Is my home a good place for a solar electric system?
The most important considerations for a potential site are orientation and shading. Typically panels are mounted on the roof. So, your roof should be free from shading by trees, nearby buildings, and other obstructions. It is best to have no shading between 10 am and 6 pm – the peak solar hours.
Skylights, chimneys, stovepipes, and roof vents can limit the area available on the roof. Also the roof structure must be strong enough. Most roofs are, as solar arrays weigh only about 3 pounds per square foot. But some older homes may have structural issues.
Generally, solar panels should face as close to south as possible. West-facing roofs can be fine too, particularly if “time-of-use” metering makes sense for you.
How does a grid-tie system integrate with my current electrical service?
It’s simple. The connection between your grid-tied solar system and your electric service takes place in the existing main service panel or a subpanel. It consists simply of an additional circuit breaker, through which the solar electricity is fed into your home.
At night there is no solar power being produced, so the circuits are being fed by the utility as usual. When the sun comes up in the morning and the system starts to produce a little, this is fed into the panel, and reduces the amount of watts being supplied by the grid. As production ramps up as the sun rises higher, there will usually be a time when all the electricity is being supplied by solar, and none by the grid. Later still, the solar system may produce even more than the home is using, and the excess will feed from the service panel, back through the meter, and into the grid. The meter will record a credit for you while it is running backwards. You are actually selling power to PG&E. As the sun gets lower in the sky and then sets, this process is reversed, and utility power will prevail.
In a system that is designed to provide all or most of a home’s annual usage, it is sized so that the credits accumulated during the days, will offset the purchases made at night and on cloudy days. There is a seasonal component to this as well, as most excess production will happen in the summer when there are longer days.
But isn’t the coast too foggy for solar to work?
We have a number of satisfied customers whose systems are installed practically down to the water’s edge. So yes, solar works fine on the coast.
Although fog is a factor, there are still many clear days at the coast. And even on foggy or cloudy days, solar generation still happens, but at a lower level, proportional to the level of sunlight reaching the ground. The result is that immediate coastal installations lose about 15% of production compared to inland, on an annual basis, but the results are still well within the range to make solar a viable activity.
The energy in sunlight that causes PV panels to produce electricity is measured in watts-per square-meter (wm2). Full sun is roughly 1000 wm2, and in clouds or fog it may be 200-400 wm2). Power production will vary accordingly.
Another factor in favor of coastal solar is the cooler temperatures. Solar electricity is not produced by the sun’s heat, but by the physics of how the semiconductor cells work. They actually work better the colder they are. So those hot inland systems are actually losing some output on hot summer days, compared to their cool coastal cousins.
What are other financing options?
Ask us about unsecured solar loans available through our partners, either SunPower or Clean Power Finance, with reasonable rates and terms from 5 to 20 years.
What is the payback?
A better question to ask would be “what’s the return on my investment?” For solar it’s generally excellent, and for a zero-down lease, it’s unbelievable! With absolutely no money upfront, you could save every month for 20 years, totaling up to tens of thousands of dollars. How do you even calculate that as an investment?
For systems paid for up front, the return varies, but ranges from better than anything you can get in a low-risk investment, to double digit returns. We’ve had more than one customer run our proposal by their financial advisor, and they were told “That’s the best place you could be putting your money now.”
Another way to look at it is to ask “What’s the payback on that new car I bought?”, or kitchen remodel, for instance. A solar system is one of the only investments you can make that not only doesn’t cost anything to operate, but actually more than pays for itself over its long, trouble free lifetime.
Planning a new home?
Consider talking to your designer or architect about simple ways to make your new home solar ready. For example: placing the vents, chimney, stovepipe on the north or east roof.
What about maintenance for these systems?
There is almost none. That’s the beauty of elegant solar technology, which converts sunlight to electricity silently, with no moving parts. The only maintenance is keeping the panels clean and free of shade.
How do solar panels work?
There are 2 types of solar panels: solar thermal, which are used for heating water, and solar electric (also called photovoltaic, or “PV”), which are used to generate electricity. Here we are only talking about PV panels.
PV panels are made of groups of solar cells, which are made from silicon, a glassy semiconductor material which is also used to make computer “chips”. Through a process of physics, photons of sunlight striking the cells enable electrons to flow in the material, producing an electric current. They work anytime the sun is shining, but more electricity will be produced when the light is more intense (a sunny day) and is striking the panels directly (when the sun’s rays are perpendicular to the solar panels).
Unlike with solar thermal panels, it is not the heat of the sun that produces electric power. PV panels actually produce more power on clear, cooler days.
What are the components of a PV system?
There are three main parts: the mounting system, the solar modules themselves (PV array), and the inverter. (Systems with battery back-up have more parts)
The mounting system is typically aluminum rails on the roof, but can also be a ground-mounted rack, or a pole-mount system.
The solar modules make direct-current (DC) electricity, which is transmitted to the inverter.
The inverter is an electronic device that converts the DC into AC (alternating current) which is the type of electricity used in the grid and your home. The inverter is wired into a circuit breaker in your home distribution panel. This is where the solar electricity is fed into your home and into the grid.
Is there a risk of roof leaks?
We follow all industry best practices, which virtually eliminates the risk of leaks. We use special flashed roof mounting penetrations, developed for the solar industry, which will seal the connection for the life of the system. There is no mystery to a properly installed roof flashing, which is performed routinely by roofers and solar contractors daily. There is no more risk than for the plumbing vents, etc, which are already in your roof.
Will I be going “off the grid?”
If you already have utility power, there is no need to disconnect from the grid. It’s cheaper and simpler to install a grid-tied system, as described below.
Do I need batteries?
No, the most commonly installed systems do not have batteries. These “grid-tied” systems are connected to the home’s electrical service, and feed any excess power being produced, beyond what the house is consuming at the moment, back into the grid. This back-fed power will literally run the meter backwards, providing the home with a credit to be used later. Grid power is always available to make up for any electrical needs not being supplied by the solar system, such as on cloudy days, and of course at night. This is sometimes referred to as “using the grid as the battery”.
Will my solar system protect me from outages?
Only if you install the battery-back-up option. Otherwise, the grid-tied inverter will shut down automatically in an outage to protect linemen from back-fed power. The inverter will restart automatically when power is restored.
However, batteries are an option for solar power systems designed for blackout protection, so when power goes out the batteries will operate either special isolated circuits in your home, or your entire service. This option adds several thousand dollars to the cost, and will require more maintenance for the batteries. Usually a back-up generator will still be required, since most outages occur during storms, when there tends to be little sunlight to recharge the batteries.
Batteries are integral, however, for off-grid systems, where the solar electric system stands alone and does not tie into the existing utility, most commonly in remote areas where power lines do not reach or are too costly to install. See below for further information.
Can I add batteries later?
It’s possible, but not cost effective. It’s best to decide upfront whether you want the benefits of battery back-up, and if the extra cost is justifiable for your needs. If you think you will want to add batteries in the future, pre-planning is necessary to make the transition easier. In any case, it will cost thousands of dollars.
Do you design and install off grid systems?
Yes, this is one of our specialties. We’ve built solar electric systems for everything from tiny cabins to full-size 6000 square foot new homes. Designing for an off-grid system starts with a careful analysis of the loads, to properly size the PV array and battery storage. Modern off-grid technology has advanced tremendously in recent years, making it easier and more affordable than ever to live comfortably without utility bills.
Do I need to manage or control the solar system?
No, a straight grid-tied system operates automatically and invisibly to you. You don’t have to do anything, and the only way you will know it is working is by your lower electric bills/credits, or by checking out the inverter display or the monitoring system.
The system will go to sleep automatically at night, and wake up in the morning when there is enough light to operate. Also, it will shut off automatically in an outage, and restart itself when grid power returns.
Do I have to give up my favorite toaster, microwave, hot tub, etc?
No, your home’s electrical system will operate as it always has. The only difference is that your circuits are being fed by a second, supplemental source when the sun is shining. The grid is always available to provide any power you need.
Imagine your circuit breaker panel as being fed by two utilities now. One is PG&E, always there as usual. Your new second utility is your sun-powered system, which only operates during daylight hours. What it produces varies with the season, the time of day, and the weather conditions. But whatever it is generating at the moment, all of it is being fed into your house’s distribution panel, and either reducing what must be bought from PG&E, or actually being sold back to PG&E, when there is a surplus being produced.
How long do PV systems last? What is the warranty on these systems?
Photovoltaic systems have been around for over 50 years, and many original systems are still working just fine. PV panels tend to see a slow (<1/2% per year) decrease in output throughout the system’s life. The manufacturer’s power output warranty for solar modules is 25 years. Usually they are warranted for 90% of new production after 10 or 12 years, and 80% after 25 years. This is in addition to a workmanship warranty, which is 10 years on the SunPower brand modules we usually use.
State rebate regulations for grid-tied systems require a minimum 10-year warranty on all parts and installation, (excluding batteries, if there are any.)
There are no moving parts in these systems, and essentially no maintenance required, beyond cleaning the panels when they get dirty. Inverters are complex electronic devices, and will likely not last as long as the panels, but they are warranted for ten years, with some extended warranties available. Inverters are generally expected to last about 15 years.
What do I do next if I want to see about getting a solar system on my house?
Call Mendocino Solar Service at 707-937-1701 or contact us via the web site.
We will evaluate your electric usage and discuss your goals for going solar. Then we will come to your home, look at your solar accessibility and discuss the options. We will need to see a twelve-month history of your PG&E bills so we can properly size your system. We can assist you in getting this information. We are located in Mendocino County. If you are out of the northern California area, go to www.findsolar.com for an installer in your area.
Mendocino Solar Service has installed over 200 systems in Mendocino County and will be happy to work with you on a system that will fit your interest and vision. We do not give quotes without visiting your home and doing a careful analysis. We look forward to hearing from you.
If you are considering solar-generated electricity for your home, you probably have a lot of questions. Give us a call at 707 937 1701 or schedule a free consultation online and we'll happily discuss them with you.
Meet Bruce, Maggie, Andreas, and the rest of our team. We all live, work, and play in the local community. Visit our Staff page and get to know the folks who can provide renewable energy for your home or business!