Double check my system for me..

Fordguy64

Well I've been researching for a while and I think I'm ready to start pulling the trigger and ordering some stuff..

Purpose of the system:
1. Lower my electric bill about 25-30%
2. Run my freezer and fridge and also have some extra power for when the power goes out or shtf.

ThAt being said I'm looking at getting 8 sharp 230watt panels for a total of 1840watts. ( I'm pretty sure this will be a little small for the 840amp hour battery)

Batteries: I'm looking at getting 4 batteries at 6v 420amp hour batteries to run them in series at 420amp hour and 24v and have the ability to wire in series and parallel for 24v at 840 amp hours when I really need the extra capacity..

Inverter I'm looking at the outback gvfx3524 inverter and the outback mx60 charge controller with the mate.

Planning on mounting the inverter on a midnite e panel for simplicity..



Also will be looking at one of the Honda eu2000 generators for when needed and also a larger diesel generator..

Really want to do this right the first time

Thoughts? Anything I missed?

Thanks guys!!

Cariboocoot

Re: Double check my system for me..

Welcome to the forum.

Let's start with that first one: "Lower my electric bill about 25-30%"
You can lower your electric bill with solar, but that's not the same as saving money. Solar equipment is expensive and has a finite lifespan. Economically it tends not to make sense except for GT applications in certain areas. You could probably lower your bill that much for less investment by doing an energy audit and replacing things that use too much power.

Now the second one, having power when the utility goes out, can be done cheaper with a generator most of the time.

The third one, which you didn't really ask, is backwards. You don't start with the panels you start with the loads. So buy a Kill-A-Watt meter and measure how much that refrigerator and freezer use in a typical day. Don't be surprised if it's upwards of 2 kW hours per day each. These things are big power consumers and have heavy start-up demands.

Your choice of a 24 Volt system is a good idea. 420 Amp hours just might work too, as it's roughly 4.5 kW hours AC at 50% DOD. I run one refrigerator on 232 Amp hours @ 24 Volts, plus everything else. It's a bit marginal: works fine in Summer, can't be done in Winter (6 hour days).

What can you expect from 1840 Watts of array? Just about 60 Amps peak current, which is more than enough for 420 Amp hours @ 24 Volts by far but as you suspect low for 840. At 7%, though, it would still work. You could also expect perhaps 3.8 kW hours AC minimum per day from it.

If this is not going to be a grid-tie system don't get the GVFX inverter. Although grid-tie would make more sense economically because you could make full use of the panel capacity any time the grid is up. They don't make the MX60 anymore, so if you're buying new it would be an FM60.

On the whole, it's a pretty-well-thought-out design. You must have been doing a lot of reading around here.

BB.

Re: Double check my system for me..

Back to basics... Is this the amount of power you are expecting?

Using PV Watts for Chicago area (guess) 1,840 watt solar array, off grid at ~0.52 derating, fixed array tilted to latitude will give you:

"Station Identification"
"City:","Chicago"
"State:","Illinois"
"Lat (deg N):", 41.78
"Long (deg W):", 87.75
"Elev (m): ", 190
"PV System Specifications"
"DC Rating:"," 1.8 kW"
"DC to AC Derate Factor:"," 0.520"
"AC Rating:"," 1.0 kW"
"Array Type: Fixed Tilt"
"Array Tilt:"," 42.0"
"Array Azimuth:","180.0"

"Energy Specifications"
"Cost of Electricity:"," 8.4 cents/kWh"

"Results"
"Month", "Solar Radiation (kWh/m^2/day)", "AC Energy (kWh)", "Energy Value ($)"
1, 3.04, 91, 7.64
2, 3.78, 102, 8.57
3, 4.34, 128, 10.75
4, 5.11, 138, 11.59
5, 5.68, 151, 12.68
6, 5.66, 142, 11.93
7, 5.92, 151, 12.68
8, 5.22, 135, 11.34
9, 4.94, 126, 10.58
10, 4.26, 118, 9.91
11, 2.83, 77, 6.47
12, 2.27, 66, 5.54
"Year", 4.42, 1424, 119.62

Or round 66 to 151 kWH per month... If you are an "average" North American home, you use around 1,000 kWH per month--And this system will supply about 1/10th of that amount of power.

In terms of "emergency power", such a solar array will provide "enough to live on" (fridge, lighting, laptop, small pump, etc.) for February through October (call it 100 kWH per month or 3.3 kWH per day). The November through January, you probably would want to use a genset for backup power and/or perhaps some sort of "cold box" for winter storage of food (seems cold enough, on average, you could skip the fridge).

Battery Bank size--if you have a 1,840 watt solar array and a 5% to 13% rate of charge (based on bank's 20 Hour rating):

• 420 AH * 29 volts charging * 1/0.77 panel+controller derating * 0.05 rate of charge = 790 Watt array minimum
• 420 AH * 29 volts charging * 1/0.77 panel+controller derating * 0.10 rate of charge = 1,582 Watt array nominal
• 420 AH * 29 volts charging * 1/0.77 panel+controller derating * 0.13 rate of charge = 2,056 Watt array "cost effective maximum"

So, you are looking to be OK on the panel to battery ratio too (for a well used/cycled system).

-Bill

Fordguy64

Re: Double check my system for me..

Thanks for the input guys.. I have 3 kill a watts.. So I've got a good idea on my electrical needs.. Like I said main goal is to run the fridge and freezer in a power outage. They both use right around 1.2 kwh a day. I've done what I can already to lower my electrical uses before hand and I've been averaging about 500kwh a month lowest bill at about 250 highest at about 1200 in the summer..

niel

Re: Double check my system for me..

i would ask you why not just go to a 48v battery bank rather than paralleling 2 battery banks at 24v? as you will see in my link the 48v version is about the same price and will allow better battery symmetry, better efficiency, and possibly smaller wires. now this would require a higher input voltage and i do not know the specs of the pvs for the best arrangement of the pvs possible. pv voltages may dictate different quantities/arrangements.
http://www.solar-electric.com/oupogrsiwain.html

sorry forgot link.

Fordguy64

Re: Double check my system for me..

Well I would go 48v but I'm not sure I can afford the extra 1200$ for the batteries required to get me to 48v. I realize that it is the better option but its that whole $$$ thing that always gets in the way. But I will think about it

Cariboocoot

Re: Double check my system for me..

Fordguy64 wrote: »

Well I would go 48v but I'm not sure I can afford the extra 1200$ for the batteries required to get me to 48v. I realize that it is the better option but its that whole $$$ thing that always gets in the way. But I will think about it

There would not be any "extra" batteries involved in going from 24 to 48 Volts if you were planning on running two parallel battery strings anyway. Have a read through this:
http://forum.solar-electric.com/showthread.php?15989-Battery-System-Voltages-and-equivalent-power

mtdoc

Re: Double check my system for me..

Agree with 48 Volts. No extra expense going to the 48 volt Outback inverter and it will be easier to expand in the future.

I would go with a Midnite Classic 150 rather than the Outback CC. I face this same choice when I put together my system and am very happy with the choice I made.

The Midnite ePanels are great and if you decide to go with their CC, getting one of their pre-wired ePanels with the Outback inverter will greatly simplify things with minimal added cost.

niel

Re: Double check my system for me..

you should know that you shouldn't mix odd batteries and that applies to batteries that are the same make and model, but are of different ages/abuse levels. to opt for a single 24v battery string is fine to do with the intent of any expansion of the battery bank within a year if taken care of reasonably. the reason is that the batteries you buy later will be dragged down to the same level of the older batteries. the same time constraints could allow the 48v battery bank to be bought, but maybe a bit later timewise that you'd have realized the other 24v string to be added.

it is your decision, but if you can put off instituting the system to save some $ you may be able to reap the 48v advantages. just go over the pv configurations that would be necessary under a 48v battery bank to see if it works out well for the present number of pvs.

Fordguy64

Re: Double check my system for me..

Well I was just going to get 4 batteries.. I mean I guess as far as batteries go your not supposed to add more in later so if you over do anything in the start it should be the battery system.. Hmm.. It's only money right?? Lol

niel

Re: Double check my system for me..

Fordguy64 wrote: »

Well I was just going to get 4 batteries.. I mean I guess as far as batteries go your not supposed to add more in later so if you over do anything in the start it should be the battery system.. Hmm.. It's only money right?? Lol

yes, it's only money, but we are cheapskates here and doing it right upfront is often the cheapest route to take. don't get me wrong as it can work out well for you at 24v too, but you are going to buy the extra batteries anyway.

there are only 2 disadvantages to you saving for the 48v system. the first is the time factor. you won't have something going sooner if you have to continue to save. the other would be that any expansions on the pvs will be larger groupings to allow the higher 48v batteries to charge from a higher voltage source.

oh, i guess i should mention that a controller operating at 48v out will be able to handle twice the amount of pv power that same controller would handle at 24v out. this may allow for expanding the pvs without buying another controller.

Fordguy64

Re: Double check my system for me..

Well I'm going to go talk to the battery guy Friday and see about getting 8 batteries.. I'm looking at the us battery l16hc xc it's 6v at 420 amp hour.. I can get them for 275 each and that's with the core charge..

Fordguy64

Re: Double check my system for me..

What size wire will I need to hook that bank up in 48v

Cariboocoot

Re: Double check my system for me..

Fordguy64 wrote: »

What size wire will I need to hook that bank up in 48v

That's a question of how much current will be drawn and how far from the batteries the inverter is.
If you were to use the Outback 3648 inverter, for instance, the average current at full power is about 75 Amps. That's easy to handle: 2 AWG would do it. The higher Voltage reduces, but does not eliminate, the V-drop issue. To the point where that 2 AWG should handle it up to 10 feet with ease.

Fordguy64

Re: Double check my system for me..

Hmm well the guy I was going to get the sharp panels from keeps changing his price on me.. Ive been looking around and I keep running across these mx solar panels made in new jersey? Are they any good?

Fordguy64

Re: Double check my system for me..

Ok so this is what I've got I can get 10 230 watt sharp panels for 2600 to my door. Now these are grade b brand new in box. These will carry a warranty

http://files.sharpusa.com/Downloads/Solar/Products/sol_dow_NDU230Q2.pdf


Then the other option is 10 mx solar panels for 2000 to the door with basically no warranty because mx went out of business


http://www.solardesigntool.com/components/module-panel-solar/MX-Solar-USA/1565/MX60-230/specification-data-sheet.html

niel

Re: Double check my system for me..

getting bargains can be good, but if a few of the pvs have defects in them you will wind up eating them and their costs and that's upfront for then you'd have to ask about what to do if the others develop problems down the road. a couple of sour pvs may make it a break even in costs, but then factoring in future problems makes the non warranted pvs just too expensive given you can get some with warranties at about the same cost then. hope you're following me on this as i've been up all night. i believe the non warranted pvs are a bit too risky for the given price differences.

Fordguy64

Re: Double check my system for me..

Yea that's what I was thinking just wanted another opinion.. I'll probably just end up making this thread my "build thread" too.. I'll be picking up the batteries on Friday all 950 plus pounds of them.. Still haven't decided if I'm going to put all this stuff in the basement or in the garage.. I'm kinda thinking I'll end up putting in the basement just because my garage is a little small as it is..

BB.

Re: Double check my system for me..

A couple of thoughts... Basement the issue of access (carrying batteries) and does/can it flood (you don't want your emergency power to fail during the worst of the weather. Plus ventilation/battery box--You don't want the little bit of acid mist to add to the slow decay rate of basement storage/humidity.

Noise--Inverters+fans--If you are sensitive to noise, make sure that the install does not bother you in the home.

-Bill

Fordguy64

Re: Double check my system for me..

Well it doesn't flood and shouldn't really ever flood.. But who really knows lol I think I'm just going to put them in the garage.. I picked up 8 batteries today and boy are they large.. Now I'm just going to build a work bench over them in some kind of creative way.. Ordered the panels also still waiting on a delivery date for them. Then I just gotta get the inverter and the other misc things.. Still trying to decide on panel placement I'm looking at building an awning over my patio on the back of the house or rebuilding the shed and just putting the panels on it

paulskirocks

Re: Double check my system for me..

Fordguy64 wrote: »

I picked up 8 batteries today and boy are they large.. Now I'm just going to build a work bench over them in some kind of creative way.. Ordered the panels also still waiting on a delivery date for them. Then I just gotta get the inverter and the other misc things.. Still trying to decide on panel placement I'm looking at building an awning over my patio on the back of the house or rebuilding the shed and just putting the panels on it

Wouldn't it make more sense to get everything pretty much installed before getting the batteries? I've also been getting all my stuff together, but figured on waiting until I could actually use and charge the batteries...

BB.

Re: Double check my system for me..

Batteries age from the day they are put together (dry charged or wet filled).

Flooded cells should be charged at least once per month (AGM's probably once per three months) at a minimum.

Never let the batteries set, unmonitored, for longer than a month without checking SG/Voltages and (probably) recharging.

So, yes, I would agree that getting batteries at the end of the project can be less work and lost costs (charging, perhaps a generator to charge if off grid). Especially if you are talking about months between the start and end of the project.

-Bill "in my humble opinion" B.

Fordguy64

Re: Double check my system for me..

Well I work a lot during the week and the battery place was never open during the week when I'm not working.. So I kinda had to get them when I had time.. And I should have the panels in the next week or 2 and all I have to do is click the button for the inverter and what not..

Fordguy64

Re: Double check my system for me..

So I found some spi panels that are new grade A 10 panels at 210 watts each for 1995 shipped or 10 230 watt sharp grade b for 2600 shipped??

Are the spi any good?

Fordguy64

Re: Double check my system for me..

No one has any input on the spi panels? I can't seem to find any reviews on them.. Looks like the company is around and doing well so that's good?

niel

Re: Double check my system for me..

i can't vouch for them personally, but i know of them somewhat. they actually have a place not too far from me (hour or so drive) and i have never gone there to see the place. i emailed them to ask if they sold pvs there and they said yes. i then asked for how much and they did not reply. the place i refer to does, or at least did, manufacture the pvs and used to be 5 miles away from me before they decided to move and were known here as a company called ebara. that is the extent of my knowledge of them for whatever that's worth.