|Four Panels on Roof|
It starts with the panels mounted on the roof of our small two story home. The roof, as you can see, is a very steep pitch, which is perfect for winter sun, and also has a very good south south-west exposure. This picture was taken today at exactly 9:58 AM, to demonstrate how ideal the solar collection time is.
Solar energy was a very exotic, and not very cost-effective means of generating electricity as little as five years ago. Back then, panels were about $4 per watt, and also, to have adequate efficiency, had to be quite large. But things have changed - I purchased these panels this month from a local solar contractor for exactly $1 per watt. They're 250 Watts each, there are four of them, and so 1000 Watts cost me $1000. This is not the only cost of a PVC installation - far from it, and the grand total is far more than that, as I will show you. I still consider it to be not quite cost effective, but it is rapidly getting there, and a lot depends on what you are doing with the power being generated. You can get by "on the cheap" with some, albeit major, lifestyle changes.
The next essential component in a system is the Charge Controller -
|MorningStar 45 Amp Charge Controller|
Let's get back to that Charge Controller before we move on. This one is the best on the market, and cost $500. There are less expensive ones available, but with this device, you really do get what you pay for. In actual fact, it is a battery charger with an electronic brain. It converts the 60-70 Volts DC coming down from the solar panels into the 12V, 24V or 48VDC needed to charge the batteries. The thing is, every battery type has unique charging requirements, as they go through various stages of charging. A Charge Controller such as this will figure this all out and actually improve upon it as every day goes by, as it stores your load demand and charging cycles in it's computer memory. In theory, this device could be not used at all, if you were to wire your batteries in a series 48 Volt configuration, and connect the solar panels directly to them. The problem with doing this is that your batteries, the most expensive part of the whole installation, would be ruined in a matter of weeks or months, because they wouldn't be cycled properly. Potentially dangerous situations could also be created, as your ruined batteries begin leaking acids and hydrogen. The Charge Controller then, is the brain of the system, and in fact, makes real magic happen. I find that after a whole night of discharging, this little box actually recharges my batteries back to full power within two hours of the sunrise, and once it has done that, manages to keep them at "float voltage" for the rest of the day, as the solar panels produce a surprising amount of electricity very quickly, and even on cloudy days; even when covered with a layer of ice and snow!
Next are the batteries -
|4X 139 Amp-Hour Batteries = 556 Amp-Hours|
Many people are building "hybrid" systems that use both Grid-Tie and batteries, with the former carrying most of the load, and he batteries kept charged and ready to automatically kick in when the power grid goes down. This is the "Cadillac" way to go, if you have the money to invest in it, remembering that batteries are still the most expensive bit.
Notice how large (in diameter, or gauge) my wiring is which interconnects the batteries. This is because of a "golden rule of electricity", Ohm's Law, that basically states for any given Power (P) consumption, the lower the system voltage (V), the greater the Amperage (A) (current) is required to transfer that Power. I am using the lowest system Voltage possible (12V - I'll tell you why in the next paragraph); therefore I am creating the need for the maximum possible Amperage at the batteries, and to accomplish this, I require the largest wires at the batteries. Wires this large are expensive, and very hard to work with - there is a better way. Simply wire four 12 Volt batteries in series, and you have a 48 Volt system, which requires 1/4th of the Amperage at the batteries to produce the same power, and this way, you can use wires that are 1/4th of the size.
My problem here is that I locked myself in at 12V with this purchase, from Canadian Tire-
|MotoMaster Power Inverter|
Along with the PVC Panels and Charge Inverter, I also bought one of these-
|Magnum Energy Power Inverter|
|MagnaSine AC Connections|
I've shown you all the major components involved in a basic PV Solar emergency power set-up. I know the vast majority of people would simply buy a gasoline AC Generator for emergency power - all Hardware and Canadian Tire type stores have stacks of these available for less than $500. I know all about that - I once owned one. In fact, mine was Diesel, not gas, because I knew that during an extended black-out, it would be rather difficult to find gasoline, if gas retailer's pumps are subject to the same blackout. A Diesel generator makes far more sense if (like I do) you heat your house with oil, because Diesel fuel and home heating oil (HHO) are the same stuff, and both have a storage life of several years, while gasoline only lasts one year if you're lucky. But the problem with generators is - up until this past Tuesday, we've never had a blackout in the twelve years we've been living here! I never had to use it, but yet, I had to go out and start it up several times through the year to keep it from seizing. I wonder - would a typical hardware store gas generator owner even think of that??? Anyway, I sold the generator last year.
But I still want emergency power. And believe it or not, I'm still stuck with the same problem - sort of. In order for all this equipment, and the batteries, to last, just like a gasoline generator, it all needs to be exercised. Batteries have a shelf life, and the electronics involved will get all corroded inside if they're not turned on and actually used, at least occasionally. But, unlike a gasoline generator, I can actually use my PV system all of the time, which is exactly what I'm doing.
|The Yellow Exercise Wire|
Finally, the matter of safety and protection. The PV system needs to be fused at three points:
|The 200 Amp Fuse Between Inverter and Batteries|
|The 15 Amp DC Breaker Between the Solar Panels and Charge Controller|
|The 50 Amp "Maxi-Fuse ((Automotive) Between the Charge Controller Output and the Batteries|
Also, every piece of equipment in this system should be grounded to the same point:
|Ground Wire From the Solar Panels|
There's a lot more I could talk about here - maybe a Part B is in order? One thing is that the Canadian Tire Inverter is a "Modified Sine Wave" unit, and the MagnaSine is a "Pure Sine Wave" unit. I should explain the difference - another time. Meanwhile, you can probably guess at which one is better.