Frequently Asked Questions
Solar Electric FAQs
How much do I need to power my house?
We have found that most people use between 10 to 30 kWh a day. You can find this number on your PG+E bill. If a household were to use 10 kWh a day, this number would be divided by the average sun hours per day to come up with the system size. Time of use metering would make the system size drop a bit. A 2.5 kW system would be appropriate a residence that used 10kW a day.
10 kW / 4.1 average sun hours a day in Eureka=2.45 kilowatt system
How much does it cost?
Solar electric systems generally cost between 9 to 11 dollars a watt. If we used the example above and $10 a watt we would get $25,000
What rebates are available?
Starting in 2007 rebates will be $1.95 watt. For a 2.5 kW system there would be a rebate of $4875. For the most current rebate information go to PG&E
What type of roof do I need?
Typically you need about 100 square feet per kilowatt. The roof should be in good shape and facing south. We have also installed panels on west facing roof that will produce up to 90% of what a south array will produce. Scurfield Solar can work with all types of roofs that include composition, shake, metal, tile and tar and gravel.
What other incentives are available?
A federal investment tax credit is available of 30% of the systems net cost. This credit is capped at $2000 for residential systems. Solar systems are exempt from California property tax. For more info go to DSIRE
What’s the payback?
Most systems payback in 7to 15 years. Scurfield Solar can do a detailed payback analysis for people interested in payback. Remember PG+E is never going to pay you back. When you purchase a solar system you are essentially pre-paying your electric bill for 20 years.
What about battery back up?
Scurfield Solar does offer battery back up systems. For people with PG+E power we offer small battery back ups that will power critical loads like the refrigerator, computer and lights. We also offer complete off grid systems. Battery back up systems typically cost 30% more that systems with no batteries. Most grid tied systems are tied to a breaker in the breaker box. When you are generating more than you use it is a credit on your bill. When it is cloudy you can use that credit. With no battery back up when the grid goes down so does your solar system.
For more information about solar electric systems and informational links go to our RESOURCES PAGE
Solar Hot Water FAQs
How many panels do I need for my house?
Generally a household of 3 to 4 people would need (2) 4x8 collectors or 30 to 40 evacuated tubes. You would need 40 to 100 square feet of area on the roof. It is best to have these panels close to the water heater and on a south facing roof. Over four people you would generally be looking at (2) 4x10 collectors or 40 to 50 evacuated tubes.
Do I need another tank?
In most circumstances you need another tank. The recovery time for a solar water heater is all day versus a gas water heater that can recover its heat very quickly. Also a gas water heater is heated from the bottom. This presents a problem if you are trying to send cool water to the panels to be heated.
Should I use evacuated tubes or flat plate collectors?
Flat plates collectors are the tried and true. With selective absorber coating like black chrome most flat plate collectors perform similar to evacuated tubes for heating domestic hot water. Evacuated tubes do well in high wind areas; achieve higher efficiency with low radiation and support space heating applications more effectively. Flat plates will cost less and they will not have vacuums that eventually fail. For some people one or the other might be more aesthetically pleasing. Lastly, evacuated tubes usually take up less room on the roof than flat plate collectors.
How much does it cost?
Systems for domestic hot water cost any where from $7,500 to $10,000 for homes.
What’s the payback?
The payback is usually about 5 to 10 years. Scurfield Solar can do financial analysis.
Are there any tax incentives?
There is a federal investment tax credit of 30% of the system's net cost. There is a cap of $2000 for residential. Solar systems are also exempt from California property tax.
For more information about solar hot water systems and informational links go to our RESOURCES PAGE