**This webinar had technical difficulties in the first several minutes. The webinar does begin shortly so please be patient or scroll forward to an appropriate time frame in the recording. Thank you.
SUNMAXX SOLAR HOT WATER SOLUTIONS
Working with T*SOL Pro 4.5
Presented by: Sam Portnoff
Date: 01/10/2011
Everything should be up and running. So, my name is Sam Portnoff, I’m an engineer here at SunMaxx Solar, and today we’re going to talk about working with T*SOL Pro 4.5. T*SOL is a solar thermal simulating software that we use. So, I’m just going to go and take you through that. We do have a couple of things I want to talk about today so let’s begin.
Start off with, here we go, so what is T*SOL? T*SOL simulates solar thermal system production. It allows for a variety of collectors in storage tanks to be used, and multiple system variables to be adjusted. Basically what this is, is a simulating tool that the engineers use at SunMaxx to figure out what solar system we should use and size up for you. We can substitute in different collectors, we can flat plates, we can have our VHPs and see how many collectors will produce the best solar fraction and system efficiency for you, as well as changing tank sizes, flow rates, piping runs, and a variety of other variables. Actually, this allows us to figure out which system is best suited to your individual needs. What makes T*SOL unique is that it works from calculating the demand and then works backwards to figure out system efficiency and solar fraction. So what that means is that rather than saying “how much energy is the sun producing, therefore what are my collectors producing”, we are working from demand rather than the efficiency. Hold on one second… is everyone able to see the PowerPoint presentation I put together? Is that available? No, huh, hold on one second.
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Okay, I think we should be back on track, so let me get back to the PowerPoint presentation. So today we’re going to be talking about T*SOL 4.5. And so one of the questions I saw is why do we choose to use T*SOL? And this is based off its demand, it’s ability to work from the load demand to calculate solar fraction and efficiency rather than based off solar input. So the system says how much energy is being used, how much hot water is used at a certain time, and when is that hot water used, and then if figures out based off of those figures how can it use the solar thermal energy. This is different from a program like RETScreen, which works based off of calculating solar energy produced by the sun and then directly putting that onto the system, so there’s a little bit of a nuance there. This works from demand versus from production. Having the system sized based on demand gives you a more accurate result. So RETScreen is still good, still useful, you just need to know its limitation. T*SOL also has its own limitations. One of the limitations is that it only simulates predetermined solar thermal systems. The difference here is that rather than allow you to custom our systems, T*SOL has built in about 50 or so prepackaged, predetermined system layouts, which they think are optimal systems. And they do work about 9 out of 10 systems, any sort of domestic hot water, any sort of space heating system, any sort of large domestic hot water scale system, or even pool heating system, T*SOL will work really well for. However, if you are starting to do more unique situations, say for instance you have a factory and you need to used a certain amount of hot water for a certain application then things… All right, let’s see if people see my PowerPoint now, is everybody able to see this?
[Technical difficulties break]
I think I have a PowerPoint that should be shared now can people see this is this working? So as I mentioned we’re looking at T*SOL and for today’s topics were going to look at a couple different things in T*SOL. We’re going to look at simple domestic hot water systems, how to read T*SOL reports and basic Combi Systems with pools and commercial systems in terms of pre-heating domestic hot water.
So let’s keep going. So simple domestic hot water systems I’m going to show an example here in a little bit. Let’s imagine you have a customer in New York and he owns a house inhabited by five people and they’re looking to offset their solar thermal cost. They have a pre-existing fifty gallon domestic hot water tank. So the question is how do we figure out what sort of system this size for them? What do we want to offer? And so we would jump over to T*SOL. Let me share that with you.
Can everybody see T*SOL is this working for people? So we should have T*SOL up and running. So he we have a system. We have five people in a house they have a fifty gallon pre-existing hot water tank and they’re looking to do some sort of solar thermal system. So I’m going to open up. We create a new project and in this case I’ll open because I had one created for this webinar.
So we do a solar domestic hot water system. This is based off of our store max using our store max sec tanks in our empire kits. Right now the empire kits are being offered in New York. They are set up to get the maximum amount of credit possible the New York state rebate offers $1.50 for every kilowatt hour of solar energy produced. So we’re a going to set up a T*SOL model based of that. This system here you can choose in T*SOL you have a system selection tool bar. We are going to look at what T*SOL systems we have available.
For domestic hot water often times we’re going to use the system A2 which is our domestic hot water system with two tanks. So this assumes that the first tank over on the right is the pre-existing tank this is the one that your customer or client will already have in their house. The second tank is the new solar tank in this case its’ the store max SE tank that we’re going to be using. So we’ll select that and this is the layout we have. Once we get into the layout we can begin to modify things.
So first we begin by modifying the hot water. You would just double click on the faucet and we change its regular hot water usage. The general rule of thumb is twenty gallons per person per day. So our average daily consumption for a house with five people in it is 100 gallons. So that’s what we’ll set up. We’re going to have for profile we’ll say it’s a house with max water usage in the evening. If people are mornings we can change it to mornings max. Select the right profile is helpful. So we’ll go here we’ve selected what our lobe looks like. This is our pre-existing 50 gallon tank. T*SOL has a lot of generalizations when they put tanks in and we can use their standard tank to do an estimate and approximation.
So then we’ll change for the solar tank we’ll have our SolarMaxx SE tank. So there are three sizes of the empire kits. They are fifty gallon, eighty gallon and one hundred and nineteen gallon. We’re going to start off by Titan Power plus Su2. We can change the collector that we want to use if we want to sub in. So we click on select and we can sub in a Titan Power VHP20 if we wanted. That’s another version of the kit. So we can have that. For our purposes we’ll go with the Titan Power plus SU2 and run it.
One other thing you want to change is setting up your flow rate. So we have our collector loop and typically we do a gallon per minute per square meter of collector surface area. So for flat plates the flow rate for a Titan Power plus SU2 is .44 gallons per minute. The collector is approximately 2 square meters so in here we’d enter in .22 as our volume metric flow rate.
Let’s begin by simulating this to see what we can get. We click this button here which is the simulation button and if you click here you can view how the temperatures change over time. You can have it set to thirty minutes so you see every thirty minutes what’s happening. Sixty minutes goes even faster. Or you can just turn off the view and let the system just calculate data by itself. After you finish calculating it you’ll do a project report.
This will show you what sort of production you have. So as you can see there are a couple things to notice. First on the first page importance is the results of annual simulation. So this shows off how much annually power is going to be produced by your solar thermal system. It starts by calculating the surface area of the collectors and how much solar energy is going to hit that area. Then based off of certain losses it will calculate how much energy is going to be produced by the collector. So you see that we have 8.72 million Btu’s produced per year. But the total energy or energy put on the system the total energy produced is going to be about 4.55 million Btu’s per year. This is used then to calculate your system efficiency. So high system efficiency is based off of being able to convert all the radiation on the specific area to energy in your collector loop.
You can also look at the domestic hot water solar fraction which is 20% which is pretty low. Typically for domestic hot water you want to be between 50-70% of a solar fraction. We figure out that our solar contribution to domestic hot water is 4.82 million Btu’s per year. In New York State right now the incentive is $1.50 dollars per kilowatt hour for the system production over the course of the year. So we can convert 4.92 Btu’s and it converted that into our kilowatt hours and figuring out the rebate for this system would be about $2,000. But we want to improve our solar fraction.
So we’re going to increase the size of our system. So we’ll change this to an 80 gallon SolarMaxx SE tank and change this to two collectors. Let’s take a look at this production. So we’ll simulate the system again. We’ll look at our project report. You’ll notice that there’s a pretty big jump. We moved from about 20% solar fraction to 40% solar fraction. We’re still seeing 50% system efficiency so an efficient system. The solar contribution to domestic hot water is 9.18. So quickly jumping over here 9.18 converts to $4,000 worth of rebate which is the maximum rebate that you’re able to apply for in New York State for the empire kit.
For this family using an empire kit eighty gallon system on top of their pre-existing fifty gallon tank would give them a 40% solar fraction and 50% system efficiency and $4,000 back from the state automatically on top of the 30% federal credit and 25% state credit. So there’s a lot of money that people could get back for a system like this. We’re quickly able to simulate that. So the first page of your results are always very important. The top graph up here looks at the total solar contribution compared to the total energy consumption. Your goal is for this yellow line basically to be below your orange line because if you’re having more solar production then consumption you enter into periods of stagnation. Which are to be avoided when designing solar thermal systems.
Another important to look at is your daily maximum collector temperature. Which your goal is to keep that below 200 degrees. This is what the maximum temperature your collectors are going to reach. If you keep it below 200 degrees you don’t have to worry about your heat transfer fluid vaporizing. So this is really good for your solar system overall. As you can see here we’re looking at max temperature of maybe 151.60 so this is good.
Page four of our report is something people have often times are confused about. So I just want to take a little bit of time to explain this. This is an energy balance schematic. It works based off of energy input and energy output. We’ll start at the top up here number one is the collector surface area. This is the amount of radiation solar installation that is going to affect or going to land upon or solar collectors. So the amount is listed below 17.5 or 17,500.7 killi Btu’s per year. Then we have losses in our collectors. So optical losses which is 1.1 and thermal losses which is 1.2. You see this is a certain amount of percentage of your initial energy is lost to these things. The difference is the energy produced by the collector array. So that then flows into your piping and your piping has some of its own losses. It’s internal and external pipe losses. That energy is transferred from your piping into your solar hot water tank.
Then you look at what the losses are in those tanks individually so 4.1 and 3.1 are losses from having hot water sit in those tanks. Six is the energy you use. So propane or natural gas that’s burned is used by your heater to heat up water. So that energy is transferred over in 6.1 and then nine looks at the total amount of hot water that you’re using in your system. So the energy that you need overall is number nine and the way energy for number nine supplies through six and one.
It’s a fairly helpful way of looking at your solar system in terms of thinking through where can you improve and make your system more efficient overall. But sometimes when using this with customers’ people can get confused about what’s happening. So I wanted to take a minute to go over that.
I realize that it’s already 12:30 and there’s a lot more that I was hoping to cover. Sorry for the technical issues. I want to talk about one other thing real quick. I want to look at Combi systems so I’ll open up my Combi systems webinar. If we look at our initial systems A2 is the system that we’d choose for domestic hot water primarily. A5 is the system that I would choose for doing a space heating and domestic hot water system so our Combi systems. That’s what I’ve selected here. This is actually a model of our C-tech tank. Our C-tech storage tank is 211 gallons and it has a coil for our solar loop. The domestic hot water actually doesn’t stay in this tank itself it passes through this upper coil and heats up and then comes off the top. So we have our solar power in the tank as well you have a gas or wood boiler directly connected into your tank as well.
You’d set your load at whatever you have it. So you set your load for your hot water the normal way you do it. But you change things for space heating. Typically for space heating there’s two things to look at. First is the heating energy requirement which you see on the left is just a little house button.
So I’m getting a question about the C-tech tank if it’s ASME-certified. The C-tech tank design is really interesting ASME ratings state if your tank is over 130 gallons or 120 gallons. Then a domestic hot water must be certified through the American Society for Mechanical Engineers. The C-tech tank has an interesting way of getting around this. So there’s 211 gallons of water storage inside the tank. However the water inside of the tank isn’t powerable water. The only water stored inside the tank is the water that’s in this internal coil here.
What’s actually really nice about this system is that we have our solar loop collector here and then our domestic hot water loop over here. So this fits the profile for a double walled heat exchanger because we have one wall here and then another wall here. So that’s separates the solar fluid from domestic hot water. So this is a really efficient design and a very compact design as well. So you only need one tank to do both space heating and hot water. We choose our heating energy requirements often times we will look at the square footage for the house. So if we had a 2,000 square foot house or a 2,500 square foot house we’d just enter in the size house. The other requirement to enter is its standard kind of heat loss per hour so the building. The general rule of thumb this is kind of a rough estimation is that you typically lose 10 to 40 btus per hour per square foot. Ten Btu’s per hour per square foot is very well insulated house. Forty Btu’s per hour is a very poorly insulated house. So I’ll play with these figures so for I said 50 you give me 20 Btu’s per hour per square foot. So this is a medium level installation for the house and then we have two sorts of heating systems.
We have high temp heating and low temp heating. Low temp heating is typically what you would use for radiant floor. So you could enter in the design supply and return temps. High temps are usually used for a forced air or radiant baseboards. Often times you’ll have radiant floor on the bottom on the first floor and then either forced air or something else on the second floor. So you have a split. High temp is used 35% of the time and low temp is used 60% of the time mainly because the temperature from the bottom from the first floor rises up to the second floor. So we’ll set up our system. For C-tech system we would have six flat plates. This is the helium max Combi FP120 I think. That number is based off the active collector surface area so 120. With that we’ll run a simulation and see what sort of results we get.
So this is for a 2,500 square foot house we have 120 feet of collectors surface area. We see we have a fairly low collector surface area. So 17% solar fraction and 37% system efficiency. So it’s doing some work you know but it’s not a great amount of production. So we’re going to make some changes to the design. We know we need more collectors and if we’re going to have more collectors for a space heating system. We’re going to need a larger storage tank.
One of the great features on T*SOL is it allows you to create multiple variance. So I’m going to go here to file and create new variant. So what I’m doing here is I’m using all that information I’ve inputted into this initial system and I’m going to select a system with new hydraulics using the current values. I will actually use the same system again but you can change a system if you so choose. We’re going to change so we have our tank is going to become a SunMaxx NP tank. These are our large non-pressurized tanks. So we’ll use a 328 gallon tank. The major change we need to make here is it’s height versus its diameter. So our C-tech tanks are great for stratification. Our NP tanks work well but they aren’t as good. So this number here 1.6. I’m going to change that and we can also then up the number of collectors. So with this those changes we have everything else as it was before.
Now we’ll run the simulation to see how this system using an NP tank functions comparatively to our C-tech tank. You see here we have a little bit higher solar fraction we’re taking care of a lot more of the domestic hot water. Our maximum collector temperatures are a little bit down from what they were earlier.
We’re going to try one other thing here let’s add a new variance again. Accept this time rather then having adjusted the heating of your living space. We’re also going to have a pool. Having the pool with space heating is great way of setting up a solar thermal system.
I think it should be back online again. Hopefully we won’t have any other internet connectivity issues. So we’re going to change this to a SunMaxx NP 328 gallons 1.6 height and diameter. Change this to 35%. So we have our system setup the same as it was before. Change our collectors so we had eight collectors before. We can increase the number of collectors we have, if we have a heat dump like a pool. Here we have our system but now we’re going to add a pool into it. T*SOL struggles to calculate pools well. So you have to take its system sizing with a grain of salt. Often times I like to work with T*SOL pools if I have a base heating system to supplement it. But if I’m just doing a pool by itself T*SOL doesn’t simulate pools as well as I would like it too.
So we’re going to have our swimming pool season be mid May to September 1st. The ground temperature in February in Elmira is a lot colder so it’s 35. But in August it will get up to 55. A really important number here is the daily fresh water requirement. This can be guessed from the number of swimmers per day. So if I said five swimmers it would re-calculate how many gallons of fresh water I needed. So it changes things accordingly. This a good rule of thumb if you don’t have a good sense of how much fresh water they’re putting into their pool. But if you have an actual number that you have from your client you can enter that number right here. For the pool we’ll enter its length 25X15X5. Our desired pool temp of 72 and max pool temp of 85. You can enter in any sheltering and you can have how much wind impression it has and the color of the ground. So a darker pool tile will absorb more solar energy. You can say if it has a pool cover or not.
Hot tub requests are pretty interesting when compared to pools. You can try to size them up in T*SOL by setting your pool size to a specific kind of length, width and depth. Then changing your desired temperatures accordingly. However what I found to be a more effective way of sizing systems you can use T*SOL to produce some kind of report for them. My general rule of thumb though is to look at what sort of energy requirements they want or they use for their hot tub. So if you can get a statement kind of looking at either how much water and energy goes into it and then kind of calculating backwards. So I could kind of adjust it by saying “I know a hot tub should be about 110 degrees.” And then work backwards to determine how many Btu’s I need to heat up that hot tub to get to that desired temperature. Then with those Btu’s in hand figure out what sort of solar system I need. I’ve definitely seen people size up hot tubs. I actually talked with one customer who recently did a hot tub. Who was saying that it heated his hot tub so well that he actually got a second one. So they have two hot tubs and the use them as efficient and productive.
So you go through the process of setting these things up and when you have it all good to go. Our speed .23. We’ll run our simulation again. Look through the simulation process. You can see with ten collectors we have a 71% solar fraction per hot water and a 44% solar fraction for our overall. Our system average pool temperature is 71.4 which is really good. Our system efficiency is at 41%. So overall this is really good. You can see here that there’s some spikes on our energy consumption that are above the amount for…Our solar contribution sometimes exceeds our energy contribution. This is okay during the summertime only because we have a pool where we can dump that excess energy to. If we didn’t have that pool we would have some issues. We can see that here the majority of the time our collectors are below 200 degrees. We have a couple of months after the pool season is over before space heating this really needed that our collectors spike to above 240. This is all right and this isn’t the end of the world because it’s a periodic thing so not all the time. However if we wanted to prevent against that we could either add more storage or take away one of the collectors or change the angle at which our collectors are tilted. So all those are good options.
If everybody has time I have one more thing I’d like to show off. Which is how we calculate our commercial systems. Commercial systems the best one to choose from in T*SOL. So go to T*SOL and choose their large scale systems. C3 is the top system which we have selected here. This way works based off of a large buffer tank that pre-heats water going into the pre-existing domestic hot water tank. So we have our collector loop which heats up and transfers energy to our buffer tank and then as new water is requested into this domestic hot water tank. It will go through here and get heated up through this buffer tank and then go into the pre-existing hot water tank.
So I have this set-up for a school system. So if we look at our load we can see. We can see what the energy consumption looks like at a given time. We see that throughout the week it’s consistent and over the weekends energy uses change. Energy is high during the regular week and low during the weekends. Over the course of the year it’s high during the regular school year and drops during holidays. So we’re going to use a 1,000 gallon NP storage tank. We’re going to use 40 collectors. So if we were to estimate 3,000 gallons of hot water per day 3,200. The best way to figure out what sort of ball park collectors you should size for would be to divide the number of gallons by 2 and then divide that number by 20. So the basic rule of thumb is that 2 gallons of hot water can be produced by one square foot of collector surface area. Our Titan Power plus is approximately 20 square feet. So 3,250 divided by 2 divided by 20 is equal to 81. So we aren’t going to want to put 81 collectors on a school which has low loads during the summertime.
One of the really important things to note when doing a commercial system is that sizing is based off of system efficiency rather than solar fraction. A pet peeve of mine is when folks who have commercial applications come to us asking for a high solar fraction because the reality is when you have such a large demand. You need a ridiculously large solar system. That becomes economically not feasible. So what you want is the most efficient solar system. The most bang for your buck. So rather then doing 80 collectors we’ll try 40 collectors as a starting point. What we get is about a 25-27% solar fraction with a system efficiency of above 50%. This is the goal you want to have a system efficiency above 50% when doing commercial systems. That’s the thing you want to size on. You’ll see here we have a high load we don’t need all that load but we’re doing it pretty efficiently.
The other thing you can note is we have a 140-150 degree max temperature year round. So our collectors are working well the system functions very well. It doesn’t have the high solar fraction of a small domestic hot water system for a home but it works and it does the job and it’s cost effective. Those are all important things when selling a commercial job.
So I know we kind of got off track and had to get rushed through some technical issues. But I want to open it up to any questions you might have about T*SOL or how we use T*SOL here.
