in the dark and wanting too buy

Skippy · April 2013

Well, I have an interesting story for you guys.

I took 2 of my friends to look at these 218 watt solar panels . . two or three weeks ago . . . and one of them wanted to buy them all (30 panels) and put them up on his house, he lives out in the country and has lots of space to build. Well, by quoting you guys on here, I kinda talked him out of spending a whole bunch of money until, he either reduced his hydro bill, OR had a good handle on his loads - i.e. just how much power DOES he use so he could size the system accordingly , I also asked him where are you going to put them all up ?
In a case of the WORSE timing I have ever seen, we just had a severe ice storm, and this poor guy has been without hydro for the last 4 days . . he is in the dark, and wanting to buy.
As far as I know, right now, he is using his car to power a 1.5 kw inverter to keep his fridge and 2 chest freezers cold alternating one to the other ... running the car for 4 hours turning it off, and starting it again . . . so he doesn't burn anything out . . hopefully . .
I am still sticking with the idea that he has to figure out what he wants to power (loads) and reduce his usage.

I have tried to talk to him about the whole grid intertie and or net metering, but he would still be in the dark now (not helpfull)

So here is the big question for ya : Hypothetically :

If he does go out and purchases 30 - 218 watt solar panels for an off grid system, what would he need to go with it ? He has all the usual power hungry devices such as a 4 ton heat pump - 2 chest freezers - fridge - electric range - electric water heater - you know the standard house.

My recomendations so far : get a wood stove - turn off the heat pump. put in a solar water heater and get a propane on demand for back up - get a propane stove and or fridge to go with the water heater. . . then he can get an electrician to put in a split panel so he can switch to grid if needed . . he already has the lines to his house - then he can figure out what is left over to power.

Any other suggestions I can give ? I have already told him to log on here, and ask BEFORE he does anything, but - since he is sitting in the dark, with no power, he gave me an interesting answer I won't repeat here

:D:D

30 panels @ 218 watts = 6540 watts
At a 13 % charge would be :
6540 watt array* 1/50 (?) bat. charging voltage* o.77 losses * 1/0.13 charge rate = would he need a 775 amp hour battery @ 48 volts ?

too derate the panels, would be 6540 * 0.77 = 5036 watt array. divided by 48 V = 105 amps.

I am trying to talk him out of this large of a purchase, but it gives me the chance to work thru some of the math you guys have been trying to get me to do

. . how did I do so far ? not sure what a 48 V battery would charge at . .

Blackcherry04 · April 2013

Re: in the dark and wanting too buy

Buy a Generator, if he had all the panels hooked up in a complete system the Ice Storm would have compromised them and he'd still be on generator power.

While I have 8.2 kw of solar, it's not in my emergency plan. Thats a bank of batteries and a Inverter serving as a catcher with a Generator supplying the power for the batteries. Yes, I have 2 generators, in case one takes a flake. If none of that works, I am leaving ....lol

Cariboocoot · April 2013

Re: in the dark and wanting too buy

That's what generators are for: occasional power outages to keep the essentials going. Investing thousands of dollars in off-grid equipment for this makes no sense whatsoever. Panels do not work well in storm conditions either, and can be damaged by ice.

Before he goes grid tie with batteries, is it going to be worthwhile? Selling surplus back to the utility?

Sounds like your advice so far has been spot-on in terms of reducing usage of and reliance on electricity.

Couple of ways of looking at that 6540 Watt array:
6540 * 4 hours * 0.52 efficiency = 13.6 kW hours per day (check local with PV Watts to see what can be expected there).
6540 * 0.77 = 5035 / 48 Volt nominal = 105 Amps current (two controllers) and a huge 1000 +/- Amp hour battery bank for up to 24 kW hours @ 50%, 12 kW hours @ 25% (works well with above formula).

The other missing piece is what the maximum load would be at any given time which would determine inverter capacity. But this would not be a cheap (or simple) system by any means.

Skippy · April 2013

Re: in the dark and wanting too buy

He mentioned a generator, but went right on with the solar panel idea, I will have to suggest the generator thing to him again . . . he can always buy a few (4 or 5 ) panels to "play" with - if he wants too . .

I know you can get a special plug installed underneath your hydro meter that automatically disconnects grid power to plug in the genny. . .

Thanks for the input guys, as he is STILL in the dark.. . (no hydro)

Blackcherry04 · April 2013

Re: in the dark and wanting too buy

It's so hard to know what to do. I bought a piece of crap generator 20 years ago. I never took it out of the box for 15 years. It cost maybe $350-$400 has a Briggs motor and 5000w. I used it once for 8 days. It burned a lot of gas, made a lot of noise. All in all it did a good job. What I have now cost maybe $3,000, in the end it won't be any better, it'll just be nicer and easier on me if it happens again in my life time, I am old, so I might miss the next one.

Cariboocoot · April 2013

Re: in the dark and wanting too buy

The thing is, to make full use of that 6kW array you end up buying two controllers, 1000 Amp hours of 48 Volt battery, an outback Radian, and wires, fuses, breakers, hardware, et cetera. So you tip out $20,000 total.

How many generators and how much fuel would that buy? A good inverter-gen and a lot of lawnmower gas. You'd need a really good grid-connect deal to make it worthwhile.

Skippy · April 2013

Re: in the dark and wanting too buy

Cariboocoot wrote: »

So you tip out $20,000 total..... How many generators and how much fuel would that buy?

I am going to have to remember to tell him that one . . good point !

mikeo · April 2013

Re: in the dark and wanting too buy

Then there is an intermediate route, wire the house with a few important must have devices on it on circuit. Put in an array of say half that size and batteries and inverter to handle them. If grid tie is available, then go for a hybrid system. If not size the loads to basically run off the panels during the day and switch to grid when the panels do not generate enough power. This way the batteries are only used as a UPS for the emergency circuit. You would still need a generator to charge the batteries during an extended outage when the Sun doesn't produce enough power. This way you get to use your panels to reduce your electric bill which is not economically justifiable on it on, but you get the backup peace of mind and you need and use the panels all the time.

Skippy · April 2013

Re: in the dark and wanting too buy

Good idea too, at one point I told him to install a split box, bottom half on the batteries, and top half on grid, throw the switch to have the whole house on grid, power goes out, switch back to run essential loads . .

Keep them ideas coming, when he gets power back, (and stops cursing me for suggesting it

;) ) I will tell him to log on here and check this thread out. . .

westbranch · April 2013

Re: in the dark and wanting too buy

A nice QUIET Honda or Yama Inverter genny and some rewiring for essential circuits, food, heat, water would be the cheapest and most reliable, if he still wants to PV it up he can still use the genny...

Timinator · April 2013

Re: in the dark and wanting too buy

I would buy a nice propane Inverter Generator then have two 500 gallon tanks installed and filled. He'll have the extra propane for any heating or cooking requirements that could come up in an emergency and he'll have a source of energy that doesn't go bad over time like gasoline.

Blackcherry04 · April 2013

Re: in the dark and wanting too buy

westbranch wrote: »

A nice QUIET Honda or Yama Inverter genny and some rewiring for essential circuits, food, heat, water would be the cheapest and most reliable, if he still wants to PV it up he can still use the genny...

All true, in my case we had water the first day, then the sewers started backing up because the city had no electricity to run the sewer lift pumps, so they cut the water off. Thats one thing that I didn't plan for, flooded basement. I got a plumber to dig up my sewer line and install a cut-off valve at my property line, problem solved, $1,000. Every situation and location is unique, hard to be prepared everything, it just takes one thing to put you out of business.

kellylipp · April 2013

Re: in the dark and wanting too buy

And the minute you think you have thought of all that could possibly happen, something else will come up. It's called the Black Swan. Before people saw the first black swan they didn't think one could possibly exist. Excellent book and has a lot to say about diminishing returns...

K

Skippy · April 2013

Re: in the dark and wanting too buy

Well, he has the power back on. . . and I have told him about starting this thread. . . Thanks for the input guys, and yes, I agree that you can't plan for everything . . build a super insulated house, run it all off renewables, and have a good bank account - then a tornado comes around, and sends it all to Oz.

Don't even start with the zombies.

niel · April 2013

Re: in the dark and wanting too buy

zombies you need not worry about as i am often plagued by some guy named murphy. that aside it would be the aliens as they are smerter and faster than zombies. pass out the tin hats and keep murphy drunk.:p

solar_dave · April 2013

Re: in the dark and wanting too buy

niel wrote: »

keep murphy drunk.:p

You must know my in-laws!

in the dark and wanting too buy

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