What is a Value-of-Solar Tariff?

A value-of-solar tariff, or VOST, is a rate design policy that gives customers with solar panels credit for the electricity they generate at a specific price. The credit is then applied to the customer’s utility bill. A VOST usually clarifies how much energy is sold from the customer to utility company and from the utility company to customer; it also determines at what rate the energy is valued. Value-of-solar tariffs are generally viewed as unfair and for two main reasons: the value of the tariff is lower than market rate in most areas and the benefits of VOSTs aren’t broadly advertised. But VOSTs don’t HAVE to be unfair.

As of right now, there aren’t many markets that have fair compensation for solar in the form of VOSTs. The two main places that are under the current implementation of value-of-solar tariffs, Minnesota and Austin, Texas, purchase all of their energy at the utility’s retail rate and pay out a separate VOS rate in dollars per kilowatt hour. In Minnesota, the VOST rate is about $0.145 per kilowatt-hour which is above the residential retail electricity rate of $0.115 per kilowatt-hour. This rate means that for every kilowatt-hour a solar user produces, the user doesn’t have to pay for a kilowatt-hour and they save a little on the electricity they don’t produce but still use. Why would a state or utility pay higher than retail? Because through a VOST process, IF the total value of solar energy is taken into account, there may be cases where it is in fact worth more than retail.  This type of VOST is very customer friendly to encourage the residents of Minnesota to begin producing solar energy themselves; unfortunately, outside of Austin, Texas, the same cannot be said for other states. One of the reasons for less than market rate compensation is the cost of providing the VOST in the first place or other services that utilities must provide for you to sell to them.

What is the unseen value of a VOST?

An end financial value of a VOST is made up of many subparts. For example, some value components include: avoided cost (money saved by the utility from not having to buy additional fuel for the power plant), environmental (the value of reducing harm to the environment and its subsequent cleanup), and transmission system impact (less strain on power lines due to generation being located closer to where it is being used), among others.

For a user to successfully produce and sell back solar energy to a utility company, they have to use the grid. Even if a customer produces the same amount of energy as they use, there are still costs to selling the energy back and for energy used from the grid when solar is not producing. When paying out for solar, utilities have to consider the cost of business (grid maintenance, labor, parts, etc.), which takes a portion out of the amount the customer receives. The need utilities to receive compensation for their services in a VOST to maintain the grid cannot be overlooked.

The second reason value-of-solar tariffs can get a bad reputation is customer lack of knowledge about its benefits. Utilities can better understand customer load, timing, and volume because a VOST separates electricity generated by the consumer from electricity consumed. This is valuable information that utilities can use to better predict when peak times might occur and how much electricity they’re actually using. However, customers may not understand all the variables that make up a VOST or why they are there.

Another reason is how customers receive compensation based on utility-specific benefits and costs of their electricity generation, instead of fixed retail rates that may span many regions. Customers are able to select what VOST is most beneficial to them depending on their energy production and use, as opposed to going with the rate of their region no matter the circumstances.

Value-of-solar tariffs are one of several viable options for solar users to sell back their solar energy, and there are both good (Minnesota and Austin, Texas) and bad (almost everywhere else) ways of providing it to customers. One important aspect that cannot be overlooked is how a VOST is beneficial to the energy system (e.g. the grid) as a whole. With a true integrated value, a VOST can provide the grid with much needed support and gives utilities valuable information; but as it becomes more widespread, concrete worth needs to be given to the value provided from things like environmental and avoided energy costs. VOST has a bright future if implemented correctly, and as more states follow Minnesota’s example, solar will continue to grow more valuable.

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