Please Help Me Finish My PV System

Tuber

Please Help Me Finish My PV System

First time post here.

WHAT I HAVE SO FAR
- Right now I have a Xantrex PowerHub 1800, with an additional battery box. Some specs: It is a MSW inverter, it has a surge power up to 2880 watts, continuous up to 1440 watts. It can receive up to 1000 watts of RE (renewable energy). You can read about it here.
- I have a 440 Ahr AGM battery bank, 12 watts DC, of four batteries total.
- My house has a whole house automatic generator with a automatic transfer switch. I can plug in the PowerHub to recharge the batteries during days of no sun.

WHAT I PLAN TO RUN
- I would like to run a few 120 Vac LED lights, a fireplace blower/fan, and a 25 cubic ft refrigerator/freezer that (according to the yellow tag energy guide) uses 477kWh per year. Eventually, I plan on hard wiring the PowerHub, so I have a separate off-grid AC outlets throughout the house. Please see the attached spreadsheet. The spreadsheet is someting I came up with. It allows to calculate what you need for solar panels and batteries.
- Question: What kind of problems could I have with a MSW inverter? What could it do to my refrigerator?

ADDITIONAL INFO
- I live in central Virginia. I have some electrical and carpentry skills. I can only budget about $700 per month on my PV project. I plan on running the PV panel, landscape orientation, across the top of the house. Please see the attached picture of the house to see where I am going to place the PV panels. - First, I plan to purchase the PV roof mounting panels, then the charge controller, finally the PV panels. I can only spend about $700 per month, so I will do this in phases.
- Question: I live on the east coast. What RE vendors do you recommend that have decent shipping costs? Northern Tool has where I can pick up the PV panels to save on shipping costs.

WHAT I NEED
PV Roof Mounting Brackets
- I plan on running my panel landscape orientation across the top of the roof. I have asphalt shingles on a plywood roof.
- Question: What is the best cost effective PV roof mounting brackets that you all recommend? Something that does not leak!!

Recommended PV Panels
- According to my measurements, I can runs the panels in a landscape orientation across the top part of the roof, just below the peak of the roof. I am going to run two groups of PV panels. One set to the left of the large center dormer, the other to the right (see picture). The measurements for each group is: 250” inches long, by 54” inches deep.
- Question: Who do you recommended cost effective wise for PV panels based on my power needs (up to 1000 watts) and measurements? Ideally, I could have a total of two 500 watt panels, one on each side of the center dormer, as long as they do not exceed a depth of 54 inches.

Charge Controller
- Question: What is your best cost effective 12v charge controller?

Additional Items
- Question: Wiring Gauge Size: What gauge wire do you recommend to run from the PV panels sets, to the charge controller (assuming I am running 1000 total watts from all my PV panels)? I figure the run from the closest PV panel to the charge controller is 125 inches, from the charge controller to the PowerHub is 70 inches.


Thanks to all who read this and help me out!

Cariboocoot

Re: Please Help Me Finish My PV System

Welcome to the forum.

Let's see what we can do to help.
What problems would you have with an MSW inverter? Some things won't run at all on it, some will run poorly, some will be fine. You just don't know until you try. I got tired of listening to my refrigerator clatter ever time is started on my Xantrex MSW inverter, so I bought an Outback sine wave.
I don't recommend any equipment dealers as I'm not in the same country even. But I will suggest you look at the forum host NAWS http://www.solar-electric.com/ if only to get an idea what sort of equipment is available and at what prices.
I don't recommend specific roof brackets either, as they have to meet local codes for install. Really it's an "as per" basis, but any of the commercial mounting racks ought to be good enough 90% of the time.
You're not going to find 500 Watt panels. Not yet, anyway. 300 Watts are 'new'. You will also find that the large panels are difficult to handle as they are large and heavy and fragile. They are also not going to be "12 Volt" panels. Meaning if you want to use them on a 12 Volt system you'll need an MPPT type controller to adjust the output Voltage. These are more expensive than PWM types of course.
440 Amp hours of 12 Volt battery would need about 685 Watts of panel. Much depends on the exact installation.
The size of the wire will depend on three things: the length, the amount of current, and the Voltage being used. This is one of the last things to be determined after you pick the panels and controller.

Not much help, I'm afraid, but at least it's a start.

vtmaps

Re: Please Help Me Finish My PV System

You need to rethink your system before you spend any more money. For starters, you need to raise your system voltage to 24 or 48 volts if you are going to be running a 25 cu ft fridge along with your other loads.

It would also help for us to give advice if we knew what you hope to accomplish with your system. Are you on the grid? If so, you should know that what you are planning will not save you any money. Do you have frequent or long lasting grid outages? If not, a generator is the most cost effective way to keep things running for occasional outages.

--vtMaps

icarus

Re: Please Help Me Finish My PV System

Ready, fire, aim!

Defing eyour loads, both daily kwh and peak Watts, and relay the info to us, then designate entire system around those loads. Any other design path is a recipe for a "camel" system.

Welcome, and keep in touch,

Tony

Tuber

Re: Please Help Me Finish My PV System

Just to clarafy, the 25 cubit foot fridge is 120 Vac. They system that I have so far is 12 Vdc. Please correct me if am wrong, but If I have 1000 watts of panels, the inverter puts out 1440 watts, and a battery bank that has 440 amp hours, I thought I would have enough power.
I want just enough power to run the ref, a few LED light bulbs, and a fireplace blower fan.
To answer your question, I am on the grid, I have have a genny, but we have long lasting power outages.

Thank you

icarus

Re: Please Help Me Finish My PV System

Unfortunatly you thought wrong.

You need to understand some essentials about PV and batteries. I suggest you read and understand the following links:

http://www.windsun.com/Batteries/Battery_FAQ.htm#Lifespan%20of%20Batteries

http://www.batteryfaq.org/

Then, you will realize, for example that it takes more power to recharge a battery than the battery can give back...tot he tune of about 20% more. For example, if y draw 100 ah out of a battery, it will take ~ 120 ah of power to put back in the ener taken out.

Second, y need to realize that the are multiple system loses in any PV system, but it is especially bad with a batter based system, nearing 50 %! PV loses, wiring loses, charge control loses, basic battery efficincy (loses) inverter losses etc.

My rule of thumb is this,, take the name plate rating of the PV, divide by two to account for ALL CUMULATIVE system loses, then multiply that number by 4 to account for the average hours of GOOD sun you can reasonably expect, on average, per day over the course of the year.

So, for example, 1000 watts of PV might deliver something like this:1000/2=500*4=2000 watt/hours/day. (WH/day)


Your 440 ah of battery will deliver ~200 ah of power before being discharged to 50%, (or ~2.4 kwh)

Once again, define your loads, and design the batteries around those loads, and then the charge regimen for those batteries.

Tony

Tuber

Re: Please Help Me Finish My PV System

"Once again, define your loads, and design the batteries around those loads, and then the charge regimen for those batteries.

Tony"

Tony, thanks for the calculations.

I am coming up with a load of 1619 watt hours per day. That is from my spreadsheet (see attached). I do not have a kill-a-watt device to see how much my ref uses per day. I got the daily kWh per day for the ref from the yellow Energy Guide. It says that the ref/freezer uses 477 kWh per year.

If possible, I respectfully request that you review it, and please tell me if the numbers make sense. I am aware of the inherent inefficiencies a PV system. I did calculate the inefficiencies in the spreadsheet. Let me know if you agree with my calculations.


Thank you.

westbranch

Re: Please Help Me Finish My PV System

Please explain what you did in your spread sheet.....???

I do not understand what you have done, items are listed and miraculously drop from the calculations. AS I see it the 3512Wh is your demand/load figure

2Guido

Re: Please Help Me Finish My PV System

As a newbie and have learnt the hard way...First of all, a MSW Inverter does not like LED bulbs as well as Motor devices. For example, ceiling fans will have an annoying hum, and LED dimmable bulbs will flicker when dimmed or may not dim at all. What I have learned also is where my energy is being sucked away...like cable boxes, computers, satellite boxes so if you are into saving some $$ off your electric bill then the Solar experience will certainly educate you on this. You need massive arrays and massive storage and a good charge controller to put together a system that will get you off the grid for an appreciable amount of time each sunny day. But remember, those batteries need to be properly charged to keep your system efficient...Hope this helps.....

Tuber

Re: Please Help Me Finish My PV System

You are right about some of the calculations being incorrect for the applicances.

For now, please go with my total watt hours in cell L16. For now, I just wanted to calculate the total watt hours for 2 CFL bulbs, the 25.1 cubic ref, and the fireplace blower.

I came up with a total of 1619 (cell L16) watt hours per day for the 2 CFL bulbs, the 25.1 cubic ref, and the fireplace blower.

Thanks