Posts tagged with "microgrid"

Battery Options for Mi-Grid

We are often asked, “What kind of batteries do you use?” Mi-Grid systems are offered with 3 choices:

High-Quality Absorb Glass Mat (AGM) batteries
Advanced Lead Acid – Nano Carbon batteries
Lithium

AGM

Absorb Glass Mat (AGM) batteries

Our standard offering uses high-quality AGM batteries. For a system where the batteries are a backup, or are not cycled very often, our standard AGM is the most cost-effective. AGM batteries are a form of lead acid battery. Instead of liquid sulphuric acid, the battery is filled with fiberglass mat and the mat is made “wet.” This allows the battery to be mounted in any direction, and there is no chance of spilling. If the battery case were damaged, it may dry out, but the acid fluid cannot leak. These are considered, “non-hazardous”.

For Mi-Grid systems connected to utility power, the batteries are kept full. Only when the utility power fails will the batteries be cycled. These batteries are also used wherever the system is set up for up to 80% depth of discharge (what percent of the total battery is used). AGM batteries, if treated properly should last a minimum of 5 years, possibly as long as 10 years.

Nano-Carbon

Nano-Carbon batteries

Nano Carbon batteries are called “Advanced Lead Acid.” The ones we use are also an AGM battery with all of the benefits. The internal parts of the battery are covered with a nanoparticle carbon coating. This increases the life of the battery in places where it cycles a lot. The batteries operate best in a “partial state of charge.” The controls are reprogrammed to operate the battery in the middle of its range and the usable portion is about 50-60% of “full” capacity. This is how they are able to achieve 3000 cycles.

These are great in high-cycling applications, where the batteries are charged and discharged every day, possibly more than once a day. They cost about 30% more than the regular AGM batteries. Great applications for these are off-grid, grid-connected cycling and mobile applications, such as food trucks and RVs.

Lithium

Lithium Ferro Phosphate batteries.

Lithium batteries, depending on the type, offer light-weight, smaller batteries with very high-cycle life. There are many types of lithium batteries. The type in your phone is typically Lithium Cobalt, due to the very high energy density. They are limited to about 500 charge-discharge cycles before losing significant capacity.

We use Lithium Ferro Phosphate batteries. They have a lower energy density (size vs. charge), but much higher cycle life. When used correctly, they may exceed 10,000 cycles! Typical is 5000-7000 cycles. For the same usable charge, they are about 2.5 times the cost of nano-carbon batteries. With the higher cycle life, they are comparative to the nano-carbon. You may never have to replace these batteries! They are also smaller and weigh about 60-70% less than either AGM battery.

These are best in high-cycle, mobile and applications in places where you do not want to change the batteries often. The prices are coming down, so these will probably be the best replacement battery, when the time comes.

Every type of battery has its place. I would say the Lithium batteries are “best.” But you may not want to pay that much at the beginning. If the batteries are in a grid-tied type system, the regular AGM batteries are best. The nano-carbons are the most cost-effective in a cycling application.

Update: The lithium batteries continue to fall in price, including LiFePo4. If you take into account the life of the battery, LiFePo4 is now cheaper than any form of lead-acid.

Mi-Grid Can Connect with Either AC or DC Coupling for Solar

We design our microgrids with flexibility in mind. For instance, Mi-Grid can be installed with either AC or DC power coupling. We can power you either way. Our systems can work with solar or wind power too.

AC VS. DC COUPLING MI-GRID

Mi-Grid AC vs. DC

Solar panels can be connected to Mi-Grid in two different ways. They can be DC coupled or AC coupled. Coupling is simply the term we use for the connection of the solar panels to the Mi- Grid system.

Mi-Grid—DC

DC coupling is the traditional way to connect solar panels to the Mi-Grid system. It is also the most efficient. Solar panels are DC (Direct Current), like a battery. It is easiest and most efficient to keep the power DC when storing to the batteries.

Mi-Grid—AC

AC coupling means the power is converted to Alternating Current, like your household power, before connecting to the Mi-Grid system. This means Mi-Grid can be retrofitted onto existing grid-tied solar systems. The advantage is a more simple installation of the solar array.

Which is better?

For Off-Grid systems, where efficiency is extremely important, DC coupling is definitely preferred. With most Grid-Tied applications, the efficiency loss only shows up when the utility is offline. And AC coupling allows a larger solar array to be connected to a smaller inverter battery system, maximizing savings, while reducing installed cost.

Retrofit systems connect the Mi-Grid system with AC coupling. With little change to a standard grid-tied system, you gain peace of mind with battery storage and generator backup. Mi-Grid keeps you going.

AC vs. DC cost

At the time of a new installation, similar AC and DC systems are nearly the same cost.

Where the budget is constrained, an AC coupled essential system is best. The system can be upgraded later if more inverter power is needed.

DC systems are best when off-grid. Efficient storage of the energy provides the most predictable power around the clock.

Looking to build a custom solar power? Great, get in touch with our engineers by submitting a form with your specifications and needs here.

How a Mi-Grid microgrid can be configured with AC power.

Diagram of a Mi-Grid coupled with AC power.

Mi-Grid Systems: How Our Models Are Sized for Different Applications

Our microgrids can be sized for any amount of demand and our Mi-Grid systems are configured for different applications, including residential, business and mobile (RVs, food trucks, etc.). Originally designed for off-shore platforms, we have systems configured from 2kW to 2MW!

Standard Models

Mi-Grid’s have 5 standard models. Even the “standard” models have options. They are configured based on size to match the demand (power load). Pricing can vary, some customers already own a component of the Mi-Grid system, such as a generator or a solar array.

Models also range in price depending configuration and options. Is the system grid-tied or off-grid? Is it AC or DC coupled to the solar panels? Is it applied to an appropriately sized dwelling for that model’s design or is a smaller-sized system applied to a larger dwelling, requiring additional sources of energy, i.e. a larger generator.

Other cost variables include installation costs, shipping, taxes and possibly duties. For each model below, we provide a price range, which does not include solar arrays and installation. As for the installed cost of solar panels, including mounting hardware and labor, that can range from $2.00-$4.00 per Watt, in the continental United States. Depending on where it is installed, there may be additional charges for shipping and duties. All price estimates provided here are in USD and for installations in the continental United States. These estimates are approximate as of January 2018.

Mi-Grid is an energy management system, meaning, at its core, it has a heart (hardware, controls and modules ) and a brain (software combined with our proprietary engineering design and safety considerations). All components are tested and certified to UL standards.

Mi-Grid 2000

Mi-Grid 250 & 500:

Both of these systems are 120VAC, single phase. They are DC coupled and were designed for off-grid. They are the least expensive/most cost-effective systems. They can be grid-tied, but cannot export/sell power.

Mi-Grid—250:

Tiny, but fierce! The main unit is 36” x 24” x 16”, and the batteries are inside! It is 2200 Watts and will power lights, outlets and a small window Air Conditioner. Up to 1.2kW of solar panels can be connected. Price range: $4,500 – $6,500, with standard batteries.

Mi-Grid—500:

Probably the most cost-effective system. The main unit is 48” x 24” x 16”, and the batteries are inside! It is 4000 Watts and will power lights, outlets and up to 1 large or 2 small mini-split Air Conditioners. Up to 3 kW of Solar can be connected. Price range: $7,500 – $10,000

Mi-Grid—1000-4000:

120/240VAC. The generator is typically a home-style propane/natural gas unit and can be “oversized” to power more external equipment. Solar can be AC or DC coupled.

Mi-Grid—1000:

Similar power to a Mi-Grid 500, but split-phase 240VAC and can connect up to 8kW AC Coupled (6kW DC coupled) of solar. Price range: $14,000 – $22,000

Mi-Grid—2000:

Same as a Mi-Grid 1000, but 8kW of power output. Price range: $21,000 – $30,000

Mi-Grid—4000:

A double unit Mi-Grid 2000, 16kW of power output. And up to 20kW of solar. $40,000 – $65,000 (The $65,000 unit includes a 48 kW generator!!!)

Which is better?

For Off-Grid systems, any system can work.

If 120VAC only will work for you, then the Mi-Grid 250 and 500 are very cost-effective.

For grid-tied, generally where you might sell excess power or if you have an existing grid-tied system, the Mi-Grid 1000-4000 are best.

If you need 240VAC power, you must choose a Mi-Grid 1000-4000.

Options:

All systems may have a larger generator. It will allow more items to be powered when the generator runs. And some items can be setup to be powered only when the generator runs
Any System can be purchased without a generator. Only remote startable generators can be controlled by a Mi-Grid. Most home type permanently installed generators can be controlled. A limited number of portable type generators can be controlled.
More batteries and more solar (up to a point!) can be added for longer run time without generator help.
Systems with limited solar can still be useful minimizing generator run time and fuel consumption.
Special Lithium batteries can be used which have 3 times the life of our best Advanced AGM batteries. Expensive, but in the long run, cost effective.

For more information, Contact us or a local Representative.