Today I was in my office and our Office Manager, Sabrina, asked me “How much does solar cost?” So I asked her to explain. Sabrina fields most of our new solar and storage prospects and she explained when prospects call asking about energy storage, she can quote the estimated cost for storage, but the next question usually asked is “How much is solar?”Residential roof-mount solar panels in Sonoma County

It got me thinking that there is not an easy answer to this, ,and I thought I would give it a go. First, a few general rules of thumb – I will be focusing on roof mount solar costs. Ground mount systems can cost 25% more due to increased permit costs, trenching, post hole digging and concrete.   Ground mount costs can also be increased by long trenches (which require additional digging, conduit and wire size), rocky soil, and array size. Smaller arrays are more expensive per watt due to the high infrastructure costs. For both ground mount and roof arrays, if you have a Zinsco or a Federal Pacific meter main, or  your meter main is undersize, we will require that it is replaced for safety. On average, a 125-amp meter  main may be upgraded  for $1,900 while a 200-amp  may be done for $2,500. Prices can vary but this is a good baseline. The good news is that if  this work is done in conjunction with the solar installation, it also qualifies for the Federal Tax Credit.

The biggest cost variables for a roof installation are pitched roofs over 30 degrees, installing on multiple roof plains, distance to the electrical connection, and concrete tile roofs, all of which require more labor. For purposes of this analysis, I will assume a composition shingle roof with a 22 degree pitch and a meter main less than 50’ from the solar array. The biggest variable in sizing solar systems is the amount of energy use in a home.  Other factors that impact sizing include shading, pitch, roof direction and size of the available roof. In all the cases below, as in real life, my goal will be to zero out the usage charges.  All our solar systems include microinverters, all black modules and black racking.

Let’s do three examples; homeowners with an average PG&E and Sonoma Clean Power bill of $160, one at $318 and  one at $648 per month. It is common for homeowners to have different usage during different seasons, so note that these are averages. Some may think this high over their current bill, and I have been seeing the electric side of the bills increasing as homeowners move to electric cars and away from gas/propane appliances.  These are actual proposals and will also include storage as an option.

Prospect one – PG&E bill average $160 per month. These folks came to Synergy after the PG&E Public Safety Power Shutoffs (PSPS).  PSPSs are planned outages to mitigate threat of fire during our exceptionally dry, windy season. These folks lost a refrigerator full of food, several very expensive tropical fish and needed a hotel for five Residential ground-mount solar panels in Sonoma Countynights – estimated cost $2,000.  They have a low pitch, composition shingle roof, and a 125-amp meter main which allows for 20 solar panels (6.2 KW DC rated). The storage was complicated (meter main on one side of the house and storage located on the other) and they required more battery than usual for the continuously operating fish tank. The 15-kWh storage system cost $32,000, and the 20 solar module system cost $22,500, for a total cost of $55,500. The cost after the federal tax credit of 26% is $41,100. This system provided them a purchase payback of 14.5 years with a 25-year internal rate of return (IRR) before taxes of 6% and they get backup. I like to use IRR, as it represents the return we receive on our money – like interest in a bank account.  This was justified based solely on the PG&E costs. If you take into consideration the losses incurred during the PSPS of food, pets and hotel bills, the payback is even greater (more than doubled).

Prospect two – PG&E bill average $318 per month. This family is rebuilding their home after the fires in our county.  It is a 3,100 square foot home with well and septic pumps. Also, they will be adding a pool and hot tub. Since it is new construction, the electrical work is less costly than a retro fit.  The cost of the 12.5 kWh of battery storage system is $27,700. The 30-module solar system (9.3 kW DC rated) will be installed on a single standing seam metal roof plane, with a cost of $30,800. Total system cost is $58,500 or $43,300 after 26% Federal tax credit. The payback on this system was 9.25 years with a 25-year internal rate of return of 11%, and they will have backup. Again, this justification was based solely on the PG&E costs.

Prospect three – PG&E bill average $648 per month. This homeowner has a large country property with multiple out buildings.  Their loads are all in one place so the storage system is pretty straight forward. The cost for a 12.5 kWh storage system is $28,500. The cost for a 48-module solar system (14.88 KW DC rated) would be $52,800. The total cost would be $81,300, less the federal tax credit would be $60,200. Payback period based on PG&E savings would be 7 years. Internal rate of return over 25 years would be 16%.

It is rare when I do a proposal for solar and storage, that the long term costs do not come out less then PG&E.  With the PSPS’s from PG&E becoming an annual reality in our County, back-up systems are becoming more common.  And when looking to back up your home, while a generator may feel like an easy fix, running a generator when our air quality is already bad, is an issue (not to mention the noise).  When combining Solar to storage, you are joining the solution of providing our area with clean, locally stored and renewable energy for our future!