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Q:I am looking for information about the relationship between ambient temperature and the temperature acheived with solar hot water heaters. can you help me please?


With solar hot water heaters, the ultimate goal is to achieve thermal equilibrium, which means that the temperature of the water inside the tank is similar enough to the ambient temperature that minimal heat inside the tank is lost. When a solar water heater increases the temperature of the water inside the tank, it starts to lose its heat to the environment outside of the tank until it reaches the same temperature. Heat is lost through the processes of conduction, convection and thermal radiation. This effectively neutralizes your water heater because the temperature keeps lowering after it rises. This is why thermal equilibrium is necessary.

One way to achieve a thermal equilibrium of the necessary temperature, put your solar water heater in a thermally insulated box. This box has a glass top and all other walls and surfaces are insulated and optimally, reflective. This allows the sun to heat your tank through the glass top with minimal loss of heat thanks to the insulated walls and reflective surfaces. There are many options that accomplish this, but this is a relatively simple and common solution.

06-29-2015 by Nick Category: Solar Water Heaters

Q:I have a solar panel to feed my green house ventilation. At full sun the fan is not cloudy or afternoon sun it runs slowley. At full sun without fan it reads 20 V and 1 ma. ..after connecting fan it reads 0.6 V and the same 1 ma. I tested with different fans and it is the same. Please guide. Thanks, vafa


It seems like you probably need more home solar panels to power the fan you are trying to run. One solar panel might not be generating enough energy to run the fan. It largely depends on the size of the fan you are trying to run, but, generally, 24v+ is needed to properly run a greenhouse ventilation fan.

06-28-2015 by Vafa Category: Solar Panels

Q:I want to setup 3 100w (12v) panels to charge batteries (12v) to run a sump pump. The batteries and sump is in the basement and the panels will be approx 30 ft above them on the roof (3 + stories). Ideally they should be on the opposite side of the house that is another 30 ft away. So I am looking at running cable between 30 and 60ft. What size of cable is needed and will a controller handle the required size?


I figured high to be on the safe side, but with the information you gave, you may want to try an 8-gauge wire at 60 ft., which would produce a loss of 3 percent efficiency. If you are okay with taking a slightly higher efficiency loss (4 or 5 percent as opposed to 3), you can use a 9 or 10-gauge wire. Since you are running a 36v system, you would go with a 48v charge controller. When in doubt, there is no problem (other than a higher price) with using a higher volt and/or amp rated charge controller. In fact, it allows you some room to expand your system later down the road if you so choose. Regardless, yes, a charge controller will handle the cable size you will need.

06-27-2015 by bob m Category: Solar Panels

Q:I am looking for info on the TPM4 mounting hardware. What diameter pole will this fit. can it be mounted at approx. 19' above the ground. What will the angle of tilt need to be in Spokane, Washington. How quick can these ship, I will need 2 of them.


The size of the pole varies based on the square footage of the solar array. You may want to contact us or consult with a pole mounting guide that helps determine the total length and quantity above/below ground for each size. For example, if the module area is 20 square feet, the pole size  should be about 2.5" SCH40 (2-7/8" OD), the length in the ground 34"-40", the height above ground 48"-72", and the hole diameter 10"-14". The tilt for Spokane would be approx 45 degrees.

06-23-2015 by Todd B Category: Solar Panels

Q:I have a 8'x24' shipping container that I am storing a vehicle in for 3 years while I am overseas. I live in Las Vegas where it gets 120degrees in the summer and 150 inside the container. I have some turbines on the top to release the heat. I wanted to put a couple of house fans inside for move the air and run them with solar power. I have no other resource for power there. Can I use a 45w solar panel kit? What all do I need, suck as batteries, inverters and so on. I have never done this and no one will be here to check on it, so I need to know if this is possible and a way to keep it a little cooler in the day.


First things first, how many house fans and how many volts and amps do they need to run? That is the first thing in determining if a 45w solar system will be enough. 45w solar panel kits are generally in a parallel circuit and not in a series, which will give you about 29 watts to work with, which is not a lot. That probably won't power house fans. The biggest potential problem is the length of time that you will be gone. Three years is a long time, and while there are systems and parts that you can buy that require minimal to no manual upkeep, it is still a very long time to leave a system completely unattended. However, I will go into more detail regardless. It would be an off-grid system as I am sure you do not have a resource to tie the system in to. In terms of batteries, since you won't be there for three years and you won't be able to check on the batteries as well as the system itself, you might be able to run a battery-less system. In this case, your fans would run throughout the day, as long as they were getting sunlight, then at night when the sun goes down, the fans would turn off. This largely depends on how cool it gets at night and if you were okay with the lack of air circulation through the night, but a battery-less system would cut down on cost. With batteries, your system would run the fans off of solar energy throughout the day, and then off the batteries at night. However, with the length of time that you will be gone, the batteries would need to be changed, which you will not be able to do. With a battery bank, your system would run the fans off of solar energy throughout the day and store any excess energy in the battery bank for later use, like at night. This may be the most efficient way to run the system, but at an additional cost of a battery bank and a brand that you can leave for an extended period of time without needing to be checked and maintained. In terms of inverters, the system would most likely be smaller, and in Las Vegas, I would assume there is minimal to no shading over your system, which means you could go with the more affordable option of a central inverter as opposed to micro-inverters. If you were to go with one of the battery options, you would need a charge controller to ensure that your batteries do not overcharge, but in a battery-less system you would not need to worry about that. Finally, seeing as how you would be gone for 3 years, investing in a solar tracker would be very beneficial. It would allow your panels to track the sun's path automatically for maximum solar exposure throughout the days, months and years.

06-20-2015 by chris Category: RV and Marine

Q:Found your website and wondered if you can advise or point me in the right direction or even supply me some. I’m building a small PV system for my shed, nothing fancy maybe, 2 x 25w panels with a Morningstar charge controller and feeding into a basic 9 or 18 amp sealed lead acid battery to run some LED lights for the shed and a USB 5v charger. I understand the importance of using fuses but finding info on what to get is being a task From the looks of it I fast blow fuses. I would assume I need 12v fuses but they seem hard to find and info again on what I really need it hard to find. Do I need 12v fuses? Your advise would be great, I would like to have a inline fuse on every positive line I’m using just in case. Because my panels are not really going to be making more than 2 amp I would assume a 2-3 amp fuse would be all that is required.Again is that correct ? And will 10 awg wire be fine? Do I need circuit breakers on system like this, I dont really see myself using an inverter at this time. I understand you may be geared up for a more pro install than this but i want to be safe.


First of all, you are going to need an off-grid nverter for your system because all solar energy is generated in DC power, and most everything these days is run on AC power, which is what the inverter is going to do. Convert the generated DC power into AC power so it can be used. Unless your LED lights and USB charger run on DC power, you will need an inverter. If you run an off-grid system, you won't need circuit breakers because the system will not be tied into a pre-existing resource. However, if the system is tied into, say, the system for your house, then it will. A circuit breaker can be useful if you want insurance on blown fuses, mainly if you want to stick with lower rated amp and voltage parts to save money, but otherwise, you won't need them. Fuses on the other hand, are a different story. You won't need a fuse on your solar panels unless there are more than two in parallel, which it doesn't seem like there will be. However, if you want to be safe, a 3-amp fuse for your solar panel will do. You should have a fuse for your charge controller, but what size depends on the voltage of your charge controller. You definitely need a fuse between the battery and the inverter, but again, that would depend on the volts of the charge controller. A 10-gauge wire should suffice for your system needs, but you can bump it up to 8-gauge if you want to be 100 percent sure.

06-11-2015 by Ray A Category: Solar Panels

Q:i want to know that my tube well water level is 280 feet ,if i fix 15 hp so how much soalr panal should be use??


I am having trouble figuring out exactly what you are asking, however, in regards to the second part of your question, you can use the following information. One horsepower equals 746 watts. Therefore, 15 horsepower would equal about 12,000 watts, which in turn means that you would need 48 solar panels to run. That number could vary slightly as well depending on where you live and how much direct sunlight your system gets.

06-06-2015 by qazi Category: Solar Panels

Q:Hi, I was wanting to rig a van with solar panels to run a small window unit a/c, water pump, small fridge, maybe a small range, maybe a small tankless water heater and maybe a couple outlets and a light. I don't really know how many panels or batteries I need. Well I really I don't know much about any of it. Also I wanted to maybe use the van's alternators to help charge the batteries. Any suggestions?


The short answer is that you should look at some of the kits in SolarTown's catalog under RV and Marine Solar Kits, which have all of parts required in one solution. But if you wanted to put this together yourself, you are going to have to design a system that will meet your needs. We assume the vehicle in question is an RV or similar size vehicle. Panels on an RV generally operate at much higher temperatures than normal and because of this, there is a significant voltage drop. To overcome this, you can wire your solar panels (standard 36 cell solar panels) in series to double your voltage, but with vehicles, shade and other factors that reduce solar exposure are a very common concern, and even the slightest bit of shade will reduce your solar system amperage to almost nothing. Therefore, it is recommended to wire your panels together in parallel. The second possibility is to use solar panels operating at high voltages combined with a heavier gauge wire than normal. This will allow your system to overcome the voltage drop and still produce the necessary charging amperage even in the hottest conditions. In regards to using your alternator to help charge the batteries, that all depends. If by "help charge the batteries" you mean you have a primary method for charging them and your alternator is there simply to charge them quicker or something like that, then that should be fine. If your alternator is the sole charger for your batteries, then there are a couple of things to consider. If the alternator is stock, then you probably won't be able to use it to solely charge the batteries because the alternator's amperage would max out. Best case scenario, it would take a long time to charge them. Longer than what would be worth it. However, if you have an upgraded alternator (120 or 300 amps), then you may have better results. Charging dead batteries with your alternator is a bad idea, as it will shorten the life of your alternator. Charging the batteries through your solar system is the best method, however. In terms of how many panels and batteries you need, again, that would depend on your vehicle and the voltage required of the appliances you listed. It also depends on your energy use. If the vehicle in question is an RV, one thing to do would be to go out and run your RV from full to dead while going about your normal energy using routine. Generally, most people consume 75-150 amp-hours of energy per day depending on their lifestyles and frugality with energy. This would require three to five 100 watt solar panels in order to break even on a daily basis (this is based on your solar system getting 5-6 peak sun hours per day).

06-05-2015 by Jace A Category: RV and Marine

Q:Hi, I am trying to finish up a project started by another group here at our college. They ordered the Sunsaver SS-10L-12V charge controller (P/N: SPEE-2641), the PowerUP AGM-PUBP-110A (P/N: SPPU-0522), and the Lightway 240W Solar Panel (P/N: SPNT-2913). When I went to install the charge controller it seems that it will not work correctly with this solar panel. Can you please confirm/negate this assumption? If my thoughts are correct, do you have a suggestion for the correct charge controller? Thank you in advance for your help!


I don't believe the problem is with your panel, but with your battery and charge controller. The SunSaver charge controllers cannot be used with AGM batteries, as AGM batteries operate very differently than other types. Your charge controller is a PWM. With an AGM battery, you should use a MPPT charge controller. Bottom line, if your charge controller doesn't have an AGM setting on it, then you shouldn't use it.

05-29-2015 by Hunter Category: Solar Panels

Q:Please may I know how many solar panels,battries of 200AH, inverters,controllers for à three phase(3Q) 3hp submesimble water.pump pumping at depth of 110mtrs and delivery only 15mtrs high


One thing to consider is how long the pump will be running. That will factor in to how many panels you will need. Overall, 1 horsepower equals 746 watts. A 3 horsepower submersible pump would require about 2300 watts. At 250 watts per panel, you would need 10 panels to run the pump. One big factor is if this is running off grid or grid tie-in. Off-grid is far more expensive and if you need a battery back-up, it usually means that you will look at other alternatives. If your utility power is reliable (as in you don't get rolling blackouts and events of that nature often), grid tie-in is recommended. You will need at least a 6kW inverter to be able to soft-start the motor and keep it running, and it is recommended to have a backup battery just in case. The number of batteries you need depends on how long you want the pump to run. The longer it runs, the more batteries you will need. This in turn affects the type of charge controller you need as well. One other thing to consider, is this a dedicated solar pump, or a normal/older pump that you are trying to run off of solar? If it is an older pump that you are trying to convert to using solar, it is recommended that you switch to a dedicated solar pump, as it will lower costs and ease installation.

05-23-2015 by Robert Category: Solar Water Pumps


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