Solar Energy In General
You should probably know where Iím coming from. My father was a city planner and was concerned about over population. Then I spent two years in the Peace Corps in India and got to see too many people for too little resources. I also got to see great recycling, in 1966. They had soda bottles that were used over and over, caps included. The folks there didnít have a lot of ďstuffĒ and when something broke they fixed it rather than bought new. On returning to the US, we seemed to be wasteful, inefficient and taking more than our share (see the Story of Stuff). Iíd love to see every twenty year old spend time in such a place. I then worked in academic theatre for forty years. In the theatre you have a dream and a budget. The first is always bigger than the latter. Then there is the definition of academic, ďthe contemplation of that for which one does not have the money.Ē We had to get a lot of show for not much money. Finally I must admit that Iím frugal, Scottish heritage and all that. So when it came to building a house I wanted the most recycled and energy efficient thing I could build.
I installed a drain back solar hot water and then a photovoltaic (PV) battery back up system about thirty five years ago when the house was built. I did it chiefly to save money and secondly because it seemed a good idea for the environment. Now these causes have been reversed. I have had grid tied PV installed on principle. I donít plan to talk much about specific equipment here. Installers and web research (see links) to do that. As usual get at least three bids and let them know about each other. For a more complete information on my house please see Here, for Networx site and Energysage for more statistics on the house.
Now if you are considering a solar installation, please realize that you will have to change your relationship with hot water and/or electricity. These systems are more complex and new. Just as you are spending more time with trash now that we recycle, solar energy will take a bit more of your attention.
The first problem is the folks who do the installation and maintenance. Both hot water and PV are developing technologies and we are all learning. There are installers who are just starting and learning on you but are not too costly. There are a few installers who have done the work for years and are more expensive but very good. Bear in mind that slowly the former become the latter. Also the latter may not have the latest training. Then there are installers who are crooks and are even more expensive as you will need to pay to have their mess fixed. You need to spend time finding the right person. Over the years my hot water system has, bit by bit, been totally replaced. Iíve dealt with all three types of installers. The more you can do yourself the better.
Can the sun get to your collectors? Are the trees in the way and can you cut down some or all of them? Even a six inch shadow on a panel will shut down the whole panel.
Tree growth and removal is an ongoing problem. This tree was not in the way thirty years ago but grew to be a problem and had to be cut down in 2009. It was my favorate tree but had to go to save many other trees. Now I'm planting small trees instead.
Lets talk about trees and photovoltaic (PV) solar. In discussions on installing PV, trees are a frequent drawback. They are too beautiful around the house to remove. We should not clear cut land for PV. But how do we define clear cutting. I have a neighbor who cut down all the trees around the house so that the garden might have sun. Others cut trees to build a house or several houses. Is that clear cutting?
I define clear cutting as more than an acre of land. I lived in the Seattle and saw the land laid bare for as far as the eye could see by loggers. I hated it! On the other hand I finally cut down my favorite tree because it had grown to shade my solar panels. Like many things in life it is not a black and white issue. Trees do not have nearly the carbon offset of PV solar. Do we keep every tree only to lose them all to the drought of climate change?
There is a problem with tree zoning laws against PV in South Hadley. SHELD, often with the Town of South Hadley, is likely to be the only entity to install any large scale PV array. SHELD is not a nasty out of town developer planning to denude us of trees.
Right now there is no need to put up large solar arrays in the woods. South Hadley has parking lots, large roofs and open fields for PV arrays. South Hadley is also one of the slowest towns in the state to act against climate change.
CARBON FOOTPRINT TREES VS SOLAR
According to American Forests, one tree stores about 0.5 metric tons of CO2
over its lifetime. Producing a typical 5 kWh solar system emits about 10
metric tons of CO2, so the total CO2 emissions associated with removing one
tree and installing a residential solar power system are about 10.5 metric
tons.Your solar panels should generate at least 6000 kWh of electricity per
year, and should last for approximately 25 years.This means that over the lifetime of your panels, you will produce about
150,000 kWh of emissions-free electricity. This translates to a whopping
103 metric tons of CO2 offsets over the life of the panels!For the removal of the tree to make sense, the net CO2 reduction will need
to exceed 10.5 metric tons. That seems like a lot at first, but when you
calculate the CO2 emissions you will offset by switching to solar from
fossil fuels, it isn't much at all.
Subtracting the original 10.5 metric tons of CO2 emissions needed to
install the 5 kWh solar panels from the 103 metric tons of CO2 benefits
they will generate results in a net benefit of 92.5 metric tons of CO2
offsets– the equivalent of planting more than 180 trees.
End of tree talk.
Is you roof south facing? Is the roof at the right pitch? If not, at what angles the will panels be set? Often it can be at very odd angles to solar south. Can you put the panels on the ground? If you plan to put solar panels on the roof, how old are your shingles? It is best to have a newly replaced the roof with 40 year shingles. Taking solar panels off the roof, redoing the roof, and putting the panels back is expensive. Roofers don't like it. The Installer will also need to check the roof stregnth for the weight of the panels. If the roof is steep enough the panels will shed the snow load after each snow. The problem is that is that the panels weight is transfered to the roof by small legs at four foot intervals. The weight of the snow is not distributed over the whole roof. It is a point source on ten of twelve locations.
One day after storm, the snow has slipped off the panels. Roof rake was used on left. Note the hot water solar panels on the left roof are still burried since the lower roof catches the snow.
Solar Hot Water
The first step is to conserve. Use low use showerheads, cold water for washing clothes, insulate your hot water pipes, use movable insulation on windows and so on. Please see ENERGY SAVE. You can do these things yourself. There is some dispute over how hot to set your hot water tank. Some say 120 degrees is best to save electricity and some say 150 degrees in order to prevent NTM disease (check Time – “What’s in Your Pipes”)
The value of solar hot water systems increases with the number of people in the house (quantity of hot water needed) and the further south you are. If you live by yourself in New England, solar hot water will take a long time to break even. It is not just a mater of installation cost vs. long term savings. Once the payback time is into decades, you need to consider the upkeep cost. The system needs periodic check ups on the propylene glycol and moving parts. Any service call from a quality installer can cost as much as a call from a plumber. The storage tank, like a traditional hot water heater, has a ten to fifteen year warranty. A new storage tank can cost $1500 installed. I found it wasn'worth it.
The air to air heat pump hot water heater takes heat out of the air in your basement and puts it into the hot water tank. It has a back up electric heating element for quick recovery if hot water demand is high. I added one in 2014 and removed the hot water roof panels.The rebates can pay for much of the heater.
As with hot water do the easy things first: use CFL bulbs, put vampire loads on power strips with switches, etc. A generator tied to the furnace is handy in an ice storm. Grid tied PV doesn’t provide power in a black out. It is best to own the system, as opposed to leasing or PPA.
I like PV because there are no transmission losses and it makes electricity during peek hours so we may have to build fewer power plants. The PV panels last a long time. My 25 year old panels were still working, albeit a tad less efficiently, when I removed them to upgrede the system. Grid tied systems need almost no maintenance and have no moving parts. Batteries are not long lived and have several problems. Grid tied systems seem to be the way to go now that electric companies in MA have to go along with it. If you have a muni (municipal power company), they may not have any incentives. Contact them directly or see Munihelps. The state and federal (page down) tax rebates will help. My one worry is the inverters. Inverters donít have great warranties, only 10-15 years so they may need replacing thus raising the long term pay back.
Solar saves you money(see Financing PV). Much depends on future energy costs and incentives.The costs will certainly go up. There may be better incentives in the future. In the 1970’s they were much better than the present so there’s hope. I am retired. I put in solar and bought a Volt so that my energy costs will be fixed in the future.
More convincing is all we read about global warming, pollution causing health problems and the use of oil for fuel instead of all its many other products. We will have to do something new in the future so we might as well get started. It is the right thing to do.
If you build a house, have a friend who is doing so, or even see a site being cleared, Please Please Please get them to orient the new house and roof to solar south. Itís a crime not to find solar south and face the roof and a wall of glass towards it. It is so easy to do before building and so impossible later.
PV systems vary greatly in their output. If there is snow on the panels they do not make electricity. If a panel has a square foot of shade on it the output drops to almost nothing. On a cold sunny day in the winter a 4 kw system meter reads just over 4,000 watts. On a cloudy day it reads 2,000 watts. In the summer a system in MA can produce three much electricity as in the winter. When the panels are hot in the summer, the output is reduced due to electronics not liking heat.