Pump and Pipe Sizing for a Solar Water or Space Heating System. Search The Renewable Energy site for Do-It-Yourselfers Overview of Sizing the Plumbing and Pump for Solar Collectors The basic underlying requirement is that you want a pump and plumbing system that will push enough heat transfer fluid (typically water) through your solar collectors to efficiently remove the heat that the sun is depositing in them. Too little flow, and the collectors will run hotter and less efficiently, too much flow and you are wasting money on bigger pipes and pumps than the system needs, and using more pump power than you need to. The steps involved in the pump and plumbing sizing: Calculate the flow that the collectors need Measure the vertical distance between the top of the collector and the tank water level Calculate the pressure drop and flow velocity for the plumbing system.
The Example I will use my Solar Shed project as an example. In a nutshell, it has 6 collectors of 40 sqft each. Step 1: Calculate the Flow to the Collectors Pipe Pressure Losses.
Home Depot. The $1000 Solar Water Heating System. Search The Renewable Energy site for Do-It-Yourselfers Directory -- for the system overview provided on this page: This page gives an overview of the $1K Solar Water Heating System. Important: This page is just a quick overview of the system, but there are 20+ pages covering the design, construction, testing, cost, and performance of the system in great detail -- see this ROAD MAP for all of the gory details. Objectives for the System The objectives for this project are to design and build a domestic solar water heating system that: Costs less than $1000 using all new high quality parts and materials. This is a fairly formidable set of goals given that commercial systems for cold climates often cost 5 to 8 times the $1000 target.
To accomplish the goals, the design uses these somewhat unique features: Two collector designs are covered -- either one can be used -- both are easy to build: The first collector design uses low cost PEX tubing instead of copper to pick up heat from aluminum fins. 24' X 8' Solar Panel. After lots of success with my solar water, air and electric projects, it was time to get serious and build big! The first step was to choose a site that had lots of sun, but was out of the way of our other activities and had the best overall appearance. I spent months just walking around the house, imagining different locations and designs in my mind. After lots of consideration, I opted to build a ground mounted panel in the back yard by the tree line (all construction details below).
The advantages are that it is completely out of the way, neighborhood friendly and being ground mounted, very easy to construct. Really, the only disadvantage was the day it took to dig the 100 foot trench (by hand with shovel) out to the panel. So far, I'm really pleased with my placement decision and everything about this project, which turned out to be a huge amount of fun to build and an activity that the whole family enjoyed! Tilt: The next question was to decide how much tilt to give the collector: DIY Thermal Differential Controller (Solar Hot Water Pump Controller) | EcoRenovator.org. Photo: BotheredByBees I’ve been looking into solar hot water systems for home heating and domestic hot water purposes for a while now.
I simply love the idea that I could have free, clean heat and hot water. I’m also a big fan of Gary’s work over on BuildItSolar.com. Reading his site, I noticed that many people are interested in his $1000 solar hot water system. Its a great experimental setup. However, the cost of the thermal differential controller eats up a lot of that budget. So, what the heck is a thermal differential controller anyway? It sounds pretty simple doesn’t it? So, I’ve decided to develop my own thermal differential controller. For more info on the controller, visit the forum thread here. Homemade Absorber Plate. Determining Solar Water Heating Collector Flow Rate. Search The Renewable Energy site for Do-It-Yourselfers Skip to the bottom line... Background The main thing you want is a flow rate that efficiently removes the heat that the sun is depositing in the collector. Basically, flow rates that are too low will not remove the heat efficiently from the collector, and the efficiency of the system will be low.
The heat into the collector is the Solar Intensity times the efficiency of the collector. QsolarIn = SolarIntensity * Eficiency = (300 BTU/hr-sf) * (0.5) = 150 BTU/hr per sqft of collector. So, for typical full sun conditions, 150 BTU of energy need to be removed from the collector for each sqft of collector. The heat that the fluid flowing through the collector will remove is: Qout = Trise * FlowRate * SpecificHeat Where Trise is the temperature rise in the fluid as it passthrough the collector.
What is the effect of change the flow rate? If the flow rate is quite low, then Trise must be high in order to remove the solar heat. Best Flow Rate Gary. Solar energy projects for Do It Yourselfers to save money and reduce pollution. Construction of Copper/Aluminum Hybrid Collector. Search The Renewable Energy site for Do-It-Yourselfers This is nothing fancy, and is easy to build with ordinary tools and skills, and it looks pretty good (at least to me :). Most people will find all the materials are available locally.
Building the Copper Pipe Grid The size of the absorber is 46 inches wide by 94 inches high. This size basically comes from working backwards from what two sheets of SunTuf polycarbonate glazing will cover and adjusting fro the width of the frame. Within reason, you can make the collector any size you like -- that's one of the advantages of building it yourself. Cut a sheet of half inch plywood to the size of the absorber. Cut the risers to length: Click on the pictures for full size versions. After cutting, clean up any burs left inside the tube -- the tubing cutter leaves a ridge inside the tube all the way around that must be cleaned out with the blade that is included on the back of most cutters. Work out the riser spacing: Solder the grid together: Glazing.