# How many 200w pvs?

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• Solar Expert Posts: 4,765 ✭✭✭✭
Re: How many 200w pvs?
Foxtrapper wrote: »
Going solar is like moving into your first apartment...the feeling of total freedom from the parents!:cool:

OK you got that right!!! All the costs at once, I guess I'm kinda glad my folks gave me 2 weeks after high school before I had to start paying rent!

So you want some numbers, I gave you mine, let me do a quick look at yours, loads 800 Kwh a month breaks down to about 24Kwh a day. Every thing starts with loads and this is your know load.

Your minimal solar Insolation will be around 2.3, a guess based on your western NY location. This basically equates to the amount of charging hours you will recieve on average for Dec.

So you must generate and store for use 24 KWH of electric energy and you have 2.3 hours to do it in...

...but, we skipped over a couple things, generate and store costs energy, the panels aren't 100% effiecent, and the charge controller uses energy and the batteries aren't 100% effiecent, so you lose about 25% of your panel rating. The other part is 'for use' inverters aren't 100% effiecent and use some energy also wiring etc draws current, so you lose another 15% of the 75% so begining to end you only get about 50% of the panel value to use per hour of exposure....

Ooops a winter front is coming through, so you need to store enought energy for 2-3 cloudy days, lets use 2 expecting you to ru the genny after that (die hards use 3-4!)

So you need to generate 24 Kwh x 2(for through put) x 2 for cloudy day= 98 KWh in 2.3 hour of average daylight so you need a 98/2.3 = 43 Kw array...

To store 98,000 watt hours in a 48 volt battery bank, you need a 98000/48 = 2040 AMp Hour 48 volt battery...

...Ooops but you can't run the battery dry, you need some extra capacity since your daily use is 24,000 Wh x 1.2 = 28,800 Wh (inverter ineffiecency) 28,800/48 = 600Amp hours consider that the top 15% allowing you to go down close to 50% on those cloudy days. 600 /15 x 100 = 4000 Amp hour 48 volt battery. 48 - 1766Ah 2v cells should work at \$880 each or 4 of these 1720Ah forklift batteries at \$6,800 each They make 48V fork lift batteries, but NAWS doesn't list them.

Then you'll need minor things, I think you can squeek by on 10 midnite classic charge controllers, at \$5-600 each

I'll need more information on how you use you 24 KwH to know what kind of inverter you'll need, but if you just what what you have, 200, 300 Amp service, it'll be pretty ugly, I haven't seen that size, I know Exeltech makes a 20Kw redundent inverter, but I've never seen a price on it, that would get you close to 200 amp service...

Just some numbers to think about...

"Mom I wanna move back home..." Really I love my mother, though they charged me rent 2 weeks after HS they just applied it toward my college expenses...
Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
• Solar Expert Posts: 5,108 ✭✭✭✭
Re: How many 200w pvs?

On the subject of storing fuel, i am sort of an expert, since all our fuel needs to be hauled in the summer, and is stored throughout e year. The reall issue is, the large the container e better. Small fuel tanks and carbs are often the culprit. Stale fuel gumming up carbs is common, end the cure is to live fuel tanks and carbs dry, leaving fuel in larger tanks and drums. We have stored gasoline for several years at a time in 45 gallon (55 us) drums that are sealed. We always try to burn the oldest first, and on blance, with full drums we have never had a problem.

Mixed 2 cycle gas on the other hand does not like to be stored for more than a month or so, especially in tiny cans for saws, weed eaters etc. If, on the other hand, have a ready supply of fresh fuel, it is always better to use it, rather than stirring it indefinitely. My rule, 5 gallon can, use in a couple of months, drum fuel, try to use it in a year or at most two. (I leave all my engines dry when not being used for more than a couple of weeks,, especially chain saws, outboards and snowmobiles.

We also store diesel fuel for years on end with little effect.

Tony
• Registered Users Posts: 21
Re: How many 200w pvs?

"Just some numbers to think about...

"Mom I wanna move back home...""

I guess I will have to do it alittle bit at a time...really just need the heat and the freezers for now. I can put a handpump on the well...get rid of the dryer, and all that's left is the computer, lights, and tv...which I proably won't need anyway..
• Banned Posts: 17,615 ✭✭
Re: How many 200w pvs?
Foxtrapper wrote: »
"Just some numbers to think about...

"Mom I wanna move back home...""

I guess I will have to do it alittle bit at a time...really just need the heat and the freezers for now. I can put a handpump on the well...get rid of the dryer, and all that's left is the computer, lights, and tv...which I proably won't need anyway..

Conservation is your best friend. Money spent on that will return the investment faster and better than anything else. Plus, if you do go off grid you don't have to supply so much power at about \$1 per kW hour. Your 24 kW hours per day is higher than our in-town house, which still has electric hot water and dryer (both of which are on death row). It is also nearly 10X what we use off-grid at the cabin.

Some people think we're a bit weird on this solar forum because we don't tell everyone to rush out and buy tons of solar for every home. Actually we're realistic. People need to know what they are getting in to in terms of cost as well as technology. Otherwise they will be disappointed, and that gives the industry a bad name. There are too many crooks out there in Internet Land telling people they can buy \$100 worth of solar panel and eliminate their electric bill forever. It simply is not so.
• Registered Users Posts: 21
Re: How many 200w pvs?

I did alot of reading pior to starting this project...I had a pretty good idea of what I "could" do with the money I had, just not a good idea of the componets I need to makeup the system. At this point, I am only concerened about the freezers, and the outside woodstove, those are items we can't live without..well, could live without 4 freezers, but....anyway, that's where i'm headed with this..
• Banned Posts: 17,615 ✭✭
Re: How many 200w pvs?

So get a Kill-A-Watt, plug each freezer into it in turn, let run for a few days, and get some actual usage data.
Have paramedics standing by when you read the results; some refrigeration equipment is really awful on power usage!

A sort of minimal 'frige/freezer system would be something like this:
1200 Watt hours per day, supplied by 12 Volt 220 Amp hour golf cart batteries through an 1100 Watt inverter (like the Exceltech) recharged by three KD 140 Watt panels through a 30 Amp PWM charge controller. About \$2,000. You could multiply that by four, or switch it from one freezer to the next to keep them cooled, or size the system up (gets a bit cheaper per Watt when you use a bigger system).

For the wood burner's pumps you might measure the current with a clamp-on meter or interrupt the wiring and use the K-A-W (I don't know the details of how its wired). Depending on the size of the pumps this could be easy, or another big power sucker.
• Registered Users Posts: 21
Re: How many 200w pvs?

Pumps run 24/7, so they proably consume alot of power..
• Registered Users Posts: 21
Re: How many 200w pvs?

Well I bought these...reasonable, and located just 2 miles from my house...no shipping!!

Off-grid solar power system components for sale, settling estate.

New 200 watt photovoltaic solar panels from Sun Electronics Model SV-T-200-fc1, twenty available, never installed.

One new Xantrex Hybrid Inverter / Charger model XW6048.

One new Midnight Charge Controller 150
Panels could be sold individually for \$250 each
• Banned Posts: 17,615 ✭✭
Re: How many 200w pvs?

Ah! There's nothing like buying a bunch of random equipment and then trying to get it to work for your needs. Especially when you haven't determined what those needs are yet! :roll:

The charge controller is great and can be used for a huge number of system designs.
If you got all twenty of the 200 Watt panels you've got 4kW of array which can power quite a bit.
The XW6048 is over-sized for the array, cantankerous in operation, and has grid-tie function which would make it more valuable (you can have GT and back-up power).

Now you need about 600 Amps hours of 48 Volt battery and some appropriate mounting and connecting hardware.
• Registered Users Posts: 21
Re: How many 200w pvs?

"Ah! There's nothing like buying a bunch of random equipment and then trying to get it to work for your needs. Especially when you haven't determined what those needs are yet!"

I'm so good at it though...seriously, it saved alot on shipping, all I got to do is go 2m to get them..how many 6v, 195ah batteries? I got 10 ordered, at a good price..now I have to figure out mounting and wiring...
• Banned Posts: 17,615 ✭✭
Re: How many 200w pvs?

Un-order those batteries if you can.

For 48 Volts you need eight 6 Volts in series.
To get to 600 Amp hours with 195 Amp hour batteries you'd need four parallel strings (you need to go over the minimum, not under it) which is 780 and that's more than you want. That would be thirty-two batteries.
If you buy the standard 220 or 225 Amp hour golf cart/T105's you need only three parallel strings (660 to 675 Amp hours). That would be twenty-four batteries.
If you buy L16 'A' @ 320 Amp hours you only need two strings of eight: sixteen batteries to get 640 Amp hours @ 48 Volts. Much easier to connect and maintain, even though they are more expensive batteries.

Price comparison:
Twenty-four Crown 225 Amp hour 6 Volt batteries: \$3,000
Sixteen Crown 305 Amp hour 6 Volt batteries: \$3,904

Batteries are something you definitely have to do some serious shopping-around for.
• Solar Expert Posts: 5,108 ✭✭✭✭
Re: How many 200w pvs?

Probably the single most expensive misitake in RE!

Tony
• Solar Expert Posts: 10,311 ✭✭✭✭
Re: How many 200w pvs?

maybe they will understand ready, fire, aim better if we put it in other terms.

LOOK,
OOPS
:roll::p
• Registered Users Posts: 21
Re: How many 200w pvs?
niel wrote: »
maybe they will understand ready, fire, aim better if we put it in other terms.

LOOK,
OOPS
:roll::p

I may be doing a gridtie system anyway:D, may do the wind turbine and oddball solar panel on a battery bank to get some experiance...
• Solar Expert Posts: 5,108 ✭✭✭✭
Re: How many 200w pvs?

Except now you will have ten batteries wasting away. Does not seem like a good use of resources, financial and otherwise.

T.
• Registered Users Posts: 21
Re: How many 200w pvs?
icarus wrote: »
Except now you will have ten batteries wasting away. Does not seem like a good use of resources, financial and otherwise.

T.

No, i'll set them up as a backup to the grid if I lose power..for the woodstove or freezers..
• Solar Expert Posts: 4,765 ✭✭✭✭
Re: How many 200w pvs?

Be careful and check with your utility company, some of the Sun Electronics panels don't carry UL listing and can/could be rejected by the utility. Perhaps that's why the former owner decided not to install?
Home system 4000 watt (Evergreen) array standing, with 2 Midnite Classic Lites,  Midnite E-panel, Prosine 1800 and Exeltech 1100, 660 ah 24v ForkLift battery. Off grid for @16 of last 17 years. Assorted other systems, and to many panels in the closet to not do more...lol
• Registered Users Posts: 21
Re: How many 200w pvs?

Former owner passed away...they are settling his estate..that is a good point..didn't think to look for ul listing..
• Banned Posts: 17,615 ✭✭
Re: How many 200w pvs?
Foxtrapper wrote: »
No, i'll set them up as a backup to the grid if I lose power..for the woodstove or freezers..

Just so we're clear on this: the XW6048 must have a battery bank of at least 400 Amp hours (with that 4kW array) to be used at all. It will then provide back-up power if the utility goes down.
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