Tom M's posts

Paul, just looked at your new setup. Looks good and looks like you found a good solution to keep the pump primed. Only thing is, (Though I know it is just for display and demonstration), you would be using recycled water from the shower drain. Perhaps you could install a holding tank above the SHW panel and either hook up a hose to the tank inlet or just use a gravity feed. This would eliminate the need for electricity. The higher the tank the more pressure you would get. Or perhaps you can install a small filter on the return to reuse the recycled water.

Tom, one other suggestion, if you can get your hands on some old cast iron radiators, they may be better than using regular baseboard heaters. At least they will hold the heat and radiate longer. A radiant heat zone in an insulated slab is good too, though I am sure your garage already has a finished concrete floor.

Tom, if you are looking for an easy and cheap way out, use a closed loop with antifreeze. Then you can either use a differential controller to turn the pump on whenever the panels are hotter than the garage. Or just use a manual switch wired to the pump and turn it on manually whenever sun is available. You can incorporate a 110 volt thermostat too if you want to....

James, why not incorporate your wood stove to produce hot water. Use solar during the day and the stove at night. Solar hot water panels will still produce in the winter. You just don't get as much sun hours due to the shorter days as you mention. 

Tom, where are you located? If you are in a cold climate a closed loop system utilizing antifreeze is the norm. A heat exchanger tank should be included, if this is the case, for hot water storage. Locate the panels in whatever spot gets the most sun each day and throughout the year. Most times the roof is not the best spot. Standard circulators for heating are usually the norm for these closed loop systems.

Paul, the only problem I see with the display is the location of the pump. You may have to lower it to a location that is below the water level of the tank you propose to use. (I assume it is to be on the ground under the apparatus). Since it is an open system, it may not be able to prime itself from that height.

Soloman, don't forget, Tesla went through the same thing. His work wasn't recognized until he was dead.

David, still not to clear. You say you have three inverters. One services a dedicated common area with it's own dedicated PV panels and it's own dedicated meter. That's clear.
 It's the second system that seems wacked.
 You have two inverters serving one meter. One PV array is dedicated to the two inverters. You have two separate AC disconnects after each inverter. You have two separate DC disconnects.
 This is the part I don't get. One shut off for two inverters that connects to one meter. How can this be? Sounds like the inverters are competing with each other for power somehow by being connected through this shut off.
  Hard to really say without a schematic of what the installer did. What type or brand inverters are you using?

James, you can just add a cheap relay in conjunction with the AC diff. controllers you sell. Basically use the AC output to the pump as the switching power for the relay that the 12 Volt load is attached to, or attach it to a transformer. (120V AC - 12 V DC). Though you have to plug the controller into an AC socket first.

Paul, what is the display anyway? Is it a model of a system for heating hot water? Or is it some type of fountain or something of that sort?

Jerry, I would recommend flat plates. If you ever add to the system, it's a lot easy to match and connect flat plates. Evacuated tube designs are still changing to rapidly.
 Is the front of the house and the roof the only location you have to install the panels? Where is the hot tub and other utilities located? How much piping will be needed? Is snow a problem where you are located? Is there room for expansion? Can you add a second, cheaper hot water system dedicated to the tub? How many panels are you planning on using for both the tub and domestic hot water?.....
 Just some other questions for you to think about when installing a SHW system.

Paul, the best way is to add a battery. Wire the PV and battery to the controller to properly charge the battery from the PV panel. Then wire the pump to the load output on the controller for a consistent 12 Volt output. Adding a battery with enough power storage for 2-3 days with no sun is usually the norm.
 

You have to check with your town officials in NH to get the ball rolling on rebates on solar installation. Some towns may grant you something. Live free or die. Installing solar allows you to live more free I guess, so it's all just part of living in NH, nothing to get paid for. 

David, why or how are the two inverters tied together?

Jerry, the only way I recommend using solar for heating a hot tub is to draw the water from the drain of the tub and return it back into the tub using a hose. This way here you do not mess with the manufacturers plumbing that could void warranties. You can pump the water directly from the drain into SHW panels or into a heat exchanger as you mentioned. If you want to incorporate it with solar for domestic hot water,you will need a double heat exchanger tank.

Gordon, way to go! In my opinion all PV should be installed as a means to reduce your dependant load on the grid and to grow until you no longer need them. Soon the electric barons will be the same as today's oil barons!
 But do consider using batteries for storage and supply to your inverter. Sacrifice a couple hundred Watts for now and purchase some batteries. Also use a charge controller. You can use small, cheaper ones in parallel or make an investment for the future with a larger one. Diversion loads can be made or purchased when using the larger controllers.
 One other thing, panels should be installed in the location that gets the most sun over the entire day and year. Sometimes the roof is not always the best spot, for this and other reasons.
 Good luck and I'm sure the folks here will help you in getting just what you need.

Jerry, most SHW panels are basically the same. Copper on copper or copper on aluminum in an insulated aluminum box. Check out the selection here. Try to buy local to keep our economy going. The rest of the system is just plumbing. Looks like you are thinking of installing on a roof. Last resort in my opinion. Keep it simple and keep it cheap for minimal maintenence and faster payback......Glad to see you reconsidered buying evacuated tubes. As you said more money, hard to replace old models and can't be repaired easily.

Allen, you could try using newer, less power drawing pumps and reduce your power demand. You can get common circulators that run at 1/32 HP or around 20-25 Watts at 110 Volts. Though you may have to purchase a small inverter to run off your 24 volt system. This would be almost the same cost as adding more PV.

Jerry, make sure you take the height of the panels with respect to the tank into consideration if you plan on using an El Cid pump. I believe it is rated for a head of only 3 ft. (Great for a radiant heat zone at the same level as the tank.) Here in the NE area, pumps such as a Grundfos or Taco are used in closed loop systems...

Travis, check out the charge controllers here. Something like the C-40. It has a built in diversion load control.

William, I think it would be tough to install hydro on your roof, but along that route, have you thought of solar hot water?

Paul, there are calclators out there but they are a little more complex than laying out tile which is why people tend to charge for this type of service. You are dealing with multiple dimensions as well as earth and sun angles that change daily. Trackers use algorithms base on these inputs to track the sun throughout the year. For your project you may just have to simply figure out the sun angles at your location, usually 15 degrees +\- from your latitude, and using the height of your panels, along with a little geometry, you should easily be able to tell where a maximum and minimum shadow is going to extend during the year with regards to your panel angle.
CAD will make it easier since it would calculate all the spacing and angles for you.

Chriss, sound like your confusing yourself a little. The measured numbers for the panel look good. So the panels should be good. Your numbers for load, current and power seem to be accurate mathematically. I just think you don't believe the numbers, since they are so small and your expectations are higher. Don't forget that voltage from the panels will change according to exposure conditions. The controller should compensate for this change so try taking your measurements after the controller and see what you get. Still won't be much, but something is better than nothing.

Ryan, same deal as with the pump. You should be able to find any type of insulation you need at any plumbing supply or major hardware chain. I usually double up on exterior insulation. I use the black foam insulation along with the white fiberglass insulation designed for steam systems over the smaller black insulation. That way there you can buy the tape that goes with it to seal against the weather and it will fit better in roof collars if you are installing it on a roof.

Ryan, any type circulator for hot water heating systems should work just fine. Use a Taco or Grunfos that should be available at any plumbing supply or major hardware chain.

Your welcome Carli, I know JD is always looking for other opportunities to expand the project so who knows what the contact may do for you and yours. Good luck and I am glad I could help.

Carli, I was involved with helping to establish a similar program at UMass Lowell. The program, Peruml, now Village Empowerment, deals mainly with medical clinics and health issues in rural villages in the Andes of Peru. You can contact John Duffy, in the mechanical engineering dept., for some information that may be helpful in your endeavor. He may have some contacts for you in regards to getting donations for such projects along with system designs. You should be able to do an internet search and find him easily. 

gj, have you consider a solar shower? If you can get your hands on some black poly pipe that is used for water service from your local plumbing supplier, you can put a roll or two in a sunny spot and hook that up to your shower or go with solar hot water panels with glycol and a heat exchanger tank if you plan on using it year round. You could then use the proposed pump along with a small PV setup for circulation and auxilary 12 V DC lighting.

Tom T., just a quick question with regards to the inverter that keeps shutting down. Does the cooling fan come on?

Paul, if you locate the pump 400m or so upstream, why would you run the wire all the way downstream? I would think that you would try to locate the PV panels as near the pump as possible to reduce power loss. Also you should check pipe flow resistance, over the length of the delivery pipe (450m), to make sure you will have enough pressure at the end of the line, to lift the water to the tanks above your house.