Ask an Expert

Q:What size inverter will I need for 1.65w of panels please?

A:

To properly size up an inverter it comes down to choosing between whether you want to have a central inverter or micro inverter. If the system is off-grid then you will have to consider other options. On grid-tied systems and heading toward the route of central inverter make sure your inverter can handle to the output of your home solar powered system. In your situation you're probably looking at a central inverter that can handle 1.65kW of power coming from your solar panels. Sunny Boy make some of the best central inverters in the market, a SMA2000 will work with well if you head toward a central inverter system. Fronius and Outback also make top notch central inverters so take a look at some of their inverters.

If you want to head toward a micro inverter system, take a look at Enphase Microinverters. Micro inverters may be an option depending upon what you want to achieve. For homeowners choosing between the two can be a challenge, SolarTown has learning and research articles comparing a central inverter to a microinverter system to make choosing the right system easier for homeowners.

There may be a few other variables to consider but one thing I always remind homeowners and many forget to remind homeowners is "Will the homeowner want to upgrade the system in the future? If that is indeed the case, maybe a larger inverter will make more sense so that you will not need to buy an additional central inverter.

If you have any questions, feel free to contact SolarTown or use our new Live Chat.

12-16-2011 by Ned Category: Solar Panels

Q:If I'm consuming around 300Kwh daily, what would be the size of my panel(s) to install? What is the ratio for energy generation (KWH)of panels per square feet or square meter with 50 efficiency?

A:

If you are consuming 300kWh per day, you must either have a huge home or have a small factory somewhere. By way of comparison, in the US, the average home is consuming roughly 1000 kWh per month. How much space you will need to install solar panels on your home to meet this entire consumption (we really hope that you are not using that much in your home) depends on a number of factors, such as location, efficiency of the panels, and the size of the panels. The efficiency of solar panels today is in the 14-17% range. Take a look at our learning article on choosing solar panels. If the roof on your home is a constraining factor, you will definitely want to compare the size of the solar panels you are considering. As we point out in that article, if you only had 500 square feet, the number of panels could vary from 24 to 32 panels.  The efficiency of panels has improved since we wrote that article, but talking in round numbers, if you are using 110,000 kWh per year (based on your numbers), you are going to need roughly 5,500 square feet of space on your roof or mansion or factory, whatever you have, to accommodate roughly 330 solar modules. Call us up at SolarTown and we would be happy to take your order.

08-23-2011 by Amir A Category: Solar Panels

Q:We are in the process of putting a PV system on our roof. The conditions are not ideal: we do not face south, but W/SW. In this case, would panel efficiency be the single most important element in designing and configuring a PV system for the house?

A:

Congratulations on going solar and installing solar panels on your home. What you are most concerned about is how much output will you get from your solar energy system, and there are a number of factors that can affect the output of your system. The reason that a southern facing exposure from your house is optimal (assuming you are in the Northern Hemisphere) is because the solar modules on your home will catch more of the sun's rays for longer during the day when they are facing south. But there are other factors that you should consider as well, such as obstructions like a tall chimney, or a high neighbor's house, or a large tree that casts a long shadow on your solar panels. You want more direct sun to hit your solar panels to generate the highest output. And if you have some space constraints on your home, you may want to consider some of the higher efficiency solar panels to get the most output out of the space you have. You can still generate a lot of juice from your solar panels even if the roof on your home is facing as you say W/SW so long as you have a good design. Good luck with your solar project!

08-19-2011 by Patrice Category: Solar Panels

Q:Hi I'm trying to introduce solar to a small village that i do mission work for in Cameroon Africa the power source is 220-240 I'm trying to power 4 -20 watts bulbs and 1 14 inch TV for about 4 hours a day.

A:

It doesn't matter whether you are putting solar panels on your home in New Jersey or you are putting solar panels on your ger in Mongolia, or your hut in Cameroon, you need to do an energy audit to figure out how much energy you are using.  Based on your needs, it looks like you will need about 230 kWh of electricity every year for your application. You may be able to get away with one large 240 watt solar panel, or two smaller panels to meet your needs. Remember that you are looking for an off-grid application so you will need a charge controller, solar battery and off grid solar inverter.

07-24-2011 by Sue S Category: Solar Panels

Q:hello, if my house uses 20kwh how many solar panels do i need!!!!

A: 

Glad to hear that you will be installing home solar panels. If you are just starting out your journey, then you need to look at the SolarTown Learning Section, which has most of the answers on solar panels and other equipment that you will need, like solar inverters and solar racking. We assume that you mean that you use 20 kWh on a daily basis, which would put you below the average consumption for the US.  You already have a good start in that you know how much your consumer. If you peruse our Learning Section, you will find out that how many solar modules you will need to put on your roof depends on several factors, including the efficiency of the panels you have in mind and where you are located in the US.  If you are looking for a general response, you will need approximately a 4.4 kW system or roughly 20 solar modules to meet 100% of your needs, but again that could depend on where you live in the US.

07-23-2011 by Venny C Category: Solar Panels

Q:can we run a DC motor with help of PV panel? if it is possible then how? if it is not possible then why?

A:

If your motor runs on DC power, you can run the motor using solar panels. The power generated from solar panels is DC which can power DC devices, equipment and hardware (and you will not need a solar inverter). To properly size up the solar system, please evaluate the specifications of the motor to determine the appropriate sizing using solar modules. The actual configuration can be straight forward, using the cabling from the solar modules to the motor, but that may ultimately change depending upon the motor configuration. All devices that require an energy source can be powered by solar. It just comes down to determining the amount of energy a device or equipment will need and your application runtime.

07-11-2011 by kapil Category: Solar Panels

Q:hi, I have a 12 vdc motor 1800 rpm and rated 39 amps. How many and what panels do i need to run that motor for 10 hrs a day ?

A:

If your motor runs on DC power, you can run the motor using solar panels. The power generated from solar panels is DC which can directly power DC devices, equipment and hardware (without using an inverter). To properly size up the solar system, please evaluate the specifications of the motor to determine the appropriate sizing using solar modules. The actual configuration can be straight forward, using the cabling from the solar modules to the motor, but that may ultimately change depending upon the motor configuration. All devices that require an energy source can be powered by solar. It just comes down to determining the amount of energy a device or equipment will need and your application runtime.

07-11-2011 by Jesse Category: Solar Panels

Q:I have 2 arrays of solar panels, 24 panels going to one inverter, and 11 panels going into another inverter. both are tied to the grid and go through a 40 A breaker. The max power AC is about 7kW for both arrays. The first year of operation, we did not have any problems, but once each month for the last 3 months our circuit breaker has blown. We have a sunnyboy monitoring system, so we know that the blows between noon and 12:30 each time, and the message the system gives is Warning / Grid voltage fault. We have had out solar company out and they say its a grid problem, and the Power company has check and said there is not a problems with the power coming in. Any ideas? is a 40 A breaker large enough for this application? Any help would be appreciated.

A:

You may want to study the specs for your solar inverter. Standard operating procedure is to install a combiner box which collects all the array wire runs into a 'combined' wire that feeds into a disconnect, which then feeds into an inverter. Amperage is increased when panels are wired 'in parallel' and voltage is increased when panels are wired 'in series'. Both wiring methodologies commonly use a combiner box and the inverter will specify the startup voltages, and acceptable voltage and/or amperage range. Using a combiner box and a DC disconnect are essential pieces of your array.

06-22-2011 by Mark N Category: Solar Panels

Q:I currently have 2 solar arrays, each consisting of 4 180 watt panels. They each have their own inverter. Each inverter is rated for only 550 watts, and each array has never peaked over 500 watts. The question is each inverter is plugged into a outlet, but both outlets are on the same circuit. Is this a problem???

A:

Wow - scary question!

It sounds like you are back-feeding electricity straight into an outlet. This can be done, but you should not trying this without an electrician around. You can cause a lot of damage to yourself and your property if you don't have a master electrician working on this system.

Critical to this are two things: one, are the solar inverters you are using grid tie inverters? This is required - if they are not grid-tie your solar energy system won't work. Two, if they are plugged into two separate outlets on the same circuit the circuit breaker will trip if the amperage exceeds the circuit breaker (typically 15A or 20A).

Most solar inverters on smaller solar energy systems are designed to provide power for a specified load. In this instance you are trying to back-feed to the grid with an uknown inverter. It is also not known how much other load you are carrying on the circuit. You need to identify everything on the circuit so you know how much load is being accommodated by the circuit.

05-12-2011 by garrett Category: Solar Panels

Q:How to choose a suitable inverter to connect let say a 10kWp PV to the main grid? Please advise

A:

In general, when choosing an inverter you want to first check the maximum input values for the inverter that you wish to use. For example, the SMA manufactures a Sunny Boy 10000TL-US that has a maximum recommended PV power at 12,500 watt. Carefully evaluate the STC value of the home or commercial solar panels you will be using and ensure that it does not exceed the maximum threshold. Solar inverter manufacturers will have the technical benchmarks in which the solar energy system you're targeting should not exceed. Satcon is also manufacturer of larger central inverters used for home solar installation or commercial solar installation or you can choose a microinverter. 

For more information on inverters and microinverters please visit the SolarTown Learning center for an article on choosing between a central inverter and a microinverter.

Secondly but more importantly, be careful when handling large solar energy production from your solar energy system. High voltage system should be handled with care and every safety precaution should be used when working with the high current.

04-11-2011 by rflamun Category: Solar Panels