Batteries

How would you characterize the short-term outlook for solar in Hawaii?

In the short term, solar installations in Hawai’i may slow somewhat. As understanding of the new HECO program grows, and the public becomes aware of available options, the solar industry will pick up again.

Will cap halt residential solar altogether?

As Mark Twain allegedly once said, “rumors of my demise have been greatly exaggerated.” This holds true for solar as well. With new technologies and lower and lower equipment prices, the solar companies and their customers will find ways to work with onerous regulations and arbitrary limits imposed by HECO and the PUC.

Will some solar companies go out of business? Do current solar owners need to be aware of this due to service and warranty fulfillment?

Some solar companies will most likely close their doors. Those that embrace newer technologies and find creative ways to work with HECO will continue to thrive. Solar company closures may impact service and warranty contracts. Be sure to use a reputable installer that utilizes established brands as the longest and most important warranties are through equipment manufacturers. Also keep in mind that a sub-par installation by a company that has gone out of business can create numerous and expensive problems down the road. An amazing deal today might not look as great 5-10 years from now when facing costly repairs.

Old ROI versus new ROI? How long will it take to reach 100%?

For residential customers, typical ROI will now be somewhere around 8 to 10 years. However, with the new DER program, ROI will depend heavily on a customer’s usage profile (i.e. when they use power). The more a customer can use during daytime hours, the higher and quicker the ROI will be.

For commercial customers, whose majority of use occurs during the day, ROI will probably be around 3 to 4 years.
These figures are now more in line with the mainland. Clearly, ROI figures like this have not slowed solar in areas like California and the Southwest. Solar is even thriving in the Northeast, an area not typically associated with an abundance of solar resources.

Because of this, we believe Hawai’i will continue to be a leader in the solar industry.

How good are batteries now? What are some things people should look for in batteries?

Truly viable battery technology has arrived! With a flurry of investment over the past few years by established global companies like Sony and well funded start-ups like Aquion, battery technology is better than ever and represents a real alternative to grid power in certain applications. There are several factors to consider when buying batteries:

Use: How will you use your batteries? Are you looking for a battery to back up critical loads in case of utility outage or do you want to go off grid and cut your connection to HECO altogether? Or perhaps you’re a business owner looking to decrease HECO demand charges (also known as peak shaving). Different types of batteries are better suited to different uses.

Safety: Most batteries are stored inside your home or business. Well-publicized incidents of battery fires have created legitimate safety concerns for certain types of batteries. Furthermore, some batteries contain hazardous chemicals like sulfuric acid and can off-gas when charging and discharging, requiring external ventilation. Be sure to research battery technology and chemistries to determine their safety record and material composition.

Maintenance: Are you willing to do regular maintenance or do you let your car go 20,000 miles between oil changes? Some batteries like traditional lead acid require watering and equalizing on a monthly basis (old timers like me remember those in dad’s old car). Other batteries require no maintenance at all.

Modularity: Like most people, your energy demands fluctuate. When a new baby arrives or auntie moves in, you need more power. Certain kinds of batteries can be easily expanded and others cannot.
Energy Density: If you have unlimited space to store batteries, this isn’t an issue. If you don’t, energy density (how much charge a battery can hold for its size) can be very important. Some batteries technologies provide great energy density; others require lots of space in your garage or storage room.

Durability/Reliability: Like the battery in your car, certain batteries last a few years, others can last over twenty years. Likewise, some batteries are manufactured to be completely, or almost completely discharged. Other batteries can only be discharged a certain percentage. For example, traditional lead acid batteries cannot be discharged more than 50% on a regular basis without significantly shortening their lifespan. So, look for a battery rating and a good warranty. Battery ratings will be given in the number of cycles, or how many times the battery is discharged then recharged. For a home PV system, this generally occurs once a day. Then look for the depth of discharge given in a percentage. Examples will look like this: 3000 cycles at 100% depth of discharge or 3800 cycles at 40% depth of discharge. Most batteries have a 3 to 5 year warranty and a few come with as much as a 10 year warranty.

Battery Bank Sizing: This is a tricky one and has been the source of premature death for thousands of batteries. There are several factors that go into sizing a battery bank including: your current and future loads (usually discussed in terms of kWh used per day), your current and future load profile (usually discussed in terms of kW being used at any given time), battery specs, battery performance characteristics, and so on. The best way to size your batteries is to accurately measure your loads with a monitoring device that can upload this data to the web. Installers then plug that data into sizing programs that take other factors into consideration like to accurately size your battery bank. As discussed in Question #3, your best bet is to find a reputable company that will install quality products that will last for years.

And last but not least,

Price: This might seem simple but isn’t. At first glance, a battery bank that costs $7,200 is a much better deal than a battery bank that costs $14,000 if both provide the same amount of power per day. However, it’s important to look at lifespan and price per kWh (kilowatt hour). Let’s say that each of the batteries above provides 12 kWh of useable energy per cycle (see section vi). The first battery has a lifespan of 7 years and will provide 30,660 kWh’s of energy (12 kWh x 365 days x 7 years) for a price of $7,200. The second has a lifespan of 20 years and provides 87,600 kWh’s of energy (12 kWh x 365 days x 20 years) for a price of $14,000. The price per kWh for the first battery is a little over 23 cents. The price per kWh for the second battery is less than 16 cents. After calculating price per kWh, the second battery bank is actually a much better deal.