Thursday, May 27, 2010

Reducing the installed cost of solar

I have a simple idea that can reduce the installed cost of solar.

Pre-assemble the solar panels into multi-panel blocks before shipping to the customer roof. Make (and test) all the electrical and physical connections between the each of the panels in the block at the factory or warehouse. This will reduce the number of connections the installation team needs to make on the roof which will allow a team to install more kW each day.

Imagine connecting 5 200W panels into a 1kw block at the factory. You may pay a little more to ship the panels to the customer site and lifting the panels to the roof (assuming a roof mount), but once on the roof you will be connecting 1kw blocks with basically the same labor you used to need to connect 200W.

There will be some optimal size to the pre-assembled blocks that balances out the on roof savings with the extra transport and lifting costs. Smaller firms may only want 3 panel blocks so a two man team can handle the panels on the roof, while a large commercial installer with trucks and equipment could pre-assemble full strings of panels.

The pre-assembly should take place in a workspace (factory) designed to facilitate the assembly work, and it goes without saying that factory labor is cheaper (not to mention safer and more comfortable) than on roof labor. I'd guess this could lower installed cost by $0.20/watt--perhaps more in high labor cost locals.

Hopefully someone (panel manufacturer? distributor? installer) will seize on this simple idea.


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At 7:03 PM, Anonymous Mona Reese, Brightstar Solar said...

I think you bring up a good point that factory labor is cheaper than those working on the roof. However, I am concerned that the shipping and lifting costs and reduced flexibility will outweigh the savings achieved from factory assembly. I hope someone can prove me wrong because I'm all for any idea that would reduce the installed cost of solar and increase capacity.

At 11:16 PM, Blogger Daniel said...

Hi Mona Reese, thanks for the comment. As noted in the post I also worry about the additional shipping and lifting costs offsetting the gains of pre-assembly.

Since you appear to work for an installer, I think you would be well placed to do the math. I've been told that on-roof labor costs run $50-$60/hr (and can be much higher in union town/states)
Meanwhile I'd be surprised if simple light-assembly jobs paid more than $20/hr. (Rates would be even less if you assemble offshore.) So you save $30-$40 (or more) for each man-hour that you can shift off-roof. a.k.a. $1,000 per project for every 25-30 hours you can shift.

It is my understanding that panel shipping costs (i.e from China to the US) are on the order of 2% of panel costs or ~5c/watt. [That may only get your panels to the US distributor, but it does put shipping costs in perspective.] Even if pre-assembly added 50% to shipping costs we are only talking about a few cents/watt.

That leaves lifting costs. For many people lifting = cranes (which can be costly unless your job is already big enough to need one). But using a crane may be overkill for smaller installs, where using a pulley w/ a swing arm could easily get the job done...yeah its not as sexy as a crane, but its much cheaper!

There will be some optimal number of panels to pre-assemble into blocks which will depend on the size/scale of the installer, that balances the labor savings against the shipping and lifting costs.

At 11:42 AM, Anonymous Anonymous said...

At 10:18 PM, Anonymous xanax said...

My how times have changed.


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