Solar Thermal/PV and Renewable Portfolio Standards:

Solar thermal systems and renewable energy credits.

Photo By

Special advertising supplement to the Reno News & Review.

Nevada has one of the country’s best renewable energy incentive programs, but are we getting the best bang for our renewable buck? There’s a very low tech, low cost technology available that could pay significant dividends if it were included as part of the NV Energy rebate programs, both on the renewable energy as well as climate change side.

This distinction is important, since to address climate change we need to both find new sources of energy, to offset “dirty” sources of electricity, as well as use less of the ones we’re already using.

That technology is commonly referred to as Solar Technology Systems, or STS, and it’s easy to understand for anyone who’s sat in front of a window on a warm summer day. In a nutshell, the sun’s energy is delivered in two formats: light, and heat. Photovoltaic or PV systems capture the light, and turn it into electricity. STS captures the heat, primarily via hot water systems, and in so doing offsets the need to use energy in another form, such as natural gas, which is often burned to heat water.

A successful program to incentivize STS could significantly reduce our use of fossil fuels, while helping us reach Nevada’s Renewable Portfolio Standards (RPS) at less cost to ratepayers, as well as address the common hurtles of time delays for approval and high cost that often stop PV systems from being built. In other words, we could do more, with less, and do it sooner, with STS than with PV. Accordingly, the Nevada legislation is considering adding STS to the types of technologies being rebated under the Renewable Generations program.

Nevada’s RPS states that 20% of power produced in Nevada must come from renewable energy such as geothermal, solar, biomass, wind and hydro. A minimum of 5% of that power production must come from solar. The way that the Standard is tracked is by monitoring the total amount of power production in Kilowatt-hours (kWh) from conventional power plants and comparing that to the total production of renewable energy power systems. These systems can be renewable energy power plants or systems owned by individual consumers. The tracking mechanism of kWh has an equal value as a Renewable Energy Credit (REC), or also known as Renewable Energy Certificates, Green tags, or Tradable Renewable Certificates.

It is widely known within the solar industry that solar water heating systems are one of the most cost effective solar systems available. They typically have the ability to store one to two days worth of energy and when installed correctly can have a life span of over 30 years.

Unfortunately most incentive programs and consumers in the US overlook this and create incentives to purchase less efficient and more costly photovoltaic systems. One of the other advantages of STS is they are well within the budget of most consumers.

For a further comparison of costs and REC production: The STS in Northern Nevada pictured below is 460 square feet of evacuated tube solar collectors and is providing solar heat for a 20’ X 40’ seasonal pool, pool house heat, 3500 square foot main house heat as well as domestic hot water heat for the main house. As of September 12, 2008 this system was maintaining the pool temperature at 83 degrees without any other heating source and is designed to provide 70 to 80% of the heating needs for the pool and main house as well as the domestic hot water. The system is being monitored with an Onicon System 2 calibrated BTU metered that converts BTU’s to kWh; the read out on the meter is in kWh.

The STS compared in this article are approximately 75% less expensive, take up 80% less space and produce 82% more REC per square foot than PVS.

Looking at solar as a tool for producing REC and assisting utilities in meeting the required Renewable Portfolio Standard, STS have the ability to meet that Standard with less cost and space than a PVS. From a consumer’s standpoint, the STS is a much more affordable alternative than a PVS, as well as taking up less space for the installation and producing more energy for dollars spent.

Photo By

As of June 2008 the Solar Generations program for PVS rebates had installed 290 residential systems for a total of 1,144 kW. The total estimated cost to the individual consumers and the utility ratepayers is $10,296,000. Using the above examples of PVS production the total installed PVS production is an estimated 22,880 REC per day or 8,351,200 per year. Using the above examples and the same dollar amount spent on installing STS, these systems would have produced an estimated 38,896 REC per day or 14,197,040. That is a difference of 5,845,840 (41%) more REC produced per year by STS for the same dollar amount spent on installed systems. The average residential solar thermal domestic hot water system in Northern Nevada sells for $9,000. If the $10,296,000 were spent on installing STS there would have been approximately 1,144 systems installed or 75% more STS than PVS.

According to the Solar Generations team the year 5-rebate program had a 50% attrition rate and the top reasons given for dropping out of the program were system cost and return on investment. With a rebate program for STS equal to the rebate for PVS I believe this would not have been an issue or an excuse to drop out. If I am correct, more consumers would have installed more solar systems which would have made a greater impact on the amount of energy produced/saved/REC generated for the same dollar amount spent and would have gotten more people involved and interested in solar. More people involved and interested in solar should equate to more solar installations and interest.

Reference materials, related articles and support:

REC Inspection Notes (M. Harris) PUC 5/09/08 Carson Valley Swim Center

Thanks to Sustainable Energy Solutions for data and continued support.

Special advertising supplement to the Reno News & Review.