My first solar electricity projet

System · January 2007

Hello,

I've heard too much from my parents complaining about having to pay expensive electricty bill. And I'm not wealthy enough to buy those expensive all-ready solar power system neither, so I'm really looking forward to build something on my own to save a bit. However, I have very limited knowledge regarding electricity work. And I'm also not to sure if living in Canada (snowy winter) would make it not so worthwhile building it. If I can only power the stove or my computer, I'd be really satisfied already. Can somebody kindly orient me in the direction to get at least something started. Any step-by-step plan I can follow to build one? I welcome any recommendation.

Dom

BB. · January 2007

Re: My first solar electricity projet

When you talk about your utility bill--we need to start with the three "C's"... Conserve, Conserve, Conserve... (doing a take-off on the three most important things when buying or selling a home--Location, location, location)...

Basically, look at your bill and break it into the electric, gas, oil, whatever sections and you can figure out how much you can "spend to save"... So, assuming that you get 5% on your money, your break even point for saving $10 per month in your power bill:

Monthly Savings * 12 months/year / Rate of Return = $10 per month * 12 months per year / 5% return per year = $2,400

So, you would break even spending $2,400 to replace a refrigerator if it saved you $10 per month (roughly 100 kWhr per month savings in electricity at $0.10 per kWhr). If you spent more than $2,400 to save $10/month--it may not be worth it. If you spend only $800 to save $10 per month, that is a great deal.

You can plug in the rate of return (or cost of money if you are borrowing) to calculate the break even point (the point at which it costs you just as much to save as to just buy the fuel).

Next, you can look at what it costs you to generate "power".... Power is in quotes here because you specifically asked about electricity, but, in reality, to generate electricity is the most "expensive" mode of gathering power for Solar.... Examples (using US dollars--estimates only--your numbers may vary by +/- 20% more or less):

To Generate 1 kW of electricity, you would need about $5,000 in solar cells ($5.00/watt list price), plus about $1,000 for an inverter (about $0.50 to $1.00 per watt), and about $1 per watt for mounting/wiring. And lastly, about $3.00 per watt for installation (again, these numbers are rough estimates based on my system near SF California--not a cheap place to build--you numbers can be less for labor in your area--and prices will change based on supply and demand for panels, wiring, and your actual labor required). Call it $10/watt installed (list price, no rebates).

For my area (OK sun, not quite facing south, some minor shadowing by trees), my 3,500 watt (STC) Grid Tie system (3 kW PTC rated by California) generates about 4,800 kWatts per year. Assume 25 year life that is:

Cost of Power = total Cost/total kWhr (life) = 4,800 kWhr *90% (20% derating over 25 years) * 25 yrs / $30,000 list price = $0.28 per kWhr--Currently my power cost are between $0.09 and $0.50 per kWhr (typically, about $0.115 per kWhr average) cost.

I have go right now--I will update this post later this evening.

-Bill

SolarJohn · January 2007

Re: My first solar electricity projet

Dom,

I might be wrong, but I'm going to guess that you want to build a system because you're tired of hearing your mom and dad complain that you're wasting electricity. If I'm right, then I have a suggestion.

First, ask your mom and dad if they'll help you pay for a system that will generate all of the electricity that you use in your room. (Don't consider heating or cooling, as that would require a large and expensive system).

Second, make a list of the "watts" needed. Do that by looking at the power requirements of each device. For instance, your computer might use 60 watts, and the monitor might use 100. A 60 watt light bulb uses 60 watts (of course), but you can get a compact fluoresecnt bulb that puts out the same amount of light but only runs at only 13 watts. Add up the total watts, and multiply by the number of hours. For instance, a 13 watt light bulb times 4 hours (52 watts), plus a 60 watt computer times 2 hours (120 watts), etc.

Knowing how much power you need, you can then shop for solar panel(s) and the rest of the equipment to complete your system. Some internet browsing, or back issues of Home Power magazine, will help with the design details. Basically, you need panel(s), battery(s), inverter, wire and wiring hardware, mounting hardware, fuse(s).

Good Luck!
John
http://solarjohn.blogspot.com

SolarJohn · January 2007

Re: My first solar electricity projet

Dom,

I forgot to include a Charge Controller in the list of items you'll need. They start out at about $35.00.

John

System2 · January 2007

Re: My first solar electricity projet

I appreciate the input from you two, but confuse about all the calculation.

To clarify my situation, I've already made some effort to conserve. I'm using CFL bulbs everywhere indoor, LCD for monitor, etc. My parents will also be willing to cover a big part of the expense, if I can convince them of the pros outweighting the cons. I've calculated the total expense for 1 yr of electricity ($2300), which comes down to ~$190/mth. I'm hoping to save at least 10% ($20) per mth if possible.

So according to that formula Bill showed me: $20 * 12 / 0.05 = $4800. I'm not too sure about the rate of return, does it imply that it would take 20 yrs to break even if I were to pay $4800 to get the whole thing set up? That's like forever. I have heard from people saying making your money back in 5-10 yrs.

$4800 sounds a lot to me. Do I need to pay that much just to cover the electricity in my room alone? Am I aiming a bit too high? Just ignore about my idea of powering the stove (I think it requires much more energy). Just my room alone, the PC power supply (300 Watts) + LCD (48 Watts) + 1 CFL (22 Watts) = 370 Watts total. The latter X 8 hrs/day = 2960 Watts/day.

My calculation has to stop here because I can't integrate the rest of your logic with my logic. Can you please help me out with the rest (Q: does it still worth getting the system set up?) If saving 5% sounds more plausible, that would do too. But I'm really confuse right now with all the calculation...

BB. · January 2007

Re: My first solar electricity projet

To Continue with the Solar power discussion, my system performence was based on my location (sun angle, weather, etc.). Your area will be different... So, you need to look at charts like these below to find out how much sun you have in your location:

http://rredc.nrel.gov/solar/pubs/redbook/

It is not real complicated to size a system, but you need to account for losses, seasons, and other random issues (orientation, local shadows, temperature, dust, etc.)... There are lots of other threads hear that discuss the issues to death--Best would be for you to say how much power you need (monthly at least in kWatt Hours), your location, how much shading you have, seasonal use of power, and price of power for your home to get started.

Now, there are other areas you can also generate solar power--and that is using collectors that either use water/anti-freeze. The thermal collectors themselves are much less expensive, in general, than photo-voltaic type. A standard solar electric panel costs about $5 per watt, and a thermal solar collector only costs around $0.50 per watt. So these types are very useful for hot water and space heating.

However, there are more issues with installing thermal solar--have to install pipes instead of wiring, may need anti-freeze, water storage tanks and such. So there are also additional maintenance issues with thermal systems too. The advantages are the thermal panels are 1/10 the cost of solar electric, work better with partial shading, and also are 2-4x more efficient at gathering energy than solar electric panels (less roof space needed for thermal panels).

Anyway, to end this--Spending money on conservation is always the place to start. Solar Electric (and to a lesser extent solar thermal) is an expensive technology and it is always cheaper to first conserve than to generate. If they live in a newer home, there is probably not a whole bunch to do (other than to turn off lights, reduce temperature, etc.). If, they live in a 60 year home, there is probably a lot that can be done to conserve.

Ceiling insulation, wall insulation, double pane vinyl windows (in your area in Canada--probably not needed--in California our older homes have zero insulation and single pane aluminum windows and the rule), weather stripping, looking into replacing any major appliances that are over 10 years old, looking at the heating system to see if it should be replaced with something better, finding any unneeded loads (old refrigerators/freezers, TV's, use florescent lights where-ever possible, etc.) could reduce their bill by quite a large amount.

-Bill

PS: Dom, I see you have posted some more questions... I will attempt to answer them in the next post. -Bill

BB. · January 2007

Re: My first solar electricity projet

Dom,

The formula I gave you gave you was a first guess at whether or not spending the money on any particular conservation project was worth it or not... The 5% I used here assumed that if you put $4,800 in the bank at 5% interest would give you $240 per year in interest ($20 per month). So, in this case, it would be the same if you put the money in the bank to pay for the extra electricity or spent that amount to save $20 per month in electricity. It is not a great rate of return--it is, more or less, the minimum rate of return that I would recommend even attempting to justify a solar/conservation project.

There are other ways to look the costs--like a 5 year payback, which would be the same as using 20% for a rate of return (or cost of money) in my sample equation... Which in this case would mean that you would not want to spend more than $1,200 to save $20 per month. Anything that works for you is fine.

Obviously, if your payback rate of return is 20%, that is much better than 5%.

A really good tool to look at standard plug-in loads (PC's, fridges, freezers, TV's, etc.) is the Kill-A-Watt meter (around $38-$40 USD$). It is available from many places--Wind-Sun does sell them too (however, given import duties and shipping issues, it may be better for you to find a Canadian source):

http://store.solar-electric.com/kiacpomome.html

Generally, most items do not use their nameplate ratings 24 hours per day, 7 days per week--especially if they cycle like refrigerator. The Kill-A-Watt meter is a very quick and nice way for you to calculate how much energy you use.

For your computer, assuming the numbers are accurate, that is about 3 kWhrs per day or 90 kWhrs per month. I don't know your power rates, but for me, that can be anywhere from $0.09 to $0.50 per kWhr (at $190 per month, I would guess that would be typically be around $0.20 per kWhr at that usage tier)--so that would be about $18.00 per month for your room.

Just to give you an idea about conservation (I have natural gas for heating/hot water/cooking), I can get down to about 6 kWhrs per day (180 kWhrs per month) during spring/summer months (2 adults, 2 kids, work/school at home full time). During winter I am about 300 kWhrs per month (sometimes using electric space heaters for just a couple rooms).

As a suggestion for saving energy--my old laptop computer uses about 20-30 watts when running--or about 0.240 kWhrs for an eight hour period vs the 3 kWhrs for your current setup.

But, of course, it depends on what you need the computer for... A low power laptop may not have enough processing power for you... I don't know.

But, in any case, knowing your kWhr usage, and how much you pay for power (in our area, the more power we use, the higher rates we pay--so saving the first 100 kWhrs per month saves us $0.20-$0.30 per kWhr. Whereas saving the last 100 kWhrs per month will only save me around $0.09 to $0.115 per kWhr).

So, in the end, suggesting conservation here as a starting point, if you can use a laptop computer for 90%+ of your work, that could save you about $20 per month (round numbers). If you want a 5 year payback, $20 per month savings * 12months/year * 5 years would indicate that you could buy a second laptop computer (or other lower power computer) for $1,200 (or less) and come out ahead in savings.

You could also install a solar Photo Voltaic system--and depending on your regulatory environment (can you use Grid-Tied Solar system so you don't have to use batteries) to generate 90 kWhrs per month (on average--generate most of your power outside of winter months)--but that is going to be an expensive system and it would probably take (I don't know where you live), at least, 800 watts of panels--at $5 per watt for solar PV panels, that would be ~$4,000 worth of solar panels alone (excluding inverter, installation, wiring, permits, etc.). If you live in an area with poor solar radiation, the amount of panels needed would even be more.

I am going to stop here--because I don't want to frustrate you even more--I am making huge guesses in your costs of power, location, and I have no idea about your other energy usage patterns. I am trying to show how you can see your next steps and/or questions.

Generally, addressing your largest electric loads first is the best place to start to look at conservation (fridge, freezer, lighting, computers, pumps, TV/AV systems, heating/cooling/cooking if electric).

-Bill

Roderick · January 2007

Re: My first solar electricity projet

Hi, Dom.

When a PC's power supply says 300 watts, that generally refers to the maximum that the supply is capable of putting out. The good news is, the PC doesn't use nearly that much. If your PC was made in the past few years, most likely it doesn't draw more than about 100 watts. If you have Windows 2000 or XP, or Linux, you can set your computer to power itself down after a certain period of inactivity. As for the LCD monitor, again, hopefully you can set your operating system to turn off the display after 20 minutes of inactivity. And the CFL is good as is. What I'm trying to say is, your room doesn't sound like it's drawing that much electricity. If you keep an electric heater on, that's another story.

If your parents are concerned that you're spending too much time on the computer, they may very well be right, but the electricity cost would not be the real reason.

Still, an interest in solar is commendable, and possibly the best way to figure out if it makes sense financially is to locate some solar installers near you and invite them to analyze your situation and make proposals. Whether you decide to go with them or not, you'll surely learn a lot about the economics of solar. If the numbers look fishy, come back here, there are lots of folks that can tell you whether they make sense or not. Solar electricity can take 10 or 20 years to pay back, or may never pay back.

Now, if your parents' real interest is in saving money, Bill is absolutely right - conservation pays. Extra insulation is not sexy like photovoltaic, but is a bargain in terms of cost/benefit.

niel · January 2007

Re: My first solar electricity projet

i agree with all that's been said and it sounds like you are getting a better grip on what you use. the kill-a-watt meter is very good in pinpointing real loads, rather than nameplate ratings, and will even show what the totals are over time. you may even be able to throw it back at your parents and make them question their usages.

now you mention a stove and don't say its type or usage(s). you may be cooking with it or heating the room with it or both. if your are cooking with it then i'd like to suggest a microwave oven. for most applications other than wood stoves, the microwave will cook or defrost better and faster than other methods and if done right will save energy/money. taste and appearance can also come into play so start the cooking on one of them and finish with the other in cases like that.
if the stove is for heating it's only good if we aren't talking about an electric stove. electric heat is very expensive as each watt is about 3.4 btus. gas stoves are better, but have to be vented just as wood stoves and still is costly in terms of fuel costs. a wood stove is great if you've got one. btw, the heat can be turned down further at bedtime if you use electric blankets.

crewzer · January 2007

Re: My first solar electricity projet

Dom,

Generating electrical energy from the Sun is indeed a fun and rewarding undertaking. However, I think that $2,300/yr is a lot of money (even $CDN) for residential electricity. By comparison, my family of 4 spends ~US$1,000/yr on electricity (~12,800 kWh/yr) for our suburban home that’s all electric except for gas- and wood heat. My solar energy system offsets but ~2% of my energy use.

Accordingly, I’d second the previous recommendations to look for ways to conserve.

Two investments where the “pro’s outweigh the con’s” are Energy Star (Energy Guide in Canada?) rated fridges and washing machines (typically HE front loaders). For example, the Sears Kenmore models 67172, 67174 and 67179 are 20.6 cf, cost ~US$550, and are rated at 432 kWh/yr, or ~1.2 kWh/day. The larger 21.7 cf models 64232 and 64242 (bigger freezer) are rated at 448 kWh/yr.

These fridges use ~1/2 the energy of units that are just 10 years old. So, a US$550 investment could cut your energy use by ~432 kWh/yr or more, but you’d spend a lot more than US$550 to buy the PV modules, converter, batteries, inverter, and other doo-dads required to generate 432 kWh/yr (~1.2 kWh/day net).

Similarly, HE washing machines use not only less electrical energy to operate, but they use less water as well, which by itself is a triple savings: less natural resource (water) consumed, less energy required to heat a smaller volume of water, and less waste water expelled.

Good luck with your project!
Jim / crewzer

SolarJohn · January 2007

Re: My first solar electricity projet

Dom,

Here are the components of a small system that might meet your needs:

- A 85-watt solar panel ($400)
- A 110ah, 12-volt marine battery ($60)
- A 10-amp charge controller ($50)
- A 125-watt sine wave inverter ($205)

You’ll have to add wire and mounting hardware to the list, but the entire system can be built for about $800.00. This is a good starter system, and you can run cf lights, a computer, tv, radio, etc. You'll have to be conservative with the power you use, but you could also add another panel and battery if you need more.

John

BruceM · January 2007

Re: My first solar electricity projet

Just a quick note: a laptop chosen for low power consumption will typically use less than your LCD display alone.
Bruce M

BB. · January 2007

Re: My first solar electricity projet

Another item which may help save on your heating bills. That is an Energy Recovery Ventilator (I think that is the correct term):

http://www.greenbuilder.com/sourcebook/EnergyRecoveryVent.html

If you are in a very cold and/or hot area, you want to bring outside air in and exhaust the are inside your home. Assuming you have an old home, air exchange was never a big issue as the homes leaked 1/2 of their air (more or less) every hour--so you had lots of fresh are available. With upgraded/newer homes (house wrap, insulation, weather stripping, new windows, etc.), you have very little fresh air exchange (good for saving energy, not good for people living inside with stale air, cooking odors, humidity, etc.).

Basically, if your home is unsealed, you are constantly heating/cooling/controlling humidity as air exchanges "happen". With a "sealed" home, you either have to crack a couple windows to get circulation, or the home feels stuffy.

Get one of these exchangers, you blow out 70F (20C) air from inside the house, through a heat exchanger which then (if it is winter) takes the 70F exhaust air and uses its heat to warm the incoming cold air (and vice versa in summer). So the exhaust air becomes very close to the outside temperature, and the fresh air coming in is very close to room temperature without any additional energy needed (heat/AC) other than just a small circulation fan.

There is at least one person here that has installed a unit and is very happy with its performance.

I don't have one on my home (don't normally need one)--so I will leave it to other to suggest good brands/suppliers.

-Bill

mike95490 · January 2007

Re: My first solar electricity projet

SolarJohn wrote:

Dom,

Here are the components of a small system that might meet your needs:

- A 85-watt solar panel ($400)
- A 110ah, 12-volt marine battery ($60)
- A 10-amp charge controller ($50)
- A 125-watt sine wave inverter ($205)

You’ll have to add wire and mounting hardware to the list, but the entire system can be built for about $800.00. This is a good starter system, and you can run cf lights, a computer, tv, radio, etc. You'll have to be conservative with the power you use, but you could also add another panel and battery if you need more.

John

Don't try to connect this to the household circuits. Only use a powerstrip off the inverter. The inverter here, does not sync with the power company's phae of power, and you will make a lot of smelly smoke if you ty to connect it to the "grid"

System2 · January 2007

Re: My first solar electricity projet

That's a lot of info. It's going to take me some time to digest. Other than making an effort to conserve, is there any other way to bring the cost down in terms of building the system (such as building my own solar panel)?

BB. · January 2007

Re: My first solar electricity projet

You can look for used equipment--Batteries are frequently available if you can find a company that changes out UPS batteries (telephone company, IT servers) on schedule or is doing an equipment upgrade (frequently the new equipment uses much less power so there are bunches of old batteries available).

You cannot really build your own solar PV arrays/panels very easily. Finding used is about the only way to save money--and many times, the used ones are not that much cheaper.

Again, if you want to do something on your own (build it yourself), thermal type solar systems are a very reasonable project. There are two basic types, fluid and air.

The fluid types are probably more complex, especially for your location because of freezing conditions. You either have to drain them before they freeze, or fill them with (hopefully) non-toxic antifreeze. Have been mixed reports here about using antifreeze in recirculation systems (corrosion/plugging issues--possibly in a gas boiler type system--I am not sure).

The other type is to use Air as your medium. You can buy panels for something like $0.50 a watt (vs the $5.00 a watt for solar PV). Build and insulated box, place a metal plate in the chamber painted black, and a glass cover on top. Put this on your roof or next to the house and use a small fan to force air through the panel and exhaust the heated air back into the home.

Really lends itself well to a home project and using recycled materials. Read about one where a guy with a south facing shop wall built the thermal panels right on the side of the wall and used corrugated fiberglass panels instead of glass to heat his shop.

Use Google to search around and you can find quite a bit of information on the rules and suggestions for building thermal panels for home and farm.

There is a thread here with a little more information--and suggestions for pellet and/or corn cob burning stoves (if that material is available in your area):

http://www.wind-sun.com/smf/index.php?topic=1965.msg14142;topicseen#msg14142

You could probably build a panel or two as an experiment just using old sliding glass door (or window glass--make sure that it is not coated with any IR reflective film), some plywood and Styrofoam as an experiment (by the way, in summer these panels can get very hot and you will need insulation that can withstand the higher temperatures--Styrofoam will not).

Hate to say it, but if you are trying to do Solar on a small budget, stay away from Solar Electric systems--they are not cheap. And look at the positive side--if you save $20 in electricity or $20 in gas/oil/wood -- you still save $20 (and with thermal collectors, since they are so much less expensive, you have much quicker payback).

-Bill

SolarJohn · January 2007

Re: My first solar electricity projet

Dom,

I can't seem to find it now, but I once saw an ad for broken and damaged photocell pieces. They still produce power, and you could build your own modules with them if you can solder the connections. However, it's still an expensive option and I wouldn't advise it. New modules, although expensive, have a 20 year warranty and will look better on your roof.

I cut my costs somewhat by building my own mounts. I use 1/8" X 1" angle aluminum. I found a bargain on some of the wiring at a surplus electronics store. I also started out with throw-away batteries from computer UPS units where I work. I started out with a cheap "Modified Sine Wave" inverter, but I wouldn't advise using that for anything but lights.

John

niel · January 2007

Re: My first solar electricity projet

a little extra note on bb's thermal solar panel with air. the fan he mentions can be a quality 12v fan and it can be powered with a pv. no batteries are needed as it shouldn't run when the air inside the solar collector isn't being heated by the sun. you will need to regulate the voltage though to prevent burning out the fan motor. a low end controller can do this(like the sunsavers) or if you have some electronics knowledge you can build a simple regulator. just be sure the components match for power. ie, you don't want a 15w pv(1.25amp) trying to power a fan drawing 28w(2.25amps). another example is too much pv power is being wasted into a fan that can't pass that much power. costs more too. the regulator/controller should handle at least 1.25x what the pv is rated though.

My first solar electricity projet

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