Ask an Expert

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 want to buy your mosaic tabletop solar lamp for my third-floor apartment balcony. I have a small patio set where I sometimes sit to eat at night and would like a little lamp on the table to provide some lighting. Balcony receives lots of sunlight in the afternoon, but it is not direct light. I dont know how direct the light has to be for the lamp to work. Any advice appreciated. Thanks.

A:

Solar powered lights need sunlight to store in their batteries. The more direct sunlight during the day, the more your solar lights will shine at night. It sounds like your balcony gets enough sun during the day so that you should have enough energy to brighten your table. Most people use the solar table lights you are talking about for ambience, and we sell them also to restaurants who want to replace their messy candles. Let us know if we can help you.

08-01-2011 by Deyanira Category: Solar Lights and Garden

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:We have a remote cabin. We are looking into a solar electric freezer or fridge and freezer and a few lights. We would need roof mounted panels (too forested for ground mount). The roof peak runs N/S so we would need a rack that will work with that. We were wondering if we should get an AC fridge and inverter, or if it would be cheaper to use a DC fridge and a few DC lights. Also wondering about having just a small freezer and swapping out freezer packs into a non powered cooler to be used as our fridge? Comments on that? Can you recommend what of your products we would need (panel, rack, wiring, charge controller, freezer, lights, etc)?

A:

SunDanzer Solar Refrigerators or Solar Freezers are what you are looking for, although Kelly, it depends on how much storage space you will need. SunDanzer make a  1.8 , 5.8 and a 8.0 cubic feet refrigerator or freezer. The easiest and most straightforward refrigerator will be the SunDanzer DDR165 Solar Refrigerator which operates as a direct drive solar refrigerator where all you need is the DDR165 refrigerator and a solar module. For backup storage on the DDR165 you can purchase the SunDanzer Thermal Packs where you can purchase one or more depending upon the amount of reserve backup you will need. The DDR165 is great for cabins on vacation time because you do not need to maintain battery banks and other equipment. You simply install the solar panel and it will be fully functional whenever you arrive in the cabin (just make sure you do not leave food in the refrigerator whenever you go away for an extended period of time).

The Solar Refrigerators or Solar Freezers that operate using a batter bank is also suitable and can also provide additional energy to power lights. The SunDanzer Solar Refrigerator or Solar Freezer Packages will have a solar battery that provides backup energy for the refrigerator but can be used to power a light if you install a discount solar inverter to run AC lights or you can install a DC light. Just keep in mind that as you draw from the battery the number of reserve backup days for the refrigerator or freezer will dwindle down. Feel free to contact SolarTown for additional support.

07-18-2011 by Kelly Category: Solar Outdoors

Q:Have a Sundanzer 8 cu ft freezer with a solar panel in at a fishing camp just purchases. What type of battery and controler or inverter do I need? Also have propane fridgeration and wondering about solar fridges, but don't see too many out there that have decent size. Any thoughts or should I just stay with propane. It is up in northern Saskatchewan and have plenty of light.

A:

The SunDanzer DCF225 8 cu ft freezer can be properly configured with different setups depending on the conditions you intend to use your solar freezer. The solar fridges and freezers that we sell are very popular for remote locations.  We sell them both as a stand alone unit or as a system including the solar panels.

If you can provide additional information on where the SunDanzer DCF225 will be used such as location, area temperature or the material stored you can optimize the equipment you will need to power the solar freezer. For example, in a default test environment where the ambient temperature is 86F you will require about of 350w-380w of power from your solar panels. With that power range required, it is probably best to have an 24v solar battery bank @ 243 Ah to enough power to power the solar freezer with about 4 day backup energy. You can however size the system for a 12v solar battery bank but the solar modules will then require 12v modules or a MPPT solar charge controller.

Heading the 12v route may possibly lead to a higher budget or overrun so that I will leave up to you. The best part about sizing the system for 24v is that you limit the additional equipment you will need unless you already have that equipment which is then moot. You do have the flexibility in also adjusting the amount of backup power for any solar system. Good luck with your solar project and feel free to contact SolarTown for additional support with your SunDanzer Solar Freezer.

07-13-2011 by Troy C Category: Solar Outdoors

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 have a solar Lamp. I replace battery cleaned it up but a new battery but it is working. There is a button above battery should that be pressed in or out

A:

Can you tell us what solar lights you are using? Without knowing what type of solar powered lights you are using, I'm not sure what the button on the battery would do. Some batteries will have a refresh option which you should press every month or so for maintenance purposes to refresh the memory bank on the battery. Let us know what solar lamp you are using or what the battery is. You can contact our customer service or send a message back and we will see if we can help you.

06-12-2011 by Jim Category: Solar Lights and Garden