Adding a Battery and EV Charger to a Solar System

Part of SEG’s “Energy Chats” Series with SEG’s Lead Electrician Joe Nelson

SEG Customer Question:

If my home already has a Solaredge inverter with solar and I want to add a battery and an electric car charger, how is that going to look? 

Answer by Joe Nelson (Licensed Electrician):

Solar Edge is the manufacturer of our primary grid-tied inverter equipment, as well as the battery components that will store energy from the solar when you are not directly using it in your home during its generation. The excess energy not used can go one of two places provided you have a battery to store your energy in. If your battery is already topped off and full of energy for use later in the evening or during emergencies, then the excess energy goes back into the utility grid through your electrical meter and credits you for the energy you collected that you did NOT use, for future draw out of the utility (at times when there is no sun available or your battery is not charged up completely).  

Because Solar Edge has such a large audience and is working hard at maintaining their market share, they have been designing for the future and really planning ahead. They have designed all their enclosures and equipment to have a similar design look and the appearance of them will continue to be unified in a way that makes multiple pieces of equipment installed on your wall look similar enough to create elegance, instead of chaos. There are older models of the inverter that do not support a battery connection, these models of inverter will have to be changed out if you want to support the battery backup component of the system. These decisions are important to make in advance if you think you might have a need for backup power or have a desire to control your energy “arbitrage” in the future. The more you can plan for your end goal the more you can control the costs of modifying and installing all this equipment into your electrical infrastructure, which is no small feat and a big investment in your future. You have the options between a more affordable “non battery compatible” inverter, or the inverter designed for a connection to a battery. The lower cost inverter*  

Their design was centered around being a great inverter for the solar panels, but to reduce cost did not necessarily have the “battery backup” portion included into the design. (As few as 3 years ago the drive and desire for battery backup was scarce compared to what it is presently).  

Yes there are options to add more equipment to the system like a BUI to enable the older version inverters to charge a battery, but in the end, it would be better from an electrical standpoint and more efficient to swap out for the newest inverter.  

Solar Edge has been designing for future expansion and needs of our clients and this includes everything from integrated EV charging (allowing you to “boost” your EV charge with DC energy directly from your solar system during the day) to comprehensive offerings such as including Smart Management of circuits and HVAC systems based on your energy habits. They even have a beautiful water heater that heats itself through your inverter connection utilizing any excess energy generated to make sure you have hot water always available at the highest efficiency possible.  

To help answer your question directly, most customers can add an EV charger to their existing system but since charging an EV will add about 30% more energy to the total energy needed often time more solar panels are added which in turn may involve a new inverter to meet those needs. Because much of the components of a system are already installed an inverter swap to allow more energy generation will pay for itself in a short amount of time, especially instead of paying the rising costs from PG&E to charge your new Electric Vehicle. The same holds true for a battery capable inverter, you will realize the benefits immediately and it will pay for the additional investment in a short period of time. 

The “Brand Packaged” themes by every manufacturer in our lives now balances Form with Function.  Solar Edge is not the only manufacturer doing so, and you will see many other beautiful and well thought out pieces of equipment offered by a variety of solar brands. In summary the new era of solar equipment is even more reliable and robust than ever. Combined with the quality of materials and designs, they are all ready to capture the energy you need on your own roof or from your own backyard. Take your power needs into your own control, by starting on the path to “energy independence”. Ask for multiple bids from professional contractors, don’t be afraid to ask lots of questions, and there is no reason to delay, as the benefits will always outweigh the drawbacks. 

The same way owning a home secures your shelter, owning your own energy is the next step to our custodial role, for our children and our future.  

All of these developments in recent years have opened new doors and new opportunities to change the way we think about power and the relationship humans have with energy and electricity. There are now many “Micro-Grids” forming out of necessity and a desire to control and decentralize electric energy.

This is a great direction for us to go as a people, since the electrical “grid” we have now known for generations is approaching its end-of-life and needs to be addressed in a way that empowers us all individually, instead of continuing to create a profit for shareholders all the while deferring upgrades and maintenance on one of the world’s largest and most valuable electrical grids.

There are layers of benefits for not only creating, but also storing at least some of the energy you need on site at your home or business.

The first benefit comes in the form of efficiency, creating and storing energy at your home is factors more efficient than using a Natural Gas or Nuclear generator hundreds of miles away to create this energy. This is one of the driving forces for communities and groups of businesses (or even homeowners) getting together and forming a Micro-Grid. You also get to control the “cost” of this energy, which no utility really wants to give up, as you are the bread and butter the shareholder stake a claim to very possessively.

If you make energy during daylight hours, and the utility will only pay you $0.18/kWh for that energy but storing some onsite at your home means you can use that energy at 9pm at night when the utility wants to charge you $0.38/kWh, you have just created the beginning pathway to managing the cost of your own energy.

You will hear terms like “Peak shaving” and “Time Of Use” which are both subjects relating to how you might generate and store your electricity in a way that strategically benefits you more than the utility. Besides Environmental and Financial benefits, we additionally have the need to access this energy when WE need it and are ready. This can no longer be assured from our utilities, as they have spent over half a century bloating their pockets in the name of profits, only to realize now we might be coming for some of the empty promises they have made.

If we are to follow any of the trends of the last few years, our aging electrical grid will only see more and more stress and outages, summer and winter, and the only way to have this energy ready for you when you want it is to generate it and store it onsite. The more electricity is involved in every aspect of our lives, the more we will need to understand, take charge, and champion our own part we play in this.  

The New Frontiers of Solar – CPV Concentrator Photovoltaics

Part of SEG’s “Energy Chats” Series with Joe Nelson

Question by an SEG Customer:

The panels and equipment that you installed in ’17 are working well. My question has to do with photons. Energy produced by the panels converts what wavelengths of the sun’s spectrum to electrical energy? Is it everything except infrared?

Could properly placed reflective mirrors (either silvered or just a highly reflective metal) increase the panels’ production? Would the extra heat produced cause damage?

 

Answer by Joe Nelson (Licensed Electrician) :

 

Let’s talk physics for a moment.

 

Light (energetically) is made up of photons, even light not visible to our eye is still comprised of photons. These photons at the upper and lower level of light (outside our visible range) are typically either moving too quickly or too slowly for efficient conversion into Photovoltaic electricity, therefore most solar panels are designed primarily to use the visible light spectrum most efficiently. Ultraviolet light has too much energy, and its byproduct is heat which lowers the panel’s ability to convert photons to electricity. On the other hand, the infrared end of the spectrum just does not have enough impact to knock loose those pesky electrons on the solar panel.

 

Your logic is sound, in that the two limitations to capturing solar energy are a) intensity of the sun’s energy and b) heat. You are may be familiar with “Concentrated PV,” in this configuration they use lenses to focus the intensity of the sun onto the surface of the solar cell, they then use water to bathe it all in and wash away as much heat as possible wringing the most efficiency out of it as possible. you absolutely could increase the intensity of the sun either with a reflective surface OR a lens, and at that point your production would go “up”, this would be counter balanced by the loss of efficiency as the material heated up and in a roundabout manner the gain would be a wash against the losses.

 

 

This would not “damage” the solar cells (other than the risk of truly overheating them and cooking the material) but it would “shorten their lifespan” by accelerating their deterioration. Therefore, most of the design schemes you see are experimental in nature. When NREL is testing differing types and strategies for modifying these technologies they are seeking to increase efficiencies by fractions of a single digit percent, we have the luxury of designing inside an “achievable goal” in this case the client says, “make my PG&E bill go away”. I know with absolutely certainty there is an increase in efficiency I can gain somewhere! But is that gain and its cost worth the reward realized? Usually, the answer is no.

 

 

To play devil’s advocate, if we took your system off the roof and placed it in the backyard, and were able to wash water across the surface of all the panels like a recycling fountain(with a large enough volume of water to remove the heat and shed it to the ambient environment), and then place either mirrors or Fresnel lenses arranged to increase the intensity on the solar cell’s surface, you would see a gain in collected energy.