Home Solar Panels Solar Service
Written by Rick Peters

Solar Plus Storage is Ready for Prime-Time Backup Power for your Home

As we’ve seen the cost of solar drop rapidly in the last ten years (more than 80%), we continued to endure those naysayers in the distance arguing that “no matter how cheap you make solar; much like wind, it will never dominate the energy landscape because of intermittency.” It’s hard to believe people still say “Never” in the context of technology? That term only provokes our great American drive and ingenuity, which continues to deliver. Witness electric storage costs have dropped 80% in the last eight years, outpacing the dramatic solar cost reductions!

Battery technology today

Today, electric batteries continue to back up solar in more and more markets every year. Batteries are giving solar system owners a lot more control and choice about energy independence, while giving grid operators a game changing tool to help manage the modern grid with greater economic efficiency. We’ll talk more about the how and why, later in this post.

Storage market is heating up

So far SES has contracted for 7 battery installs already this year in Maryland, up dramatically from 2017. The residential solar plus storage market has begun to take off in many markets. In fact, the preferred battery suppliers were out of stock for more than 4 months this year, both from increased demand to complement solar projects, but also due to the soaring demand increase for Electric Vehicles (EVs) that use the same battery technologies.

Storage is like bacon

Why is storage so valuable? One of my favorite energy experts, Katherine Hamilton (https://38northsolutions.com/team/bios/) once said that “storage is like bacon, it makes everything better.” Storage has almost a dozen value streams that can be monetized now or in the future. The two biggest and most obvious value streams are that it can provide extra capacity in times of high demand, and it can provide extra demand in times of excess capacity. In both cases, it provides stabilizing value to the grid and more efficient use of generating assets.

A testament to the value of storage on the grid was seen several years ago when the California Public Utilities Commission required utilities to procure a minimum amount of storage. Not only did the major utilities comply, they all procured more storage than mandated. They are well aware, storage helps them modulate an increasingly dynamic and decentralized grid.

Residential Solar Panels Anne Arundel County MD

Why should I consider solar plus storage for my home?

If you deploy solar along with your energy storage solution, you can utilize the same federal tax benefits as you do for solar, namely the 30% investment tax credit. In Maryland, you are eligible for an income tax credit on the storage portion of the system, in addition to the other state solar incentives (https://energy.maryland.gov/business/Pages/EnergyStorage.aspx). As a result, the economics in Maryland for residential solar + storage are much improved from a few years ago.

The main reason our residential customers are deploying energy storage is for backup power during a grid outage. This is typically done by way of an essential loads subpanel in their electric system. SES often installs these subpanels as part of our solar + storage project.

Another factor driving this trend is a residential customer’s desire to position themselves to cut the cord in the future, if the utility relationship becomes unappealing or uneconomical for them.

Lastly, future changes to electric rate design and/or net metering policy, could present solar + storage owners the ability to increase their savings or even generate revenue from the services that their frequently-idle storage can provide.

Are you building a new home and want to be sure it is ready for the energy architecture of the future? It’s easier than you think. Ask your builder or electrician to insure you have an essential loads subpanel (to use with electric battery storage, or possibly a generator). Secondly, request they install an empty (capped) electrical conduit from attic to electric room for us to easily add your solar energy conducting wire in the future.

Please see Roger Perry’s technical writeup on residential storage applications recently implemented by SES.

What has brought about this market opportunity?

Electric storage has long been an essential part of any true off-grid solar/wind application and this is where the earliest developments have taken place. As solar began to penetrate the grid in the last 10 years, there has been a lot of R&D investment in this future “holy grail” of renewable energy development. The investment is now paying off.

Storage broke into the US grid-tied market about five years ago. In the case of Hawaii, it was mostly a market driven change. Extremely expensive power, a grid congested with rapid solar growth, denials and delays of solar interconnection applications, and abundant sunshine, all contributed to the new paradigm. This resulted in economics that justified a certain segment of residential customers in Hawaii to cut the cord and embrace storage as a long-term solution. This sent an alarming message to utilities around the world: You better embrace these changes or plan to go the way of the buggy whip!

At about the same time, California’s PUC mandated a specific quantity of storage on the grid, much of it behind the meter. The utilities went on to exceed that mandate in the first auction and later in 2017, the target was increased again, with little to no resistance. In the past year, we’ve seen California utilities choose new battery storage over new gas fired peaker plants to meet peak loads in three separate cases. This is a tremendous validation of the economics of storage, particularly in an age of record low natural gas prices.

What’s ahead for energy storage?

The horse is out of the barn. Distributed energy generation combined with storage, will be the foundation of the future electric grid. The role that storage will play in this transformation will be enormous at the macro level, but somewhat uncertain at the micro level due to regulatory policy, incentives, and local market conditions.

We should expect to see strong storage growth in markets with the following attributes:

  • Places where local or state incentives are promoting storage – Maryland is one of them.
  • Markets where system owners can capture supplemental revenue from their storage investments (Our grid operator, PJM has piloted bundling distributed storage as a revenue generating resource for storage system owners)
  • Markets with high electric rates or Time of Use (TOU) rates.
  • Markets where electric “demand charges” represent a large cost for commercial and industrial (C&I) customers. This is because storage can dramatically lower a building’s electricity demand profile, and thus add energy bill relief to a portion of the bill where solar has had limited impact.
  • Microgrids are increasingly popular, particularly with campus style environments and military installations. These applications will increase storage demand and further drive down costs through scale and experience.

Next steps

Be sure to contact SES if you are interested in solar + storage. We will be happy to design a system that is customized to your needs. As always, we’ll provide you all the support you need to capture the Maryland solar grant and the storage tax credit (which has a limited budget) so contact us right away.

Solar Energy Solar Panel Washington DC Solar
Written by Roger Perry

Practical Considerations for a Battery System

As long as I’ve been doing solar, people have been asking about batteries. The response has always been “yes, we can do them, but it will cost a lot”. That usually ended the conversation.

One question to ask is “why do you want batteries?” Do you lose power frequently? If not, a portable generator will keep your refrigerator, freezer, computers, tv and some lights going. Downsides are; noise, fumes, refueling, having to run extension cords to where needed and putting everything away when power comes back. Not too bad once in a while and it’s very cost effective. Just hope you aren’t out of town when power goes out. There is nothing automatic about this set-up.

If you lose power often and don’t want to do the portable generator dance every few months, you can get a permanently installed generator with automatic start. These are close to $5000 installed for the ones that will run most of your house when the power goes out (a larger one can be installed for a few thousand more that will run everything). This is what hospitals and critical buildings use. Power goes out, the generator starts automatically and powers the house with only a momentary loss of electricity.

Downsides? Noisy, they need maintenance and, if propane or diesel powered, they need the fuel tanks to be kept filled.

What if you lose power often, don’t want the noise, maintenance and fuel expense of a generator? What if you want a system that is environmentally friendly, will turn on automatically, is silent, will run pretty much nonstop without refueling? You should look into installing a battery back-up system connected with a solar system.

What are the downsides? Well, cost is one. While not as expensive as in years past, battery back-up systems are still costly. Compared to a permanently installed generator, battery backups tend to run few thousand more. Ask your accountant but you may be able to take the 30% solar tax credit on the additional cost of the batteries. This brings the price in line with a generator.

Another downside is you can’t run everything in your house. Things a battery cannot run for any length of time are air conditioners or heat pumps, electric water heaters, electric dryer or electric ranges. What they can run are gas or solar water heaters, gas or oil boilers, refrigerators, freezers, lights, tvs, computers, fans and pretty much everything else. Well pumps are on the edge depending on how efficient they are. While running a modern variable speed well pump is not an issue, older well pumps require a large startup current which can be too much for the battery to handle. We are about to install a “soft start” control to try and reduce a well pumps surge demand for one of our customers but the jury is still out.

We are now installing LG Chem lithium Ion batteries. LI batteries have a lot of advantages over the old lead acid batteries. The big advantage they have is they are not damaged by running them dead, whereas lead acid batteries do not like being discharged to less than 50% of charge, a Lithium Ion battery will give you it’s full rating. The one we use is rated for 10 Kilowatthour (KWH). A lead acid battery would need to be rated at 20 KHW to achieve the same capacity. Lithium batteries are also much lighter (not that the customer will have to move them) and can be charged much faster.

The big downsize of LI batteries is the upfront cost compared to LA but they will last much, much longer and they are maintenance free.

In a future blog I will discuss the two different ways to interface a solar system with the batteries, AC coupled and DC coupled and the pros and cons of each as well as what a 10 KWH battery will give you as far as run times for various appliances. I’ll also talk about how a battery system can be retrofitted to your existing solar system.

Electric Charging, Solar, Annapolis MD
Written by Lisa Walsh

Solar Systems with Integrated Electric Vehicle Chargers

….like Peas and Carrots

Solar Panel, Solar energy, Annapolis MDAs referenced in our accompanying EV Growth Blogs, the adoption of Electric Vehicles has skyrocketed in recent years. This is small wonder considering EV purchasers can look forward to a 30% federal tax credit on the upfront cost, reduction of fuel costs of at least 60% (according to this Nissan Leaf owner’s calculations), and State Grants/tax credits where applicable (Maryland, for example) and the negation of various oil changes and maintenance costs that accompany an internal combustion engine. For homeowners who have discovered the substantial energy savings by purchasing (not leasing!) a solar residential system, it’s a natural step to want to extend these savings to their current, or future, electrified vehicle.

Ahead of the curve on this natural progression is an innovative new product from inverter manufacturer SolarEdge. All solar systems have two major components 1. Solar panel arrays 2. Inverter(s) that convert incoming DC energy to appliance-ready AC energy. As the national leader in residential inverter supply, SolarEdge made a great move in developing an Inverter that has a built-in EV Charger with a 25’ charge connector. Net energy meter customers (NEM) or energy generating customers interconnected to Pepco are not eligible to apply for the R-PIV rate.

Electric Charging,Solar, Annapolis MD

Why not choose a separate EV Charger?

Four reasons:

  1. Cost. Upgrading to an inverter that has a built-in EV Car Charger comes at around a $1000 cost increase (assuming one inverter/car charger). However, this upgrade – as part of the solar installation – qualifies for the 30% federal tax credit, putting the material cost at around the same as a separate stand-alone EV Charger such as Clipper City. In addition, the integrated inverter has no additional labor or electrician charges – its all covered in the solar install.
  2. Warranty. Popular stand-alone Car Chargers such as Clipper City come with a 3- year warranty. Solar Edge’s integrated inverter has a 12-year warranty, with upgrades up to 25 years available.
  3. Design Elegance. Between service panels, routers, generators and other wall-mounted electronics – its nice to have a 2-in-1 solution and save some wall space. No additional wiring or conduits needed. Of course, the inverter does need to be placed within 25’ of where the EV will be parked nightly.
  4. All Pros no Cons. As with Stand-alone chargers, Solar Edge’s integrated solution allows for indoor/outdoor placement, comes with a 25’ connector and offers software that tracks your EV’s energy consumption that is accessible from desktop or phone, and can be controlled remotely.

Thinking Ahead

Due to the clear advantages, and seeming inevitability of rapid EV adoption by the majority of Americans by the Year 2030, we now ask all of our prospective solar shoppers two questions:

  1. “Do you plan to buy an Electric Vehicle in the not-so-distant future?”
  2. If so, “ What is your expected weekly/annual mileage?”

Mileage calculations inform how many solar panels we should add to the array in order to cover as much EV car use as possible (as roof space allows). Worth noting for our Washington DC/Montgomery County solar customers, PEPCO does require us to fill out an Electrical Usage Calculation Sheet if the solar system is sized over 120% larger than the past 12 months usage history. In those cases we simply submit the estimated kWh increase (as per expected mileage calculations) that the EV will add.

Written by Lisa Walsh

PEPCO Incentives for Electric Vehicle Owners in Maryland and DC

PEPCO has an Electric Vehicle (EV) Program for residential customers in Maryland. It is open to all qualified residents throughout the state. You can participate in the program if your electric vehicle is registered in Maryland.

This program was created to encourage off-peak vehicle charging. The benefits include lower off-peak electric rates for charging during the 16 hours of off-peak hours available Monday through Friday and all day Saturday and Sunday. This policy lightens the load and strain on the electric grid which improves the reliability for everyone. It also encourage the shift to clean energy which will reduce car emissions. And if you choose to charge your car with solar panels, you will achieve an even greater impact.

Another way you can make a difference is by shifting your energy usage to night time. Run your big appliances at night. Wash and dry your clothes at night. Run your dishwasher at night. Again, this will lower the burden on our power plants and it will also lower your electric bill too.

In DC, PEPCO is proposing special incentives to owner’s of electric vehicles. The program will offer lower electric rates to owners of EVs that charge their cars during off-peak hours. Some customers will also qualify for discounts on Level 2 smart charging stations that includes 100% of the cost of installation. For commercial property owners, PEPCO will install charging stations at a discount and they will also install them for free. PEPCO is also planning to install 20 fast charging stations along the main roads and in each Ward and in each quadrant of the city. Finally, PEPCO will be creating a $1,000,000 fund that is designed to provide grants for people and organizations with ideas that can help encourage a greater shift towards electric cars.

Let’s also help PEPCO increase electrification by considering a shift towards renewable sources from solar panels. Please contact us via this website or call us at (410) 923-6090. We have hundreds of installations throughout the Baltimore/Washington/Annapolis area. We look forward to helping you too.

Written by Lisa Walsh

Incentives for Electric and Hybrid Cars in DC

Washington DC’s government is encouraging the ownership of electric and hybrid cars with incentives that will save you time and money. For one, if you own an electric vehicle, you are exempt from emissions testing. If your car emits nothing, there is nothing to test. You simply need to register it with the DMV in DC. And if your car is a hybrid that is both electric and gas powered, you only need to pass a smog test. For questions about this, you can call the DC Department of Motor Vehicles at (202) 737-4404.

Fuel Efficient Cars get Reduced Registration Fees

You can also qualify for a discount on the first-time vehicle registration for a qualifying electric, hybrid or clean fuel vehicle. Their rules state that your car must get at least 40 miles per gallon in city driving. Check www.fueleconomy.gov to see how your car rates. You also must be the original owner of the car. If your car is used, you are eligible for the excise tax exemption. This exemption is the tax you pay upon purchase of a vehicle. So, the exemption can be a nice savings for you.

You might also qualify for federal tax credits. Eligible cars include electric, hybrid, plug-in hybrids, diesels and alternative fuel vehicles. Ask your accountant about how this might benefit you. And another benefit is that your insurance company might offer a discount. If they don’t, you might want to call around to find a carrier that does. These savings can really add up.

And finally, if your business has a fleet of 10 or more clean fuel automobiles, you can qualify for an exemption to the HOV lane. Again, call the DC DMV at (202) 737-4404 to find out about this benefit. Going electric and fuel efficient will put you in the fast lane in so many ways.

And, of course, we are always available to help you power your electric car with solar panels at your home, in your community or at your business. Please contact us if you have questions about generating most, or all, of your energy from solar.

Residential Solar Panels, Solar Installer
Written by Lisa Walsh

Solar on Slate Roofs in Washington DC

Residential Solar Panels, Solar InstallerWith Washington DC offering homeowners the best solar incentives in the country – its small wonder that solar panels are going up like hotcakes. In order to meet the demand, most solar installers are adept at designing and efficiently installing solar panel systems on most roof types in DC: namely flat roofs and asphalt shingle. However, homeowners with a traditional slate roof will need to shop around for a qualified, slate-savvy installer.

Slate Roof Challenge

Washington DC Solar,Solar ServiceIn this order, the most common types of residential rooftops in Washington DC are flat, asphalt shingle and slate. Asphalt shingle are generally the simplest type of roof to attach to. They are flexible, soft and flashing/sealing all of the attachments has been fine-tuned to near perfection by the solar industry. Flat roofs are generally installed using no/few penetrations either with parapet-to-parapet rails or ballast-weighted systems. Slate, however, is among the most challenging roof type to work on for the following reasons:

  1. Expertise Tools and Labor Required

    Solar Service, Home Solar PanelsTraining a work crew adept at installing solar on a slate roof takes a significant investment of time, tools and techniques. As slate is a type of stone material – specialized diamond-tipped drills and copper replacement nails are required to penetrate and reattach the slate; drill too fast – and you’re likely to break the slate. Even with the most cautious of installers, a number of slates are still likely to end up broken and spares need to be kept on hand. Ideally – artificial slate can be used for replacing broken slates. Specialized flashings designed for use with the larger slate tiles must be used to seal around the attachment.

  2. Additional Labor

    Due to the fact that slate is essentially a smooth, slippery thin stone – this can be particularly challenging for installers to navigate. Couple this with a steep pitch, and extended hours on the roof due to time-consuming drilling techniques, labor estimates can easily double or triple when compared to an asphalt shingle roof; not to mention a particularly challenging and long day(s) for the installation crew.

The above two points ultimately result in increased costs for the customer. Fortunately, for DC residents with slate roofs, the financial incentives are such that paybacks are still generally under (or around) the 5 year mark – with many years of clear income to follow. Furthermore, as slate roofs can last 100 years or more, the roof and solar combination is set for a minimum 25 year relationship – and likely a good decade beyond that.

Solar panel, solar energy,Solar in Critical Areas Annapolis
Written by John Marrah III

Solar in Critical Areas – Maryland, Virginia and Delaware

Solar Panels, Solar Energy, Solar in Critical Areas AnnapolisWhat is the Critical Area?

The Critical Area includes all land within 1,000 feet of Maryland’s tidal waters and tidal wetlands. Along our precious shoreline of the Chesapeake Bay and its tributaries, we have had many homeowners looking to take advantage of enhancing their waterfront landscape with solar panels.

Aside from the clear economic advantages, we are in solar for all the right reasons; to protect the environment, preserve our natural resources, and to leave the world a better place. With that said, installing solar in the critical areas encourages us to comply with two important regulations that ensure shoreline preservation.

Lot Coverage

In the critical area, you are allotted a certain amount of lot coverage depending on the size of your lot. Our first step in the process is to prepare a “Lot Coverage Calculation” worksheet that indicates how much lot coverage you have available and ensures that there is legally enough space to account for the square footage of your new solar panels.

Buffer Management Plan

Though lot coverage is not impacted by solar installations outside of the critical area, the total area of additional lot coverage leads us to our next calculation. The Buffer Management Plan requires that every square foot of additional lot coverage is mitigated by planting either grasses, shrubs, or trees within 100 feet of the shoreline. The goal for this mitigation is to slow down the erosion of the shoreline, and we are big supporters of this mission. There is some flexibility with the types of flora that can be planted in this area, so we consult the homeowner in selecting preferred plants for their new shoreline oasis.

Though this process involves a few more steps in terms of permits, we have become subject matter experts thanks to our waterfront solar supporters in Kent County, Queen Anne’s County, Talbot County, Dorchester County and Anne Arundel County. Every county has a slightly different twist on their permitting requirements, and this helps local companies like SES thrive.

Home Solar Panel ,Solar Service
Written by Rick Peters

Peters’ Journey to Net Zero

Solar Service,Home Solar PanelsWhat Net Zero Meant for Us? Our Severna Park based, four-person family was looking to offset some of our home’s dirty energy, but we really did not have an expectation we could offset it all, but we had to start somewhere. We took our first step shortly after I joined the solar industry in 2008.

Low Hanging Fruit. In February 2009, we installed a 120-square foot solar water heating system to offset most of our water heating, and a small portion of our space heating for the first floor of our home. We saw big savings from this 3-panel system right away. Ever since, I enjoy the act of turning off the back-up water heating in April and leaving it off until almost October. For us, offsetting a dirty and expensive oil-fired boiler was the obvious low hanging fruit. We would later convert that remaining load to natural gas when the utility extended the pipeline to our home.

Solar Electric (PV) With the rest of the heat, A/C, and appliances all running off electric, it was time to look at the next opportunity. A few years later, when budget allowed, we decided to add a 5 kW solar PV system to our second story roof which faces SSE. My best determination was that we offset just over 40% of our electric load with that PV system. We were happy, but knew we’d want to find a way to get to NetZero eventually. , . I began to evaluate the remaining rooftops and consider what it would take to get us there. Solar panel efficiencies had improved a lot over the past several years so this reduced the remaining roof space we’d need to hit our goal

Phase 2 (PV). In the spring of 2016 we finished filling the balance of the south roof with some slightly higher wattage panels. As part of the same expansion, we added 24 relatively high efficiency panels to the E/W, low slope, rooftop of our one-story garage. We now had a total of 6.6 kW Equivalent of solar thermal and 13.8 kW of PV.

Not There Yet….We almost tripled our PV with the last upgrade and according to my calculations, this would get us to NetZero electricity. We’d know for sure by April, the annual true-up time frame for netmetering with BGE. When April 2017 came around, we were disappointed to come up a bit short (unfortunately, with a couple teenagers in the house, my usage predictions were a little off). Where do we go from here? I was not ready to put panels on the north roof, there had to be something available to us on the demand side.

Oops – More Low Hanging Fruit…One thing about Energy Efficiency, there’s always more opportunity. I had changed out many bulbs to LED over the prior several years, mostly through attrition, but I had not replaced any of the more than 2 dozen canister lights we had throughout the ceiling upstairs and down. Not only were these lights very inefficient, but the heat they generated in the summer was just adding to our air-conditioning load. We found the LED replacements on sale and replaced them all, as well as the remaining few incandescent lights in the house.

Commercial Solar Energy,Solar ServiceEureka. we have arrived!… In April of 2018 we received a $46 check from BGE for the annual overage from solar. With the kids heading off to college soon and a new refrigerator around the corner, I’m confident our checks from BGE will be getting bigger for the near future. At least until we purchase an electric car…

Solar Service,Commercial Solar Service
Written by Lisa Walsh

The Fairytale of the 25 year Solar Workmanship Warranty

Commercial Solar Service,Solar ServiceIf you’re like most solar shoppers, you prefer two or three bids on a substantial home improvement project; enabling you to sanity-check pricing, design options and find the overall best contractor-fit.  Included in these proposal comparisons is the Warranty. Most solar systems come with 3 warranties:

  1. Solar module manufacturer’s warranty; usually 25 – 30 years,
  2. Inverter(s) manufacturer’s warranty; usually 10 – 25 years (inverters convert DC energy to home-accessible AC energy)
  3. Workmanship warranty – entirely separate from 1 & 2 above. This insures the design and installation, insofar as contractor/labor portion of your install is covered for a given period of time, as determined by the installation company.

Industry Standard

As the popularity of solar has increased – so has the number of competing contractors and their accompanying solar proposals. All of these proposals should include a workmanship warranty. What will differ is the duration of the workmanship warranty. The standard duration for a residential solar system was always 5 – 10 years until a couple of years ago when some contractors started offering an unprecedented 25-year workmanship warranty. This is a good thing, right? On paper…sure.

Compete only to Beat

With over 35 years in the solar industry, it’s fair to say we’ve seen a lot of solar installers come and go; especially in the last five years. The go-ing usually brings with it a slew of phone calls to our service department as solar system owners panic about no longer having their contractor around to honor the workmanship warranty; particularly those looking to resolve existing issues. Ironically, these are sometimes homeowners that chose the contractor over us due to a workmanship warranty of shorter duration. We have stuck with the industry-standard of 10 years, whereas some other installers have increased to 25 years to match the manufacturer warranties.

So, the big question – and the reason for this current article is – Why? If some of our competitors are offering a 25-year warranty – why don’t we? Seems only natural, given the fact that we’ve been in business for longer than 99% of them – greatly increasing the probability that we’ll be around to honor an extended workmanship warranty.

The Big Answer (in two parts)

  1. We’re keeping it Real: Understandably, a 25-year workmanship warranty is attractive to a homeowner because – by design – it matches the 25-year solar panel warranty. This does not change the fact that a workmanship warranty exists entirely independent of the installed equipment warranty(s). A contractor’s history, fiscal health and future plans have little or nothing to do with the equipment warranties. Given this, we avoid inflating the language in our contracts to provide misleading comfort to a home or business owner, with the sole purpose of beating out the competition at contract-signing time.
  1. We’re still keeping it Real: Of all the orphaned solar projects we’ve come across – we cannot cite a single known instance where a homeowner has taken legal action over an abandoned workmanship warranty item; simply not worth the court fees or the hassle. Most exert their energy on finding a contractor who will fix the problem as soon as possible and get their solar system restored to full working condition. Hence, the true value of the workmanship warranty is contractor integrity and the likelihood of whether they both intend to and will remain in business to honor their contractual agreement. For most solar contractors, the standard ten-year commitment reflects a realistic forecast of longevity and commitment; avoiding the temptation to head off into fairytale land in order to beat-out the competition.
Eastern Shore MD,Solar Service, Home Solar Panels
Written by Lisa Walsh

Non-South facing solar panel installs in Maryland, DC and Virginia

The Design

Eastern Shore ,MD,Solar Service, Home Solar PanelsWhen planning a solar panel system for your home, the first consideration for any solar designer is the tilt and orientation of your roof areas.  We need to know which roof(s) will ensure the most optimum solar output – which translates to the best Return on Investment.   For us here in Maryland, the most optimum solar roof orientation is Due South at 180 degrees.  Of course, not everyone has this perfectly oriented roof and our customer base consists of homes that have South, West, East and everything-in-between orientations.  Occasionally we even install on North-facing roofs if the pitch of the roof is low enough that panels are close to flat, or can be tilted southerly.

For homes that face East-West, you may be wondering which roof would best suited for solar.  This is a good question given the fact that the output of your solar panels is directly related to your Return on Investment and how quickly the panels can pay for themselves.

If either East or West favors a more Southerly angle, then that would likely be a more favorable roof.  Assuming that there aren’t issues related to shadingor obstructions caused by chimneys, vents, skylights and other roof-placed items.

If the house has a perfectly split East-West orientation, with all things equal – the next consideration would be roof angle; the lower the tilt (i.e. closer to horizontal) – the more solar energy will be generated over the course of the day.  If the tilt on either side is the same then we would usually favor the West facing side.   Here in Maryland, DC and Virginia we tend to have cloudier mornings, and sunnier afternoons going into dusk.  Therefore we want to capture the late afternoon sun (west facing) more than early morning sun (East facing).  Of course, should you happen to have a tree, chimney or other obstructing factor(s) on the West roof – we’d favor the East.

The Economics

Homeowners looking at an East-West installation often have concerns as to whether or not their system will be profitable enough, compared to its south-facing counterparts.    Disqualifiers for cost-effective solar systems include shading and limited available roof space.  Rarely, however, is a home found unsuitable due to a Non-Southerly facing roof alone.

To illustrate, following is a comparison of a 10kW system’s output respective to East, West and South facing orientations.  Data compiled using the National Renewable Energy Laboratory (NREL) weather data patterns for Baltimore, MD –

10kW system installed on a 20 degree pitched roof with zero shade

 SOUTH (180 degrees)WEST (270 degrees)EAST (90 degrees)
ANNUAL OUTPUT13,224kWh11,389kWh11,328 kWh
*Annual $avings$1853 per year$1594 per year$1586

*Savings based on a conservative $3.00/watt installation, and $0.14/watt BGE rate

Data from PV WATTS

As illustrated, although perfectly South would be ideal, the East and West orientations provide a competitive amount of solar and would add only a few months to the payback period.  If you were choosing between East and West (as opposed to installing on both), the difference is nominal.  The choice of which roof may come down to aesthetic preference, distance to utility meter and regional weather patterns.

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