The Benefits of Intelligently Controlled Solar Plus Storage Microgrids

Amanda Kabak, chief technology officer and principal architect at CleanSpark

Solar energy has gained traction in the energy market, altering the load profiles that utilities have to satisfy. This is forcing them to adapt and evolve. Increasing solar generation in the afternoon is offsetting the high demand during those hours. Load continues to surge into the evening when solar generation is no longer available, exacerbating the rise.

Utilities are changing their pricing structures to cope with these variations, which is where storage comes into play. As peak price hours shift later into the day, when solar generation is unavailable, storage can be used to capitalize on the potential benefits. We’re entering a more sophisticated utility environment that no longer rewards solar only installations; adding storage is becoming necessary to make microgrids more economically viable.

It would be naive to believe that utilities will not continue making adjustments in the future. They will endeavor to stay ahead of the renewables curve, and customers are getting smarter about gaining an economic advantage from the utility rates. Using intelligent controls rather than scheduled controls is one way to achieve this. With ‘set it and forget it’ scheduled controls, a battery is set to charge before the known high rate time period, and set to discharge during that expensive period. When the utility changes that window, those settings have to be changed on every microgrid, or economic opportunities will be missed.

Self-modifying intelligent controls

Intelligent controls, on the other hand, modify themselves under changing conditions. The controls can allocate energy, or decide when to discharge the battery and by how much, in response to changes in the utility rate structure. Thresholds can be automatically altered based on assessments of demand changes, and the system can respond to live weather data, for example carefully managing the energy stored in a battery if an increase in cloud cover is predicted.

At CleanSpark, intelligent controls are applied for an off-grid microgrid in the deserts of California. The goal is to minimize the use of the rented diesel generator, to reduce cost. The facility is in the growth phase, so the site has been modeled to understand the most appropriate sizes for future diesel generation, solar and storage. Real time controls balance the load, solar, and storage to reduce the running of the generator. As a result, the generator did not run during the second half of August, saving an enormous amount of money.

For grid-connected microgrids, like CleanSpark’s two sites in Costa Rica, more advanced control functionality can be applied. Energy demand and solar PV generation is forecast based on the next 24 hours of weather data, as well as the historical operation of the solar arrays. This information is overlaid onto the utility rate structure over the next 24 hours, creating a roadmap for the optimal control strategy for that time period. This roadmap is refreshed every three minutes, multiple times during a utility’s billing period, which is normally at 15-minute intervals.

Responding to real time signals

The utility in Costa Rica updates pricing every quarter. As soon as these are updated on CleanSpark’s site, they are pushed to each microgrid system, automatically adjusting the control algorithm based on the new prices.

The algorithm can process real time pricing and respond to signals for programs like demand response, currently taking place in California and New England. Peak pricing events are called a day ahead, based on predictions of the load on the grid. Customers can be charged, or paid ten times more for their energy during these events to incentivize reduced energy consumption, or additional generation. Intelligent controls adjust the algorithm accordingly to account for these signals. It is also possible to hook intelligent controls into a building management system and shed non-critical loads to reduce consumption during peak pricing times.

The energy market will continue to evolve; so it is beneficial to have self-adjusting control algorithms that can keep up with rapid change. It is also becoming more favorable to invest in adding storage to solar in a microgrid. Programs offering incentives to deal with the impacts of solar on utilities are springing up, and the upfront costs are diminishing. The environment for adding storage is becoming friendlier and the technologies are continuing to evolve to become more cost effective, safe, and efficient.

Amanda Kabak is the chief technology officer and principal architect at CleanSpark.