Net Metering and feeding back to the grid

After weeks of barely any progress waiting on permits and red tape we are finally starting install tomorrow, January 31st! Only 2.5 months after signing on our system! The vendor Yellowlite sub-contracted the install to a local vendor, Strawberry Solar, and things get underway at 10 am. Install will be completed by Thursday but then we must wait on city electrical inspection and DTE inspection before our production will be underway... In the meantime on to my next blog post.

https://www.strawberrysolar.com

Image courtesy of CPI:

https://www.cpi.coop/home-energy-use/renewables/net-metering/

Most states have laws governing solar panels and power production. Utility providers have goals to meet in providing clean energy. One of the ways they do so is allowing customers to purchase solar panel systems and feed energy back to the grid. This benefits the utility company in three ways:

1) It takes the investment in the panels away from the utility company and puts it on the customer.

2) The clean energy produced by your solar panels counts towards the utility companies clean energy goal.

3) Any excess energy produced cannot be carried over year to year. 

The laws in place governing solar energy are not friendly to private citizens that produce electricity and, for the most part, favor the utility companies. In Michigan if you are already connected to a utility company that provides electric, you cannot disconnect from the company and produce your power 100%. You also cannot utilize a battery backup to store excess energy as it must be fed back to the grid. The system to credit this energy production on your electric bill has been labeled Net Metering and this is the method the majority of states have adopted. Net Metering as shown in the graphic uses a bi-directional meter to count the watts your solar panels produce and the watts your home uses. It then credits the excess energy sent to the grid on your energy bill. Your electric bill will only charge you for the watts used over your solar energy production.

DTE and other electric providers will not let you install a system that is estimated to over produce your average annual usage. This is because they do not want excess production and the system is set up so that DTE wipes your energy credits clean at the start of the new year. So over producing is not necessarily advantageous to you and it would mostly benefit your electric company because they get free energy from your system. Potentially, at the end of the year, before the credits are wiped, if you have a credit of excess production you can call and request a cash out. I have not tried this so I can neither confirm or deny this claim but I will hopefully be able to eventually verify this once my panels are installed. 

To be completely off the grid you must build a new home that has never been connected to a utility company. This would not apply to a tear down and rebuild but it would apply to a lot that was split with an old home and a new home, with new service. The new home would be able to be off the grid by purchasing a solar system with a battery backup. The battery systems that come with solar panels are quite expensive and once the life of the battery is up they must be disposed of. The bright side of adding solar after already having an electric utility provider is that the large battery investment is not needed and there is no need to eventually worry about battery disposal.

Another question might be what happens when there is a power outage? Unfortunately, without a battery system when the grid goes down your solar production will continue but will cease to be Net Metered to prevent damage to the grid and the power will still go out. There are small battery backup systems that can be used to store your power and prevent a power outage at your home. These systems are allowed to work with a grid connected home solar system. In the event of a power outage you would flip a manual switch to allow your system to begin sending power to the battery backup system that can keep your home powered for a short period of time. However, such a system would need to be started during daylight hours and have active energy production to prevent having the power out. The cost of this setup would far outweigh the cost of a generator for use in such times.

After reading all this you might think "why go solar?" Obviously the number 1 reason is that it is the green thing to do and an excellent step in reducing your households carbon footprint. Another reason is that Net Metering looks at 1 watt of energy production as 1 watt of energy production. This correlation will not change over the 25 plus life span of your solar energy system. In Michigan electric costs are currently 15.7 cents per watt in 2017 up from 12.11 cents per watt in 2011. This is roughly a 29% increase in 6 years or approximately 4.9% increase per year. If this trend continues a solar system will provide an excellent return on investment as the value of energy produced would not be subject to the price increase on electric. Personally, for my household the cost of going solar will not cost more than my monthly electric bill. After the 30% federal tax reduction for going solar the loan payment will be equal to what we would pay in electric costs. If electric rates continue to increase, we will see a monthly payment reduction. In 11 years the solar system will be paid off and there will still be 14 plus years of use left to the system. At that point our electric bill will be 80% or less than it would be without solar panels at that point it is pure return on investment. Another point to mention is that solar panels are an investment in your home no matter if you plan to live there 2 years or 50 years. The research I found regarding home value after solar panel install notes that a homes value will increase 10 to 15 times the annual savings on your electric bill. So if a solar system saves $1000 per year on the electric bill you can expect the home value to increase approximately $10,000. Not a bad investment for producing clean energy!

Solar power is a household decision and can be catered to fit all needs, budgets and uses. Personally, I would hope that everyone would want to go solar. I am blogging about it in hopes of getting the word out with our experience on solar and possibly encourage those thinking about it to go for it. I did create an excel file, that after entering pertinent information, can help you estimate money savings over the life of a solar system. If I can I will try to add the spreadsheet with instructions for download. More to follow on that...

Sizing your Solar System

When calculating the size of your system it is important to know how much power your system is anticipated to generate. The PV Watts link below helps to determine how much power you can expect to generate using the exact location and orientation of where you plan to put the solar array.

http://pvwatts.nrel.gov

Here you enter your address, the kilowatt size of your system and anticipated power reduction factors. In any solar array the best possible setup would a south facing roof with a 34° pitch with no shading. This will allow your array to provide maximum output, weather permitting of course. In the PV Watts site the reduction factors account for the soiling, shade, roof pitch or array angle, electrical losses (leave these at default) and the Azimuth or the direction the array will face. The PV Watts site has information that help you determine your reduction factors and it is very user friendly. It is even not too bad to access from a mobile device but much easier to navigate on a laptop or desktop computer. 

In the photo above it helps to explain how to calculate system size. For our system we  are getting 24 Silfab premium 310 Watt solar panels. They will be mounted on the South facing (180°) roof with an approximate 30°-35° pitch, the roof is never shaded by trees. The PV Watts website allows for a number of variables that affect power generation. A premium panel has a higher efficiency than a standard panel and this refers to how efficient a panel is at converting sunlight to energy under standard operating conditions. The data sheets for solar panels will provide all pertinent information about the panel, including the standard operating range. In the midwest soiling is rarely a factor due to frequent rain so set this to 0 for Michigan. To get system size we take 24 panels times 310 watts each, totaling 7440 Watts. For our 7440 Watt array, using the PV Watts calculator we can anticipate approximately 10,500 watts production per year. This obviously depends on weather and can vary slightly higher or lower. Based on our consumption of 980 watts per month we will cover roughly 90% of our 11,772 Watts yearly energy needs. Now if we account for the reduced consumption of 939 Watts since we have winterized our hot tub we have now bumped up to just over 93% of our energy needs. 

Higher wattage systems cost less per watt. As we progressed through our investigation of solar panels we received quotes from several vendors. With each vendor we provided our monthly usage of 980 watts. The first vendor offered 20 Solar World 290 watt standard panels totalling a 5800 watt system. The annual production would have been roughly 8000 watts or just about 70% of our annual usage.  This system was quoted at $5.24 per watt. Another vendor quoted 31 JinkoSolar 295 watt premium panels totalling 9145 watts that would cover about 98% of our energy needs. This system was $2.82 per watt. The system we are getting is 24 Canadian made Silfab premium 310 watt panels totalling 7440 watts at $3.07 per watt. Less panels and lower wattage raised the cost per watt. I found it interesting that each vendor varied the system size starting with the same monthly usage.

It is important to remember that solar arrays can be as few as 1 panel to even larger than 24 panels. How many used depends on your electric usage, how much of your electric needs you want to cover and your budget. There are many different panel manufacturers and various panel wattage's available so finding an arrangement to best fit your needs is easy. No matter how many solar panels you decide on, your system will help you save money and the environment!

NOTE: Without using PV Watts a quick rough estimate of system production would be to take system size and divide it by 70% or 0.7. This gives you a ball park figure to work with. The ideal and most accurate way to determine your system production is to use the PV Watts website or another similar site that takes into account all the factors discussed.

Calculating your Energy Needs

I apologize for taking a hiatus over the holidays, but the solar process is slow going. After signing in November we finally anticipate install to start sometime in February. We have already made our first payments and anticipate claiming the tax credit when we file our taxes this year. As soon as all the permits are finalized we schedule install, mother nature willing since we need temperatures above 30 degrees to install panels on the roof. My blog will go into detail on the process in order and the full timing but for now first things first...

This post and the post to follow will be the not so fun posts involving math but essential steps to get your solar system in place to start saving money and the environment.

Photo compliments of Everblue Training Institute.

One of the first things you should do when you begin researching solar energy is to calculate your energy needs so that you can right size your solar system.  To calculate the size of system needed you must know your average electric use over the past 12 months. This will give you the most accurate consumption for your family. To find this information I went through my electric bills. The graph attached was found in a DTE electric bill.  It details 12 months of average daily electric use in kilowatt hours. To find out monthly usage you have to multiply the average daily use by the number of days in that month. For example this November we used 30.3 average wattage per day. To find Novembers monthly usage you must multiply 30.3 watts/day * 30 days in November which totalled 909 watts used in November. To get the average monthly usage for the last year you caculate the average monthly usage for each month for the past 12 months. Then you add them all up and then divide by 12. Our average monthly usage is 980 watts per month and our yearly usage is approximately 11,772 watts per year.

There are a number of variables that will effect your energy use and production. One that has changed ours is the fact that last winter we ran our electric hot tub all winter, this year we winterized it. While waiting on our panel install I recalculated our energy use not running the hot tub this year in October, November and December so far our average monthly use decreased 31 watts! This changes our yearly use to 11,352 watts. This will actually cause our rated system to cover more of our energy needs... precisely 3% more than we anticipated and winter isn't over yet.

My next post I will talk about panel size and how to take the monthly and yearly usage that was calculated and determine your system size. This will include the discussion of electric providers, laws and regulations regarding solar panel installation. Believe me there is more to it than I ever imagined!

Photo compliments of us.sunpower.com