PV Gap

Corey Said:

What is the best solar panel to buy?

We Answered:

I am assuming you are talking about photovoltaic panels, not solar thermal?

If you do plan on buying one, and not building one yourself, then there are only a few things you need to consider to compare panels. Most solar panels are very very similar. They almost all offer the same guarantee (25 years material & workmanship, declining power guarantee). There are only one or two or three things that differentiate one from the other.

First, look at the cost per watt of rated power. Now, you are never going to get the rated power out of your panel - just like you won't get your rated MPG on your car - but it will let you know which panels give you most bang for the buck.

Second, if you are hoping to get a rebate or incentive on your panels, make sure that they are on the qualified list of panels that are eligible for a rebate.

Third, check out the "power tolerance" and look for one that is as low as possible. 10% is high. 5% is okay. 2% is great. This tells you how much more or less than the rating your panel can provide. If you buy a 100 watt panel with a 10% tolerance, then your panel is considered acceptable by the manufacturer if it puts out anything over 90 watts.

Finally, the best panel to buy may be the one you can get your hands on. Right now, there is a tremendous panel shortage. My suppliers are telling me that if I want a large quantity of matched panels I will need to wait until at least this fall. They just can't make them fast enough right now.

Good luck.

Agnes Said:

Which is the best Solar Panel Service?

We Answered:

Your location is going to be a major determinant on price/feasibility. I would recommend checking out Global Solar Center (http://www.globalsolarcenter.com/) They helped me immensely when I was pursuing solar power. If you visit their site you may request a free solar quote and receive all the information you need regarding all the incentives you will be eligible for, payback period, annual energy bill savings and return on investment. If you want to collect all the information to make a smart decision definitely visit their site as they're a great resource to get started with your solar plans.

Francisco Said:

Which is the Best Solar Panel Service?

We Answered:

By your figures you need 42 amps (5000w/120v).

The solar panels efficency is constantly changing as they keep improving with billions invested in research and development. The efficency is amount of voltage and current the solar panel can put out per the same size area of panels.

The what about night time power? Battery back up charged in the day time or no battery back up?

Some solar panels even take water through electrolysis and split the hydrogen and oxygen. the catch and save the hydrogen to power hydrogen powered generators at night.

Is the federal income tax energy credits still available?

Can you afford the best system? Will take many years before you reach the break even point over money saved paying to the electric company.

Perry Said:

What is the best Solar panel to install in a House?

We Answered:

Hi there.

Here is some useful info for you.

Solar Power, An Introduction
Solar panels or modules convert sunlight directly in to D.C. electricity. This is a semiconductor process within the silicon cells. The light energy is transferred to electrons where it is available as electricity, from this you will see that the output is dependent on the amount of light energy falling on the panel. Temperature has an effect but is negligible in comparison. Panels are usually designed to charge a battery of 12volts, during charging a higher voltage of about 14volts is required to force a charge in to the battery. A panel will have a voltage of about 20volts with no load. When the panel is connected to the battery a charging current will flow in to the battery causing the panel voltage to drop to the battery voltage of 12-14volts. Panels can also be connected in parallel, this increases the power output by adding together current produced by each panel.

The power output depends on the weather, siting of panels and many other variables - therefore exact figures are very difficult. From experience in clear sunny weather an output peak of about 80-100% of the panels rated output power can be expected. An average of 50% over the day can be improved upon by moving the panel to track the sun. As it is difficult to define light levels without expensive equipment, a guide to when panels begin to charge the battery system is that dark and grey clouds remove the direct light that the panels require to give a useful output, white clouds allow enough direct light to pass through. Overcast days will usually produce sufficient to overcome battery self discharge.

Solar Regulator
A regulator/charge controller is required when the maximum current in to the battery exceeds 10% of battery capacity in Amp hours. Use of a regulator/charge controller will prevent over-charging of the battery, and is essential with large panels or when using small capacity batteries. If the output of a solar panel is less than 10% of the battery capacity a diode may be used instead of a regulator. When the panel is able to supply power to the battery, the diode lets it through, when the panel cannot supply power (at night or in bad weather) the diode prevents the battery discharging back through the panel. Fuses should be used as a safety measure, and fitted as close to the battery as possible.

Panels can also power equipment directly, these should be loads such as fans and pumps, not voltage sensitive equipment like televisions, radios etc. When using solar power to charge a battery, equipment can be connected and used at the same time, the battery will stabilise the voltage.

Types of Solar Cells
Essentially four solar cell technologies are available commercially:

Single Crystal Silicon (Mono-Crystalline)
Cells are sliced from a pure crystalline silicon ingot.
(~15% conversion efficiency).

CIS (Copper Indium Diselenide)
Representing the latest development in Thin film technology solar cells. Approximately 11% efficient.

Poly-Crystalline or Multi-Crystalline Silicon
Molten silicon is poured into a mould and then sliced into cells. Now the most efficient technology (~16% conversion efficiency).

Amorphous Silicon
Commonly used in toys, calculators and consumer electronics. Thin film technology, inexpensive but least efficient alternative (~8% efficient).


What size of panel do I need?Required for 12 Volt Battery Charging (ideal conditions).

This depends on the size of battery you have, the amount of power you use and the amount of light available each day. In power terms we measure the amount of energy consumed in amp hours. A 1 Amp draw over 2 hours is a total of 2 Amp hours (AHr) of current.

Determine the number of Amp hours you will use to run your electrical equipment in one day such as lights, TV, Stereo. If you divide the wattage of the equpment by 12 this will give you an approximate Amp per hour rate.

e.g A typical 15" LCD Television rated at 36 watts uses approximately 3 Amps per hour.

The maximum current available from a solar panel is given by dividing the panel Wattage by 17.

e.g. A 75 Watt solar panel will give a maximum charging current of: 75 divided by 17 = 4.4 Amps per hour.

Where possible it is a good idea to reduce the amount of energy you consume our low power TV's and Low energy Lights are good solutions.

Catherine Said:

Which is the best option, solar panel or wind turbine?

We Answered:

Some valid thoughts so far.

First of all you should consider that the initial investment will take time to pay for itself, pretty much like buying a Hybrid vehicle.

You'd need an ARRAY of either, not just a single unit, and all the needed hardware, etc. to make it work.

I live in South West Florida, and while it can be breezy at times, there is most often, more Sun. Obviously that doesn't apply at night, and would equate to "storing" the energy. Sun Hot water is common, but again the solar collection to power a house would be pricey.