Another Noob....

System · April 2008

Hey guys!

Just wanted to introduce myself. I'm a licensed, self-employed electrician and I want to set up a small system as a pet project. I have no intention of adding this type of work to my daily routine, but I want to know how it works, and if its a feasible alternative. I currently have the majority of my home on backup generator, but I lose power very infrequently. Maybe once or twice a year for an hour or 2.

I have Reef Tanks that consume an enormous amount of power and I doubt if I'd ever be able to produce enough to maintain those. So all I'm looking to do is power my desk, which consists of a full size dell XPS, flat screen monitor, speakers,....oh and a 40" LCD TV:roll:

I do have a 12X24 roof directly outside my office with a 1/12 pitch that faces southwest, so any wiring wouldn't have to travel more than 20 feet.

I just ordered the Kill O Watt and as soon as I put some numbers together I'll have 100 more questions for you guys....

Thanx, Butch

BB. · April 2008

Re: Another Noob....

My two cents... Look at grid tie solar (if your local utility allows utility interactive solar PV systems) and keep the generator for your emergency backup...

Will be the easiest and most cost effective use of solar power. If you want a battery backed solar system... You can look at the new Xantrex XW system... Is very neat (but not cheap).

-Bill

niel · April 2008

Re: Another Noob....

i agree with bill that unless your pet project is to either totally power or just be backed up with solar rather than the generator, then you should go batteryless grid tie. if you opt for battery backed grid tie or an independant off grid system, that batteries and pvs will need to be chosen more carefully and will depend on the total power to be used over time. i assume that was what the kill-a-watt meter was bought for?

System2 · April 2008

Re: Another Noob....

I'm definately planning on a battery backed system, but I intented to be simply independant. Whatever I choose to run, I want operational 24/7 from that source, and I highly doubt that I'd ever be capable of producing enough power to consider grid tie.

mike95490 · April 2008

Re: Another Noob....

whatevva wrote: »

I have Reef Tanks that consume an enormous amount of power and I doubt if I'd ever be able to produce enough to maintain those.

all I'm looking to do is power my desk, which consists of a full size dell XPS, flat screen monitor, speakers,....oh and a 40" LCD TV

I'm definately planning on a battery backed system, but I intented to be simply independant. Whatever I choose to run, I want operational 24/7 from that source, and I highly doubt that I'd ever be capable of producing enough power to consider grid tie.

So if you think you can't produce enough for grid-tie, which is about the MOST efficient way, modern inverters are at 95% efficient. Battery systems are MUCH less efficient. And if the grid drops off, how do you keep the reef tanks alive ?

There are MANY small grid tie systems on line, ranging from 800W - 5KW arrays. No maintenance, except to wash dirt off the panels.

BB. · April 2008

Re: Another Noob....

Realistically, Grid Tie is pretty close to ~95% efficient at converting energy from your solar panels to AC electric power... Power that can either be used in your home or "stored" on the utility network for up to one year (if you have Net Metering with a 1 year billing cycle).

An Off-Grid system, you loose another ~20% and another ~15% for inverter loses (in addition to the 95% efficiency of a charge controller). ~65% efficiency vs Grid Tie.

And, given that you can probably never use 100% of the energy collected (on average--you can never store more than ~1-3 days of energy from an "average" sized battery bank) from your off-grid system--You probably will get, at the very least, twice the amount of energy for half the price vs a reasonable grid tied system (from a given set of panels).

So back to your original question "...I want to know how it works, and if its a feasible alternative..." Yes, it will work just fine, it is "feasible" in the sense if your load is less than available solar panel power, it will work fine.

But, if "feasible" means cost effective, spend the 2x costs that would have gone into building the home off-grid office and instead install a 2x larger grid tie system (again, assuming your power company allows grid tied solar + net metering). You will get a much better return on your money.

In the end, if you want to build a small off-grid system for your home office with AC Mains/Generator backup--by all means go for it. It will work well as a large UPS with "silent" backup power. Get a nice true sine wave inverter with AC input and internal charger (Outback would be a nice choice), and you can have the best of both worlds... AC power when your batteries are low, quick recharging if "we" get rolling blackouts in the next few years, and still have the solar panels for green operations.

-Bill

Another Noob....

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