Solar Power Frequently Asked Questions
What will our solar payback be? What assumptions do you use in a solar payback analysis?
The solar payback analysis is specific to each location. There are complexities with the roof, with structural details, with siting analysis, with electrical interface, with permitting jurisdictions and so forth. We must look at all those in order to come to a final proposal. However, we can often demonstrate a payback of 5 to 7 years, equivalent to an internal rate of return of 15 to 20 percent. Given the interest rate climate and the other benefits of the system, its long life, its public relations value and its environmental benefit, this is an excellent investment!
We need to analyze your rate structure to do an intelligent payback analysis. We also look at the peak demands that are reduced with a solar power system. If the building has a large transformer on the primary side of the wiring, we can come into the secondary side of that and save the transformer losses.
Our solar panels shade the roof substantially, and the decrease on the load of your air conditioning can be calculated. We factor in the effect of the CEC rebates, state tax credits, federal tax credits, the 5year accelerated depreciation allowance and the cost of financing, if any, to give you a good picture of the economics of the project.
Will we lose power during installation?
For most of the project, we will be working independently of your facility. At some point, however, it will be necessary to turn off the power to the point where we interface with the grid. If that is the main power panel, then the main power will be turned off at the transformer. In order not to be overly disruptive, this is typically done at night, after all computers have been backed up and shut down.
Our business has critical computer and other systems that must remain running 24/7. Is solar power reliable?
Solar power can be combined with large Uninterruptible Power Source (UPS) systems, capable of providing emergency power when you need it. The solar energy produced is first used to keep the batteries topped off. Excess power is put back on the grid, as a credit to your usage. Because we add only a solar power capability, we subtract nothing from your existing connection to the grid. We can even set up the solar power system to continue charging your batteries in the event of an interruption to your power, extending the capability of your backup system. Backup systems can also have autostart generators, so that they will come on automatically if the batteries are nearing a state of discharge.
How long does a project take? And will business be disrupted during this time?
The time a project will take is directly proportional to its size and complexity. The building permitting and CEC approval process can take several months before any work is physically done. Then, depending on the size of the project, it may take from several weeks to a month or more. Operations should not be unduly disrupted. For the most part we will be working away from the primary activities of the company, on the roof or in a remote area of the property. There may be minimal disruption when we finally have to interface the solar power system to the main power, but this is usually done at night.
How much does a solar power system generator cost?
Well, that's kind of like asking what a car costs, and the answer is similar. You can get a small system for about the cost of Kia. You can pay just about anything for an exotic system, like you might expect to pay for a new Ferrari. Typically, you should expect to pay around $9 per installed watt or less, before California rebates and tax incentives, for a solar power system that does not involve too many exotic aspects to the installation.
Will this increase our property tax assessment?
Not in California. The law varies in other states. Check www.dsireusa.org/ for a state-by-state description of tax incentives for renewable energy.
How about government incentives to help pay for the project?
Will the solar power system make noise?
Different technologies make different amounts of noise. Grid-tied inverters make almost none. Battery back-up systems are louder; you might not want to mount them on the wall behind your bedroom.
What kind of construction and remodeling work can I expect?
It depends on what you are doing. A simple grid-tie solar power installation will involve nothing more than bringing conduit from where the solar panels are mounted to the area near your existing power meter (typically), where the inverter, an AC and a DC disconnect are placed. A battery backup system, however, needs to be placed out of the weather, often in a garage. Some consideration needs to be given as to where and how batteries will be stored. Inverters used for battery backup installations are larger than the grid-tie inverters and will need more space. There will also be an interface with your existing electrical service, in that certain circuits will be backed up by means of a secondary sub-panel.
Other construction considerations might include questions about where and how the panels are to be mounted. If on the roof, you might look hard at the integrity of the roof. The solar power system lasts a long time. Maybe now would be a good time to replace that roof, even if it still has a bit of life left in it. It's always best to do a solar power system in conjunction with a re-roof. Proper stand-offs can be mounted to the roof deck when the old roof is off. The roofer can then place flashing around those standoffs as he completes the re-roof. Later, we can come along and bolt the racks that hold the solar panels right to those jacks and then the rest of the solar panels to that.
How much can we expect to save on utility bills?
Of course that depends on the cost per kilowatt you pay. One of our Net Gain® systems will provide in excess of 4,000 kwh per year, more if you live in a very sunny area, less if you life in a forest.
Can we sell my excess power back to the utility company?
Many people think you will get a check from the power company for any excess solar power you produce. It's not quite that easy. You will get a credit for power you generate in excess of your usage. Over a period of time, generally once a year, your utility will apply credits against usage and arrive at a net usage. The utility will send you statements every month, letting you know whether you are piling up credits or using power. However, they "true up" the account on the anniversary of the day the system was placed in operation. At that time, you'll get a bill for your net usage over the year... If you have generated excess power, you'll lose the credit and start all over again at zero. We like to size your solar power system to produce a little less than your anticipated usage. That's why we ask you to call the power company to find out what your kilowatt-hour usage was for the past 12 months.
Will the meter really turn backwards?
Yes. Most meters are built to be bi-directional. However, upon inspecting your solar power system for parallel operation to theirs, the utility company will change out your existing meter with a new one. That will not cost anything, unless you're installing a Time-of-Use meter.
What is Time-of-Use? Do I want that?
TOU metering values electricity more at periods of the year when demand is the highest. That is generally weekday afternoons on the 6 hottest months of the year. Power may be valued at $.37/ kWh during those periods of time, when solar production is at its peak. TOU metering also gives you a break in off-peak times, i.e. mornings, evenings and weekends when power is much cheaper. $.08/ kWh is typical. If you have the kind of usage habits where you can avoid using power when it is expensive, and just let the solar power system work hard for you, you may be a good candidate for TOU metering. You can do those activities that require power during off-peak times, and try to keep your usage to a minimum when the rates are high. A special meter is needed. The utility installs this for a reasonable cost, often about $277.
You can also combine Time-of-Use and net metering, for the best of all possible worlds! You can apply the credit you get in the summer at $.37/ kWh to those times you must use power in the winter. Since your off-peak winter usage is only valued at $.08/ kWh, every summer hour of production is worth almost 4 hours of winter usage! With the right kind of habits, your TOU net metering solar power system can be 30% more cost effective that one without TOU.
What if we are located in a foggy climate?
We are located in such a climate in coastal California, so we're familiar with this. The inverters that we use have electronics that compensate for foggy or cloudy conditions. UV rays are still coming through the fog and clouds. You can get substantial power out of your solar power system, even when it is overcast. A bright, foggy day may give you 25-30% the power you'd otherwise get on a bright, sunny one. Sometimes it is even useful to orient the array more towards the west, in order to take advantage of fog burn-off and maximize the period of time you can take advantage of Time-Of-Use metering (the afternoon).
What kind of maintenance is required?
Not much. You'll want to clean the solar panels periodically. The grid-tie inverters have a big heat sink on top of them. They work most efficiently if that is brushed off from time to time.
Do your systems come with a warranty?
Absolutely! Click here for information on our solar power warranties.
How big a system do we need?
We will analyze your power usage to determine a maximum sized system. However, there are really three things that determine how big your system should be:
1. How much power production is too much, given that you can't sell the excess beyond what you use.
2. How much roof or other area do you have to devote to the solar power system? You can't put a system in where you don't have to room to do it!
3. What is your comfort level with the cost of the solar power system? Even with rebates and tax incentives, solar power systems cost something. If you have a comfort level for cost, let us know. We'll engineer a system around that level of comfort. Since our systems are modular, you can always come back later and get another
"module" of solar power. We'll just be sure that when we install the first solar panel that we leave room for growth!
Do we need permits for any of this?
Yes. Often this is just an "over the counter" permit. If the solar power system involves placement other than on a roof, the permitting jurisdiction may want details on where you are putting it and how. If it's on a slope, they may require geotechnical information. They will also want to see that it doesn't violate setback laws. If the solar energy system will be on a commercial building, they will probably want details of the roof construction and a drawing of how you propose to interface to the roof and to the electrical system. Of course, if you have us do the work for you, we take care of those details. By the way, if you want to interface to the utility company and if you want to get those nice state rebates, they will ask to see a copy of the signed-off building permit.
What other paperwork is there, and do you handle that too?
If you are in California, we will apply for a rebate reservation on your behalf from the California Energy Commission or the utility company, which administers funds made available from the Public Utilities Commission. We will also handle the paperwork necessary to connect you to the utility. They have paperwork, and lots of it!
My roof doesn't face south. Will solar panels still work?
Maybe, maybe not. We have installed solar power arrays facing south, tilted on west or east-facing roofs. We have even "rooster-tailed" arrays over the tops of north facing roofs, so that the solar panels face south. If you are oriented to the southeast or southwest, that's not a big deal. You lose only a few percent efficiency orienting in those directions. It would be best to talk to us about your specifics. | 
