Saturday, February 21, 2009
The Story of the Solar Hot Water System
My husband who is a self-described political junkie is also deeply interested in the world of economics. He follows several newspapers, economic websites, and has developed a lot of interesting and beneficial connections as a blogger of one of those sites. For all the hours he spent online reading, posting and doing the research...I have to say it really has paid off (in more ways than one - perhaps another post for another time). The idea for a pellet stove and the solar system were just such pay offs.
Just like the pellet stove, the solar hot water system came about as a solution to the rising oil costs. In June, our friend called to say that his pre-buy quote for heating oil was $4.98 a gallon. This sent us into a strategic planning mode. We started thinking about alternatives to giving up $5.00/gallon or more (because,let's face it, if it costs that much in June...well then one might as well add an additional $2.00 gallon for cash price during the season.) So, the research began.
Initially our ambition was to "get off the grid". We thought we wanted to install photovoltaic panels in conjunction with an electric hot water heater. We also thought it would be really cool to have the electric company pay us for a change. A friendly neighbor welcomed our questions about his photovoltaic panels and solar hot water tubes. He shared his trials and tribulations and helped to guide our decision making. After obtaining project quotes, the ultimate decision was pared down to a domestic solar hot water system. Our home would have required about 30 photovoltaic panels and an expensive battery system (too fiscally ambitious for us) to come off the grid. And otherwise dissapointing news, the electric company (CMP) no longer cuts checks for those who put into the electric grid rather than drawing from it. Instead, an energy producing home can receive credits on their account to be applied to future bills...which is fine, but the cost/benefit ratio just didn't add up...plus I understand there can be a lot of issues with inverters.
Due in September, our installation actually didn't happen until November. The solar hot water tubes were back ordered due to sudden and increased demand for them. This frustrated my husband to no end...all he could see was wasted solar generation. Not me, I actually felt happy that it was back-ordered for seemingly positive reasons. (I would love to see more households go as green as they can afford...I would also like to see lots of stimulus money made available to make this happen...I mean if we are going to spend that kind of tax payer money lets invest it in something that will help more tax paying citizens come ahead in the long term...stop throwing money at bad banks and their reckless CEO's!) Okay, I digress.
For anyone who is curious; our solar hot water system is made up of two panels containing 20 vaccum tubes each. The sun heats the tubes to a temperature of up to 400 degrees. The heat generated is used to heat a glycol solution which runs through copper pipes and into two coils in our water storage tank. The glycol is circulated by a pump and a small computer controls the flow of glycol according to programmable temperatures on the panels as well as the tank. If the glycol solution is too hot it stops flowing so that the storage tank does not overheat. Conversely, if the glycol is colder than the water in the storage tank it is not circulated. Our water coming in from the city goes first to the solar storage tank where it is at the least preheated so our furnace does not have to heat the water from 45 degrees or so. Even on overcast days the solar tank is at least 80-90 degrees which means our furnace only needs to warm the water between 30 and 40 degrees to achieve the preset 120 degrees of our hot water tank. Unfortunately the system is not big enough at this point in time to support our hot water baseboard heat. (That would require a bigger and more expensive water storage tank.) But for now it is nice to know that I am not expending a limited resource to heat water for showers, dishes or laundry...at least not a majority of the time.
On sunny days (even with below zero temperatures) the furnace does not appear to run as often or for as long. I attribute this to the fact that we make the best of efforts to do laundry on sunny days only and run the dishwasher during peak daylight hours (10 am - 2 pm). And this is only winter. We look forward to taking advantage of the system more as the year wears on and we have more sunlight to work with. This energy conservation feels good...I hope to boost our conservation efforts of water and electricity with a future investment in HE washer and dryer (after I save the cash...of course). But, it is good to have goals, right? One thing at a time.