Wednesday, March 19, 2014

My Solar Power Project

Four Panels on Roof
I haven't mentioned what I've been up to lately, and what has been occupying a bit of my time. I've invested in a small Solar Photo-Voltaic Cell (PVC) project, intended for emergency backup power. You might consider this a photo-documentary of the project, not to mention that these are "photo-cells", and so photography related - they catch light!

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
This device is rather puzzling as to exactly what it does, but in actual fact, it does just about everything. First of all, it can be equated to the Electrical Entrance of your system. Remember way back decades ago when houses were said to have a "40 Amp Entrance"? Yes, your Great-Grandfather's old place might have made do with this capacity, but then, your Great-Grandmother was probably doing the laundry with a wash-board and clothesline, and your "ice-box" was exactly that - an insulated box with real ice dug from the river in the bottom! Houses nowadays must have a minimum 100 Amp Entrance, because our electricity demands are now so much greater. You should now be starting to realize what can be done with 1000 Watts of solar power - the answer is, about the same as what your Great-Grandparents were doing with a 40 Amp electrical entrance! To put it in perspective, my total winter month electrical consumption from the Power Company is just over 700 kilowatt hours. My 1000 Watt PVC installation will provide me with 180 kWh, which is one-quarter of our winter consumption. This is obviously not adequate, but yet, it's pretty close to what our Great-Grandparents might have used. For someone willing to make a major lifestyle change, a four panel installation like I have done might be just all you need.

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
This is actually the part I started with. They were government surplus, and I bought them at 1/3 the retail price. If you buy batteries retail, expect to pay around $1200.00 for this measure of capacity. Like I said above, the batteries are the most expensive, and potentially the most trouble prone part of your system. This is why many people are opting to set up a "Grid-Tie" system, which doesn't use batteries, but instead, connects your AC Power output directly to the Power Company's "Grid". Money savings are realized as your electric meter actually spins backward when your solar panels are producing more power than you are using. This is a great idea, except for one thing - you're still at the mercy of the power grid, and when it goes down, you're completely without power, just like everyone else. I've been worried of late if I actually made the right choice, but just yesterday, my doubts were completely allayed. We actually had a life-affecting 3 hour power outage, just at the time when supper was in the oven! No worries - I simply plugged in our table-top convection oven into my home system, relocated the chicken burgers and fries into it, and supper was ready in 20 minutes! After supper, as the sun was setting, I wanted to do some reading, so I simply plugged a lamp into the system, and enjoyed my book. If I had wanted to watch TV, I could've plugged the entertainment system into the Solar and everything would've been fine. Oh yes, I wanted a cup of hot tea as I read my book, so I put a couple of tea bags into the coffee maker and plugged it in. All of this plugging in is done via running long extension cords around the house, by the way - far from being legal where electrical codes are concerned, but this set-up is for emergency power, much like a gas powered generator. So, you see, the batteries are very useful when the power company has an unplanned interruption.

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
Although it works just fine, it was a mistake - even though it was on sale at a real good price ($300), it was still a mistake. I'll explain first what a Power Inverter does. It's the next link in the chain, after the batteries. It "inverts" the DC voltage from the batteries into usable 120V AC standard household current. This is where your system battery voltage gets "locked in" so to speak. This particular Inverter is more at home in an RV or boat, which strictly use, like a car does, 12 Volt electrical systems. My fateful decision to buy this meant that everything I did from then on had to be set up to work on 12 Volts, meaning that to get full Amperage from my batteries, I need to use much heavier, and more expensive wire, and suffer a moderate loss in efficiency too.

Along with the PVC Panels and Charge Inverter, I also bought one of these-

Magnum Energy Power Inverter
Now, this one is the serious business. It is not intended for RV or Boat use (although it certainly could be used that way). It is designed for long, happy years in a residential PV Solar application - as you can see here, it connects to household AC wiring on the output side:

MagnaSine AC Connections
However, because my purchase of the MotoMaster Inverter, I had to purchase the 12 Volt version of this beast - it is also available in a 24 Volt version, which makes far more sense, and either way, the price is $800. It also has a bigger brother, which puts out 4 times as much household AC power from a 24 Volt battery set-up, for $1875 - a price I was not yet ready for, especially as I would have to triple my Solar Panels and Batteries in order to match it, in which case I would be looking at a complete off-grid system which is wired directly to the existing house wiring too, via that Magnum E-Panel also shown. If you're going to do this, there are some big decisions you need to make in terms of scale versus affordability. My budget this year for this project had to stay under $4000.00, and so my set-up is scaled for an "emergency only" purpose.

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
See that bright yellow wire? That is a heavy duty contractor's outdoor extension cord which runs from the MagnaSine Inverter to the back of the house, where it re-enters, and is connected to our deep freeze and refrigerator - two moderately light loads that are always switching of and on, thus keeping my whole system dis-charging and re-charging in a permanent maintenance mode. It also takes two big appliances off the grid, saving me a little money in the long run. It would be very difficult, with the added cost of gasoline, to exercise a gas generator in this way. Yet, it is essential to the extended life of your system.

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
The final item will be soon replaced with a 50 Amp Breaker Switch, to be mounted neatly inside a box, along with the 15 Amp input breaker. Also, At some point, I am going to build a much safer housing for the batteries, so that the terminals are not so dangerously exposed. This explains my temporary measure of laying that pathetic little strip of wood along the battery's +ve terminals.

Also, every piece of equipment in this system should be grounded to the same point:

Ground Wire From the Solar Panels
I'm waiting for the snow to melt so I can get my ground wires through that hatch into my cellar, where the house electrical ground point is located.

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.

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