Battery Inverter selection

Solar Storage Battery Systems 

The quantity of new products entering the solar storage sector is growing at a fast pace. That can cause confusion with selecting a system; especially since there are many differences in how they are configured and operate. In this article I am going to break them down into categories and key differences to help simplify the process of selecting the best system for your needs. 

There are many ways to group the Solar Storage Battery Systems; the grouping I have chosen is not the only way to do so. I have grouped them as follows: (1) Stand-alone systems, (2) Multimodal systems, (3) Smart Multimodal systems. 

There are a multitude of battery inverters that fall in to the Stand-alone category.  

  • Many of them are low-cost single circuit inverters that are DC coupled with a charge controller to manage PV energy into the batteries. 
  • Several have a large capacity battery inverter that feeds an AC distribution panel with multiple branch circuits. These are designed to support a small cabin, backup power to a grid connected home, a large boat or a motor home. Most of these systems are DC coupled with a charge controller managing the PV energy into the batteries. One or two of these models can also be AC coupled to an interactive inverter. These larger inverters can be connected to the grid and/or a generator for load support; they are not able to sell excess energy into the grid.

Multimodal systems are similar to large capacity battery inverters plus they designed and listed to sell excess energy into the grid. These systems often have a controller where all to the system settings are adjusted depending on the capacity of the inverter(s), the battery bank and the battery charging parameters. 

  • The standard model uses DC coupled charge controllers to manage the PV energy into the batteries. 
  • Most of these inverters can be programed to control battery charge through AC coupling of an interactive inverter.  

Smart multimodal systems are the fastest growing category of Solar Storage Battery Systems. These smart systems have a controller that monitors solar production and energy consumption. The controller will control energy flow from all sources. It is possible to operate in self-consumption mode or another energy management mode. These controller/inverters are usually listed to comply with California’s CA Rule 21 and Hawaii’s HI Rule 14H; with these modes the controller/inverter can communicate with the utility to enhance grid performance. It is important to know the differences each manufacturer offers.  

  • They differ in that some can only be DC coupled, others can only be AC coupled, and a few can be either DC or AC coupled. 
  • Some of the ones with DC coupling also provide GFDI, AFCI and Rapid Shutdown for rooftop installations. Other do not provide these National Electrical Codd requirements. These NEC compliances are usually met with AC coupled systems since an interactive inverter is present and is usually equipped with these NEC requirements. 
  • Battery options are often limited especially if the systems is a UL listed Energy Storage Systems (ESS). If the system controller requires a high voltage Lithium battery, there are only a few to pick from. System that are designed for low voltage (48 nominal) usually allow for any lithium or lead-acid battery. If it is an AC coupling only ESS, lead-acid batteries most likely will not be allowed. 

With smart multimodal systems, it is important to consider all of the above-mentioned differences. My favorite system is one that offers the most options for connecting solar PV and for energy storage. The charts below show the key differences of several brands. 

Chart1

Chart2

 Kelly Provence
Solairgen
www.solairgen.com 

 

Styrofoam packing

Shouldn’t Packaging of Renewable Components be Renewable Too?

As far as pure energy goes, it doesn’t get better than solar energy. Photovoltaic (PV) energy technologies are improving and growing at an impressive rate. This industry hopes to be a major source of electrical energy on Earth in the not-too-distant future. At the rate it is growing, that will probably happen within 10 to 20 years. That sounds great but there is a dark side to the PV industry’s growth and it is in the way materials are facilitated to the complete installation of a PV system.

Before I talk about this environmental dark side of the solar PV industry it is worth noting its bright clean side. If all the energy required to manufacture and facilitate the installation of the PV system was derived from fossil fuels, it would take only two years of operation to offset that non-renewable fossil-fuel energy. As renewable energies become more dominant that figure will become shorter. Ultimately the process of offsetting the non-renewable, fossil-fuel energy required to manufacture and implement a PV system could be close to zero. Unfortunately, there is still an environmental dark side that has not been offset. This has to do with the negative effects of the front end and back end of product manufacturing, mining and packaging.

On the front end, mining is necessary to get the raw materials to manufacture PV cells, PV modules, inverters, batteries, support structures and electrical conductors. It is possible to reduce the effects of mining by using materials that are more plentiful in the Earth’s crust but there will always be a requirement for mining. It is also possible to recycle materials that are currently reaching the end of their useful life. The obstacle here is usually financial since it is often lower cost to mine for new raw materials than to recycle them from previously manufactured products containing these same raw materials. Interestingly, even if it takes less energy to recycle a material, it may be more difficult and more expensive to completely facilitate the recycling process. When recycling is disadvantaged by these economics, tax incentives or subsidies should be put in place to make recycling more lucrative. The back end of manufacturing is packaging.

Almost every manufactured product is packaged before being sent into the marketplace.

PV modules are packaged on wooded pallets with plastic separators. They are often wrapped in stretch plastic or they are packaged in pairs with cardboard. Plastic is a forever-material that is almost completely non-recyclable. Wood and cardboard-based packaging is much more recyclable. Its recycling should be encouraged though tax incentives or subsidies.

  • Inverters are packaged in cardboard and protected internally with either Styrofoam, polystyrene or corrugated fiberboard. Styrofoam and polystyrene are forever-materials that are non-recyclable and should not be used. Paper based products like cardboard should be used instead.
  • Batteries are typically packaged the same way as inverters but primarily with cardboard.
  • Small balance-of-system components (BOS) are shipped in cardboard, plastic and they use bubble wrap and foam peanuts to secure the items during shipment.

Inverter packaging

Packaging PV products with forever-products that are non-renewable and non-biodegradable is completely unacceptable. The purchaser of these products has a lot of influence over how these products a packaged; the best action is an email or phone call to the sales associate for the manufacturer as well as to the distributor of the products. Solar PV is a renewable product industry, we need to remove non-renewable, non-biodegradable products from the packaging process.

Kelly Provence
Solairgen, Inc.
IREC and NABCEP Certified PV Trainer
www.solairgen.com
706-867-0678
800-262-7560

Solar Training Education and Learning Text

COVID-19 Assistance

Everyone is feeling the effects of the corona virus, and most people are concerned for their family and friends and anyone affected by COVID-19. It has adversely affected the health of many and the economic position of almost everyone. We understand that many find themselves in a position of reduced income, a surplus of time, and a restricted social agenda.

Solairgen would like to offer some assistance by reducing the costs of our online training courses until this health crisis is contained. If you have time and you would like to expand your career, or get some continuing education credits, we hope our price reductions will make it easier to achieve.

For the months April and May, we are reducing the prices listed on the website for online classes by 40%. Your discount will be shown and taken at checkout.

Stay safe.

Mr. Kelly Provence
Certified Master PV Trainer
Solairgen School of Solar Technology
706-867-0678

www.solairgen.com

 

On Grid Solar Farm

Working with Electric Utilities

Balancing the Needs of PV Customers with Utilities

Solar contractors and solar customers often find themselves on the adversarial side of utilities when interconnecting PV systems to the electrical grid. Most of the time this is due to a lack of seeing the other’s side and/or understanding of the other’s position.

Let’s first look at the utility’s position regarding PV systems. Many utilities offer incentives or encourage their residential customers to have PV systems installed on their properties. The reason for this is almost always for the purpose of appeasing the wishes of their customers. This an effort of goodwill because they know that electrical customers like the idea of energy coming from a clean renewable source and most of them also like the idea of owning their own energy. The benefit to the utility is not financial unless the PV system energy reduces load demand during periods when the cost to generate that power from other sources is high.

With residential customers, those periods are mostly in the afternoon and evening and then again in the morning as the sun starts to rise. This being the case, the PV systems with smart energy storage are the only systems that could financially benefit the utility as well as the owner of the system. They store the energy produced during the middle of the day and then feed it into the home and grid during the peak load periods.

With commercial customers the situation is different. The peak load period may be during the normal business hors of the day or 24 hours a day. These customers with PV systems may be shaving loads throughout the day or they may need to shift loads to a time of day other than the solar hours of the day. For the utility to benefit financially, a load demand study must be made for the specific customer. These customers with PV systems will also need energy storage for load shifting, peak load demand reduction and to provide consistent load support during climatic events that vary frequently during the day. The truth is that PV systems without smart energy storage do not save the utility money.

The exception to this would be with smart inverter technology that is controlled by the utility. California and Hawaii are both working through this process and it will become a more universal option in the very near future. However, these smart inverters and smart energy storage systems don’t address another issue for the utility. They understand how to regulate and shift energy supply with the energy sources they now have, the difficult task is how do they do this with customer-based power systems; the customer has far too much independence for their comfort. Customers would need to become liable to the utility for failure problems or let the utility have operational control of the system performance and operation.

Now let’s look at the customer’s position. The customer doesn’t have a choice when shopping for a utility; moving to another location is the only option if you don’t like the utility in your area. This is often a source of discontent for the customer. Customers depend heavily on electrical power for almost every appliance in the home and business. Natural gas, propane and fuel oil for heat are the exceptions.
Electricity seems expensive because we use so much of it; in fact, it is pretty cheap. In order to generate all your own electrical energy on-site, the cost will be excessive. In order to meet the cost per kWh from the utility, the PV system cost needs to be amortized over a 25-year period. Most residential customers do not appreciate how difficult it is to provide constant electrical power and how reasonable the price actually is. Commercial customers are more aware of this yet they would still like to be more independent for the utility if it is possible.

An important factor to both residential and commercial PV system customers is the return on investment. The customer wants the highest price for the kWh generated from their PV energy and they feel justified because they are generating clean energy and contributing to the reduction of conventional fuel sources with known hazards to our environment. This actually makes sense when looking long range. If the utility can absorb some of the cost of integrating PV energy into the grid, the industry will continue to grow and reduce initial coasts and therefore operating cost. Eventually the cost of PV systems with smart energy storage will be cheaper than any other energy source. It is rational to expect a public utility or a customer owned utility to invest in solar for the future by offering premium rates for the solar kWh. The problem with this position is that the rate to the customer will need to decrease over time with greater solar penetration, otherwise the investment from the utility will not have a positive return and the cost of electricity will have to go up. This is a difficult point to make to customers; someone needs to educate the electrical customer on how this will work to their advantage. The salesman for the solar contractor is unlikely do it and the customer will be much less likely to trust that information coming from the utility itself.

Effective open communication between the solar customer, the solar contractor and the electric utility is essential. Avoid adversarial positions and look for positions that benefits each entity.

 

Kelly Provence
Solairgen School of Solar Technology

 

Solar Shingle

The Future of Solar PV Shingles

Solar shingles seem like the most logical application for the future of solar PV systems, serving two purposes – a roof and a solar PV system – by simply integrating the shingles into photovoltaic roofing. There are problems with the solar shingle system, slowing its mainstream marketability, but may work if the following obstacles can be overcome:

(1) The cost of solar shingles is not competitive with conventional solar electric PV modules. Costs might balance with high penetration into the photovoltaic industry, but that takes time.

(2) The physical constraints of solar electric roofing shingles do not allow for custom fitting to varying roof dimensions. This is an obstacle that is difficult and expensive to overcome.

(3) The solar roofing contractor’s training is limited to the narrow market of solar shingle manufacturers. The manufacturers will not train contractors in areas where sales are not profitable, so the solar shingle market restricts customers’ choices and is controlled exclusively by the manufacturer.

(4) Roof warranties can only be fulfilled by the solar roofing manufacturer and its own factory-trained solar roofers. Repairs may be delayed if there is not a trained contractor in the customer’s area. Roof damage not covered by the solar roofing manufacturer would be difficult or impossible to have repaired by conventional roofers who are not trained to work with solar shingles.

I would like to see this product succeed in the market, but no manufacturer has made a successful long-term run with residential solar roofing to date, and some who are attempting it have yet to make a profit in the photovoltaic industry.

Mainstream success of solar shingle roofing may happen, but it doesn’t appear to be coming in the near future.

 

Kelly Provence
NABCEP Certified Professional PV Installer
IREC Certified Master PV Trainer
Solairgen, Inc.
706-867-0678
info@solairgen.com

Solar Training Education and Learning Text

Training for Changes in the Solar PV Industry

Why We Keep Up with Industry Changes

There is no argument that the only constant in the world seems to be change. This is even truer for the solar industry as changes in the solar market happen fast. The only constant appears to be the solar resource itself, our sun.

Training courses must be updated regularly to meet those industry changes and to prepare students who are either just entering the solar business or professionals who are currently working in it. Solairgen is constantly editing its courses for these changes. When necessary, we’ve been known to completely rewrite courses to address industry changes due to product innovations, code changes, regulated utility interconnection requirements, and rapid industry growth.

Here are the most recent changes to our training curriculum:

PV301 NABCEP Associate Installer Credential Exam Prep:
Recently we added a NABCEP Associate Credential exam prep course to follow our PV201 Introduction to PV Design and Installation online course.  PV301 is free to our PV201 students and costs just $185 for anyone who has not taken PV201, but has met the training prerequisite to sit for the Associate Credential exam but needs exam prep study material.

PV202 Solar PV Technical Design
Our online PV202 course now focuses on the technical design aspects of residential, commercial and energy storage systems. It is the next step for designers and installers after completing PV201.

PV210 PV Sales and Cost Analysis
We have introduced a new course, PV210 PV Sales and Cost Analysis that focuses on training students to focus on the marketing aspects of solar: identifying the solar customer and their energy needs, system costs and financing methods, the value of the investment, environmental impacts and proposal writing.

PV221 – PV224 Advanced Online Series
The advanced training workshop and advanced online series have been updated to address new solar products and changes to the NEC codes. These courses include PV221 PV System and the NEC, PV222 Interactive PV System Configuration, PV223 PV Maintenance and Troubleshooting and PV224 Energy Storage PV System Configuration.

Solar is growing faster than any other energy industry so change means growth, and we believe you will enjoy being a part of it. The changes happening today are exciting innovations that make the solar industry stronger and our training produces strong professionals in the field.

Kelly Provence
IREC Certified Master PV Trainer
Solairgen School of Solar Training