PV Gap

Ryan Said:

What two types of surface on Earth are most important for absorbing solar energy and keeping the planet warm?

We Answered:

i'm going to say oceans (water) and forests.

Kelly Said:

Is solar energy good for all types of energy needs?

We Answered:

The technology has not been perfected to power everything. Solar panels capture sunlight but from what I know they capture less than 40% of the energy from it. Additionally when there is no light you have to rely on betteries with stored energy. As it improves I'm sure it will be distributed and implemented more.

Deanna Said:

What are the different types of storing the solar energy (other than battery)?

We Answered:

Solar energy comes to us as heat and light energy. Typically it is more efficient to store energy with a method similar to what you are capturing but it is possible to convert from one type of storage to another. Some of the proposed solutions in use or proposed are:

Pumped hydro: Water is pumped to a higher elevation when power is cheap (off peak) and then used when power is expensive.

CAES: (Compressed Air Energy Storage) is being explored. Like pumped hydro this may be limited to favorable locations. CAES is cheaper where there are available underground caverns or mines. More recently CAES is discussed in conjunction with Wind and electrical production.

Flywheel storage: Flywheels store more energy by moving faster than by being massive. Therefore flywheels are being built to spin in a vacuum and are held up by magnetic bearings. Speeds up to 100,000 rpm have been used. Flywheel facilities are being used for frequency regulation of the power grid. Typically this is for a short duration.

Ultra-capacitors store electricity as a static charge and so are a little different then a chemical battery.

Hydrogen storage has been used in a number of small scale solar installations. Hydrogen is manufactured with excess electricity and then used in a fuel cell to produce electricity.

Heat storage: is dependent upon the amount of heat a substance can hold. Water has a high specific heat about double that of rocks or masonry, but some PCM (phase change materials) can have 8 or more times the specific heat of water. These materials typically come in the form of waxes and salts that store heat when they change from one phase (solid, liquid, gas) to another.

Glen Said:

In what types of batteries do you store solar energy in?

We Answered:

I have mix of deep cycle and golf cart batteries.

Fork lift batteries are also something for consideration due to the heavier dutly plate construction.

Batteries should never be fully discharged. The longest life can be achieved by never discharging below 80 percent capacity as measured by electrolyte density. Running a battery to full discharge weakens the plates and they can short out.

Most deep cycle batteries are little more than a regular battery used in motor vehicles for starting- only heavier duty and more lead in the plates.

AGM's are another type sometimes used for alernative energy systems.

You can find some useful information in the book "Battery Secrets" Sold in a few places including http://www.lindsaybks.com

You can find some specific battery info here: http://www.yuasaeurope.com/eu/ or
http://www.exideworld.com

Sue Said:

How is solar energy more eco-friendly than other types of energy?

We Answered:

I'm in Kenya for the moment and it makes of course perfect sense here (lots of sun) but it depends on how long the installation lasts (approximately 20 years), then the question is how much it will cost to have it replaced. We're combing it with wind turbines (as we are in a windy area and that might be the better choice for power supply in the long run...Time will tell.