Grid vs. Off-Grid

Re: Grid vs. Off-Grid

Grid: Power supplied by electric utility company

Off-Grid: Your own supplied electricity system cut off from Grid

Which is better ? Obviously not paying the utility company for something that can be created FREE. Well, you have to fork over tens of thousand of dollars in some cases to go off grid.

We all know how Grid systems are used.

There are partial Grid/Off Grid systems. My friend has a 1kw Solar array fed into an inverter and wired up directly to the telephone pole.
Off Grid systems depend on the amount of electricity they produce.

How do they function ? Someone else can answer that one who can more appropriately answer it.

Re: Grid vs. Off-Grid

indirect question on cost.

youve mentioned batteries are 3-10 years
how long does inverters, controllers, wires last? assuming indoors and you leave them alone, always on.

Re: Grid vs. Off-Grid

[Regarding temperatures--The Engineering Rule of Thumb is for every 10C increase in temperature, you cut the life by 1/2... 30C increase is 1/2*1/2*1/2=1/8th the life. Also works the other way, cooling by 10C would double life.]

assuming 10 years (5-15 years average) is the baseline... what is the baseline temperature to work off these general calculations? 20C?

Re: Grid vs. Off-Grid

While I don't have the 20+ years of background that PhilS has I;ve been off grid most of the last 10 years. In that time i Have had one controller failure a small scs unit that lived 5 years for me inland and 2 years on my sailboat and 3-4 years on my dad's pontoon boat before failing, pretty good for a saltwater enviroment the last half of it's life.

I've also had an inverter failure, a cheap no name quasi sine wave (not a true sine wave but lots of steps) Likely I could have saved it if I paid more attention to it, The cooling fan failed and I just opened it up and ran a small fan over it continuously. worked that way for @ a year before releasing the magic smoke. I hadn't paid much for it and got what I paid for. it liked it's input voltage 22-30 volts so every month it kicked out when I did an equalizing charge, so perhaps that helped shorten it's life. I had already purchased a never used Prosine 1800, a better option as it lives outside.

I do buy lots of used equipment. about 8 years ago I paid @$2 a watt for 3 - 55 watt French Photowatt panels made in the late 70's, when I moved 3 years ago they were producing @ 80% of their rated value (sorta, at least functionally with a 60 charge controller, measured amperage off of a Trimetric, it's rated 18+ volts could have been reduced, measure input over 2 hours at solar noon. New panels are often in this range!)

I have an old 30 amp SCSII (don't think thats correct but close) charge controller that is close to the same vintage as the panels, that was functioning fine when taken down 3 years ago for the move.

While off grid, I have no backup generator, so I, Like PhilS, have spares of most anything I need, it comes with growing a system and may be the single biggest uncalculated expense.

With bargain hunting, and installing the system my self, I figure I'm about as cheap as a home system can get. BB stated that "Grid connect" going green, I think this is an important point as most off grid systems will not produce and use as much energy as it takes to create the panels and recycle the batteries. I find lots of people who think I'm "going green", and I don't doubt that having and maintaining an off grid system I use a lot less energy than grid connected people, only in this way is an off grid system green.

I'm not saying it can't be cost effective, if you have a long run to grid connect, or very high user fees (local Elec. charges $25 per month, here before you buy any elec. or I would be grid connected)

Re: Grid vs. Off-Grid

I think that the previous replies demonstrate some of the reliability of the hardware. I think a more basic question is "What is it you are trying to achieve?" I think it is clear that grid tie or off grid, or hybrid systems all have a place, and have shown themselves to be fairly reliable. The $64k question with off grid is life cycle battery cost/versus amount of net draw over the life cycle.

So by asking the "Why?" question you might come up with a multitude of answers, many of which are in some conflict with one another. For example, if your goal is to "stick it to the power company" and go off grid, you will most likely find that that is a fairly expensive endeavor. If your are trying to reduce your total environmental impact is going grid tie, and being able to effectively "use" 100% of your output "greener" than going with a battery based system, and therefore not be able to "use" 100% of your power. Additionally with an off grid system, basic system efficiency will be considerably less ~50% net/net for a battery system vs 90%+ for a grid tie. Additionally you have the issue of manufacture/disposal of potentially toxic batteries.

If it were I, and I had grid available, and I had money to spend on PV I would go batteryless grid tie any day of the week. I think you get more bang for your buck, have fewer failure points, and are most likely doing the best for the environment.

That said,,, as Bill and other have suggested I wouldn't even consider going with PV for any reason until I had done EVERY conservation improvement I could think of, and then some more! As I have always suggested, it is crazy (IMHO) to fire up a big grid tie system and not replace the light bulbs in your house with good CFLs, or insulate the attic or what ever. I also suggest that dollar for dollar solar hot water, in most climes is a faster payback investment.

So, do you homework, read and understand all you can, ask all the questions and you will begin to see what answer is correct for you. By doing so you will avoid the most expensive pitfall of all RE and that is the Ready, Fire, Aim syndrome.

Good luck and welcome to the forum,

Tony

Re: Grid vs. Off-Grid

As posted before, I have a large hybrid off grid sytem which was not cheap but brings satisfaction and independance.

For what I spent on our system, sure, I probably could have brought the grid to us but the problems that come with it too. Most important bringing the grid nearby would have put the ranch's conservation value and our lifestyle in jeopardy.

We balanced these considerations with living comfortably. Everyday, we work very hard on the land and reward ourselves.

I have come to understand there are many types of "value" in this life. Everyone has a different opinion of what "cost" is when compared to how you want to live.

Re: Grid vs. Off-Grid

I'm a bit of an oddball in this. I live right in the heart of suburbia, with a (traditionally, anyway) reliable grid, yet I installed a small off-grid system. The reason? I sat for a couple days with no power after an ice storm, and other areas were out for - in a few cases - almost two weeks! I can't imagine spending all that money on a grid-tie system that's useless if the grid goes down - I'd at least want a hybrid system.

I know the "cost effective" answer to that is to buy a generator. But who wants to have to feed a generator 24x7, or even just all day? I live alone, so when I'm asleep or at work I can't have it running yet still want some backup. I could have gone with just a big UPS, but I have always liked solar and wanted something to play with - not a bank of batteries that sat there doing nothing for a long time.

I did consider doing a hybrid system, using either the Xantrex XW system or adding an inverter to the Outback FM-80 I currently use, but I did draw the line there over the added cost. I still have some other things to do with my cash before I go that far... I also (again) like to be able to experiment with the system, and going grid-tie requires inspections and such, which means I'm not as free to tinker or change things.

My small system won't run the whole house, but it keeps the ham radio bench, a computer and internet connection going 24x7, and if/when the outages do happen I can run lights and the fridge off of it. Without the drone of a generator! 8) Although I do have a small generator as well, to run larger loads like the furnace.

I've already used the system in outages too. This past summer, I have had two mornings where the power went out for over two hours. Both times I was busy working on the computer - and didn't miss a beat. I was also able to light things up so I could make breakfast, shower and dress, all the usual morning things. The last one, all my clothes were halfway through drying in the (gas) dryer. Plugged it into the inverter, and was able to let it finish the cycle. (At 5:30AM no less, I wouldn't have wanted to drag a generator out that early anyway!)

For the first 25-30 years of my life I don't remember ever having outages more than 15-20 minutes, and those were quite rare too. The past few years have been awful. I've had two multi-day outages due to ice storms, and a number of hour-long or more outages for - well - who knows why. The power company never says!