1 Jan

Solar Panel Installation – Site Planning

Posted by Norman F

Last Update: May 2018

Sunpower solar panels

You have read Are Solar Panels for me? and decided that Solar Panels are in your future. Planning a new solar installation requires lots of analysis and planning.  You need to size your solar system, select solar equipment, select a payment option, and find a qualified local solar installer.

Get a Free Solar Power Estimate from a local vendor by clicking the advertisement above.

Sizing a Solar Electric System

Power Usage – Grab the power bills for the last year.

  • How much power do you use in a given year?  What rate plan are you on and what is it?
  • Do you want to zero out your bill (most environmentally friendly but requires bigger system) or just reduce your bill (financial benefit) by moving to lower electric bill tiers?
  • It may be more cost effective to fall into lower price tiers. In the San Francisco Bay Area most PG&E customers have tiered energy pricing (E1 Residential Pricing plan) that starts at 12 cents, but jumps to 14, 29 cents, 40 cents and 40 cents as you use more power. The solar installer you select must be able to help you here.

It pays to reduce your electricity consumption by conservation and efficiency BEFORE you size a system.  Read our tips on saving electricity.  Each $1 spent on efficiency saves almost $3 in solar costs. Consider a home energy audit.

Sizing your system – Examine your roof size, power bill, solar panel efficiency, and see how large a system you can actually install.  You may be limited by space on your roof. The very nice California Clean Power Estimator takes your power usage information, physical location information, incentive information to give you savings estimates based on solar panel size.  Other states may have similar tools.

San Francisco has a nice solar map. It shows various solar system installations and how much solar power and money savings you can expect from your location.

Select Solar Equipment

Solar Panels – Picking the right solar panels is determined by how shaded your location is, your budget, and your efficiency needs. Be sure to compare panels using AC watt ratings. Make sure you purchase solar panels with a long established track record, you want these to last 30 years. Solar panel companies have been having financial problems, check out the manufacturer before purchasing.

Cheaper panels are usually less efficient and generate less power.  Reliability may also be less.

Solar Panel orientation

Solar panels need to face the sun for a majority of the day to maximize power output. For those in the US, panels facing true South will be optimal.  If your roof faces East – West, you can try to add racks that orient them towards the south.

The optimal solar panel angel is latitude times 0.76 plus 3.1 degrees.  You could orient some panels this way and another set for optimal power production during the afternoon sun, for possible better ROI.

Power Inverters

Power Inverters – These units convert DC power to AC power. Each unit can only handle so many solar panels. Newer models have better efficiency at converting power. How many inverters do you need? Where will they be positioned?  Do you leave room for future solar panel additions?  If you get a power inverter too small, it may clip the amount of power generated during peak times.

Some communities require them to be in the shade and away from fire hazards. We recommend sticking to popular name brands like the SMA – Sunny boy.  After about 12 years, one of our inverters needed to be replaced, a typical time frame.

String inverters are the most common in the past, they allow an array of panels to be connected in series.  The downside is if there is partial shading on one panel, the power output would be severely affected on the entire string.

Micro inverters are small inverters that are usually connected to the bottom of each solar panel. Instead of having a large inverter wired to all the panels, the micro inverters convert DC power to AC power right behind the solar panel. This is best used when there is a lot of shade or many different panel orientations.

Get a price quote showing string inverters and one with Micro inverters. Ask how do these inverters stand up to weather and sun exposure?

Rule 21

California put a law into effect known as Rule 21 on 9/8/2017. It required any new installation to have compliant inverters.   In Germany, significant grid destabilization problems arose when high penetration levels of solar PV systems were reached because most of these Digistributed Energy Resources (DER) were required to trip off within fairly small frequency tolerances, causing power grid issues.

Rapid Shutdown

As part of the fire code, many jurisdictions require there to be a remote switch to de-energize the solar panels in case of a fire. Known as Rapid Shutdown or 2014 National Electric Code aka NEC 690.12 – “Rapid Shutdown of PV Systems on Buildings.”, this standard adds to fire safety. Micro inverter based systems do not need special equipment to comply.  String inverters require a separate circuit wired near your solar equipment, to turn off power from panels.

Solar Edge micro inverters have capabilities built in to control the panel.

Paying for Solar Panels

Many people do not have $30k sitting around. Do you want to buy, get a solar loan, or lease solar panels? Both have advantages and disadvantages.

Optimal Installation Date

The optimal time to get your solar panel installed is in early spring/late winter, avoid installations in fall if possible.  Very little power is produced when the days are short or when the sun does not shine.  The biggest factor affecting an  installation date is usually when tax rebates ends or when they ratchet lower.  Try balancing the two factors to optimize your solar electric system install.

Utility Company Interaction

Most utilities offer credit for excess solar electricity provided to the utility but not used by the home. Power utilities are now fighting this provision, and may stop this practice some day.

When you have your solar panels installed, you should be able to select “time of use” billing where during peak times (Weekdays 1-7pm) in the summer, you generate more power than you need and collect energy credit for the lean winter months. The rates are 2.5x higher in summer, so you can earn a lot of winter offsets. They will also have an interconnection agreement for you to sign.

PG&E has a section on their Solar Energy section on their website. Net metering changes your power bill to an annual cycle. Our power bill is still charged a minimum $5 a month. At the end of the year, we pay them how much PG&E power we actually had to use.

Finding a Qualified Solar Installer

After reviewing the above criteria, the next step is to contact a local Solar Panel installer.  They will first look at your property via online tools to see how your roof looks, examine your power bills, evaluate your goals, and see how your property is oriented.

Solar Electric installers should then visit your location to inspect it. Expect a customized solar system design, financial analysis, and options for financing.

A solar electric quote is a detailed quote a system tailored to your budget and home.

As with any vendor, look for one with a solid track record, solid references, and competitive pricing.

Questions to ask a solar electric system installer:

  1. How long have you been in business, how many installations?
  2. What is the minimum warranted power rating of the solar panels?
  3. What is the PTC per watt rating of the solar panels?
  4. Who makes the solar panels, how long have they been shipping these, factory warranty?
  5. How efficient are the solar panels and power inverter?
  6. Who makes the solar panels and power inverter?
  7. Who makes the solar panel mounting racks? Are they commercial grade? Do they optimize sun exposure angles? Do they have to make penetrations into your roof?
  8. Get a quote for a solar electric system that will zero out your electric bill and a quote for a smaller system that will kick you into the lowest electricity tier.

California has a database of Solar installers, contractors, and solar panel dealers. California Solar Energy Industries Association

Be sure to read our solar panel deals page for the latest updates in special promotions.

Once your Solar electric system is installed, you will need to maintain them as  Solar Panels will need occasional solar panel cleaning.

Do you have any other tips?

Posted on January 1st, 2018
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5 Responses to “Solar Panel Installation – Site Planning”

  1. solar panels Says:

    I think you’d better find a licensed installer to do the job for you.

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    […] Many local solar installers can walk you through these questions and help you answer them.  They will be skewed on the side of selling you a system of course. If you satisfy all the above criteria and are not scared off, read our article on Solar Panel Installation – Planning. […]

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