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(970) 403-5004

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Durango, CO 81301


Based in Durango, Colorado, Flatrock Solar is a locally owned and operated solar panel contractor and installer serving the Durango area from Cortez to Pagosa Springs and Silverton to Ignacio.  Flatrock Solar has been helping businesses, homeowners and non-profits convert Colorado sunshine into clean, renewable energy since 2010.  

Durango Solar - FAQs

Frequently asked questions about solar photovoltaic systems in Durango and their answers.  

Grid tie solar with a backup generator

Matt Helms

I get questions about how a backup generator works with a grid tie solar system so I thought I would talk about that here today. The short answer is that they work fine together, but you want the inverter on the grid side of your transfer switch. I’ll explain why below.

When the grid goes down and you have a backup generator, your automatic transfer switch will disconnect you from the grid and turn on your generator to supply your house or business with power. Where it gets confusing/interesting is what does the solar system do at this point? If it’s a sunny day, the solar panels should be producing power which is a good thing when the power is out right? Not exactly.

Luckily, here in the Durango area the grid is fairly reliable so we don’t have grid outages that often, but when it does happen it can be very inconvenient which is where the backup generator comes in. If its a sunny day you would think that having the solar system and the generator producing power at the same time would be great right? More power for your hot tub and big screen TV. Here’s the theoretical situation where damage could occur to your generator. IF you have a high end generator that produces a clean enough sine wave to make your inverter think that the grid is back up AND the generator and solar system are producing more electricity than you’re consuming THEN you might back feed your generator and damage it. Not likely to happen, but it theoretically could. So that’s why you want your solar inverter on the grid side of your transfer switch; just to be safe.

What are the current incentives for solar in the Durango area?

Matt Helms

As of March, 2019 there are two main incentives for installing solar on your home or business in the Durango area. The first is the federal tax credit of 30% of the system cost. This includes the solar panels, inverter, racking, permits and labor. This incentive is currently set to step down at the end of 2019.

The second incentive is the sale of REC’s (Renewable Energy Credits) to the local utility. Both La Plata Electric Association (LPEA) and Empire Electric Association (EEA) will purchase the REC’s generated by your solar system. LPEA will purchase 10 years of REC’s upfront and EEA will purchase them on an annual basis.

These are the main financial incentives to install solar panels on your home or business right now. Other indirect incentives are no sales tax on the solar installation and the county accessor won’t increase your property value for tax reasons because you’ve installed solar. Your actual home value is increased of course with solar, but you won’t owe property tax on this increased value.

how do I prepare my new home in the Durango area for solar?

Matt Helms

I get a lot of calls from builders and customers asking how to make their new home “solar ready” so I thought I’d answer that question here. There are three main things to consider when deciding to make your new house (or a remodel) ready for solar panels in this area whether that’s Durango, Pagosa Springs, Cortez or Bayfield.

  1. Try to have sufficient roof area that faces south, southwest or southeast. I work with builders and potential customers all the time to help them determine how much southern roof exposure they might need based on their heating, cooling and appliance choices for their new home.

  2. Consider pre-wiring your house before the insulation and drywall are installed. Optimally at the same time the rest of your wiring is put in. Running the wiring from the roof, where your solar array will be, inside the walls to where your inverter will be installed can eliminate conduit runs on the exterior of your new home to make it more ascetically pleasing. Again, I can work with your builder or electrician to make sure sufficient wiring is installed at this time to ensure you’re ready to go when you want to install the solar panels.

  3. The last consideration is roof pitch and material. There is an optimal pitch in this area to maximize your solar output and some roofing materials are better than others for attaching the solar panels to your roof. Some people even have a different material installed under the solar panels than the rest of the roof. A little bit of foresight can go a long way!

Please feel free to contact me if you have questions about making your new home “solar ready” in the Durango area.

Can I Estimate My Solar System Output Using LPEA Smarthub?

Matt Helms

Using the information captured by a net meter can tell us something about the output of the solar system, but doesn't have all the information needed to calculate the actual output of the solar system.

I’ve attached a chart from the LPEA SmartHub website for my house using the Net Meter Analysis chart.  What this chart shows is what LPEA calls Generation, Consumption and Net.  

Net Meter Chart Showing Consumption, Generation and Net Production from solar system

The Generation number (-10.17 kWh) is when your meter is ‘spinning backwards’ and your solar system is producing more energy than the house is consuming at that moment.

Consumption (5.74 kWh) is the opposite; when your house is consuming more than the system is producing at that moment and you are receiving energy from LPEA.  For example all your usage at night will be part of this number.

The Net is just Generation minus Consumption (10.17-5.74 = 4.43 kWh).  In the attached chart, my solar system produced 4.43 kWh more than I consumed on September 16, 2017.

In order to determine how much electricity my solar system produced on this day, there is a number missing.  That number is how much electricity was consumed during the day while the solar system was producing power.  This number is not on the LPEA charts and they have no way of capturing this information without a separate smart meter that measures only the output of the solar system.  For example, when my solar system is producing power and my refrigerator turns on, part of the electricity from the solar system will be consumed directly by my refrigerator and will not pass through the net meter.  How much energy is consumed instantaneously in this way is not captured by LPEA.

How do I know my SolarEdge inverter is working?

Matt Helms

Below is a picture of my inverter screen and yours should be similar.  The important things to note are:

1. Pac[W] is greater than 0 (this is how much power the inverter is producing right now so it will be 0 at night)

2. P_OK: X/X where X is the number of solar panels you have on your roof (in the picture below it means that 15 out of 15 of my solar panels are working)

3. <S_OK> (this means that the inverter is connected to the internet)


If you don't see the numbers above on the first screen, something could be wrong.


Solar Savings are Tax Free

Matt Helms

One often overlooked financial benefit of solar is that the savings are not considered income by the the federal or state tax authorities and are therefore tax free.  Depending on your effective tax rate this is an additional benefit of between 20-35% when compared to other investment options such as stocks, bonds or other equities.

Volts, Amps, Watts... Oh My!

Matt Helms

So electricity isn't intuitive like water, but there are some similarities at least in explaining the relationship between volts, amps and watts.  In solar we usually talk about Kilowatt Hours or kWhs.  This is the unit of measurement that your electric bill is in and what the estimated output of a solar system is in.  So I get the question from time to time how amps are related to kWh or something similar.  Below is an explanation I wrote to one of my customers and I thought it might be useful to someone else out there in the ether.

The equation is Watts = Volts * Amps.  If you enter in the time aspect it is Watts * Hours = Watt-hours (Wh) and when you get a thousand Wh’s you get a kilowatt hour (kWh) which is what your bill is based on.

So the common unit is kWh.  You can sort of think of electricity like water.  The pressure of the water in the pipe is volts and the diameter of the pipe is Amps.  So both of them combined give you the max amount of water that can be delivered in a given amount of time like an hour.  This is the Watt hours.

The volts you receive at your house will always be about 240 volts.  That’s what your appliances, lights, etc. are expecting and that is what the solar inverter and LPEA deliver.  The service to your house from LPEA is 200 Amps.  So you can have about 200 Amps of stuff on at your house before the main breaker trips because you are drawing too much power.  That being said, 200 Amps is a LOT of power.

For example, your 10kW electric heater uses about 42 amps maximum.  Amps = Watts / Volts.  10 kW = 10,000 Watts so Amps = 10,000 Watts / 240 Volts = 41.67 Amps.  That is probably the biggest draw in your house and it doesn’t even use a quarter of your available capacity.

I don’t know if this is answering your question, but these are the equations.

As an example of how the Watts (and therefore the Amps, but not the Volts; Volts are constantly 240) fluctuate from hour to hour and day to day, take a look at this write up I did on why a 5.2 kW system isn’t producing 5.2 kW.  Maybe this page will help with your questions:

Steps to go solar in Durango

Matt Helms

I often get asked what the steps are in installing a solar system in the Durango area.  The rough outline with time estimates is below:

  1. I like to start with obtaining your historic electrical usage from LPEA (or your utility).  This requires a signature and your account number on an LPEA form and usually takes a few days to get your usage back from LPEA.
  2. Then I'll setup a site visit to measure your roof or ground area for a ground mount.  I will also take shade analysis measurements if shading will be a factor in your location.  The site visit usually takes about an hour.
  3. With your usage and roof dimensions in hand I can then design a solar system that meets your needs in terms of electrical production.  I usually can get a proposal back to you within a day or two.
  4. After you've looked over the proposal and I've answered any questions you might have, I will send you a contract and another LPEA form that they call an Interconnection Agreement.  Basically this is a document asking them for their permission to connect your solar system to their electrical grid.  This engineering review usually takes about a week to a week and a half.  A representative from LPEA will visit your house or place of business to record your meter number, wire size of the wires coming into your building and their transformer size that is serving your building.  The LPEA engineering team will then make sure that there will be no issues with connecting your new solar system to their grid.
  5. After we have approval from LPEA I will schedule a date and time to complete the actual installation.
  6. After the system is installed, the state electrical inspector will inspect your system to make sure that everything we've done meets the National Electrical Code.  Basically they are checking to make sure the wires are the right size, type, etc. and that we've put everything together properly.
  7. Lastly, LPEA will again send a representative to your house or business to ensure that the system is working properly and will then turn on your new solar system!

So the steps install solar in Durango take a little bit of time, but most of the steps are just paperwork with a crew at your house only for a couple of days in most cases.  After the process is complete all you have to do is sit back and enjoy the Colorado sunshine!   

What should I do before installing solar in Durango?

Matt Helms

Before considering solar for your home or business, you should look for ways to reduce your electrical usage.  One easy way to do this is by installing LED light bulbs.  Diane West from Diane West Jewelry and Art, a local Durango art gallery, ask me to evaluate solar for her gallery.  Before installing solar I suggested she replace the 90 some odd light bulbs with LED to reduce her lighting and A/C costs (the LED bulbs produce much less heat when compared to incandescent bulbs).  She has now reduced her electrical usage and can offset her electric bill with a smaller solar system!

How does Net Metering work?

Matt Helms

I often get asked how the billing works with the local utility with respect to solar.  Do I need batteries for lights at night?  I use most of my power in the winter, but produce more power in the summer.  How does that work?

In the Durango area, the local utility (LPEA) 'resets the clock' so to speak on April 1st every year.  In other words, they begin to count your solar production and subtract your usage for the year on April 1.  Let's say that your solar system produces 1,000 kWh in April, but you only use 900 kWh. You would receive a credit for the extra 100 kWh that you produced and this would 'roll over' to May.  If you continue to produce more electricity with your solar system than you use your credits will continue to grow through the spring and summer.  These credits would then be used in the fall and winter as you consume more than you produce.  If the stars are aligned, you use all your credits by April 1st and the cycle starts again.  Other possible outcomes could be that your system didn't produce quite enough to get you through the year and you have a bill in February through March.  On the other hand, if you produce more than you consume in a given year, then you will receive a credit on your account or a check from the local utility for the excess production.

Another way to think about it is that you sell the electricity from your solar system to the utility at the same rate that you buy it back from them.  The 'net' is what you owe them or they owe you.

Here's an example of a meter spinning backwards with a solar system attached.

If you'd like to save money on your electric bill by having your meter spin backwards, give us a call!  We're a full service solar contractor and installer serving the Durango area that specializes in grid tied solar electric systems.

Should I wash my solar panels?

Matt Helms

I always recommend to not worry about washing your solar panels.  In southwest Colorado we get enough rain and snow to clean the panels.  Also, if your tap water has minerals in it (which I think it all does in this area) you can get water spots and mineral deposits on the panels.  A study done by the University of California at San Diego has shown that even if it hasn't rained for 145 days, in dusty southern California, it only reduces the output of your solar panels by 7.4% or about $20 for a 5 kW system.  Probably not worth the effort or expense of cleaning your panels.

Why does my 5.2 kW system not produce 5.2 kW?

Matt Helms

So a lot of people ask why their 5.2 kW in solar panels doesn't produce 5.2 kW at the inverter.  Its a good question and one that isn't super easy to explain.

This is a chart of the peak power of a 5.2 kW system:

Output of a 5.2 kW solar electric system in the Durango area.

Here is a chart of another system that I installed in the same area that is 8.5 kW with little or no shading:

Output of a Durango solar system with 8.5 kW of solar panels.

Neither system has reached its theoretical maximum of the installed size of the system and never will.  The inverter on the 5.2 kW system has a maximum output is 5 kW AC and the 8.5 kW system has a 7.6 kW inverter.

There are a couple of reasons why the installed capacity (5.25 kW) doesn’t equal the output of the inverter (charts above).  One is inefficiencies of the system (wiring losses, inverter not being 100% efficient, etc.) and the other is that solar panels are rated at what is called Standard Test Conditions (STC).  This is a laboratory test that uses artificial lighting to produce 1,000 watts per square meter, at a solar cell temperature (not ambient air temperature) of 25 degrees celsius, and an air mass of 1.5.  So for a 250W solar panel to produce 250W of power these three conditions would have to occur in the ‘wild’.  This is theoretically possible, but not likely.  You have to also remember that this 250 watts of power will equal something less than 250 watts of AC power (output of the inverter) because of inefficiencies.  

The chart above does highlight the potential spike in the fall and spring that you might see (in this case in November).  The fall and spring are when you’ll see conditions most like STC; low temps with high irradiance (sunlight).

The important number to look at with a solar system is how many kWh it produces in a month or year.  System designers look at all the environmental factors (location on Earth, weather patterns, azimuth and tilt of panels, etc.) to model the estimated output in kWh of the system.

I welcome comments or questions so I can improve on the explaination.

What types of monitoring options do you offer?

Matt Helms

Monitoring is supplied through the manufacturer of the inverter.  There are generally two types of monitoring available for residential systems, system level and panel level.  System level monitoring tells you the output, status, etc. of the entire system.  So if one panel is not working properly you might notice a slight decrease in output, but it would be harder to detect a small issue in a particular panel.  Panel level monitoring on the other hand shows the output, status, etc. of each individual solar panel.  So if one panel is having an issue, the monitoring system tells you exactly which panel.  This can be very useful for trouble shooting an issue and to ensure that all your panels are working properly.  

I've included here a link to an example site that uses panel level monitoring: 
Monitoring Example

What about maintenance?

Matt Helms

Grid tied solar systems don't require maintenance.  There are no moving parts in the system and under normal operating conditions do not require any scheduled maintenance.  This is one of the great things about solar electric systems!

What services do you offer?

Matt Helms

Flatrock Solar is a full service solar contractor specializing in solar electric or photovoltaic system design, procurement and installation.  We server the four corners area including Durango, Mancos, Dolores, Cortez, Bayfield, Ignacio, Pagosa Springs and the Aztec and Farmington areas.  The main service area includes the following zip codes: 81301, 81303, 81433, 81328, 81321, 87418, 87401, 87413, 87410, 81137, 81122 and 81147.  Our solar contracting service includes system design, financial analysis, procurement, installation and all required paperwork such as permitting and interconnection with the local utility.  For larger commercial projects we can expand our service area beyond the above residential area.  Please give us a call for a free, no obligation proposal.  You won't be disappointed by our solar contracting services!

What about batteries?

Matt Helms

Most solar systems installed today are what is called 'grid-tied' and don't use batteries.  The solar panels on your roof convert the sun into electricity which is either used immediately in your house by lights, appliances, etc. or spins your meter backwards and is 'sold' back to the utility.  This extra power is most likely used by your neighbors so they can thank you for installing a solar system!

Will I need to remove snow from my solar panels?

Matt Helms

The solar panels are made with glass which is very slippery.  The solar panels shed snow better than a metal roof such as Pro Panel.  Also they are a dark color and will warm up quickly in the sun.  There is no need to remove the snow from them, but if you feel the need, use a bamboo grass rake or a plastic rake; not metal.  You don't want to scratch the glass on the front of the panel.