Hey Fred, we actually have both here at our home. In a nutshell, solar thermal, or solar hot water is more cost effective than solar electric, but depending on where you live and how you get your hot water and electricity might make both of them bad investments in terms of money return. That does not mean they are bad ideas, but your question seems focused only on the cost return. I'll go a step further and say that you won't get good information from hacks like us online. In the 12 years we've been producing our own electricity and hot water, I've learned that there are 2 things in vast supply in solar energy, the sun, and missinformation.
Solar hot water can be expensive, when you buy devices at retail from unknown people and pay for them to install them. If you don't have any expertise in plumbing, that is probably what will end up happening. Solar electric can be even more expensive if you end up doing the same thing because you are not handy with wiring. Our solar water heater is nothing more than a used 30 gallon water tank from the inside of a discarded electric water heater, painted black, and mounted inside a plywood box with a south facing glass roof. The cold water simply flows through this tank before going to the regular water heater, and the tank heats up the water as much as it can before sending it to the basement unit to finish the job. On many days the water comes out of the "preheater" tank at 100 degrees F, so the sun is doing about 3/4 of the work. There are no circulation pumps, holding tanks, controllers or other complications. We built the device ourselves for about $30 USD in parts. Our solar water heater probably pays for itself each month over and over again. To purchase a device to heat the same amount of water to the same temperature would probably have cost $2000 USD, and it would take years to pay back.
Our solar electric was much more expensive, since even if you build the panels yourself, the parts are not cheap, then you need batteries and an inverter. Our system cost over $10,000 USD in parts, we did most the work installing ourselves, and it will take something like 25 years to get our money back. You would do better to put the same money in long term bonds. Why did we bother? It is important to me to do more than "talk" environmentally. There is also the fact that our home has not been without electricity or hot water for even a minute the last 12 years now, hard to put a price on that.
Some people drive cheap cars, some expensive ones. Both get you to work and the market, why bother buying the more expensive one? Poeple each day are buying things they don't need and will never pay for themselves, I guess our panels fit into that category for me. There are some good sources to look into if you want to learn more, I'll list them below. Take care Fred, Rudydoo
Solar Hot ater isn't remotely cost effective at the moment.
From the Energy Saving Trust website "Costs, savings and earnings"
The cost of installing a typical solar water heating system is around ￡4,800 (including VAT at 5%). Savings are moderate - the system could provide most of your hot water in the summer, but much less during colder weather.
Maintenance
Maintenance costs for solar water heating systems are generally very low. Most solar water heating systems come with a five-year or ten-year warranty and require little maintenance. Once fitted your installer should leave written details of any maintenance checks that you can carry out from time to time, ensuring everything is working properly.
Perhaps the most important thing you can check for yourself from time to time is whether there are any leaks. If there are any leaks of anti-freeze (even if you can’t see any liquid) this will have a strong smell. If you notice this you should contact your installer. In general you should keep an eye on your system to check that it is doing what it has been designed to do. If you are not getting hot water or the solar pipework is cold (when the pump is running) on warm, sunny days then again you should contact your installer. For peace of mind some installation companies offer an annual service check.
You should have your system checked more thoroughly by an accredited installer every 3-7 years, or as specified by your installer. It is likely that after this period of time the anti-freeze that is used to protect your system in the winter months will need to topped up or be replaced as it breaks down over time reducing the performance of your system. Anti-freeze lasts better if the solar water system is used throughout the year and not left unused during the warmest weeks of the year. This cost of replacing the anti-freezer is usually around ￡100.
The other thing that your installer should check is the pump. In a well maintained system, pumps can last for ten years plus and usually cost around ￡90 to replace.
Savings
Solar water heating systems can achieve savings on your energy bills. Based on the results of our recent field trial, typical savings from a well-installed and properly used system are ￡55 per year when replacing gas heating and ￡80 per year when replacing electric immersion heating; however, savings will vary from user to user.
Solar PV (Electric) costs about ￡ 7,000 for a 4kW system and should give a return of about 7 -9% tax free for a south facing roof.
Solar panels are probably best for water heating. You see plenty of them in and around the Mediterranean area but not many for electricity generation.
If you need electricity to run household devices, you will need one heck of a system, because most devices don't like the voltage getting low.
Heating water is bettter because it is very easy to store the water (you just need a tank), and the water doesn't mind if it is getting less heat for a moment when a cloud passes overhead.
In the UK go for Solar PV with the Feed-in-tariff. The return on the investment is about 13% tax free
Depends where you are, and what options you have. But Solar Water heating is certainly very cost-effective.
My guess is that you must pick up everything that have to do with solar power at www.greensolarwho.info.
I dont know
In financial terms is there common agreement on which is the best investment for the householder? Thanks.
