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What is solar energy? All "fossil fuel" comes from past ages of sunlight breaking up Carbon di-Oxide (CO2) into Cellulose and other burnable Carbon plus free Oxygen via photosynthesis. The sunlight is "stored" in this form until It’s released, usually by burning, and returned to CO2. There's a natural "cosmic carbon cycle" converting CO2 into plants, which decompose into peat, then into shale oil, coal, petroleum, and, at the deepest wells, natural gas, and then, over the ages, carboniferous rock, which is occasionally returned to atmospheric CO2 via volcanism. Our yearly burning the fruits of millions of years of sunlight is not sustainable; but our living on one year's sunlight each year would be. Simple calculations show that there is more than enough sunlight landing on unused roof space to generate all our current electric, plus make enough electric to replace gasoline in cars. Solar power dwarfs all other power sources. The American Solar Energy Society (ASES.org) estimate of current world total power demand is 18 tera-Watts (tW), but the sunlight landing on the Earth each day is on the order of 160,000 tW. First, let's distinguish between solar hot water and Solar electric. Both are pollution-free, but vastly different in complexity. There are three kinds of solar hot water systems: simply pumping to dark panels in which the water is heated; passively using city water pressure for pre-heating the water; and more complex domestic hot-water systems pumping cold water up to high-temperature panels. Solar hot water involves an entire technology unto itself. Here, we only deal with solar Electric. Roof-integrated solar panels, also called thin-film, operate at a lower voltage, higher temperature, and are less efficient than silicon panels. Usually, they are mounted flush to the roof, without an air gap, and this generates excess heat. These are much less noticeable, much more aesthetic, but mostly appropriatge for use in colder climates where they are more efficient. Most installations in warmer areas use glassy-looking silicon panels that weigh about 3 lbs. per square foot, about the same as a layer of composition tiles. They are mounted with about a 6" air gap, so that they run cooler and the building lives under shade.
Almost all solar Photo-Voltaic power production systems ("PV") are hooked up to the electric utility grid. PV produces more electric during daytime periods of peak electric usage, when it's needed most. Often, the utility will "pay" extra credit for daytime production via Time Of Use (TOU) tariffs (rate structures) for this help meeting daytime peak demand. Utilities have to plan to meet the peak, because any outage would affect many people. Without solar or other "peaker" units, they would have to build a new power plant which would sit idle 20 hours per day, an extremely expensive waste. So solar saves them money, and leverages private rooftop space and uses mostly homeowner money which would otherwise have to come from their capital expenditure budget. There are two types of PV systems, GRID-TIED and BATTERY-BACKUP, which differ based on the type of inverter and the voltage at which they are wired. It's difficult to change from one to the other, so you pretty much have to choose from the get-go which you want. Both GRID-TIED and BATTERY-BACKUP PV systems pour their electric into meeting your home usage first; any excess travels out to the grid, helping meet your neighbors' usage. This helps take some of the load off of local pole-mounted transformers, many of which are overloaded and fail during "heat storm" periods of excessive usage. Both GRID-TIED and BATTERY-BACKUP PV systems are required (by NEC 1741) to shut off the grid connection if the grid goes down, because it might be dangerous for those fixing the electric lines.
sunny day when the batteries get recharged, or until the grid comes back up. If your whole house is backed up, you won't even know the grid is down. This inverter is also "smart" enough to turn on a generator backup, if you have one; but most solar homes design their battery backup to last for two days, on the theory that it's enough to go temporarily or permanently "off-grid" for emergency usage. This type of setup also requires a CHARGE-CONTROLLER to avoid excess solar energy burning out the batteries, in the rare event that the grid goes down for an extended period; on the downside, you need space for the batteries. The BATTERY-BACKUP system is the same as an OFF-GRID system where there is no grid. The same equipment works for off-grid systems in places where there is no electric service. Note that you can install battery backup for your home whether or not you have solar panels.
There are two reasons: saving money, and becoming empowered. There are few feelings more powerful than making your own electric power. Sometimes it's a combination of the two reasons. In both cases, before doing solar, first look at your existing usage. It's possible that you can save a lot of money, if that's your goal, just by eliminating waste, more than you can save by installing solar. It is recommended that everyone considering solar power first perform an "Energy Usage Audit", supplied free by SCE and other utilities. A solar installer can assist you in doing so, which sometimes exposes inefficient appliances or avoidable energy loss. Before sizing your solar system, it's important to know how much electric you really need for your normal daily routine. While it's not recommended to stint or crimp, it's often possible to seamlessly improve your home energy efficiency in very simple ways. The Audit promotes the idea of very efficient forced-air furnaces (more than the minimum 80%) when replacing it, but not necessarily going to that expense if it's not time for replacement. This idea blends into other energy efficiency topics: front-loading washer, rack-drying, proper wall and ceiling insulation, Energy-star refrigerators and other appliances, double-pane windows (or drapes), Compact Fluorescent Light bulbs (CFL) or domestic LED lights, and so on. Look for painless ways to lower usage that don't cost too much or cause discomfort for your current lifestyle. After evaluating your usage for possible reduction of waste, you can establish your target electric usage. Most solar installers do this by looking at your previous electric bill for a complete yearly cycle, summer and winter; but if you've just done a lot of conservation, take that into account. kWh and kW, Watt-hours and Watts, a messy topic Electric power is measured in Watts, while electric energy is measured in Watts over a period of hours, or Watt-hours. The electric company uses kilo-Watts (kW) and kilo-Watt-hours (kWh). So kW is a measure of electric power, and kWh is total energy delivered. SCE bills based on total energy used, or kWh. A 100-Watt light bulb has more power than a 30-Watt light bulb, but this only tells us how much electric it can burn. To know how much energy is used, you have look at how long the bulb is on. A 100-Watt bulb that's on for 10 hours uses 1000 Watt-hours, but 1000 is abbreviated as "kilo", so it is 1 kilo-Watt-hour, written as 1 kWh. A 3000-Watt microwave appliance that runs for 2 hours uses 6,000 Watt-hours, or 6 kWh. A 1000 Watt refrigerator with a 50% "duty cycle" (the motor is on half the time) uses about 500 Watts, on average; over 10 hours, it will use about 5,000 Watt-hours, or 5 kWh. Replace the door seal, and it might only have a 25% duty cycle, using about 250 Watts; over 10 hours, its usage could be reduced to 2.5 kWh. Each appliance has a plate on it that shows how many Watts of power it uses, and from that, you can estimate how long it's on, and thus add up total energy usage. The Energy Audit can often be approximated over the telephone, just by knowing what kind of appliances are in your home. Most people looking into solar have already done what they can so conserve, in practice, but it's always a good idea to take another look to eliminate waste. The average 2000 square-foot home, without a pool but with air conditioning, is expected to use between 500 kWh and 1000 kWh per month. Really efficient homes can use as little as 300 kWh; really profligate homes, where the air conditioner is left running while the windows are open, can use 2500 kWh per month, and more. One rule of thumb is that there should be 1 kW of solar power for each person, which we will see, generates on average about 5.5 kWh per day.
There are two ratings for solar system power output, the inflated 'STC" or "manufacturer's rating", which is sometimes misleadingly called the "DC" capacity. Naturally, each manufacturer wants to rate its equipment as high as possible, so this number really is for curiosity value only. The California Energy Commission (CEC) supplies a more realistic rating, called the "PTC" or "rebate number", the actual maximum output of the system. This number is very important, because it's a real estimate of the very most power your system can put out under the very best conditions (sun at right angles, little haze, cold weather, etc.). The rebate that is granted is based directly on this PTC number and certain other factors such as predicted solar performance based on the angle and inclination, shading, inverter efficiency, and other factors. The PTC rating is sometimes misleadingly called the "AC rating". More accurately, it should be called the "real capacity". You should only use the PTC, rebate number. Some contractors sell the system based on the manufacturers' capacity, while most ethical installers use the lower PTC rating. Confusing the two can lead to incorrect evaluation of competing bids, and misunderstanding of the power your system will actually produce. If the contractor lists just one rating, make sure it's the right one; if they list two, make sure that you only pay attention to the PTC number on which the rebate is based. Estimating daily production Multiply the PTC, lower, real number, the one on which the rebate is based, times the "sunlight factor" for our latitude, between 5.0 and 5.5 in the L.A. area. This is the equivalent average hours of full sunlight per day. This gives the expected daily production in kWh. The number varies due to angle and shading, etc., but the number for a well-placed system should be at least 5.0. Thus, a solar system with a manufacturer's rating of "3.5 kW" (3,500 Watts) might have a real, PTC rating of "3.0 kW" (3,000 Watts), and an expected output over the year of at least 15 kWh per day (3.0 times 5.0). Production is higher in summer, lower in winter. This system would produce a monthly average of 450 kWh per month, if it is properly aligned and there is little shade. Sizing a solar system to suit your intentions and target usage It's a good idea to buy a system that can be expanded to meet future use. Most solar customers consider expansion, and many do. Buying a slightly bigger inverter than you need, leaving open roof space, are two strategies for making it easier to expand later. Some folks wish to allow for the possibility of purchasing an Electric car. If you could buy one and power it from your own electric, the avoided cost of gasoline could pay for your solar system in as little as three years, after which it would be free of cost. Saving money: Before choosing a system or even asking for a bid, study the rate structure and decide if you wish to zero out usage, or your bill, or just minimize your bill for minimum investment. Modern utilities use TIERED-RATES, which penalizes excess usage over a minimum baseline (typically about 300 kWh per month). Energy usage in excess of the higher tiers can be very expensive; sizing even a small system to shave off the top tiers can be one consideration, after minimizing usage to try to get as close to baseline as you can. Regulated utilities are required to offer Time Of Use (TOU) pricing, which values peak electric as more expensive than off-peak electric. Since a solar system generates electric during peak periods, usually, you can get "extra credit" by using this rate structure. For example, SCE TOU-D1 rate values peak (10 AM to 6PM weekdays) production at 30 cents, but only 10 cents for off-peak usage. You can now figure out what size system would be required to completely wipe out all your energy usage. If your target or actual use is 600 kWh per month, that means you will need to produce, on average , 20 kWh per day (600 divided by 30). Using the "sunlight factor", that means your system will have to be 4 kW (20 divided by 5.0 is 4 kW). This will produce as much energy as your projected use; but beware, if your actual use jumps, you will need a bigger system. A smaller system can be leveraged to zero-out your electric bill if TOU is available and if your system produces a surplus in the peak period. For example, using TOU, daytime peak production of 20 kWh might give you credit for night-time off-peak consumption of 60 kWh. In this way, one typical 4.2 kW system makes enough daytime electric credits for off-peak charging of a Toyota RAV4-EV for driving up to 20,000 miles per year plus domestic electric.
Solar systems are sold by the Watt, so the size or efficiency of the panel doesn't matter so far as cost is concerned. Smaller panels cover more of the roof, and might be more advantageous at lowering the ambient temperature. There are angled panels, to match the roof shape, and differing color and mounting options. Most people decide that the extra cost of battery backup isn't worth the expense, but some say if you're going to spend that much, you might as well get all the benefits. Solar is something like a moderate home addition that pays you back in real money. In terms of economic value, a solar system clearly returns more cash over a longer period of time than a purchase of an SUV, for example; but it's a large, up-front expense that you have to bear. It might be more cost-effective over the years, but it is a large chunk of money to come up with at once. Finding out as much as possible about solar power is fine; but you only need to know enough to evaluate bids and hire the right contractor. If you learn enough, you can install a system yourself, and some people do; but it's a lot more efficient, particularly from a paperwork standpoint, to hire someone who knows how to do it. You can follow along, making sure that it goes as expected, without having to do the work yourself.
If you do spend the time to learn something about solar, and are willing to hire an electrician for code advice, you can do it yourself; but don't expect to save much money. The physical labor of installation is the smallest part of system cost, typically 5% to 10%, so you can't save too much; and you still should hire an electrician for the final wiring.
Once you decide that you want to "go solar", you need to look for a solar contractor. There are 4 ways: 1. American Solar Energy Society maintains a list of somewhat verified solar installers on http://FindSolar.Com/ 2. California, through the Energy Commission, lists all solar installers: http://www.gosolarcalifornia.org/retailers/index.html 3. Word-of-mouth, knowing someone who already has installed solar electric. 4. Other ways: research, city information, solar tours, casual installers and loose talk. Evaluating the bids. The Solar business is a construction trade, even though it has a sort of "green halo". A lot of things you're going to be dealing with are hard-headed contract facts, and watching out for your pocketbook. Don't let your good intentions be an easy way to your wallet via the tunnel of misplaced optimism. In reality, the cost of solar is pretty constant; a good solar installer can give you a bid over the phone, judging by the roof configuration and shading shown on Google Earth or Zillow. The skill resides in choosing the proper system that fits your home and usage, and delivering it at a reasonable price. The current "ball park figure" for installing small solar systems is $9/Watt, or $9,000 per kW. This can vary from $8 to perhaps $10, but there should be a good explanation for any such divergence. This is the number before any rebate and before any projected tax rebates or credits, and should use the real, PTC, CEC number for system size. Make sure that you compare bids using the same numbers. Review your overall goals, your target usage, the sizing of the system, the rate schedule you will use, possible future expansion, and use the "sunshine factor" to predict usage and make sure that you compare bids on the same criteria.
Imagine what the system will look like, and imagine living with it. Will it be easy to access the Inverter, to make sure it's still working, and to read the (usual) display of daily actual production? Do you want the system to be visible from the street? Go through a mental analog of the installation process, and make sure you're comfortable with answers to all questions.
1. You, or the installer, must apply for a RESERVATION REQUEST to tell SCE and the state that you are planning a solar system, and will be asking for help in paying for it. This is a way that SCE gets you to help pay for its "peaker" plant, so it's not exactly a giveaway; you need the rebate to pay for your system, and it's fair all around. The reservation request belongs to you; you can change installers even after being granted the request. But it expires, so you have to use it or renew it. 2. The Installers should have verifiable references. Call them. 3. The Installers generate bid proposals and system design. Get three bids. Go over each carefully, make sure that you look at the real, PTC rating for the system, and make sure you see the price PRIOR to rebate and tax credit. These should be the same on all reputable bids, so calculate the real cost per real PTC Watt for comparison. If there are differences, or something you don't understand, make sure to ask, and run each explanation by all bidders, so they all get a chance to respond or explain. 4. Never accept a bid under pressure; this is a big purchase, you want it to go slowly and correctly. Don't be hustled by community meetings or fast talkers. Ask other local installers if you have doubts. Take your time, the sun always comes up. 5. The price should be good, within the ballpark, and within appearance guidelines. Make sure you understand the system size and projected performance, the rebate that was calculated, and both the total cost and the final price to you. The installer's projection of system performance is important, you will want to refer back to this after the system is in operation for a few months. 6. Where is the inverter going to be placed? It should be close to the main panel. Is it in the way? What about the conduit runs, will it be overly visible, will the installer paint it, and where will the disconnects be placed? 7. What about the roof penetrations? What's the plan? 8. The installer should do all the paperwork. You get a copy of each paper, but make sure that they do it all. 9. When you accept the bid, the deposit should only be $1000. Make sure that if you back out or choose a different installer, any unused portion will be refunded. 10. Each solar system must be certified by being awarded a City BUILDING PERMIT, which establishes standards of safety, makes sure the roof is strong enough and wasn't damaged, that the system is properly grounded and will work as intended. The technology is really in the panels and other hardware; so long as it's installed right, it will perform to specifications. There's a ten year warranty by the installer, who should be a licensed contractor, and 25-year warranty by the panel manufacturer. This is important, because VERY occasionally, a bad batch of panels will need replacement. The system must pass a BUILDING INSPECTION by the City after it is completed. The installer must do all this paperwork, not you. 11. The installer applies for a NET-METERING request from the utility. This is very important, since SCE won't let you hook up any kind of generating equipment to their system without their knowledge. Avoiding this is, curiously, called "theft of services", even though you are generating electric. SCE is a whole other level of inspections and approvals alongside the city permit. You can only hook up AFTER the system is inspected and approved by the city. The installer takes care of all these details. 12. There will be a day or two when the roof mounts are placed and the panels carefully handed up to the roof. After mounting, they will be securely grounded and wired according to the Wiring Plan. The wires are collected into one conduit on the roof and lead to an inverter. Make sure you understand where the conduit will go. It leads, usually, to a DC Disconnect, which enables you to shut off input to the inverter by flipping a switch. Make sure you are happy with the roof penetrations, you might take the time to look at the roof, making sure there is no damage. 13. The conduit then goes to the Inverter. Make sure you find out how to read it, and what to look for if it fails (red light, or "error code"? One arcane inverter only tells you it's failed by issuing "fault code 0000", which seems ironically to say that there is no fault!). 14. On a grid-tied system, the conduit then simply goes to the main electric panel, where it has its own new breaker. On a battery backup system, the inverter is wired via conduit to the main panel, but it's wired to the "IN" side of the inverter. The backed-up circuits are usually moved from your main panel to a new subpanel that draws its power from the "OUT" side of the Inverter. The Inverter has a DC side, which is connected by thick wires to the battery. 15. The City Inspector thoroughly checks to make sure the system works properly and is safely hooked up. 16. SCE may inspect the system at any time, and will issue you a small "net metering" tag to alert the meter reader that your meter may run backward. A note about Roof penetration. Rooftop solar systems must be carefully installed so that no leaks develop over years, not months. First the roof must be evaluated; a roof with less than 10 years lifespan left probably should be replaced concurrent with the solar installation. A bonded, insured and professional roofer would be best for evaluating your existing roof and for supervising all roof penetrations, whether tile, shingle, composition, sheet iron, or other type of roof. The penetrations should be hot-mopped, not just gooped, so that there is confidence in at least a 10-year lifetime with no leaks. The most difficult roof is tile, and there are techniques for installing solar on each type of tile roof. No tile should be left broken, and all surfaces must be sealed.
1) Payments on the solar system, the amortized cost of going-solar, should be less than the equivalent energy from the electric utility company. Putting in solar should save you more money than you would need to pay for your monthly payments on your solar system, if you financed it. 2) You are ahead from the start because due to the rebate and tax credit, your system increases your home resale value by about twice what you paid for it, and you can't be re-assessed thanks to the Solar Rights Act. 3) If you finance through a home-equity loan, the interest is deductible. 4) You save after-tax dollars formerly given to SCE, freeing up to 1.4 times that amount in pre-tax income for contributions to 401K, etc. 5) As electric goes up in price, you are protected, your cost stays what ever it was you paid. 6) Your money goes into hardware on your roof, not to pay for burning fuel at some faraway place. 7) Solar protects your roof, and cools while generating juice (you basically live under the shade of a 3" gap under the panels). 8) With optional battery backup, you protect against brownouts and blackouts in service. 9) Each solar system relieves the pressure on the grid, lowering wear on the transformer serving your home and your neighbors too. Solar produces energy when and where needed, lowering the need for high-voltage transmission lines and decreasing peak demand and the need for new power plants. Oh, yes, and it's the future. Obstacles to solar Utilities seem to have mixed feelings. Solar helps them meet peak but also decreases their power and revenue, since many solar customers drop right off the billing system at the same time that they give up control of a small part of the generating plant. Utilities like to remain a monopoly, not give up their power to the homeowner. Cities and Building dept. often block and stymie solar, for unknown reasons. Regulators and unions don't always like solar, because it empowers the individual and lowers the need for power plant and line maintenance jobs. Regulators demand that the system be placed to achieve maximum predicted performance, occupying usually the highest part of the roof next to the crown. Fire Dept. has an antipathy toward solar, and is now requiring that solar only use a smaller portion of the roof away from the crown, conflicting with regulators' demands for maximum performance. Solar rights law (Civil Code Sect. 714) states that no one can object to solar for "frivolous" reasons of appearance, but there are virtually no penalties for cities which choose to avoid it, and in practice, harmonious installation is best. It's always better to get your neighbors to agree to the installation beforehand, so that everyone's happy. Most neighbors are tickled by the fact that your system will be powering their home during the day when it produces excess energy, and all homeowner associations have guidelines for installation of solar panels. After all, you are putting up a sizeable chunk of money plus your private property for the public good, even if it does make you money in the long run. |
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Doug Korthof, 562-430-2495, stored on http://SoCalSolarTour.com/gosolar.htm |
