Your experience and advice re installing solar arrays?

March 30, 2009 11:39 AM

Your experience and advice re installing solar arrays?

I am considering having solar arrays installed on my roof (in LA area). Have any of you had this done, and have any tips/things I should consider? Also, recommendations for installers welcome.

posted by lemonade to home & garden (5 comments total)

(I haven't bought a solar system myself, done but used to work in the solar industry)

First of all, is your roof suitable? You need a south, or south-ish facing roof (basically, the flatter the roof is, the further you can deviate from south without significant loss of power).Each kilowatt of solar panels will cover approximately 100-150 sq. ft. of area. Trees, neighbouring buildings, vents or other shading elements will decrease your power production - if there's not significant shade between about 10am and 3pm, that's good. Will you need to repair or replace your roof in the next 5 years? If so, then you may want to wait to add your solar system during that time, or consider re-roofing now to add your system.

I'm assuming that you're looking for a grid-connected solar power system, and so you'll be buying based on a budget rather than trying to meet all your power needs.

If you have a small roof area, you'll get more power per square foot from moncrystalline or polycrystalline technology. If space is not an issue, you might be able to get a cheaper system by installing amorphous solar technology. If you live somewhere where power cuts are failrly common and having electricity available all the time is important to you, you may want to consider a system that includes a battery bank - however this will cost more, add to maintenance, and may not be allowed under local laws.

Once you've decided to go ahead, get a couple of quotes from different installers. Ask for these to be itemised. Generally you can expect a 20-25 year warranty on the solar panels, but only about 5 years on the inverter (inverters convert DC electricity from the solar panels to AC electricity yu can use in your home, and they manage the interaction between your solar power system and the local grid). Ask about extended warranties. Ask how many roof penetrations there'll be, how these will be waterproofed, and what warrranty the installer will give you on the waterproofing. Ask whether annual maintenance and checks are included. Ask for the quote to include a calculation of daily power output, and whether they're prepared to guarantee that output.

I would recommend adding about at least 5% contingency to whatever quote you've got. Do not go with an installer who tells you that solar power systems are maintenance free, because this is not true. Don't go with one who doesn't visit the property before quoting, and don't go with one who doesn't climb up and look at your roof (and the space under the roof).

As you're in California, you'll be eligible for a fairly generous feed-in tarrif - this means your local utility will pay you for any energy you export to the grid. You should find out from your utility what their going rate is and whether it is a gross or a net tariff (that is, do you get paid for everything you produce, or just the amount you produce less the amount you take from the grid). A good installer should be able to tell you how to maximise the income from a feed-in tariff.

Once it's installed, ask the installer to take you through how to check whether everything's working properly - usually you'll do this via the user interface on the inverter, but some inverters include data ports so that it can be done from a PC. Don't forget to update your home insurance to cover the system. And then sit back and feel smug about your electrons being greener than everyone else's!
posted by girlgenius at 4:26 PM on March 30, 2009 [2 favorites]

A friend is leasing his new solar array. The company he used is solarcity.com. His array is brand new so no long-term feedback yet, but on sunny days the meter runs backward, which is very satisfying to see. :-) Good luck!
posted by killy willy at 6:21 PM on March 30, 2009

Since LA roofs are often flat, is yours? If so, I would have a serious discussion with any installer about laying the panels flat on the roof vs. tilting them up from the roof. It's easier for them to install them flat, but you could increase your solar collection significantly by tilting them. This is especially true in the winter months; the summer months, not so much.
posted by exphysicist345 at 7:44 PM on March 30, 2009

Further to exphysicist345's point, if your roof is completely flat, putting the panels on a slight tilt is desirable to stop dust building up on them and lowering power output. However at the latitude of LA, the difference in power output from tilt when facing true south is going to be only about 5% over the full year.

Building a wind-rated structure to hold the panels that is significantly more tilted than the roof is going to add to your costs. You may be better off spending that money on an extra few panels or a better inverter (inverter efficiencies range typically form 85% to 95% efficient, so you can make up for the power lost through tilt through a better inverter).

Again, a good installer should be able to help you calculate the trade-off
posted by girlgenius at 8:27 PM on March 30, 2009

In California under the current state program everything will effect your state rebate, pitch, orientation, inverter efficiency and panel brand. It's all about how much power the system will produce.
A few things to keep in mind.
The array should have 6"-8" inches of space under for cooling min, the hotter the modules get the less power they produce.

Have them install a old fashion glass domed dial electric meter at the output of the system to record system output, this will be your proof of output as the inverter digital meter may get replaced or may fail during the next 10-20 years. Back up you Kw data this will be your only proof of system function and total Kw output over the life of the system.

In California there is a 10 year full job warranty (part of the program) on your total system, so keep an eye on the mounts on your roof, junctions, cables etc why? after 10 years you are sol so enforce the warranty.

The SolarWorld modules are So Cal made and have great output (yes i sell them but not in you area).

Don't expect the city/county inspector to catch anything wrong, there busy etc.

Make sure your home owners insurance covers the system, just in case.

In PG&E areas the billing system is insane, a number of customers get surprised by the "true up bill" that arrives 1 year after the system is turned on, watch the monthleys it's all there.
Feel free to mail me if you want a long distance second opinion.
Enjoy
posted by blink_left at 12:17 AM on March 31, 2009