Category Archives: Products

Specific for general details regarding solar related products!

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What are Solar Inverters?

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Solar Inverters | It’s all about compatibility

A solar inverter converts the electricity from your solar panels (DC, or direct current) into power that can be used by the plugs in your house for your TV, computer, and other wired products  (AC, or alternating current). Panels can’t create AC power by themselves; they need the helping hand of a solar inverter.

AC vs. DC

In DC power, the current of electricity flows in one direction. In AC power, the current moves in both directions along a wire– both forwards and backwards. Some products, like lightbulbs, can run on either DC or AC power. But because AC power can be sent long distances easily, electricity networks in the U.S. were set up to use AC. (AC electricity can easily change between higher and lower voltage levels, and high voltages allow long-distance transmission).

Doesn’t my laptop actually use DC power?

Yes. Phones, TVs, computers, and many other common products use DC power, and actually have to convert AC power back to DC power. That’s what’s happening in the little black ‘brick’ attached to your laptop’s power cord. Because the U.S. grid is set up for AC power, the things we buy are made to work using AC power.  The DC power created by your solar panels is converted into AC power by your inverter in order to be compatible with the grid, and then back to DC by the power supply on your electronics. Ironic? Yes. This isn’t this case in all countries; some use DC networks. Since we live in the U.S., we need inverters.

How efficient is the conversion from DC to AC (and back again)?

Typical a solar inverter is around 95% efficient, so you’ll only have about a 5% loss of power when the electricity is converted from DC to AC. The conversion from AC back to DC in your electronics is less efficient; you may lose 10-40% of the power. That happens whether you’re using ordinary power from the grid or solar power– it’s just part of the way the system is set up. When you feel the black brick on your laptop cord getting hot, that’s a sign of a low-efficiency conversion of AC to DC.

What are the different types of solar inverters?

Most homes have central inverters, which make the conversion from DC to AC from a box in one location, like your garage wall. A newer type of solar inverter, called microinverters, work directly and independently under each solar panel. These are a little more expensive and take more time to install.

What other equipment do I need in addition to inverters?

For a complete solar system, you also need solar panels and several smaller components called the “balance of system”– wiring, hardware for attaching panels to the roof, and other small parts.

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Do I need ‘batteries’ with my ‘Solar System’?

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Solar and Batteries

When some people think about solar, they might think that they will become free from “The Man,” because a battery will allow them to store any excess power they generate, thus taking them off the grid. While this is possible with solar, it doesn’t make much financial sense for most people. Allow us to explain:

  • Grid Tie Solar

    Most solar systems are “grid tied” these days. That means when the system is generating power during the day, any excess power it makes is fed back into the grid through something called “net metering.” Your meter spins backwards and the utility credits you for that power. At night or on overcast days, you’ll use grid power instead of solar, but your utility doesn’t charge you until you’ve used up all the credit you generated through your panels. More on grid tie solar.

  • It Means You Probably Don’t Need Batteries

    You don’t need batteries for your solar system if you’re already connected to the grid. It’s an option, but not one that most people use these days because the batteries are still very big and bulky. They’re also expensive and need to be replaced every five to ten years, depending on the type and how well you take care of them. Battery technology is evolving and solar batteries may become a more viable option someday, but for most people right now, it’s more practical to simply tap the grid in off hours.

  • Net metering – The Virtual Battery

    Net metering is like a virtual battery. The utility keeps track of any extra power your solar panels produce, which spins your electric meter backwards. Then at night, you simply use grid power on the credit you earned while supplying the utility company with power during the day. Net metering is maintenance-free and typically costs around $5 per month in administrative fees.

  • What about ”?

    It’s true, our name has “off the grid” in it. It’s just a metaphor. We want to take at least one block’s worth of grid energy usage out of every city per campaign, but the bottom line is that we’re here to help you buy solar panels for your home.

Solar Battery Back-up Systems

We understand that some people are interested in solar batteries in the interest of disaster preparedness, and because this is America, you’re free to spend your hard earned money any way you want. Here are a few things to consider in your decision though:

  • Battery back-up systems are reliable for those “what-if situations.”
  • However, those “what-if” situations are fairly rare. The American electric grid is over 99% reliable, and using a battery would mean you’ed be spending an extra $5,000 to $10,000 every 10 years for the 1% chance that you will need battery back up.
  • Also, disasters that upset the grid are typically repaired within days. There are, of course, exceptions like Hurricane Katrina…..but:
  • It would most likely be more cost effective to spend money on flashlights, candles, matches, batteries, extra blankets, and dry good food, water, radio, etc, and be without the modern conveniences for a few days than it would be to purchase an expensive battery. Even in Hurricane Katrina’s case, your entire roof could have been blown away and/or your battery system under water and ruined. Same for an earthquake. Having a battery back up system may not be so important if the rest of your house is unlivable.
  • Bottom line: Battery back-up systems do work, but they’re expensive for the few times they’re needed. It’s more cost effective to prepare to live for a few days without electricity until power is restored.
solar-perovskite | new material to enhance solar cells

Pervoskites Research | New material to enhance solar cells?

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Researchers at the University of Toronto have used a new material called perovskite that could make cheaper and more efficient solar panels and LEDs.

Pervoskites are good at absorbing visible light and have never been studied before in their purest form, as perfect single crystals.

Researchers used a new technique to grow perovskites and studied how electrons move through the material as light is converted to electricity.

A research team led by Professor Ted Sargent of The Edward S. Rogers Sr. Department of Electrical & Computer Engineering at the University of Toronto and Professor Osman Bakr of the King Abdullah University of Science and Technology (KAUST), used a combination of laser-based techniques to measure selected properties of the perovskite crystals.

The team was able to determine the diffusion length as well as mobility by tracking down the rapid motion of electrons in the material.

Riccardo Comin, a post-doctoral fellow with the Sargent Group said, “Our work identifies the bar for the ultimate solar energy-harvesting potential of perovskites. With these materials it’s been a race to try to get record efficiencies, and our results indicate that progress is slated to continue without slowing down”.

The efficiency of perovskite has climbed to over 20% in recent years, which is quiet close to the current best performance of commercial-grade silicon-based solar panels, which are mounted in Spanish deserts and on Californian roofs.

The light gets absorbed when it hits a sheet of perovskite, exiting the electrons in the material. These exited electrons travel easily through the material to electrical contacts on the other side where they are collected in the form of electric current.

The research team studied that if this sequence is carried out in reverse order, the perovskite will then release energy as light. By this, the material could be used to make more efficient LEDs.

The detailed research paper has been published this week in the journal Science.