solar hot water how big a system

Looking for info on how big a solar unit to put in the home. We are two people with two bathrooms and guests maybe 4-5 times a year.
I feel we need a 12 tube system and the wife says 10 tubes is plenty. Tank sizes are 120 liters for 10 tubes and 128 liters for 12 tubes. The tubes hold 3 liters each approx. so the 12 tube would be approx. 17 liters more. Male logic says get 12 tubes for insurance as cost isn't that much more. The wife says 10 tube system is enough, meets our needs and is a little cheaper. Has anyone put in a solar hot water system that was too small to supply enough water?
Bill

Make sure you have a back up propane heater. When you have a summer like this one with so much cloudiness, you are definitely not going to make enough hot water.

I sized to the high side on my solar electric system and I'm glad I did. With all the cloudiness, it has just barely kept up.

Go for the larger unit. Not much additional one time cost. More hot water reserve for a) cloudy days b) guests.

In three years with solar I've only run out of hot water once. Hey what's wrong with a room temperature shower?


SunFan

Thanks for the advise. Went with the larger unit.
bill

We have the 10 tubes and we have had the water heater on maybe 3 times this summer and we both take 2 showers a day.

The Postman wrote:Thanks for the advise. Went with the larger unit.
bill

Would you mind saying how much it cost you?
Who did you get to install it?
Will it use your current hot water gas heater as a backup?

I have been considering solar hot water for some time but have been holding back because my hot water needs are mostly in the mornings, and I have my doubts if solar is a good choice for that reason. I run a small B&B with four guest rooms and a possibility of two people per room. Most guests tend to shower in the mornings, and I suspect that solar hot water is at it's coolest at that time of the day. I know it would work well for laundry time which starts around noon and takes most of the afternoon to do. Can anyone with a solar hot water system tell me if this is the case or is there sufficient hot water in the mornings also ???

We have had our ACAL 160 Liter, 12 Heat Pipe system since July 2011, and have never run out of hot water. We thought we would, once or twice, lit the propane heater and the sun came out, so we turned it off again. That was when we had guests, so we wanted to be sure. Now, we do not even think about using gas. The solar tank holds the heat very well and there is hot water for morning showers and for a few cloudy days, etc. Go for it. Note: If hail or accident should break an evacuated tube, you will not lose your water, or that of half the neighborhood. Water filled tubes are not as effective as heat pipes. Also be sure to get a system that will operate on a pressurized water system.

We have had a similar system to RV Gringo...my wife showers at night and I shower in the morning....we do not run out of hot water...sometimes it is not as hot as I would like...in Nov and Dec but then that problem goes away as the days get longer.

We spend very little on propane.

eagles100 to answer your question on price. The 10 tube system was 4100 pesos and the 12 tube system was 4800 pesos. I brought a gravity system. The entire unit including the mounting frame is stainless steel. The store is Rosy's located  after the bus station on the same side of the street driving north towards Soriana. There is a huge banner on the front of her store above the awning. You have to go in and ask. It looks like a mini market inside and you would never guess they sell solar hot water systems from the merchandise they have on display. Look for the solaris banner as she sells the units for her son who is a distributer in Guadalajara. It is going to be installed Friday and  Saturday. If you want to see the installation  during or afterwards feel free to do so. We live in Mirasol.

Hmmm I wonder what the difference is from what we were quoted: 17,000 pesos.

eagle100
pressure systems are more expensive than gravity feed systems but much more versatile in where you can install them. There are different types of tubes with different prices. ours are the double walled vacuum. copper pipes that aid in the heat transfer cost more. Stainless steel is higher than regular metal but you don't have to paint it every couple of years. The same system was $2000 pesos more in Ajijic than Chapala so where you buy makes a difference. Many other reasons. listen to what the other posters tell you, then decide what you need and shop around. just don't hurry your decision
 our installation is not included in the price. We have a slanted tile roof with the tinaco inside an area surrounded by cement walls (cubal) the installers have to go through. The tinaco will have to be raised to get the  minimum of 60 centimeters above the gravity system needed for proper water flow to the tank and tubes. We need extra materials because of the distance to the cold water feed.  The water feed can be most any where with a pressure system which is a big plus as pressure not gravity moves the water. Also I want a plumbing system that allows me to bypass the hot water heater or solar system incase either need repair.  We have other extras add on but with all the extras the total price for all should be plus or minus $11000 pesos.
   If I had a flat roof and could install the system next to the water feed pipe going into the hot water system I was quoted $1500 pesos plus materials for total installation price.
bill

Folks,

Feel free to PM or email for any needs or questions on all types & sizes at "buy direct" pricing and with full support & service.    

You'll be glad you did, and join our thousands of other very satisfied STI clients, including many well known on this board.

ron (at) solartechnology.com.mx

Just a note re "Go Solar" for hot water installation - he delivers and backs you up and helps with any problems ... I am in the midst of a problem and Ron is coming through and backing me up - a huge relief and an important consideration .... I recommend him and the company he represents ...