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Installing Solar: Things to keep in mind when comparing bids

“Going Solar” is such an exciting decision! You already know you’re making a great financial investment decision as well as being a friend to the environment. So now you find yourself at the point where you contact different solar installers to get bids. A good installer should be able to give you a solid ball park price estimate over the phone if you provide them with your annual kilowatt usage and your address so they can look at a satellite image of you property on Google Earth. But to get an exact price quote, they will definitely have to make a site visit. So suppose you’ve received several quotes yet one is substantially lower than the others….how can this be?

This is where you have to be careful. It is tempting to go with the lowest bid, assuming that it will save you money. The old adage “If it sounds too good to be true, it probably is” definitely rings true here. It’s also true in this industry that you get what you pay for!  Unfortunately there are companies out there who will provide you with erroneous or misleading information just to get your business; or will use shoddy product and cut corners on the installation… those companies likely won’t be around in the future should something go wrong with your system and you need help.

One of the most common ploys to be aware of is “Our solar panels are more efficient than others so they will produce more power.”  This is very misleading. The efficiency of a solar panel has little to do with its power output. For example, a 300 watt solar panel is a 300 watt solar panel… it is only going to output 300 watts of power.  Therefore 2 solar panels of the same size (wattage) exposed to sunlight for the same amount of time are generally going to produce the same amount of power (kilowatt hours). The efficiency has much more to do with the physical size of the solar panel itself… NOT how much power it will produce.  If one 300 watt solar panel is more efficient than another 300 watt solar panel, that simply means it is smaller in physical size than the less efficient one.  There are however some very small differences in solar panels that may contribute to one solar panel generating more or less power than another solar panel of the same wattage (i.e. – temperature coefficient) but these are small differences and will not greatly impact the power production, contrary to what many solar installers imply.  The most important thing to remember here is that wattage is the most important consideration… a 10kW array is a 10kW array and one will not produce more than the other, regardless of solar panel efficiency.  It is also important to ensure, that the installer is using Premium Grade solar panels from a Tier 1 manufacturer that offers a 25 year linear power production warranty.  Also, ensure the solar panels have “re-insurance” to back up the warranty in case the manufacturer is not around if a warranty claim arises.

Another issue to be extremely aware of, if you are getting a roof mount system, is the type of racking that will be used to attach the solar panels to your roof. Many installers cut corners here in order provide you with a cheaper bid and win your business, but it is to your detriment. Roof mounted solar systems generally require attachments that penetrate the roofing material and attach to the roof joists or trusses in your attic.  A reputable installer will use “flashing” which is a thin metal plate covering the roof attachment point, tucked under the shingle and further secured with bead of roofing tar AND silicon rubber gaskets to ensure no leaks ever occur at the penetration point for the full life of the system. A less reputable installer will just use something called an “L Foot” without flashing which is an L shaped bracket set and drilled into the trusses from the top of the shingle, leaving an opportunity for the roof to leak at every penetration point. Most will at least use a dab of silicon on top of the lag bolt that penetrates the roof, BUT… your solar panels have a 25 year warranty and I certainly wouldn’t want to rely on a dab of silicon on top of a bolt to protect my roof from leaking for 25 years or longer… would you?  An installers cost for an attachment bracket WITH FLASHING and hardware is around $12 each versus an L Foot bracket at $2 each. Therefore, if you take a 10kW roof mount system, for example, it would require approximately 100 roof attachment points and 200 lag bolt penetrations into the roof (each roof attachment requires 2 lag bolts, if the installer is not cutting corners or using a low quality product).  That means the cost to the installer is $1200 for the flashed attachment or $200 for the L Feet. It also is much less labor intensive to install an L Foot than it is to properly install a flashed attachment bracket.  That one little trick right there allows the less reputable installer to knock approximately $1500 off your bid (parts & labor) with you being none the wiser……until your roof leaks.

Another trick commonly used by shoddy installers is to under size the inverter. It is really important to use an inverter that is large enough for your system to run at maximum efficiency. The inverter should not be sized less than 90% of the total size of the array (in kilowatts).  The inverter can be slightly smaller than your array size because there are some system losses that occur (i.e. – panel soiling, wire/connection losses, etc.) but an inverter that is too small will “clip power” on a sunny day when the sun is over head.  For example, if 10kW’s of solar panels are outputting 9kW’s of power but the system only has an 8kW inverter, then your system will only output 8kW’s because 8kW’s is the maximum output of the inverter.  In this situation, your solar panels are producing 1kW (1000 watts) more power than the inverter can handle so the inverter “clips” the excess power (to avoid damage to the inverter), thereby wasting 1000 watts of electricity at that time.  Obviously, the smaller the inverter is the less expensive it is so the installer can quote you a lower price and still tell you that you have a 10kW solar array, because you do in fact have 10kW’s of solar panels… even though it will not produce as much power as it should if the inverter were properly sized.

One final thing to be aware of… ask your installer to justify their power production calculations and make sure that all the quotes you receive use the exact same “system loss” calculations.  Many installers will misrepresent the system losses, which produces the illusion that their solar array will produce more power than the other more reputable installers.  I’ve even seen several installers say “because our system produces more power than our competitors (for whatever bogus reason), we can build a smaller system for you, which in turn saves you money on the installation cost.”  Again, total hogwash!  Bottom line is… a 10kW array is generally going produce the same amount of power as another 10kW array, if it’s properly designed and installed!  So make sure they not only provide you with the power production calculations but ALSO with their “system loss” calculations so you can verify that all installers are using the same accurate calculations and that someone is not misleading you here.

It is so important to have an excellent installer when it comes to your new solar system. The best way to find them is to ask questions. An installer worth his/her salt should take plenty of time to answer any question you have down to the very last detail… you can see, details are important.  Also, ask for references! These customers can give you feedback on the installation process, the efficiency of their system and if any problems arose, how they were dealt with. They are the best way to make sure the installation company has stood the test of time. Many companies can slap together a cheap installation but the few really good ones will provide an excellent product, outstanding service and be there for you down the road when and if you need them. Going with a reputable installer may cost a little more up front but is surely worth your peace of mind.

Please check out our website at and our Facebook page at or give us a call at 970.482.SOLAR (7652).

How Much Does it Cost to Install Solar on a Roof Top?


If your goal is to eliminate your electric bill but don’t have enough roof space or land to English: Solar panels on a roofbuild a ground mounted system, then the next best thing to do is maximize your available roof space with southern exposure. Taking this approach we can tell you what percentage of your electric bill will be off-set by the power produced from the solar array.

The first thing you’ll want to do is determine your last 12 months of kWh (kilowatt hour) usage (see Part 1 and Part 2 of our last Blog Post for instructions on how to determine this).

The next order of business is to measure the roofs dimensions, tilt and orientation
(we do this during our site analysis). The roof dimensions will determine the size of the solar system, while the tilt and orientation will determine how much power (electricity) the system will generate given its size.

It’s important that your roof have at least some southern exposure. If yours does not, this does not mean you shouldn’t install solar… it simply means that your system will not produce as much power and therefore your return on investment will not be as great. The ideal orientation for a roof is 168 degrees from north. However, anything from 135 – 205 degrees from north will yield 95% optimal results; and from 115 – 225 degrees will yield a minimum of 90% of the optimal results. Whereas, if you have a roof that faces directly east then your system will only produce at 78% of the optimal level. Likewise, if your roof faces due west then it will only be 69% of the optimal level. So as you can see, just because you don’t have a south facing roof, doesn’t mean your solar system won’t produce… it just means it won’t produce at the optimal level. However a north facing roof line is not well suited for solar here in the northern hemisphere.

The optimal tilt for solar panels in Northern Colorado is a 40 degree pitch. Most roof tops aren’t this steep but even a 20 degree pitch will provide very good results. Unless your roof is fairly flat, we typically recommend a flush mounted system since the incremental increase in electricity production usually doesn’t justify the additional cost associated with increasing the tilt of the panels. However, if your roof is fairly flat then it definitely makes sense to use a tilt-up racking design.

Once the roof dimensions, tilt and orientation are established we can then determine how many solar panels your roof will hold and how much power the system will produce. As a very broad based rule of thumb, each kW (kilowatts) of solar panels installed in Colorado will generate around 1,300 – 1,600 kWh’s annually, depending on the tilt and orientation of the solar panels.

There are many variables in determining the cost of installing solar on your home or business. But one of the most important things to understand is that solar pricing is not linear. Generally speaking, the larger the system is the lower the cost (per watt) will be. A 10kW (10,000 watts) solar system will cost a lot less per watt than a 4kW (4,000 watts) system. Of course, the total cost of a 10kW system will be higher than a 4kW system but the larger the system is the lower the cost per watt and the greater the return on investment.

In addition to size, there are many other variables that impact the cost of installing solar, which we evaluate during our site analysis (ie – breaker panel and electric service, roof structure and material, rafter/truss system, meter location, point of grid interconnection, conduit runs, etc.). However, getting to the heart of the question, the total turn-key cost of having solar installed on your home or business will typically be between $3.50/watt, for larger solar PV systems, and upwards of $6.50/watt for smaller systems. However, anyone who installs solar on their home or business is eligible for a 30% federal tax credit (this is not a tax deduction; it is a tax credit… a dollar for dollar reduction in the taxes you pay to Uncle Sam), thereby reducing your installed cost by 30%. Also, many utilities offer rebates and/or REC (Renewable Energy Credit) payments based on the size of the solar system and the amount of power it produces. These utility rebates can also drastically reduce the cost of installing solar. Please call us at 970.482.SOLAR (7652) if you want to find out what rebates your specific utility offers.

Putting it all together… we’ll use an example addressing everything we’ve discussed in this article, using the following assumptions: your kWh usage over the last 12 months was 15,325kWh’s and you don’t anticipate any change in your future usage; your roof, which faces due south (180 degrees from north), has 625 S.F. of shade free space available and has a 24 degree pitch; and of course you want to maximize the available roof space and determine how much of your electric bill will be off-set by the electric produced from the solar system.

Using 250 watt solar panels (approx. 18 S.F. each) we can determine that your available roof space will comfortably hold 32 solar panels (32 x 18 = 576 S.F. total), which equates to an 8kW system (250W x 32 panels = 8,000 watts or 8kW). Next, using our power production tools (based on 30 years of solar irradiance data collected in Colorado) we can determine that an 8kW system will produce approximately 11,859kWh’s per year (based on the roof tilt and orientation assumptions from above). Therefore, this system will reduce your on-grid electric usage by a little more than 77% (11,859kwh’s produced divided by 15,325kWh’s consumed = 77.4% reduction in your electric bill)

An 8kW roof mounted solar PV system installed by Alt E would cost around $35-36,000 ($4.50/watt), at today’s prices.

Taking the next step, using $35,000 as the installed price, you will receive a federal tax credit of $10,500, thereby bringing the cost down to $24,500. Now let’s assume your electric utility pays you a REC payment of $.13/kWh and your electric rate is $.105/kWh (this is Xcel Energy’s current REC payment price for “small solar PV systems” and its current residential electric rate). Your solar system will save you $1245/per year at today’s electric rates (11,859kWh’s produced x $.105/kWh = $1245.19 annually), PLUS Xcel will pay you under contract $1542 annually (11,859kWh’s produced x $.13/kWh REC payment = $1541.67) for each of the next 10 years (paid monthly)!! Therefore the total annual financial benefit to you is $2787 ($1245 in annual savings + $1542 in REC payments = $2787).

To do a very simple payback analysis, simply divide the net cost (after your federal tax credit) of $24,500 by the annual financial benefit (savings and REC payment) of $2787 to determine that the payback timeframe is 8.79 years. However, we all know that electric rates are only going up (average annual electric rate increase over the past 30 years has been 6.7% annually – doubling about every 11 years), so if you factor in this rate increase going forward, then your actual payback time frame is more likely around 7.5 years. This equates to an approximate 14% annual return on your investment!

However, if you want to calculate your true return on investment (R.O.I.) then it’s important to take into consideration the tax ramifications. Since savings on your electric bill are not taxable, in order to compare the true R.O.I. with other investments, which are taxable, you must ask yourself, “What would I need to earn on a $24,500 investment in order to net $2787 annually from that investment, after I pay taxes?” To answer that question, let’s assume you are in a 25% tax bracket. If that were the case then you’d need to earn $3716 from that $24,500 investment in order to net (after taxes) the same $2787 from your solar system ($3716 less 25% tax of $929). Looking at it this way (which is the proper way of calculating actual R.O.I. on your solar investment), then a simple calculation shows a payback timeframe of 6.59 years ($24,500 divided by $3716 = 6.59 years). Once again, factoring in electric rate increases, your actual payback timeframe is about 6 years or an annual return on investment of almost 17%… where else are you going to get a risk free (a contract with a utility company is about as safe of an investment as there is) return on your investment that’s anywhere close to that?!!! WHY ISN’T EVERYONE DOING THIS???

Please check out our website at and our Facebook page at or give us a call at 970.482.SOLAR (7652).

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