How Much Money Do You Save Installing Your Own PV System?

When I did my PV system two years ago, I did not really have a good way to evaluate how much money I saved by doing the install myself, let alone how this might vary over the country.  I knew how much it cost me, but, I did not really have a good number on how much an equivalent professionally installed system would cost.

The Nov/Dec issue of Solar Today answered that question by providing a state by state installed cost per watt survey.  The current US wide average turns out to be $6.80 per peak watt.   For the 20 states covered, prices ranged from $6.30  up to $8.80 a watt -- quite a range.

 Our PV system

So, armed with this new data, I decided to estimate what I would pay today for the same size and type system I put in back in 2009 and see then see how that compared to the $6.80 a watt US average the Solar Today article showed.

The details are below, but the bottom line result is that doing the installation saved us just over 50% compared to an an average US install.  This is worth about $8000 on our 2300 watt system.

If you are thinking about installing a system yourself, this might be helpful in giving you and idea what you might save. 

Updated Cost Estimate

My system is a ten module, 2150 watt system that uses Enphase micro inverters.  I bought most of it as a package from Wholesale Solar in CA.   So, I decided to just take the closest package they offer today as starting point for an updated cost.   To that I added things not included in the package such as renting tools, permit fees, wire, concrete, ...

The closest new package that Wholesale Solar now offers uses the newer and slightly larger Enphase inverter and slightly larger 230 watt panels rather than the 215's I had, but its pretty close.  The kit with 10 panels, but without mount rails is $5750.

The table below shows the estimated cost:

Item Cost Cost per watt
WholeSale  Sol 2300 watt Solar kit $5750  
       10 TrinaSolar 230 watt PV panels    
       10 215 watt Enphase micro inverters    
       Misc other parts    
Enpase Envoy and other parts $420  
Iron Ridge Mount Rails $750  
Disconnect Switch $65  
Placards $0  
 Shipping $0  
Wire -- array to house $106  
Wire -- ground and other $25  
Conduit $30  
Array Junction Box $20  
Circuit breaker $9  
Wire nuts, lugs, wire ties 30  
Trencher rental $54  
Mount Lumber $96
Mount Hardware (plates, bolts, U ftgs) $50  
Concrete $130  
Permit $45  
Labor $0  
Total $7580 $3.30 per STC watt
Federal 30% $-2274  
Montana $500 $-500  
Grand Total after rebates $4806 $2.09 per STC watt  after rebates

Estimated Saving for DIY

So, the installed cost for the DIY version in 2011 for the 2300 watt system is about $3.30 a watt. 

Compared to the $6.80 that Solar Today reports as an average,

Percentage cost saving for DIY version is $3.50 a watt, or a 52% saving.

The total dollar saving for this 2300 watt system is about $8050.

Not so bad at all.

All this is before rebates, but the same rebates (at least where we are) apply to both DIY and professional installs -- so, the percentage saving stays about the same after rebates.  This may not be true in some areas.

This may be a little conservative in that my ground mounts had some additional costs compared to the more typical roof mounts.  I also did not look for the absolute best deal -- I picked a company that had good prices, but also has a good reputation and provides support.

I suspect that the rough saving of about half holds up pretty well for larger systems as well.

I still think its a good idea to get an estimate or three before deciding to do the system yourself -- its clear that there is a lot of variation in system cost depending on where you live, and you might be lucky and live in an area with very low prices.

How Much Has the Cost Come Down Since 2009?

Comparing total system costs back in 2009 (when my system went in) to now:

Installed DIY cost per watt 2009 was $4.63 per watt.

Installed DIY cost per watt 2011 is $3.30 per watt.

So, a 29% reduction since Nov 2009.

Panel prices have probably dropped somewhat more than that, but the other components like inverters, mounts, wire have not dropped as much, or at all.

One other thing you might want to consider is that our DIY solar water heating system cost us only $1000 (before rebates) and produces nearly an identical amount of energy per year as the PV system -- so, while the $3.30 per peak watt for the PV system sounds pretty good, the price per peak watt for our solar water heater is less than 50 cents a peak watt -- wow :)

All the details on our PV install...

Gary November 8, 2011