though I don't know you, I feel almost certain you will never do this. :D BUT, if I'm wrong and you do it you must post pictures of the system for us so we can all gaze at it in awe.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    Eric L wrote: »
    Battery bank? I don't want to think about it.

    Oh, about 4000 Amp hours @ 48 Volts. Minimum. Say four 24 Volt 1875 Amp hour forklift batteries @ $8,000 each. ($32,000).
    Another $42,000 for the array (not including hardware & wiring). Seven charge controllers for another $5,000.
    And the inverter. Or possibly inverters, depending on the max load demands.
    Plus wiring, fusing, mounting hardware.
    This would easily be a $100,000 system.

    I'm with you, Eric; I would love to see that set-up! :D
  • solar_davesolar_dave Solar Expert Posts: 2,346 ✭✭✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    Oh, about 4000 Amp hours @ 48 Volts. Minimum. Say four 24 Volt 1875 Amp hour forklift batteries @ $8,000 each. ($32,000).
    Another $42,000 for the array (not including hardware & wiring). Seven charge controllers for another $5,000.
    And the inverter. Or possibly inverters, depending on the max load demands.
    Plus wiring, fusing, mounting hardware.
    This would easily be a $100,000 system.

    I'm with you, Eric; I would love to see that set-up! :D

    When I first started out I wanted to cut the utility cable, I soon found out exactly what you guys are talking about. Still when I did the grid tie system installation costs were about $6 a watt. I did have a $3 a watt rebate and a 30% tax credit to make mine work.
  • LemonChipsLemonChips Registered Users Posts: 8
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Well I don't feel It's really worth spending 100thousand on this system but just so I have a better understanding of how it works. There is no limit to how many solar panels I can have hooked up (the more I have the faster my batteries charge)? what about batteries is there a limit to how many I can have? I understand the batteries would drain without enough power charging them back up. Also can somebody please explain to me how an inverter works? I know that it inverts DC to AC but where I get lost is the wattage. For instance if it says 8000w inverter what does that mean? and as for the Outback Radian it also works as an off grid inverter/charger doesn't it? I know they can be stacked (multiple connected to make one large system) so why can't this system be expanded? I believe it was baricootboot that said it was near impossible to expand a system (Can't I just buy another Radian charger/inverter, more solar panels, more batteries and just connect/add them to my current system)??
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    Well I don't feel It's really worth spending 100thousand on this system but just so I have a better understanding of how it works. There is no limit to how many solar panels I can have hooked up (the more I have the faster my batteries charge)? what about batteries is there a limit to how many I can have? I understand the batteries would drain without enough power charging them back up. Also can somebody please explain to me how an inverter works? I know that it inverts DC to AC but where I get lost is the wattage. For instance if it says 8000w inverter what does that mean?

    There are limits.
    For instance a big charge controller like the FM80 has an output limit of 80 Amps of current on any system Voltage up to 48. At that point you are looking at an array of 48 * 80 = 3840 Watts, plus a derating factor for the panels. Total about 5kW on a 48 Volt system.

    But you can have multiple arrays & controllers on one battery bank. In theory that battery bank can be any size. In practice it becomes difficult to manage as the current levels rise. Handling 100 Amps of current is not difficult. 200 Amps somewhat more so. 400 Amps and you are in "problems with the wiring" territory.

    There are limits on how much current you can recharge a battery with too. Exactly how much depends on the particular battery, Flooded cells can't take as much current as AGM type (which are pickier about Voltage). Likewise the rate of discharge has limits, in that if you try to draw too much current at any time from a battery its Voltage drops too rapidly and so does its actual capacity (this is the Peukart Effect).

    You can have multiple inverters on one battery bank providing it is large enough to handle the potential draw. You can have multiple battery banks on one inverter providing you have some way of switching between them. You can have multiple inverters feeding the same AC output (stacking, it's called) or separate sub systems to provide power redundancy. There are ways to handle the situations.

    An 8000 Watt inverter means it is capable of 8000 Watts AC continuous power. That's 8000 Watts / 240 Volts AC = 33 Amps AC. For that same power on the input side it would draw 8000 Watts / 48 Volts DC = 167 Amps DC plus power lost in the conversion (they are only around 90+% efficient) and the power consumed by the inverter itself (30 Watts for the Radian) or about 186 Amps at peak power.
  • CariboocootCariboocoot Banned Posts: 17,615 ✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Expanding a Radian system, btw, is pretty much like expanding any other: you're buying whole other complete systems. The difference is that with the Radian (and a few others) the AC output can be coupled and the inverters "communicate" with each other. In fact the Radian is essential four 4kW 120 VAC inverters coupled inside one box to provide 8kW @ 240 VAC.

    Most systems don't have that degree of flexibility, and if you start out at the "low end" you really see how hard it is to expand. Again, you end up buying a complete new system save perhaps the panels and controller (especially when you have to shift up in system Voltage to accommodate increased power needs).

    Another inverter = another complete battery bank (even if coupled) + another controller and array to supply it.

    Ten is the limit for coupling Radian inverters, btw. That's 80 kW of power - more than the average home is wired for.
    However, that makes connecting the charge controllers a problem as the HUB only has 10 spaces; if they are all used for inverters there will be a lack of communication between controllers and inverters which can be a problem when using the charge function of the inverters.
  • BB.BB. Super Moderators, Administrators Posts: 29,747 admin
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Inverter's take the DC Voltage and Current from your battery bank and turn it into 120 or 240 VAC.

    There are two major types of inverters here... One is an "off grid" inverter that you can connect to your car battery and plug in your laptop AC adapter (an example).

    Another is a Grid Tied type inverter... The GT inverter connects to your solar array (no batteries) and to your main electrical panel. When the sun is up, the GT Inverter can pump current back into your home's wiring and even out to the utility (grid) and even turn your electrical meter backwards. In normal operation, you cannot tell if you have a GT inverter up and running in your home or not... The only thing you will see is a smaller electrical bill at the end of the month.

    There are "hybrid" inverters that do both GT (when the grid is up), and Off Grid (when the grid has failed). These type require a battery bank for operation.

    Here is some basic information about (off grid) inverters:

    All About Inverters
    Choosing an inverter for water pumping

    Note that everything above is a simplification (50,000 foot view)... There are lots of details that need to be addressed when you start designing/installing a system.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • LemonChipsLemonChips Registered Users Posts: 8
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Ok so what you're basically saying is that the expansion could be done but it would just be somewhat expensive? Good point with stacking the Radians and only having 10 spaces on the HUB I hadn't thought about that. If I have a 300watt solar panel, does that solar panel take in 300watts per hour equaling .3kw? meaning if I have (10) 300watt solar panels I would be getting 3kwh?
  • Blackcherry04Blackcherry04 Solar Expert Posts: 2,490 ✭✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    Ok so what you're basically saying is that the expansion could be done but it would just be somewhat expensive? Good point with stacking the Radians and only having 10 spaces on the HUB I hadn't thought about that. If I have a 300watt solar panel, does that solar panel take in 300watts per hour equaling .3kw? meaning if I have (10) 300watt solar panels I would be getting 3kwh?
    In a laboratory in that perfect world as long as the fake sun was shining on them and no clouds. In the real world with fixed panels and a fixed angle and temperature derating it will be a whole lot less. The Suns arc only gives you the correct angle for a little over a hour a day and maximum output depending on your location.

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  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    Yes I understand the difference between the three. I want Off-Grid
    Then be prepared to pay through the nose for it. If the grid is available, it is virtually never financially advantageous to build an off grid system. It will NEVER pay for itself. It won't even come close.

    You are talking about a LOT of money here. Unless you are a one-percenter, then you need to do a serious cost/benefit analysis of all possible scenarios including a (detailed, tedious) Watt by Watt accounting of all your energy usage before you spend the first dollar, else you will take a serious bath. If, OTOH, you have many thousands (or tens or possibly even hundreds of thousands) of dollars to burn indiscriminately, then forge on ahead. :D
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Need HELP!! New system. I don't know how much power?? KW??
    LemonChips wrote: »
    Well I don't feel It's really worth spending 100thousand on this system but just so I have a better understanding of how it works. There is no limit to how many solar panels I can have hooked up (the more I have the faster my batteries charge)? what about batteries is there a limit to how many I can have? I understand the batteries would drain without enough power charging them back up. Also can somebody please explain to me how an inverter works? I know that it inverts DC to AC but where I get lost is the wattage. For instance if it says 8000w inverter what does that mean? and as for the Outback Radian it also works as an off grid inverter/charger doesn't it? I know they can be stacked (multiple connected to make one large system) so why can't this system be expanded? I believe it was baricootboot that said it was near impossible to expand a system (Can't I just buy another Radian charger/inverter, more solar panels, more batteries and just connect/add them to my current system)??

    My advice to you is to hire someone who understands this stuff to design a system to fit your needs.
  • BB.BB. Super Moderators, Administrators Posts: 29,747 admin
    Re: Need HELP!! New system. I don't know how much power?? KW??

    Even if you hire somebody--It still does not hurt to understand how everything works so you can make sure that consultant/installer is doing things right.

    Are you familiar with an automotive electrical system (battery, alternator, loads, regulator, etc.)...

    An off grid system is very similar. The battery is the "heart" of the power system. The alternator is the charging source and works fairly similar to solar panels. When the engine is running/sun is up, the current flows to the battery to recharge it. When you have loads, they draw energy from the battery and the alternator/charge controller as needed.

    The off grid inverter--Is just another load on the battery bank which "inverts" lower voltage DC power to higher voltage AC power (some inverters also have charging capabilities from attached gensets or even grid power--sort of like a UPS, uninterruptable power supply for a computer).

    A grid tied inverter + solar panels--For all the world is very much like an AC Battery system. In this case, the "Grid" (utility power) is the "AC Battery" and your loads are supplied from the grid... While the GT inverter "recharges" the AC Grid (there is a fundamental difference between a GT and and OG inverter if you want to get into that discussion. An OG inverter can never be connected directly to the AC grid without risk of fire or worse. And a GT inverter will not run appliances like an off grid inverter if the grid is down).

    Because you only have "useful" solar power for 6-8 hours per day, the solar array has to be larger than your average loads so that it can recharge your battery banks during the day, and the battery supplies power when the sun is down (same thing for Grid Power--panels "turn the meter backwards" when the sun is up, and your loads turn the meter forward otherwise).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
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