Saturday, May 30, 2009

My Off-Grid Photovoltaic System and This Blog

You might have noticed a decline in the number of posts to this blog since the first of this year. The decline is primarily due to the fact that my off-grid system hasn’t changed much over the past 6 months. I’ve slowed down because I now pretty much have what I want; a system that can meet my basic needs for electricity during a grid power failure, and one that provides enough energy to significantly lower my electric bill. I’ve also added automation to my system, providing additional protection for my batteries while optimizing power output.

I’ll probably never have enough PV-provided electricity to meet all of my needs, but I can get by pretty comfortably most of the time with the system I now have. It’s important to mention that my need for electricity during a grid-power failure varies with each season. Lengthy periods of cold weather provide the greatest challenge. In addition to the electricity needed for lighting, refrigeration, cooking, and communications, I’ll need electricity to keep my home warm. I can easily use up all of my stored energy during extended periods of cloud cover. With that in mind, I plan to add another PV panel this year, and one or more next year. Other than that, I have no other significant upgrade plans. I’ll maintain this slow but steady progress unless I see a dramatic increase in the cost of grid-supplied electricity, or a dramatic decrease in the cost of solar panels. I hope to drive an electric car within the next two years, and I would love to power it with solar. This is not practical now, with PV panels costing $5.00 per watt.

Here is an overview of my system:

Type: Off-grid
PV: 7 X 85, or 595 watts
Batteries: GC2’s wired for 12 volts, 900ah.
Spare Battery Bank: Marine Deep Cycle, 420ah.
Controller: TriStar 60 with meter and remote temperature probe
Inverter: Exeltec 12-volt, 1100-watt pure sine wave
Automation: Morningstar Relay Driver programmed to enable/disable the inverter and an Iota Transfer Switch

When I started installing solar PV, my primary goal was to become more self-sufficient, especially in the event of a major disaster. From time to time I need to remind myself that water and food are much more important than electric lights in the event of such a disaster. That’s why you’ll find so many articles about growing and preserving food in this blogs archives. You’ll also find articles concerning alternative heating, another necessity for surviving in the event of a loss of natural gas and grid-supplied electricity.

I hope that you’ll browse my archives now and then for ideas, and comment. Let’s learn from each other.



Damon said...

Hi SJ,

I was getting worried that you'd gone all quiet!

With ~3.9kWp then we do seem to be on target to be net generators over the year (at the moment we're generating about 4x what we're using each day), though as you say when you need it most in cold weather there's least available! (Just running our mains gas central heating takes ~1kWh/day for example.)

We're still working on improving insulation to reduce the need for energy in winter...



Gerald / EnergyNovice said...

Hi John,

Great postings.. it looks like i'm on the same path as you but you are way more ahead. :). I would love to get my solar panel system set up this year and I'll be learning a lot from your experiences. I will also be blogging about it at my EneryNovice site. I definitely will be starting small because of my budget but it should be easy to extend every 6 months or so. Thanks again!

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