RESIDENTIAL SOLAR ENERGY
As you know I’m Marc. I’m your architect and my goal is to give you the knowledge so you can advance your dream of creating the ideal home for you and your family.
Since last week was all about water conservation and recycling I thought it would be fitting to discuss energy this week. Mostly solar.
Solar can be kind of confusing if your not sure how all the parts go together to create the system.
So to go through the basics and start from the beginning there are two types of solar systems. Off grid and grid tied.
At this moment in 2015 solar is still rather expensive. It takes a lot to make the panels and a lot of money to install and assemble a system that will run an entire home. Because of the costs of each watt is still rather high. Systems are usually priced per watt. In order to reduce the cost, it really pays to research how much energy you are using now and the first thing to do is to see how far you can cut back.
What can you do to reduce your consumption before you try to add solar and meet a very high demand. It is much easier to reduce your usage than to produce your needs.
I want to get right into the numbers here. Your power usage will vary each month typically rising and falling with the extremes in the temperature because a lot of our home energy use is put towards heating or cooling our house. So you could see how adding something like proper insulation or better windows could cut down your energy bill and reduce your power consumption.
Those are both things that you should do before you ever think about going to solar. Otherwise you are throwing more money at a loosing battle.
It is a lot cheaper to reduce your consumption by doing those things than it is to add solar to the roof. Let’s look at an example.
Lets say you use an average over the year of 2000 kilowatt hours each month. Some months it drops to a thousand and other months it is over 2. So we arrive at 2000 per month.
In addition to your energy usage, your bill has the environmental compliance cost the nuclear construction cost recovery the municipal franchise fee maybe and the sales tax. All the fees add up to little over 45 dollars each month. I am going to ignore the fees because the only way you can reduce those is by going off grid. Just going to focus on the usage. Our utility company is charging .087 cents per kilowatt hour. 2000 hours would be 174 dollars.
2000 kilowatt hours per month is costing us 174 dollars.
I am going to go to a system size calculator to make this easy for us. If you go to affordable-solar.com they have a calculator that you can use to customize this to your house. This site is a pretty good site with tons of information and products. You might want to check it out.
I am going to say that we want to cover 100% of our energy usage. You will also need to enter in the amount of peak sun hours for your part of the country. They have a map for you that gives you the peak hours. You are generally looking at 4 hours in most of the country and 6 in places like Nevada.
The website gives you a recommended system. For this example it says we would need a system that produces 20.83 DC kW to cover 100%.
They also tell us some stats below saying that we would add 41,760 dollars to the value of our home. Not sure about that. Not everyone will pay the premium for solar. They also say that the value would be paid off in 20 years based on electric bills.
The largest kit they have goes to 7 kWatts. And it actually has 28 (250) watt solar panels. 28 units. Each one measuring 3 feet by 5 feet. That is 420 square feet of solar panels. About 20 feet by 20 feet.
That is a pretty large area of the roof. To meet our needs of providing 100% of our usage we are looking at 3 of these systems. 1260 square feet of panels. Or 35 feet by 35 feet. So you can start to see how one limitation to providing 100% is simply roof space. Now if you live on a farm and end up putting all these on the ground then your not going to be faced with this problem but if you are planning on putting them on your roof you might have some complications. And this would assume your roof is flat or at least a shed because each change in roof pitch would have to break up the system and they are really only productive in one direction. So if you provide a solar panel on the north face of your roof you are going to get much less power out of it than if you put it facing south.
Of course this is for the northern hemisphere. Anywhere in the us the panels need to be facing south for the best results.
So for this 7000 w system they are making me call for pricing but I am going to see if the panel they list has a price on it. Affordable-Solar is making me call for pricing but I did find one on another site for $ 245 on sale from the usual $ 330. Our system had 28 units and we said we would need 3 of them so that is 84 solar panels at 245 gives us a cost just for the panels of 20,580 dollars.
You will also need the mounting system a series of micro-inverters which I can talk about cables, disconnects.
There is another site called solar home that has a 18 kw grid tie system that claims to produce 2295 kWh per month for 26,000 dollars. Don’t forget you will need someone to install the system if you are not doing it yourself and typically could range from 1/2 to full cost of the system to install. Maybe 15,000 so we are looking at 41,000 dollars.
That is very close to the 41,700 number that affordable solar gave us as added value to the home. That’s interesting.
Remember this is just the simple grid tied system. You would be spending 40,000 dollars and the power would still go out when the utilities go down.
There are a lot of people that don’t understand that when you have a grid tied system and the power from the utilities is down your power is also down.
In order to maintain power you would need to have a storage bank of power. That is achieved by providing a battery bank. Once the power goes out you switch your home to the battery system through a transfer switch that takes you off the grid and isolates your home so you can run everything off the batteries.
So why is that? The reason is that you are supplying a large amount of voltage to the grid. Your feeding the utility company rather than them feeding you, so when their system goes down they have to shut you down. They need to repair the lines and it would not be safe for the people repairing the line to have different systems feeding into the lines from various houses.
In order to meet code there is a switch that shuts the system off during a power outage. And you might be saying that if you went to all this expense to provide an energy solution to your home that you would at least want it to run during an outage. I mean can you imagine how disappointing that would be to have energy at your disposal on your roof and not be able to use it.
The solution is to install with your system a battery backup. A bank of batteries that can power your home when the utilities are down. There is a transfer switch that allows you to disconnect from the grid and run your home from the batteries and power inverter.
Since all batteries store electricity in DC or Direct Current and most of your appliances and light bulbs and computers run on AC Alternating Current you have to convert the electricity to AC from DC.
AC is able to be run over greater distances on smaller wires at a higher voltage than DC. It is cheaper to run than DC would have been so our electric grid was developed using AC which is a cheaper system. Once the high voltage AC reaches your house it is reduced at the transformer to lower voltages before entering your home. Generally 120 volts.
DC power is usually 12, 24 or 48 volts for residential use. The voltage can get much higher. The inverter creates different waveforms to create the alternating current from the direct current. The best wave form for electronics to run properly is a Sine Wave. They make sine wave inverters and this is what you would want to get for your home.
Anytime that you convert electricity there is a power loss in the conversion. That is why a lot of off grid homes that are running entirely off solar (which produces DC power) and storing in a battery bank. This is why they many times will be using a lot of DC appliances. You can get appliances that run off DC but they are made for motor homes, and boats so they are generally scaled down versions.
So if I’m producing my own electricity and I have a storage bank or energy to use, why would I tie to the grid at all? Why not just stay off grid?
If you can, do it. You would be more self reliant, more self sufficient, and not subject to increase in energy costs. But, there are drawbacks because of the amount of energy you can produce you might not be able to produce as much as you need. What if you go through a rainy time and your batteries get depleted. You might be without power. But not likely because you would usually have a way to connect in a generator, either a gas generator or propane. Some kind of generator that would allow you to recharge your batteries if you absolutely had to.
But they are loud. Generators are loud and if you are in the city with neighbors it could have them knocking on your door. But maybe if they do you could invite them in to watch some tv while their power is out because of some storm or other random power outage.
If you are off grid you are using all your own power that you’ve stored. But if you are grid tied you are actually selling all the energy you produce to the electric company. Then you buy back the electricity from them. The reason this is because they get more money from green energy. People pay more for green energy so the more credits they can get the better they like it.
I want to get into numbers here again. So right now on the Georgia Power website they are stating that they will pay a premium price of 17 cents/kilowatt hour.
But the first expense you will have to pay is to have a monitoring meter installed by Georgia Power. There is also a monthly metering fee of $4.50 for single-phase and $11.20 for poly-phase.
For your home you will most likely be using single-phase. $4.50 per month and 17 cents per kWh. Our 40,000 dollar system from earlier was producing 2295 kWh per month. 2295 x .17 is 390 minus the 4.50 so 385 dollars each month. That would be nice, and would pay off the system you purchased in 8 and a half years. But, Georgia Power has a limitation. They limit it to 1500 kW. So you are looking more like 250 dollars. which would take 13 and a half years to pay off your system. This is why it is almost more appealing to put in a smaller system. One that just max’s out the allowed by GA power and install it in a way that it can be expanded to accommodate more, since they do mention on their site that they will be increasing their limits.
Currently the website says there is a waiting list. So you cannot even join the program until you reach your turn, because the power they buy from you at the 17 cents they want to sell that to people at a premium since it is green energy and right now there are not many buyers that are willing to pay the higher premium for green energy.
So until the costs to produce solar panels and all the equipment involved drops the payback might not be there. This is an interesting figure that I heard the other day. Someone was talking about the government bailouts and all the quantitative easing numbers. So this chart I saw on Heritage.org is interesting.
It shows the total amount of money printed by the federal reserve since 2007 to be 4.4 trillion. 4,400,000,000,000.00 dollars. If you took that number and divided it by the 40,000 dollar our system would have cost. We could have put very large solar systems on 110,000,000 homes across the country. The total us population is 318 million. and the average household is 2.6 so we would almost, almost cover the entire united states with solar power. Imagine the independence this country would have then…
Instead where did the money go? I’m not sure either. Well, way to end the show on a depressing note… our gloomy future.
But there is a bright side. Solar is becoming more and more popular. It is becoming easier to get and the panels and equipment is getting much simpler and more reliable. New innovations are being developed, new products and people are at the point now where they are actually considering it as an option.
Companies are developing new ways for you to afford solar by working out leasing options for grid tied systems. The technology is there ready to be widely adopted.
If you want me to dive into solar on a deeper scale let me know. I can get into each piece of equipment and all the different manufactures. How connections are done and all that. So if you are interested in hearing more let me know.
I hope that you are having great success with the planning and construction of your home. If you want to get in touch with me please reach out to me on twitter or google plus.