What to Know About Solar Energy

SEALED LEAD ACID AGM VS. LITHIUM ION BATTERIES

Here is my humble opinion on the great battery debate:

AGM Advantages:
Inexpensive – $195 for 100 Ah
Cared for properly – keeping them charged and de-sulphated – 500-1200 cycles
98% are recycled perpetually – you could have the same lead in your car that was in your grandfather’s Buick

AGM Drawbacks
Weight – 55 pounds each
Actual available storage density – 50-70%
Must be kept fully charged as often as possible to maximize their life span

Lithium Advantages
Light weight – 30 pounds each
Accept charge and deliver charge faster and more efficiently
2000+ cycles with an 80% capacity remaining – more than 3000 cycles to end of life
High Storage density – 98% of storage is on tap
Lithium batteries do not mind a partial discharge state

Lithium Disadvantages
Price – $850
Not recycled yet

In rough terms for comparison:
It takes two lead acid batteries to deliver the power of one lithium (storage ratings of 100 Ah)
Those two lead acid batteries weigh 110 pounds vs the 30 pounds of the lithium
If you were just buying batteries to cover a 10 year period-
16 lead acid batteries would cost $3120 – that would be 8 batteries to start and 8 new batteries in 5 years
4 Lithium Batteries would cost $3400 – same battery bank for 10 years
Lead acid requires twice the storage space of the Lithium batteries

Caveats – 
If the batteries are used for emergency only, standby basis, the preference would be SLA with a maintainer/de-sulphator
Daily use favors the Lithium
If the system gets moved from time to time – Lithium
It’s hard to beat the cool factor of Lithium – when you see them and work with them, it is hard not to love them – tight, powerful packages

We offer two types of Lithium batteries – for our smaller systems that use 100-300 Ah batteries we use a manufactured battery with built in battery regulation. For 400 Ah systems and above we use an industrial battery that is managed by an AIMS inverter. We have done several homes with these batteries and customers are very enthusiastic about them. At some point, we need to put a full description of these batteries on our website. For durability and construction – I believe they are better than the Tesla Wonderwall.


BATTERY CHARGING STAGES

So, you have a 4000 W split phase inverter, two 12V batteries and two 150 W panels. Your charge controller has bars on a battery that seem to indicate that the batteries lose charge rapidly after they are charged with no load.

  • Here is the story on that charge controller depiction:
  • There are four stages of charging, each with an associated voltage:
    • Bulk – this is where your charging mechanisms are throwing everything they have (constant current) at the battery – the voltage can range from 10-14V. Bars on the charge controller can be 0-5.
    • Absorb – this where the batteries have reached a peak voltage (14.4V) and the current gradually drops until the flow to the batteries stops. Bars on the charge controller – 5
    • Float – the charging mechanism drops the voltage to something like 13.6-13.7V and just kind of hovers there. This can drop the bars to 3-4.
    • Resting – if the charging mechanism is removed (say, no sun from the solar panels or disconnect the AC charger) the batteries have a normal resting voltage of about 12.9-13.0 volts. This is 2-3 bars on the charge controller but, at this voltage, the batteries are 100% charged and happy.

SOLAR PANEL MYTHS

  1. Solar panels do not work in cold, cloudy places/states. UV light is all that’s needed and even the cloudiest of places have excelled. Germany, who ranks low in sunny days, is the solar energy capital of the world. In fact, when the solar panels are cold, they are able to better conduct electricity.
  2. Solar systems are too expensive. Solar Energy Installations are more affordable than they have ever been. In every state, incentives cover a minimum of 30% all the way up to 85% of the system costs. The cost per watt, installed, is at an all time low of $8.
  3. Solar panels require constant maintenance. The panels rarely require maintenance or cleaning, plus the average warranty lasts 25 years!
  4. Solar systems are ugly, large and bulky. Solar panels have come a long way over the years. Now systems have become virtually seamless with solar shingles. Solar cells can be combined with slate, metal, fiber-cement, and asphalt roofing.
  5. Few states offer rebates or financial incentives for solar energy installations. According to the Database of State Incentives for Renewable Energy, 48 states have a solar/renewable energy incentive on top of the 30% federal tax credit!
  6. The solar panels cannot withstand harsh climates (snow, hail, winds, sleet). The University of Vermont (who receives considerable snow fall) has a system that has proven to be effective and virtually maintenance free, even during the winter months. The color of the solar panels is dark which aides in melting the snow plus a South facing position allows for a quickened process.
  7. Solar systems are unreliable and inconsistent. On the contrary, solar electric systems can be more reliable than the utility company. They have no moving parts and off-grid systems are not subject to power outages. In fact, solar technologies are used to power many vital systems: aircraft warning lights, railroad crossing signals, navigational buoys, etc.
  8. I cannot use solar energy because I don’t have Southern roof exposure. East/West roof exposure is also effective for photovoltaic systems. Another option is a ground mounted system in which case all you need is a relatively flat, unshaded area.
  9. Solar energy is inefficient. According to the U.S. Department of Energy, solar panel efficiency has more than quadrupled since the 1970’s. With an average between 15-19% it sits in the same efficiency range as the gas in your car. Unlike gas though, the technology continues to advance, in turn, so will efficiency.
  10. I won’t live in the home long enough to make my investment back. Actually, a solar system increases the value of the home. For every $1,000 that has been saved in annual electric costs, your home’s value rises $20,000. (U.S. Department of Housing and Urban Development).

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