I am a professional photovoltaic solar panel installer. Ask me anything!

how can i determine if a solar vendor/installer is legitimate, and that they will be around when service / warranty issues might arise down the road?

That is a good question. I worked for one solar company that went bankrupt, and many of their customers are now out of luck as far as the installation warranty goes. Some already sold systems were sub-contracted out to other installers to be completed. In this volatile market, you have to beware of offers that seem too good to be true. Those great deals may lead to a company's eventual bankruptcy. I wouldn't trust quotes for less than $3 / watt unless you're getting a large-scale commercial installation quote.

Most panels have a 25 year power production warranty, and a 5-year frame warranty, and the bigger the company the more likely they are to be around to honor that warranty. I like Sunpower, LG, and Kyocera panels. If the installer has NABCEP certified installers, they are more likely to be legitimate and will generally put in a good-quality system. Make sure the installer is a licensed electrical contracter and is insured.

One thing to note is you want your roof to be relatively new since those panels may be up there for 25-50 years. Removing the panels to re-roof is a few grand. Any honest solar salesperson would take the condition of your roof into account and inform you if you should re-roof before installing solar.

You can ask your salesperson if they make a commission on the systems they sell. In my experience, non-commissioned salespeople will put less pressure on you and be more honest with their answers.

Hey mate, why are most arrays wired up in series as opposed to parallel? Is it purely cost or is there something I'm not getting?

if you wire an array in series, the voltages add up, and with high voltage you can have smaller wire size to deliver the same power. Wire sizing is dependant on how many amps the wire can carry without compromising the insulation and starting a fire... for instance #10 gauge copper wire can accept over current protection up to 30 amps in the National Electric Code.

If you have 10x200 watt panels, they probably put out around 50 volts and 4 amps each. 1 string of 10 panels will be 500 volts and 4 amps. A parallel array would be 50 volts and 40 amps, so you're going to need much bigger wire and you're going to lose more power to resistance since the volts are low.

The downsides of wiring up long strings of panels in series are ones we run into quite often. The reasons for wiring them up in series are detailed out pretty well in other people's responses, but I thought maybe I'd tackle how we get around some of the issues with wiring in series.

The most obvious problem is that if a series wire gets cut, you lose the entire string. There are companies out there that make microinverters that go on every panel, which help eliminate this problem, albeit at a higher initial cost and additional maintenance.

Shading is also a problem with series wiring. When one panel in a string gets shaded, that string can't maintain the voltage required by the inverter to operate properly, so the inverter just ignores that particular string. Microinverters also help with shading issues, but there are systems out there that mitigate the effect of shading on the arrays that result from the strings being wired in series. Tigo attempts to keep the voltage matched between strings as well as possible so you can keep your inverter operating as long as possible.

Thank you for the excellent reply! I'm glad you mentioned microinverters! the residential market is moving to these, I think.

Maintaining microinverters isn't so bad; usually they come with monitoring software which can tell you the output of each panel and the location of every failure. Then you lift a solar panel, replace the microinverter, and replace the panel.

When you match string voltage, you're usually limited to the lowest string voltage. There are Maximum Power-Point Tracking inverters which can find the optimum voltage for each string, getting a little more power. With microinverters, you don't have any power clipping; each module makes as much power as it can.

On the commercial side, I think we'll continue to see string inverters, since most commercial installs have a lower cost per watt, so can't afford the microinverters.

how can i build something on the cheap. any do it yourself projects you are aware of? I have a 600 square foot garage that i'd love to be solar powered in the manner of a rec room/den and was wondering if this would be something i could do on the cheap

On the cheap, you could use aluminum L-stock to create roof-attachments that you'd lag-bolt to your rafters through the roof, seal it with silicon sealant. make racking out of same L-stock, use bolts to attach some old solar panels, run #10 USE wire from panels to a fused disconnect, to some cheap charge-controllers, a few batteries, and a crappy 2-plug inverter.

I wouldn't want to run sensitive electronics from such an inverter, but it would be fine for lights, mini-fridge, etc.

you'd need to measure your roof, and get solar panels that would fit.

do the solar panels do anything to affect the structure of the roof shingles?

In the early days, we would use strips of butyl-tape to seal around an aluminum L-foot. A lag screw went directly through the shingle and into the decking and rafter.

Nowadays, on a typical asphalt shingle roof, we use a base plate with 2 lag screws through the shingle, sealed with silicone 50-yr sealant. Then we put a 1' wide metal flashing (with more sealant) over the base plate shingle layer and under the next 2 courses of shingles. This stops water from ever getting to the roof penetrations. Then we screw on our racking L-feet.

I've never had a leak at an installation over 6 years. :) knocks on wood

edit: here's a bad paint drawing: http://i.imgur.com/7cRZcme.png

What education did your job require? I decided to go to college for renewable technology. So I'm wondering what in your opinion is the best subject to study, and what jobs are available in your industry?

I was lucky to start in solar in 2006 through a connection with a friend. A willingness to learn and being comfortable with heights was all that was required.

Nowadays, for new hires we generally prefer a renewable energy certificate (2-year or 4-year), general construction experience, or electrical training.

Your renewable technology certificate will definitely get you a leg up on entering the industry! If I were you I'd want to take classes on Geothermal, Solar thermal, and photovoltaic solar. I knew quite a few folks that have had success starting as electrical apprentices and then specializing in solar installation/repair...

I've installed a few wind-turbines, but I don't like them since the wind is so sporadic in Colorado, and the moving parts seem to invite eventual failure. If you were to be somewhere with consistent wind, then studying wind-power installation would be good too.

Jobs available: PV designer, Renewable energy financier, Installer, Electrician, Sales person, marketing, energy auditor, Maintenance/repair guy. I know a friend who is starting his own company just installing animal guard to keep squirrels out from under the arrays.

First off, thank you for the detailed reply! Very informative. Last question, say I would want to make micro grids for homes in areas where power would not reach, is there any market out for that yet? Im intrigued by the idea of off-the-grid living and I really want to design systems that would make it possible and easy for people to do that. So would that be more of an electrical engineer job? Or do renewable technicians receive training to do this sort of thing?

a technician would probably recieve adequate training to install small battery-backup systems. To be powering multiple homes, I would certainly want the help of an electrician and / or electrical engineer.

What could one little squirrel do?

squirrels can chew through wires and cause fires and BBQs! I've seen it happen.

It seems every week I see a technology or science article about new breakthroughs in solar cell efficiency. Is there a revolution in the retail market ahead of us in the next few years? When would you advise to buy a solar panel solution? What are your thoughts on solar energy collecting windows?

I am happy to see people installing solar now, but I fear they may feel short-changed in 10 years when all this amazing technology becomes mass-produced. right now PV efficiencies are around 15-20% for mainstream solar panels. (so if full sunlight hits your roof it is about 1000 Watts or energy/ square meter... resulting in 150-200 Watts of electricity.)

I have read about this possibly tripling in the coming decade. I've been thinking I'd save up for better stuff in the future.

But if people don't buy solar now, there won't be as much financial incentive to come out with more and better solar products. Catch-22 much?

Edit: I've talked to some co-workers, and they feel the next 4 years won't bring as much solar tech improvement as the last 4 years have already given us.

TLDR; Revolutionary technology exists, it just needs funding to be mass-produced.

Solar sales guy here. This is the only comment you have made where I feel like I need to step in. People who install now will take advantage of some really nice rebate and incentive programs which are drying up. The more people who install, the faster the threshold changes for the rebate amounts. People who installed 3 years ago were in better shape than people who will install this year - and it's part of my sales pitch. People who are waiting for new tech are literally throwing their money away to their utility companies while they could be saving money and putting equity in their homes immediately by doing a PPA or lease. Even if we get 10% more efficiency out of panels, it's not worth waiting 10 years just to find out. And if we DO get 10% more efficient panels in 10 years, they will be new tech and therefore more expensive to begin with.

So the real answer to guys question is: the time to get solar was 5 years ago. The longer you wait, the more money you are losing.

You're saying buy now because it will cost more later. Pretty common sales tactic. But you are not including risk.

The only way it would be financially beneficial for me to "buy now" was through a business lease / government loan program. Basically, I borrow money from the government that is paid back over 20 years. The money transfers to a corporation as a one time payment for a 20 year lease.

The risk with this arrangement is I'm paying the installer the entire fee upfront and owe the government for 20 years. If anything fails on the system and the leasor (installer) is bankrupt then I have no way of getting warranty service AND I'm stuck paying for a broken system for up to 20 years.

In short, the leasor has no skin in the game. Most of the leasing corporations haven't been around more than a year, they are registered private, and are very secretive about their board members etc. It screams "take the money and run" after they've received 7 years of government incentives. I have no guarantee that my system would work for 20 years, yet I have to pay a loan for 20 years using my house as collateral.

It is super-important to read your lease agreement.

Thank you for this eloquent reason to buy solar now!

i'm a firefigher. we were told these units always have a charge even if you shut off the panel to the unit. the only way to prevent getting shocked was to kill the power to the unit and actually cover them so the sun can't get to them.

could you elaborate on some safety precautions that can protect us when working on a roof that has panels?

During the daytime, yes. A blanket over the panels is the absolute sure way to keep the wires cold.

But once the DC disconnect is switched off, the string of panels is an open circuit, and you can disconnect connectors between panels without danger. Sometimes you need special tools to get the panel off and access the wires, however.

If you were to run a chainsaw through the wires and conduit, you may close the circuit and get a shock, unless you used the blanket.

Also, you can walk on most panels, the tempered glass is strong. But don't do it. Walk along the frames and step on the clamp intersections, those are the most supported and give a little traction. You don't risk damaging the modules that way.

Some new fire codes are requiring clearance around the peaks and valleys of roofs, making it harder to fit a lot of solar on the house.

My step father is trying, at 53, to change his career into renewable energy. He's applying for electrical apprenticeships positions, but not having a great deal of luck.

Could you give me any ideas that I could pass on to him about getting in to the industry?

Its a tough job-field out there. Applying for electrical apprenticeship is great, but you may have to wait a while before finding an employer, and apprentice wages suck. If he can stick with it for 2 or 4 years, he could get his Residential Wireman's license, and then try to get hired by a solar company. Just keep applying for jobs, don't get discouraged! Make sure your resume states how keen you are to be saving the world one solar panel at a time! Even if a renewable energy career doesn't pan out, being an electrician is a great fall-back.

What's your educational background?

I have a Bachelor of Computer Science degree, and my NABCEP certificate. I will be starting electrical apprenticeship this year, I wish I had started that earlier.

Why didn't you go into programming.

i didn't want to be at a computer all the time... Being outdoors and getting exercise is nice.

But some days I wish I had stuck with computers for the money!

How much of a headache is it to get the necessary permits? Could a DIYer do everything up to but not including connecting to the grid?

Permits can be a headache for the uninitiated. If you have proper one-line electrical diagrams, site plans, architectural drawings and data sheets for all the equipment you're installing the permit should be a breeze. Permit fees can be 100-900 dollars for a typical residential install, depending on your jurisdiction.

If you don't connect to the grid, you could certainly get away with making your own battery-backup system! Make sure the racking is grounded, and protect your wires from damage. Check the National Electric Code to make sure your wires are sized properly for the amperage they're carrying. Use over-current protection. Batteries could explode if not charged properly, so use charge controllers and give batteries ventilation.

If you ever sell your house, the new owners may want the electrical work to be brought up to code, so I recommend getting an electrician to at least review your work.

I am currently studying to become a renewable energy technician. I am told that this is one of the jobs I would be doing. About what do you make per hour/year? Do you still enjoy your job?

I've tested for and recieved my NABCEP (North American Board of Certified Energy Practitioners) certification, and I have plenty of experience, so I currently make $18/hour. Its not the best paying job. New folks start out at less than $14/hour. If I were to also be a crew lead or electrician, I'd be making $20-25 / hour. If I were on a prevailing wage job and were an electrician, $30/hr+. I do get nice benefits, 6 weeks paid vacation and 90% of my health plan paid for. Our company is a employee-owned cooperative, so the vacation is better than most other companies.

I love my job, I used to be a computer science geek, and it was wrecking my body. Now i get to be outside and climb ladders and see the rooftop view every day. Not that the elements don't have their downsides too... VERY hot in summer, super cold in winter. Wear sunscreen and get a wide-brimmed hat!

I wish labour was more valued. I feel I do just as essential work as the sales people in our company, but they make $50k + per year, and require less education.

and sales managers make 100k+!

and the boss?

we have a cooperatively decided policy to maintain a ratio of 4:1 compensation. So the CEO could make as much as 100k if the lowest paid guy made 25k. Its pretty progressive, but I would like to see a 2:1 ratio and see the bottom at 50k!

How many years does it take to have saved enough money to cover the costs nowadays? We installed solar panels back in 2002 and it took about 10 years to have it fully covered.

a typical payback these days is 7-12 years. This depends of federal and local incentives, such as per Kilowatt rebates, or the federal 30% renewable energy tax credit.

10 year payback is around a 7% annual return on your initial investment... way better than CDs these days!

Is a 10KW system a system that can sustain 10KW? Can it sustain 10KW at night too, or if there is little sun?

What are the numbers in terms of money saved over time? How much power do houses use from the grid, even when they have a 10KW system installed? Do parts of the system have to be replaced, and how often and how much?

A 10 KW system produces 10 Kilowatts of power while optimum sun shines on them.. This could be for 6 hours per day, giving you 60 Kilowatt-hours per day. Generally due to clouds and inverter inefficiencies, a 10 KW system will actually produce less, maybe around 45 KWh / day. At 10 cents/ KWh (average residential rate in Colorado), this is like producing $4.50 / day.

Solar panels don't produce power at night. In early morning and late evening a panels may produce a little power, but not as much as its rated output, which is measured at 1000 watts of insolation / square meter.

Edit: Solar systems require very little maintenance. I expect most systems will last 25-50 years, the inverter or the roof shingles being the first things needing maintenance. The panels will need to be sprayed off if dirty.

The re-roofing could be expensive, in the rare case of inverter malfunction after 10 years, you may have to pay 1-3 grand for a new inverter. or maybe the old one could be repaired..

An average home uses 300-600 KWh / month. Installing energy efficient appliances and turning off things you don't use will save you money more easily than solar panels.

some people can offset their entire usage with a 6KW system, and there are other households that use so much energy a 10KW would produce barely 20% of how much they need.

I've heard photovoltaic panels need to be washed 4 times a year to prevent dust and residue from lowering the efficiency of the solar panel. (The 4 times was in reference to a large scale grid in a desert setting). How often would you ideally want to wash a personal unit? And how much can buildup really affect efficiency?

you can lose up to .1% production / day due to panel soiling. i'd wash my panels if i noticed production was low but it was sunny. or if they looked dirty!

Do people entertain you while you work with tales of how they will survive the coming apocalypse, or is it mostly upper middle class normal folks who buy these installations? What's the main reason driving your customers to solar?

i've met some very kooky folks.. not off-gridders since i usually install grid-tied solar, but i did hear about one customer who drank colloidal silver cause he didnt trust doctors to keep him healthy, and his skin was all grey (argyria). the best customers give me coffee and cookies and are excited for solar. some do it for savings, some for the environment.

If there weren't govt subsidies, how much more would a typical installation be increased?

a 30% fed credit right now give folks roughly a 12,000 tax credit on a large system... this means without that incentive solar would be 20-30% more expensive to the end customer. local energy utilities should be giving more incentives for solar, IMHO, but they make money from coal, and solar is actually competition for them! get voters to pass laws demanding more solar in their state!

Do some customers purposefully have their panel installed facing the street to show off to the world, Rather than have it installed in the backyard where it would be more effective?

Generally, the panels have to face south (in the northern hemisphere.)

Panels on the east and west sides of a roof make about 80% of what a south-facing array would make. This all depends on your location, shade, and other considerations. North-facing arrays don't produce enough energy to be worth it.

that said, I have know some customers who have "vanity solar" that is dummy panels that aren't even connected, they just look cool.

Which country has the most solar power usage per capita? Germany?

What do you think about geothermal heating for homes?

germany. they rock. I hear Germany has almost 50% of their needs met by renewables now. Amazing! they even have worse sun than most of the midwest!

geothermal is awesome, but pricey.

When will they be CHEAPER? And is it really helping the environment?

Solar panels themselves are actually quite cheap, under $1 / watt! its the installation, wiring, racking, and inverters that drive the prices up. I believe if you installed the panels yourself you could probably get a 10KW system up for about 20,000. The market is currently so competitive, solar panel manufacturers are dropping like flies. Bosch/Aleo solar just withdrew from the market, and Suntech went bankrupt recently.

Data from Energy Environment and Economics Inc. showed that the average solar panel gets five times more energy out than was originally put in. So yes, they do help the environment by not producing as much CO2 as other energy sources like natural gas or coal. (And not producing as many other pollutants).

I believe in another 10 years, solar panel efficiency will be much better. Already solar is half the price it was 5 years ago! hopefully this trend continues.

I helped a friend put up 6 solar panels he salvaged and hooked them up to 6 used old charge controllers and 6 used electric wheelchair batteries, wired to a small 500W inverter. He watches TV using solar power now. his system cost very little (600 bucks). Of course in a few years, he'll have to replace the batteries... Hopefully supercapacitors will replace batteries soon!

How long does the battery last?

lead acid batteries well maintained can last 12 years. Usually people abuse their batteries and they last 5-7 years. this can be a substantial cost of the off-grid system.

Would I have to shovel the snow off of them in the winter?

most panels shed snow quickly, they are slippery, and can cause an avalanche from your roof!

If it snows a lot and you can get to your roof safely it couldn't hurt to broom off the panels and get an extra day of production. but it is usually dangerous to get on a snowy roof!

What's your opinion of solarcity? It looks like they have an option with no upfront cost, but I don't know too much about them.

they are spending tons of debt money now to put up systems, hoping that in 20 years, energy prices will be high and they will be banking on it. Risky, but with great risk comes great rewards.